The Japanese Hernia Society (JHS) Guidelines for Adult Groin Hernia Management 2024

ABSTRACT

Groin hernia is a common surgical condition. The Japanese Hernia Society (JHS) Guidelines for Groin Hernia Management 2024 were developed to reflect both international evidence and the realities of clinical practice in Japan. This article is an authorized English translation of a summary of the adult section of the JHS Guidelines for Groin Hernia Management 2024, presenting key clinical questions, recommendations, and concise explanations for an international readership. It covers diagnosis, classification, surgical indications, operative approaches, mesh and fixation, anesthesia, chronic postoperative inguinal pain, recurrent and emergency hernia, training, cost‐effectiveness, and registry‐based outcome assessment; relevant differences from the international HerniaSurge guidelines are discussed. Laparoscopic repair is favored in selected patients when performed by experienced surgeons, particularly for pain reduction and early recovery, whereas open anterior mesh repair remains appropriate when general anesthesia or laparoscopy is unsuitable. For femoral hernia, chronic pain management, recurrent hernia, and incarcerated or strangulated hernia, evidence remains limited, leading to cautious or conditional recommendations.

1. Introduction

Groin hernia is one of the most common surgical diseases in adults, with more than 20 million procedures performed annually worldwide [1, 2], and it is therefore a condition that surgeons frequently encounter in clinical practice. In Japan as well, more than 110 000 operations are performed annually [3], and many of these are carried out not at specialized centers but at general practice institutions. In actual practice, surgeons perform hernia repair while undertaking operations for gastrointestinal cancers and other conditions. Thus, there was a need for clinical practice guidelines that would provide guidance not only for specialists but also for non‐specialists. In 2009, the European Hernia Society guidelines on the treatment of inguinal hernia in adult patients [4] were published by the European Hernia Society (EHS); however, because the populations evaluated, age groups, surgical procedures and their rates of dissemination, and health insurance systems differ, challenges have remained in directly applying the European and U.S. framework to clinical practice in Japan. Therefore, while referring to international evidence, it became necessary to establish clinical guidance based on the realities of medical care in Japan, and in 2015 the Japanese Hernia Society developed the Japanese Hernia Society (JHS) Guidelines for Groin Hernia Management [5], thereby presenting treatment guidance in Japan. Subsequently, with changes in surgical procedures and the emergence of new evidence, an update became necessary, and in May 2024 the fully revised edition, the Japanese Hernia Society (JHS) Guidelines for Groin Hernia Management 2024 (JHS GL 2024) [6], was published. In this edition, in accordance with the guidance of the Medical Information Distribution Service (Minds), meta‐analyses were conducted for 24 newly established CQs for adults and 8 for children, and Answers based on high levels of evidence were presented. Meanwhile, internationally, the International Guidelines (IG) [1] from the HerniaSurge Group were published in 2018, followed by their update [2] in 2023; therefore, when the JHS GL 2024 are translated into English, both their significance and their consistency with the international guidelines become matters of even greater importance. In the present article, limited to the adult field, all CQs, Answers, and explanatory texts were translated into English after summarizing their key points; however, it is also true that there are areas in which the recommendations differ between the JHS GL 2024 and the IG. These differences are attributable to factors such as differences in medical circumstances and differences in publication timing. For some CQs, the differences from the international guidelines are clearly addressed in the explanatory text, whereas for those CQs for which additional explanation was considered necessary, further discussion has been added.

It is hoped that publication of this English version of the guidelines will promote mutual understanding of groin hernia management in Japan and in the international community.

It should be noted that, in the 2023 update of the international HerniaSurge guidelines, the use of the term “incarcerated hernia” was discontinued and replaced by the more pathophysiologically appropriate terms “acutely irreducible hernia” and “chronically irreducible hernia.” However, in CQ19‐1 and CQ19‐2 of the present guidelines, the former terminology is used in order to reflect the circumstances at the time of analysis.

The authors used ChatGPT (OpenAI) to assist with the English translation and language editing of portions of this manuscript. All AI‐assisted content was carefully reviewed, verified, and revised by the authors. The authors take full responsibility for the accuracy, integrity, and final content of the manuscript.

For rapid reference, a quick‐reference summary of all clinical questions, key recommendations or conclusions, recommendation strength, and certainty of evidence is provided immediately after the Introduction. Table 1 highlights the major differences between the JHS Guidelines 2024 and the international HerniaSurge guidelines.

TABLE 1.

Major differences between the JHS Guidelines 2024 and the international HerniaSurge guidelines.

CQ/topic	Clinical question	JHS guidelines 2024	International HerniaSurge guidelines	Key difference
CQ4‐1	Which classification is recommended for groin hernia?	JHS 2021 classification is recommended	The EHS classification is recommended	Different classification systems; the JHS system was developed to align with the EHS framework while retaining JHS‐specific documentation
CQ7‐2	In primary unilateral inguinal hernia in men, are alternative open anterior mesh techniques recommended compared with the Lichtenstein method?	No major outcome difference between Lichtenstein and other open anterior mesh techniques; use the technique with which the surgeon is most experienced	The 2023 update states that an open preperitoneal flat‐mesh technique is an acceptable alternative to Lichtenstein repair when expertise and competence are available	JHS permits selection among open anterior mesh techniques according to surgeon experience, whereas HerniaSurge retains Lichtenstein as the principal anterior comparator while accepting open preperitoneal repair as an alternative
CQ8‐1	Is laparoscopic surgery recommended over other techniques for adult femoral hernia?	No definitive recommendation can be made for laparoscopic versus other approaches for adult femoral hernia	For femoral hernia, the 2018 HerniaSurge guideline recommends a preperitoneal mesh repair; in women with groin hernia, a laparo‐endoscopic repair is recommended when expertise and resources are available	JHS makes no definitive recommendation for laparoscopy in adult femoral hernia, whereas HerniaSurge provides more directive preperitoneal/laparo‐endoscopic guidance
CQ9‐1	For groin hernia in patients aged ≥ 80 years, which is recommended: open anterior mesh repair or laparoscopic inguinal hernia repair?	Either open anterior mesh repair or laparoscopic repair may be selected in patients aged ≥ 80 years	No specific HerniaSurge recommendation limited to patients aged ≥ 80 years was identified in the 2018 guideline or the 2023 update	JHS provides an age‐specific statement for patients aged ≥ 80 years; a directly corresponding age‐specific HerniaSurge recommendation was not identified
CQ12‐1	Which mesh is recommended for inguinal hernia repair?	Neither lightweight nor heavyweight mesh can be strongly preferred overall	The 2023 update strongly recommends lightweight mesh for Lichtenstein repair and heavyweight mesh for laparo‐endoscopic repair, especially for large direct hernias	The 2023 HerniaSurge update gives procedure‐specific mesh‐weight recommendations, whereas JHS does not strongly prefer lightweight or heavyweight mesh overall
CQ13‐1	In the Lichtenstein procedure for adult inguinal hernia, are mesh fixation methods different from the original technique recommended?	No clear evidence supports alternative fixation methods to the original Lichtenstein technique; routine alternative fixation is conditionally discouraged	The 2018 guideline found no consensus on a single best fixation method; some atraumatic fixation methods showed lower early postoperative pain, but the clinical importance was uncertain	JHS explicitly recommends against routine deviation from the original Lichtenstein fixation technique, whereas HerniaSurge does not identify one universally superior fixation method
CQ13‐2	Is mesh fixation recommended in preperitoneal repair for adult inguinal hernia?	Current evidence does not clearly support either routine fixation or non‐fixation; JHS conditionally recommends against routine mesh fixation	In TEP/TAPP, fixation is generally unnecessary except for large medial (M3) hernias, for which mesh fixation is recommended; atraumatic fixation may be considered when fixation is used	Both discourage routine fixation in most laparo‐endoscopic repairs, but HerniaSurge specifies large medial (M3) hernia as an indication for fixation
CQ14‐1	Does prophylactic antibiotic administration reduce SSI (surgical site infection)?	Prophylactic antibiotics are conditionally recommended to reduce SSI	The 2023 update recommends no prophylaxis for average‐risk open mesh repair in a low‐infection‐risk environment, suggests prophylaxis for high‐risk patients, recommends it in high‐risk environments, and does not suggest it for laparo‐endoscopic repair	JHS gives a general conditional recommendation in favor of prophylaxis, whereas HerniaSurge stratifies recommendations by patient risk, infection‐risk environment, and operative approach
CQ17‐2	What is the optimal method for preventing chronic pain?	Non‐fixation of an onlay mesh or fibrin glue is identified as the optimal preventive approach, but no formal recommendation is issued	The 2018/2023 HerniaSurge documents address pain prevention through operative technique, mesh and fixation recommendations, but a directly corresponding recommendation matching the JHS CQ17‐2 formulation was not identified	The topics overlap, but the recommendation structures are not directly equivalent; JHS formulates a specific CQ on prevention of chronic pain
CQ17‐3	Is surgical treatment recommended for chronic pain?	Surgery may be effective for CPIP, but evidence is insufficient for a recommendation	The 2023 update suggests a tailored CPIP surgical approach and strongly recommends centralizing CPIP evaluation and treatment in specialist centres with an experienced multidisciplinary team	HerniaSurge provides actionable recommendations despite low evidence; JHS concludes that evidence is insufficient for a formal surgical recommendation
CQ19‐1/19‐2	Is mesh repair recommended for incarcerated or strangulated groin hernia? Is laparoscopic surgery recommended over an anterior open approach for repair of incarcerated or strangulated groin hernia?	No strong recommendation for mesh versus non‐mesh repair; laparoscopy remains a research‐setting recommendation for incarcerated/strangulated cases	The 2023 update uses “acutely irreducible”/“chronically irreducible” terminology; it recommends immediate emergency surgery for suspected strangulation or failed reduction, suggests diagnostic laparoscopy when appropriate, and states that laparoscopic repair can be attempted when expertise is available	The 2023 HerniaSurge update is more prescriptive for acute management and uses revised terminology, whereas JHS retains the older terminology and remains more cautious about laparoscopy

Note: JHS statements are based on the JHS Guidelines 2024 [5]. International HerniaSurge statements are based on the 2018 guideline [1] and the 2023 update [6].

The certainty of the evidence was defined as follows.

Certainty	Definition
High ⊕⊕⊕⊕	The estimated effect is considered to adequately support the recommendation with high confidence.
Moderate ⊕⊕⊕⊖	The estimated effect is considered to adequately support the recommendation with moderate confidence.
Low ⊕⊕⊖⊖	The estimated effect is considered to adequately support the recommendation with limited confidence.
Very low ⊕⊖⊖⊖	The estimated effect is considered to adequately support the recommendation with very little confidence.

When a systematic review is difficult, the guidelines use the earlier recommendation grades and study‐design‐based evidence levels.

Grade	Meaning
A	Strongly recommended.
B	Recommended.
C1	May be considered, but sufficient scientific evidence is lacking.
C2	Not recommended because scientific evidence is lacking.
D	Recommended against.

Evidence level	Study type
I	Systematic review or meta‐analysis
II	Randomized controlled trial
III	Non‐randomized controlled trial
IV	Analytical observational study: cohort study (IVa), or case‐control/cross‐sectional study (IVb)
V	Descriptive study: case report or case series
VI	Expert committee or individual expert opinion without supporting patient data

Quick‐reference Summary of Clinical Questions, Recommendations, and Conclusions

CQ	Clinical question	Key recommendation/conclusion	Recommendation strength	Certainty of evidence
CQ1‐1	What are the risk factors for the development of adult inguinal hernia?	Risk factors for the development of inguinal hernia include male sex, advanced age, White ethnicity, and a family history	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ2‐1	What are the risk factors for the development of adult femoral hernia?	Adult femoral hernia is considered to occur more frequently in elderly, thin, multiparous women [7]; however, this is based on the hypothesis that increased intra‐abdominal pressure associated with pregnancy and childbirth leads to enlargement of the femoral ring, and there is no clear supporting evidence	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ3‐1	Is imaging recommended for the diagnosis of groin hernia?	Routine imaging is not recommended for the diagnosis of groin hernia in patients with a reducible groin bulge. For the diagnosis of groin hernia in cases where the bulge is not clearly evident, ultrasonography with the patient in the standing position and/or during the Valsalva maneuver is desirable as the first‐line modality	Conditional recommendation against routine use	Low ⊕⊕⊖⊖
CQ4‐1	Which classification is recommended for groin hernia?	The use of the Japan Hernia Society 2021 groin hernia classification (new JHS classification) is recommended	Grade C1 (conventional method)	Level IV (conventional method)
CQ5‐1	Is surgery recommended over watchful waiting for asymptomatic adult inguinal hernia?	In asymptomatic adult inguinal hernia, the absolute superiority of surgery cannot be demonstrated; both surgical intervention and watchful waiting are acceptable options with adequate patient counseling	Conditional recommendation: either option is acceptable	Low ⊕⊕⊖⊖
CQ6‐1	Is surgery recommended over watchful waiting for asymptomatic femoral hernia?	The 2015 Japanese guidelines [5] and the 2018 international guidelines [1] recommend elective surgery for femoral hernia even in asymptomatic cases	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ7‐1	For men with a preoperative diagnosis of primary unilateral inguinal hernia, which is recommended: open anterior mesh repair or laparoscopic surgery?	When performed by a surgeon with sufficient expertise in laparoscopic techniques, laparoscopic surgery is recommended for primary unilateral inguinal hernia in men. Open anterior mesh repair is recommended for patients who are not suitable for laparoscopy, such as those in whom general anesthesia cannot be performed or those with dense adhesions due to prior laparotomy	Conditional recommendation: either approach is acceptable	Moderate ⊕⊕⊕⊖
CQ7‐2	In primary unilateral inguinal hernia in men, are alternative open anterior mesh techniques recommended compared with the Lichtenstein method?	No substantial differences in clinical outcomes have been observed between the Lichtenstein method and other open anterior mesh techniques; therefore, it is desirable to perform the open anterior mesh technique with which the surgeon is most experienced	Conditional recommendation: either approach is acceptable	Moderate ⊕⊕⊕⊖
CQ7‐3	For men with a preoperative diagnosis of primary bilateral inguinal hernia, which is recommended: open anterior mesh repair or laparoscopic surgery?	There are no randomized controlled trials specifically limited to primary bilateral inguinal hernia	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ8‐1	Is laparoscopic surgery recommended over other techniques for adult femoral hernia?	Laparoscopic surgery for adult femoral hernia does not demonstrate clear differences in clinical outcomes compared with other techniques. No definitive conclusion can be drawn regarding which approach should be recommended	No recommendation	Very low ⊕⊖⊖⊖
CQ9‐1	For groin hernia in patients aged ≥ 80 years, which is recommended: open anterior mesh repair or laparoscopic inguinal hernia repair?	For groin hernia in patients aged ≥ 80 years, either open anterior mesh repair or laparoscopic inguinal hernia repair may be selected	Conditional recommendation: either approach is acceptable	Very low ⊕⊖⊖⊖
CQ10‐1	What is the definition of occult hernia?	An occult hernia refers to a hernia that was not diagnosed preoperatively but is discovered intraoperatively	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ10‐2	What are the treatment options for occult hernia?	Some reports indicate that repair of asymptomatic occult hernia is unnecessary [8], whereas other reports recommend repair when it is discovered on the contralateral side [9]	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ11‐1	Is day surgery recommended for inguinal hernia patients with severe comorbidities?	There is insufficient scientific evidence to support the routine recommendation of day‐case surgery for patients with inguinal hernia who have severe underlying comorbidities. The procedure should be considered in facilities with an appropriate healthcare delivery system in place	Conditional (weak) recommendation for day‐case surgery in appropriately selected settings	Moderate ⊕⊕⊕⊖
CQ12‐1	Which mesh is recommended for inguinal hernia repair?	It is not possible to strongly recommend either lightweight mesh or heavyweight mesh	Conditional recommendation: either mesh type may be used	Low ⊕⊕⊖⊖
CQ13‐1	In the Lichtenstein procedure for adult inguinal hernia, are mesh fixation methods different from the original technique recommended?	There is no clear evidence supporting the recommendation of mesh fixation methods different from the original technique in the Lichtenstein procedure	Conditional recommendation against routine use	Low ⊕⊕⊖⊖
CQ13‐2	Is mesh fixation recommended in preperitoneal repair for adult inguinal hernia?	Current evidence does not clearly support either routine mesh fixation or non‐fixation	Conditional recommendation against routine mesh fixation	Low ⊕⊕⊖⊖
CQ13‐3	In mesh fixation for adult inguinal hernia repair, are fixation methods such as self‐gripping mesh, tackers, or glue recommended compared with sutures?	In mesh fixation for adult inguinal hernia repair, there is no clear evidence supporting the recommendation of fixation methods such as self‐gripping mesh, tackers, or glue compared with sutures	Conditional recommendation against routine use	Low ⊕⊕⊖⊖
CQ14‐1	Does prophylactic antibiotic administration reduce SSI (surgical site infection)?	Prophylactic antibiotic administration reduces SSI (surgical site infection)	Conditional recommendation in favor of prophylactic antibiotic administration	Very low ⊕⊖⊖⊖
CQ15‐1	Which anesthesia method is recommended for open inguinal mesh repair in primary unilateral inguinal hernia?	Local anesthesia technique is recommended for open inguinal mesh repair in primary unilateral inguinal hernia. However, this does not apply in cases where local anesthesia is inappropriate or depending on the healthcare delivery system	Conditional (weak) recommendation in favor of local anesthesia	Low ⊕⊕⊖⊖
CQ16‐1	Is preoperative glycemic control immediately before surgery recommended in inguinal hernia repair?	Evidence regarding the impact of preoperative glycemic control in inguinal hernia repair is limited, and no RCTs have specifically examined the optimal timing or target blood glucose levels of perioperative management	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ17‐1	What are the risk factors for chronic pain?	Risk factors for chronic pain include female sex, age ≤ 50 years, recurrent hernia, early postoperative pain, and preoperative pain	No recommendation	Very low ⊕⊖⊖⊖
CQ17‐2	What is the optimal method for preventing chronic pain?	The optimal preventive method for chronic pain is non‐fixation of an onlay mesh or the use of fibrin glue	No recommendation	Low ⊕⊕⊖⊖
CQ17‐3	Is surgical treatment recommended for chronic pain?	Although surgical treatment may be effective, the level of evidence is insufficient to support a recommendation	No recommendation	Very low ⊕⊖⊖⊖
CQ18‐1	For recurrent inguinal hernia after anterior open groin hernia repair involving extensive preperitoneal dissection, which is recommended: an anterior open approach or a laparoscopic approach?	For recurrence after anterior open groin hernia repair involving extensive preperitoneal dissection, no high‐quality studies suitable for pooled analysis were identified	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ19‐1	Is mesh repair recommended for incarcerated or strangulated groin hernia?	At present, no conclusion can be drawn to strongly recommend either the use or non‐use of mesh for repair of incarcerated or strangulated groin hernia	No recommendation	Very low ⊕⊖⊖⊖
CQ19‐2	Is laparoscopic surgery recommended over an anterior open approach for repair of incarcerated or strangulated groin hernia?	Laparoscopic surgery for incarcerated or strangulated groin hernia may be associated with a lower recurrence rate and fewer perioperative complications compared with an anterior open approach; however, no definitive conclusion can currently be drawn as to which approach should be recommended	Recommendation limited to research settings	Very low ⊕⊖⊖⊖
CQ20‐1	Do surgical outcomes differ according to the surgeon's experience?	Differences in surgical outcomes according to the surgeon's experience have mainly been evaluated in laparoscopic surgery	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ20‐2	What is the learning curve for anterior open repair and laparoscopic hernia repair?	The learning curve for laparoscopic inguinal hernia repair has been reported in many studies	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ21‐1	What are specialists and specialized centers in inguinal hernia surgery?	Although the number of specialized hernia centers is increasing worldwide [10, 11, 12, 13, 14], there is no unified definition of a specialist or specialized center	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ22‐1	In elective surgery for primary unilateral inguinal hernia, which is recommended in terms of direct and long‐term costs: anterior open mesh repair or laparoscopic surgery?	Health economic evaluations of surgery for primary unilateral inguinal hernia are based on data from overseas studies, as there are no reports from Japan	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ23‐1	Is follow‐up investigation possible in case registration?	In Japan, case registration for groin hernia using the National Clinical Database (NCD) began in April 2021, and accumulation of detailed data is expected	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ24‐1	What outcomes are required for the evaluation of inguinal hernia surgery?	For the evaluation of inguinal hernia surgery, major outcomes include operative time, blood loss, complications, conversion rate, postoperative pain, urinary retention, sensory disturbance, length of hospital stay, time to return to daily activities/work, recurrence, chronic pain, and patient satisfaction [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39]	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024
CQ24‐2	What types of data accumulation regarding groin hernia are currently being conducted?	Data accumulation regarding groin hernia has progressed mainly in Europe and North America, and the first report was the Swedish Hernia Register [40], initiated in 1992	Not formally graded in the original JHS Guidelines 2024	Not specified in the original JHS Guidelines 2024

Note: Recommendation terminology and certainty of evidence are presented according to the assessment framework used in the original JHS Guidelines 2024. Some CQs were not formally graded in the source guideline, and CQ4‐1 was evaluated using a conventional grading method (Grade C1; Level IV). “No recommendation” indicates that the CQ was formally assessed but no recommendation was issued, whereas “Not formally graded in the original JHS Guidelines 2024” indicates that no formal recommendation grade was assigned in the source guideline. No retrospective regrading was performed for this English summary.

CQ1‐1 What are the risk factors for the development of adult inguinal hernia?

Risk factors for the development of inguinal hernia include male sex, advanced age, White ethnicity, and a family history. A normal to low BMI is associated with an increased risk, and many reports suggest that obesity is associated with a decreased risk; however, conflicting results have also been reported [41, 42, 43, 44, 45, 46]. For indirect inguinal hernia, obesity and tall stature have been identified as risk factors [47]. Regarding lifestyle factors, physical labor, alcohol consumption, and smoking are associated with the development of inguinal hernia [44, 46, 47, 48]; however, the impact of occupation differs depending on the type of hernia [46, 48]. Low income and low educational level are also considered risk factors [47]. In terms of past medical history, inguinal hernia, hiatal hernia, chronic cough, chronic obstructive pulmonary disease, radical prostatectomy, lower urinary tract symptoms, and peritoneal dialysis are associated factors [42, 43, 44, 47, 49, 50, 51, 52, 53, 54, 55]. In adults with a patent processus vaginalis, the risk of developing an indirect inguinal hernia has been reported to be approximately fourfold higher [56]. Genetic factors include polymorphisms of the collagen Type I α1 gene and the angiotensin‐converting enzyme gene [45, 57].

CQ2‐1 What are the risk factors for the development of adult femoral hernia?

Adult femoral hernia is considered to occur more frequently in elderly, thin, multiparous women [7]; however, this is based on the hypothesis that increased intra‐abdominal pressure associated with pregnancy and childbirth leads to enlargement of the femoral ring, and there is no clear supporting evidence. The 2015 inguinal hernia clinical practice guidelines also only state that femoral hernia is more common in elderly women [5]. Furthermore, the 2018 international guidelines do not include descriptions regarding femoral hernia [1], and the scientific evidence for its risk factors remains limited.

CQ3‐1 Is imaging recommended for the diagnosis of groin hernia?

Answer: Routine imaging is not recommended for the diagnosis of groin hernia in patients with a reducible groin bulge. For the diagnosis of groin hernia in cases where the bulge is not clearly evident, ultrasonography with the patient in the standing position and/or during the Valsalva maneuver is desirable as the first‐line modality.

Direction of recommendation: Conditional recommendation against routine use

Certainty of evidence: Low ⊕⊕⊖⊖

In cases presenting with a groin bulge, diagnosis can be made based on medical history and physical examination, and routine use of imaging is unnecessary [58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93]. When the bulge is unclear, or in patients with obesity or those presenting with pain alone, ultrasonography is useful, and its diagnostic accuracy improves when performed in the standing position or with the Valsalva maneuver. Herniography has the highest diagnostic accuracy; however, it may be associated with complications such as pain and bowel puncture. CT has been reported to be useful when performed in the prone position; however, due to concerns regarding radiation exposure, there is insufficient evidence to recommend its routine use. MRI is noninvasive and useful for differential diagnosis of other conditions; however, its diagnostic accuracy for inguinal hernia is not high. Therefore, imaging is not necessary when the diagnosis is clear based on medical history and physical examination, and ultrasonography is recommended as the first‐line modality when the diagnosis is unclear.

CQ4‐1 Which classification is recommended for groin hernia?

Answer: The use of the Japan Hernia Society 2021 groin hernia classification (new JHS classification) is recommended.

Recommendation grade (conventional method): C1

Level of evidence: IV

Method of evaluation: Conventional method

Groin hernia classification enables accurate diagnosis of hernia type and facilitates determination of treatment indications and comparison of outcomes [94, 95, 96, 97, 98, 99]. Previously, various classification systems existed [100, 101, 102], and there was no international standardization. However, the 2018 international guidelines [1] recommended the use of the EHS classification [103]. In Japan, the JHS classification established in 2006 [104, 105, 106] had been widely used; however, to facilitate international comparison, the new JHS classification (2021 version) [107], aligned with the EHS classification, was developed. A characteristic feature of the new classification is that it does not require documentation of hernias that have not been evaluated or do not exist. With the initiation of NCD data registration [108], it is expected that Japan will contribute to the dissemination of internationally relevant research findings.

CQ5‐1 Is surgery recommended over watchful waiting for asymptomatic adult inguinal hernia?

Answer: In asymptomatic adult inguinal hernia, the absolute superiority of surgery cannot be demonstrated; both surgical intervention and watchful waiting are acceptable options with adequate patient counseling.

Direction of recommendation: Conditional recommendation: either option is acceptable

Certainty of evidence: Low ⊕⊕⊖⊖

Although adult inguinal hernia does not resolve spontaneously, watchful waiting is an option in asymptomatic cases. Several RCTs comparing surgical intervention and watchful waiting [109, 110] have shown no significant differences in long‐term QOL or pain, although some patients in the watchful waiting group were reported to undergo surgery due to progression of symptoms.

Both the risk of complications associated with surgery and the risk of incarceration during watchful waiting are low, and either management strategy can be considered reasonable. Therefore, although complications of emergency surgery are more frequent than those of elective surgery [1], in patients with asymptomatic or minimally symptomatic inguinal hernia, it is desirable to determine the treatment strategy based on sufficient explanation, taking into account patient preference, occupation, activity level, and comorbidities.

CQ6‐1 Is surgery recommended over watchful waiting for asymptomatic femoral hernia?

The 2015 Japanese guidelines [5] and the 2018 international guidelines [1] recommend elective surgery for femoral hernia even in asymptomatic cases. The rationale is that, once incarcerated, femoral hernia is frequently associated with strangulation, which can be life‐threatening and requires emergency surgery, and that the risk of progression to incarceration is higher compared with inguinal hernia. Although sufficient evidence to draw a definitive conclusion is lacking, watchful waiting carries a high risk of leading to very severe complications [111, 112, 113]; therefore, elective surgical repair is often performed for asymptomatic femoral hernia.

CQ7‐1 For men with a preoperative diagnosis of primary unilateral inguinal hernia, which is recommended: open anterior mesh repair or laparoscopic surgery?

Answer: When performed by a surgeon with sufficient expertise in laparoscopic techniques, laparoscopic surgery is recommended for primary unilateral inguinal hernia in men. Open anterior mesh repair is recommended for patients who are not suitable for laparoscopy, such as those in whom general anesthesia cannot be performed or those with dense adhesions due to prior laparotomy.

Direction of recommendation: Conditional recommendation: either approach is acceptable

Certainty of evidence: Moderate ⊕⊕⊕⊖

In primary unilateral inguinal hernia in men, pooled analyses of multiple RCTs comparing laparoscopic surgery and open anterior mesh repair [15, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130] showed no significant differences in recurrence rate, organ injury rate, or urinary retention. Laparoscopic surgery was significantly superior in terms of acute and chronic pain, surgical site infection, and early return to normal activities. In contrast, open anterior mesh repair was significantly superior regarding vascular injury, orchialgia, conversion rate, and operative time. Therefore, laparoscopic surgery is preferable when prioritizing pain reduction and early recovery, whereas open anterior mesh repair should be selected in patients with contraindications to general anesthesia or with severe adhesions. As surgical outcomes are strongly influenced by the surgeon's level of expertise, selection of the surgical approach according to operator experience is recommended.

CQ7‐2 In primary unilateral inguinal hernia in men, are alternative open anterior mesh techniques recommended compared with the Lichtenstein method?

Answer: No substantial differences in clinical outcomes have been observed between the Lichtenstein method and other open anterior mesh techniques; therefore, it is desirable to perform the open anterior mesh technique with which the surgeon is most experienced.

Direction of recommendation: Conditional recommendation: either approach is acceptable

Certainty of evidence: Moderate ⊕⊕⊕⊖

Pooled analyses of multiple RCTs comparing the Lichtenstein method and other open anterior mesh techniques [131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145] demonstrated no significant differences in recurrence rate, chronic pain, surgical site infection rate, postoperative seroma/hematoma, urinary retention, time to return to work, operative time, or length of hospital stay. As there are no differences in major clinical outcomes, both approaches have comparable safety and efficacy. Therefore, it is appropriate to select the open anterior mesh technique with which the surgeon is most experienced.

CQ7‐3 For men with a preoperative diagnosis of primary bilateral inguinal hernia, which is recommended: open anterior mesh repair or laparoscopic surgery?

There are no randomized controlled trials specifically limited to primary bilateral inguinal hernia. However, the EHS (2009) [4], EAES (2013) [146], and the international guidelines (2018) [1] all recommend laparoscopic surgery. In particular, compared with bilateral Lichtenstein repair, laparoscopic surgery is associated with less prolongation of operative time and allows earlier return to normal activities [147].

However, in cases where general anesthesia is difficult, where one side is large and the contralateral side is mild, after radical prostatectomy, or in cases of acute incarceration, selection of the surgical approach should be individualized according to patient‐specific conditions.

Therefore, laparoscopic surgery performed by a surgeon with sufficient experience and appropriate resources is desirable; however, flexible selection of the surgical approach based on case characteristics is recommended.

CQ8‐1 Is laparoscopic surgery recommended over other techniques for adult femoral hernia?

Answer: Laparoscopic surgery for adult femoral hernia does not demonstrate clear differences in clinical outcomes compared with other techniques. No definitive conclusion can be drawn regarding which approach should be recommended.

Direction of recommendation: No recommendation

Certainty of evidence: Very low ⊕⊖⊖⊖

Femoral hernia is relatively uncommon, accounting for 2%–8% of groin hernias [148, 149]. There are no RCTs comparing treatment modalities for femoral hernia, and available evidence is limited to observational studies. In a prospective registry‐based study, there were no differences between the laparoscopic group and the open anterior approach group in terms of complications, pain, or recurrence rate; however, the laparoscopic group showed slightly better outcomes in length of hospital stay and follow‐up [150].

In a retrospective study comparing TAPP and UHS [151], seroma was more frequent with TAPP, whereas pain and foreign body sensation were more common with UHS. The international HerniaSurge guidelines [1] emphasize that 40% of reoperations for groin hernia in women are due to femoral hernia, suggesting the possibility of missed diagnosis at the initial surgery, and highlight the advantage of laparoscopic surgery in enabling the detection of concomitant hernias; thus, laparoscopic repair is recommended [152, 153, 154].

Although there is no clear evidence demonstrating superiority, laparoscopic surgery is a useful approach that allows both diagnosis and treatment and can be considered a technique that surgeons should be proficient in.

CQ9‐1 For groin hernia in patients aged ≥ 80 years, which is recommended: open anterior mesh repair or laparoscopic inguinal hernia repair?

Answer: For groin hernia in patients aged ≥ 80 years, either open anterior mesh repair or laparoscopic inguinal hernia repair may be selected.

Direction of recommendation: Conditional recommendation: either approach is acceptable

Certainty of evidence: Very low ⊕⊖⊖⊖

In elderly patients (≥ 80 years), it is necessary to consider the risks of general anesthesia and the impact of comorbidities. Compared with open repair, laparoscopic surgery is associated with less postoperative pain and allows earlier recovery; however, it requires slightly longer operative time and necessitates general anesthesia. Open anterior mesh repair can be performed under local anesthesia and is suitable for patients at high anesthetic risk.

Due to the limited number of reported cases [16, 155, 156, 157], there is insufficient evidence to compare mortality, serious complications, and recurrence rates, and no superiority of either approach can be demonstrated. At present, it is recommended that the surgical approach be selected on a case‐by‐case basis, taking into account anesthetic risk, surgeon expertise, and institutional resources.

CQ10‐1 What is the definition of occult hernia?

An occult hernia refers to a hernia that was not diagnosed preoperatively but is discovered intraoperatively. It may be incidentally detected during laparoscopic surgery for other diseases, with a reported detection rate of approximately 18% [8]. Furthermore, contralateral occult hernia is observed in 13%–22% [9, 158, 159, 160] of cases during unilateral laparoscopic inguinal hernia repair. According to the international guidelines [1], the true incidence remains unknown; however, it is well established that a certain proportion of occult hernias exist without subjective symptoms or physical findings.

CQ10‐2 What are the treatment options for occult hernia?

Some reports indicate that repair of asymptomatic occult hernia is unnecessary [8], whereas other reports recommend repair when it is discovered on the contralateral side [9]. According to the international guidelines [1], when a contralateral occult hernia is identified during TAPP repair, simultaneous repair is recommended provided that adequate preoperative explanation has been given.

When performing TAPP repair, contralateral repair can be performed through the same incision, which has the advantage of avoiding metachronous onset [159, 161]. However, caution has been expressed regarding routine repair in all cases [161]. In asymptomatic cases, there is a risk of postoperative pain [162], therefore, watchful waiting may also be considered as an option. Although exploration of the contralateral side during TEP repair is not recommended [1]; ipsilateral exploration may allow occult hernias on the same side to be detected and repaired without being overlooked, which may contribute to the prevention of recurrence [163].

CQ11‐1 Is day surgery recommended for inguinal hernia patients with severe comorbidities?

Answer: There is insufficient scientific evidence to support the routine recommendation of day‐case surgery for patients with inguinal hernia who have severe underlying comorbidities. The procedure should be considered in facilities with an appropriate healthcare delivery system in place.

Direction of recommendation: Conditional (weak) recommendation for day‐case surgery in appropriately selected settings

Certainty of evidence: Moderate ⊕⊕⊕⊖

The available evidence regarding the safety of day‐case surgery in inguinal hernia patients with severe underlying comorbidities is limited. In patients with ASA ≥ 3, a slightly higher incidence of prolonged hospital stay and urinary retention has been reported [164, 165, 166], whereas no significant differences have been observed in hematoma, infection, or readmission rates. In patients with severe underlying comorbidities, establishment of a comprehensive medical system—including preoperative assessment, selection of anesthetic technique, and postoperative management—is essential. Therefore, in cases with ASA ≥ 3, day‐case surgery should be considered cautiously with adequate safety measures, and routine use is not recommended.

CQ12‐1 Which mesh is recommended for inguinal hernia repair?

Answer: It is not possible to strongly recommend either lightweight mesh or heavyweight mesh.

Direction of recommendation: Conditional recommendation: either mesh type may be used

Certainty of evidence: Low ⊕⊕⊖⊖

Three types of mesh materials are used: lightweight mesh, heavyweight mesh, and titanium‐coated mesh. No significant differences in safety have been observed among them. The incidence of short‐term postoperative pain tends to be lower with lightweight mesh; however, this difference disappears over the long term [167, 168, 169]. Regarding recurrence rates, some RCTs [167, 168, 169, 170, 171] have reported slightly lower recurrence rates with heavyweight mesh, whereas the time to return to normal activities is reported to be shorter with lightweight mesh [17, 168, 169, 170]. Long‐term outcomes of titanium‐coated mesh do not differ from those of other meshes [169]. The international guidelines [1] do not recommend selection based on weight classification; instead, a monofilament synthetic flat mesh with large pores (1–1.5 mm) and sufficient tensile strength (≥ 16 N/cm²) is preferable.

CQ13‐1 In the Lichtenstein procedure for adult inguinal hernia, are mesh fixation methods different from the original technique recommended?

Answer: There is no clear evidence supporting the recommendation of mesh fixation methods different from the original technique in the Lichtenstein procedure.

Direction of recommendation: Conditional recommendation against routine use

Certainty of evidence: Low ⊕⊕⊖⊖

The Lichtenstein procedure is one of the standard techniques for inguinal hernia repair; however, various modified techniques have been reported. A meta‐analysis of RCTs comparing fixation methods different from the original technique (such as glue, self‐fixating mesh, tackers, or staplers) showed no significant differences in recurrence rates or the incidence of chronic pain [172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201]. The recurrence rate was 1.1% in the original technique group and 1.3% in the non‐original technique group, with an odds ratio of 1.18 [0.68, 2.05], showing no significant difference between the groups. There was also no significant difference in the incidence of chronic pain, and differences in VAS scores were not clinically meaningful. Furthermore, although some studies included control groups that were not strictly faithful to the original technique, no differences were observed in either recurrence rates or the incidence of pain even in strict comparisons. At present, superiority of fixation methods different from the original technique has not been demonstrated, and there is no evidence to support recommending such modifications. Nevertheless, there may be room for the development of safer and more efficient surgical techniques in the future.

CQ13‐2 Is mesh fixation recommended in preperitoneal repair for adult inguinal hernia?

Answer: Current evidence does not clearly support either routine mesh fixation or non‐fixation.

Direction of recommendation: Conditional recommendation against routine mesh fixation

Certainty of evidence: Low ⊕⊕⊖⊖

In preperitoneal repair for adult inguinal hernia, no clear superiority has been demonstrated regarding mesh fixation versus non‐fixation. An analysis of 15 RCTs [18, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215] found no significant differences in recurrence rate or the incidence of chronic pain. The recurrence rate was 0.6% in the fixation group and 1.0% in the non‐fixation group, with a risk ratio (RR) of 1.53 [0.52, 4.52], showing no significant difference between the groups. The incidence of chronic pain (VAS) was reported as MD = −0.33 [−0.95, 0.28], with no statistically significant difference. Subgroup analysis excluding studies using glue in the non‐fixation group similarly demonstrated no differences in recurrence rates or the incidence of pain. International guidelines indicate that mesh fixation is unnecessary in most cases during TEP repair, whereas fixation is recommended only for large M3 cases in TAPP repair [1, 216]. In Japan, fixation is still performed in many institutions; however, evidence demonstrating clear differences in recurrence or the incidence of pain between the methods is limited. At present, the choice should be made flexibly based on surgical technique, the surgeon's experience, and patient characteristics.

CQ13‐3 In mesh fixation for adult inguinal hernia repair, are fixation methods such as self‐gripping mesh, tackers, or glue recommended compared with sutures?

Answer: In mesh fixation for adult inguinal hernia repair, there is no clear evidence supporting the recommendation of fixation methods such as self‐gripping mesh, tackers, or glue compared with sutures.

Direction of recommendation: Conditional recommendation against routine use

Certainty of evidence: Low ⊕⊕⊖⊖

Mesh fixation is commonly performed; however, because it carries a risk of pain related to nerve injury, fixation may be avoided when outcomes are not compromised without fixation. An analysis of 18 studies on mesh fixation in adult Lichtenstein repair demonstrated no significant differences between suture fixation and non‐suture fixation (self‐gripping mesh, tackers, glue, etc.) in key outcomes such as recurrence rate, the incidence of chronic pain, infection rates, and patient satisfaction. In the non‐suture group, a slightly earlier return to daily activities and work was observed; however, this finding was inconsistent with differences in acute pain, and the influence of factors other than the surgical technique cannot be excluded [173, 175, 178, 179, 180, 182, 184, 186, 187, 189, 194, 195, 197, 198, 199, 217, 218, 219]. In the international guidelines, self‐gripping mesh increases cost and offers few advantages other than a shorter operative time, with no differences in recurrence or infection rates; therefore, its routine use is not actively recommended at present [1]. Accordingly, there is no evidence demonstrating substantial differences in clinical outcomes among fixation methods, and the choice of fixation method should be determined based on surgeon experience and patient characteristics.

CQ14‐1 Does prophylactic antibiotic administration reduce SSI (surgical site infection)?

Answer: Prophylactic antibiotic administration reduces SSI (surgical site infection).

Direction of recommendation: Conditional recommendation in favor of prophylactic antibiotic administration

Certainty of evidence: Very low ⊕⊖⊖⊖

In previous guidelines, the effectiveness of prophylactic antibiotics was limited in patients with a low risk of infection. However, a meta‐analysis integrating multiple recent RCTs [220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235] demonstrated that prophylactic antibiotic administration significantly reduces the incidence of SSI. Particularly in cases involving mesh use, the risk of reoperation or mesh removal due to infection is higher, and the significance of prophylactic administration is recognized.

CQ15‐1 Which anesthesia method is recommended for open inguinal mesh repair in primary unilateral inguinal hernia?

Answer: Local anesthesia technique is recommended for open inguinal mesh repair in primary unilateral inguinal hernia. However, this does not apply in cases where local anesthesia is inappropriate or depends on the healthcare delivery system.

Direction of recommendation: Conditional (weak) recommendation in favor of local anesthesia

Certainty of evidence: Low ⊕⊕⊖⊖

A pooled analysis of several low‐quality RCTs showed no major differences in key outcomes between local anesthesia and general or regional anesthesia; however, urinary retention (RR = 7.68, 95% CI = 2.10–28.08) and nausea/vomiting (RR = 2.41, 95% CI = 1.60–3.63) were significantly more frequent with general or regional anesthesia [236, 237, 238, 239, 240, 241, 242, 243, 244, 245]. Therefore, local anesthesia technique is recommended for open inguinal mesh repair in primary unilateral inguinal hernia. However, in Japan, few institutions perform the procedure under local anesthesia alone; therefore, the choice of anesthesia should be based on patient characteristics and the healthcare system.

CQ16‐1 Is preoperative glycemic control immediately before surgery recommended in inguinal hernia repair?

Evidence regarding the impact of preoperative glycemic control in inguinal hernia repair is limited, and no RCTs have specifically examined the optimal timing or target blood glucose levels of perioperative management. The EHS guidelines [4] do not provide specific recommendations. The Japan Diabetes Society [246] recommends preoperative glycemic targets of a fasting blood glucose level of 100–140 mg/dL, a postprandial blood glucose level of 160–200 mg/dL, urinary glucose ≤ 1+, and negative urinary ketones. Surgery postponement is recommended when fasting blood glucose is ≥ 200 mg/dL, postprandial blood glucose is ≥ 300 mg/dL, or urinary ketones are positive. The CDC guidelines [247] recommend maintaining perioperative blood glucose below 200 mg/dL regardless of the presence or absence of diabetes, and it is desirable to manage preoperative glycemic control for inguinal hernia repair with reference to these criteria.

CQ17‐1 What are the risk factors for chronic pain?

Answer: Risk factors for chronic pain include female sex, age ≤ 50 years, recurrent hernia, early postoperative pain, and preoperative pain.

Direction of recommendation: No recommendation

Certainty of evidence: Very low ⊕⊖⊖⊖

The incidence of chronic postoperative inguinal pain (CPIP) after inguinal hernia repair varies widely among reports [135, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263], which is considered to be due to the lack of uniformity in evaluation methods. Analyses of observational studies have identified female [248, 249, 250, 251, 252, 253, 254, 255, 256, 257], age ≤ 50 years [135, 251], recurrent hernia [248, 254, 258, 259, 261, 262, 263], early postoperative pain [253, 258], and preoperative pain [250, 253, 259, 260, 263] as risk factors. The reported risks are as follows: female (OR = 0.67, 95% CI = 0.49–0.91), age ≤ 50 years (OR = 2.50, 95% CI = 1.73–3.61), recurrent hernia (OR = 1.98, 95% CI = 1.54–2.56), early postoperative pain (OR = 2.53, 95% CI = 1.69–3.78), and preoperative pain (OR = 2.73, 95% CI = 2.27–3.29). In patients with these factors, careful attention should be paid to the development of postoperative chronic pain.

CQ17‐2 What is the optimal method for preventing chronic pain?

Answer: The optimal preventive method for chronic pain is non‐fixation of an onlay mesh or the use of fibrin glue.

Direction of recommendation: No recommendation

Certainty of evidence: Low ⊕⊕⊖⊖

A meta‐analysis including 11 randomized controlled trials (RCTs) [264, 265, 266, 267, 268, 269, 270, 271, 272, 273, 274] showed that the use of lightweight mesh (LWM) in the Lichtenstein repair did not demonstrate a preventive effect on chronic pain compared with heavyweight mesh (RR = 0.78, 95% CI = 0.59–1.03). In contrast, eight observational studies [249, 275, 276, 277, 278, 279, 280] showed that non‐fixation of an onlay mesh or the use of fibrin glue reduced chronic pain (RR = 0.47, 95% CI = 0.27–0.82). However, fibrin glue is not recommended because it is not covered by health insurance in Japan for this indication.

In an Italian multicenter study [281], the incidence of chronic pain was significantly reduced when all three nerves were identified. However, no significant difference was observed in a single‐center study, and a meta‐analysis also showed that nerve identification and preservation did not suppress chronic pain (RR = 0.30, 95% CI = 0.00–20.40). In addition, the concomitant use of a transversus abdominis plane (TAP) block or iliohypogastric/ilioinguinal nerve block did not contribute to the prevention of chronic pain (RR = 0.35, 95% CI = 0.07–1.87).

CQ17‐3 Is surgical treatment recommended for chronic pain?

Answer: Although surgical treatment may be effective, the level of evidence is insufficient to support a recommendation.

Direction of recommendation: No recommendation

Certainty of evidence: Very low ⊕⊖⊖⊖

In an RCT involving patients with chronic pain after Lichtenstein repair, the rate of pain improvement in the neurectomy group was approximately three times higher than that in the tender point infiltration group (71% vs. 22%, RR = 0.38, 95% CI = 0.19–0.72), demonstrating the efficacy of neurectomy [282]. However, there are no comparative trials with other treatment modalities, and the evidence is insufficient to recommend neurectomy as standard treatment. Therefore, surgical treatment should be applied only in selected cases after careful patient selection.

CQ18‐1 For recurrent inguinal hernia after anterior open groin hernia repair involving extensive preperitoneal dissection, which is recommended: an anterior open approach or a laparoscopic approach?

For recurrence after anterior open groin hernia repair involving extensive preperitoneal dissection, no high‐quality studies suitable for pooled analysis were identified. International and European guidelines [1, 4] recommend a laparoscopic approach for recurrence after anterior open repair and an anterior open approach for recurrence after laparoscopic repair, emphasizing that selection of a tissue plane with fewer adhesions is important from the perspective of safety.

The EAES guidelines [146] state that relaparoscopic surgery for recurrent cases may be considered as an option only when performed by experienced surgeons. In Japan, various anterior open repair techniques other than the Lichtenstein repair have been performed, including the plug method, bilayer method, TIPP method, and Kugel method. After the Kugel repair, adhesions are generally mild, and an anterior open approach is suitable for recurrence. In contrast, after the plug repair, reoperation by laparoscopy is often technically feasible. After the bilayer method or TIPP method, reoperation is technically more difficult, and the choice of surgical approach requires careful consideration.

Because adhesions and anatomical disruption caused by the previous operation increase the risk of injury to nerves, vessels, and the bladder, it is desirable to evaluate the type of recurrence and the degree of adhesions, for example by diagnostic laparoscopy, and for an experienced surgeon to select the optimal procedure according to each individual case.

CQ19‐1 Is mesh repair recommended for incarcerated or strangulated groin hernia?

Answer: At present, no conclusion can be drawn to strongly recommend either the use or non‐use of mesh for repair of incarcerated or strangulated groin hernia.

Direction of recommendation: No recommendation

Certainty of evidence: Very low ⊕⊖⊖⊖

In repair of incarcerated or strangulated groin hernia, whether mesh should be used remains controversial because of concerns regarding the risk of infection. Recent reports indicate that tension‐free repair is commonly selected, as in ordinary groin hernia repair; however, surgical site infection and mesh infection remain the major concerns. Many cases are complicated by bowel obstruction or bowel necrosis, and assessment of mortality and postoperative complications is important.

Four RCTs [283, 284, 285, 286] and one systematic review [287] are available. Given the small number of included patients and limited data on severe cases, the evidence remains insufficient to strongly favor mesh or non‐mesh repair [288, 289], and high‐quality large‐scale RCTs are still needed. The surgical procedure should therefore be selected for each patient according to infection risk, the presence or absence of bowel necrosis, and the patient's general condition.

CQ19‐2 Is laparoscopic surgery recommended over an anterior open approach for repair of incarcerated or strangulated groin hernia?

Answer: Laparoscopic surgery for incarcerated or strangulated groin hernia may be associated with a lower recurrence rate and fewer perioperative complications compared with an anterior open approach; however, no definitive conclusion can currently be drawn as to which approach should be recommended.

Direction of recommendation: Recommendation limited to research settings

Certainty of evidence: Very low ⊕⊖⊖⊖

It has been suggested that laparoscopic surgery for incarcerated or strangulated groin hernia may reduce recurrence and complication rates [290, 291, 292]. Laparoscopic surgery has the advantages of allowing assessment of the intestine from within the abdominal cavity and enabling simultaneous diagnosis and repair of a contralateral hernia [293, 294, 295, 296, 297, 298, 299, 300, 301]. On the other hand, when reduction of incarcerated contents or bowel resection is required, the procedure becomes more technically complex and is highly dependent on the surgeon's expertise.

Comparative evidence, particularly for severe cases, remains limited, and no clear superiority of either approach has been demonstrated. The EHS guidelines [4] also regard this issue as unresolved. Thus, although laparoscopic surgery is a promising option, the current evidence is insufficient to recommend it as standard treatment.

CQ20‐1 Do surgical outcomes differ according to the surgeon's experience?

Differences in surgical outcomes according to the surgeon's experience have mainly been evaluated in laparoscopic surgery. Several studies have reported that operative time decreases as surgical experience increases [302, 303, 304, 305], and that complications and recurrence rates also tend to decrease [303, 304, 306]. On the other hand, it has also been reported that, under the supervision of experienced instructors, long‐term outcomes are favorable even when the operation is performed by less experienced surgeons such as residents [307].

In minimally invasive procedures such as single‐incision laparoscopic surgery, specifically SILS‐TEP [308], and needlescopic TAPP using small‐diameter forceps [309], operative time decreased with experience; however, no effect on complications or recurrence rates was observed. Based on these findings, surgeon experience contributes to shortening operative time, but when an appropriate supervisory system is in place, it is considered that there are no major differences in safety or recurrence rates.

CQ20‐2 What is the learning curve for anterior open repair and laparoscopic hernia repair?

The learning curve for laparoscopic inguinal hernia repair has been reported in many studies. For TAPP, operative time is reported to stabilize after 14–65 cases [306, 310, 311, 312], complications after 40–50 cases [306, 312], and recurrence after approximately 40 cases [312]. For TEP, operative time is reported to stabilize after 13–80 cases [305, 310, 313, 314, 315, 316, 317, 318], and the conversion rate and recurrence rate after 30–40 cases [317, 319]. It has also been reported that safe performance becomes possible after experience with at least 20 cases [320].

Some large‐scale reports indicate a longer learning curve, with the conversion rate reaching a plateau after 250 cases and operative time and complications reaching a plateau after 450 cases [321]. International guidelines state that the learning curve for laparoscopic surgery is 50–100 cases and that the critical period is 30–50 cases [1]. SILS‐TEP is reported to stabilize after 40 cases [308], and robot‐assisted TAPP after 43 cases [322], showing no major difference from conventional procedures.

In contrast, for anterior open repair, operative time stabilizes after approximately 40 cases for the Lichtenstein repair [323] and after 40–60 cases for the Kugel repair, while the recurrence rate decreases after 50 cases [324]. Overall, experience with 40–100 cases is considered a practical benchmark for overcoming the learning curve in both laparoscopic and open procedures.

CQ21‐1 What are specialists and specialized centers in inguinal hernia surgery?

Although the number of specialized hernia centers is increasing worldwide [10, 11, 12, 13, 14], there is no unified definition of a specialist or specialized center. In Germany and Italy, society‐based accreditation systems have been proposed, and three‐level certification systems based on case volume, education, and research achievements are being introduced [325, 326, 327].

A specialist is expected to be capable of performing various surgical procedures and selecting the optimal procedure according to the individual patient. The number of cases required to achieve proficiency has not been clearly established. However, previous reports suggest that 50–63 cases are required for open surgery [58, 328, 329], and 100–400 cases for laparoscopic surgery [13]. For the Lichtenstein repair, differences in outcomes between specialists and general surgeons are small [330]. In laparoscopic surgery, however, limited experience is associated with prolonged operative time and increased recurrence rates [302, 331, 332].

It has also been reported that high‐volume centers achieve better outcomes in complex hernias and laparoscopic surgery [1, 13]. International guidelines indicate that the experience of the individual surgeon has a greater impact on surgical outcomes than institutional volume [1]. Specialized centers are expected to contribute to improving the quality of hernia treatment through education and research.

CQ22‐1 In elective surgery for primary unilateral inguinal hernia, which is recommended in terms of direct and long‐term costs: anterior open mesh repair or laparoscopic surgery?

Health economic evaluations of surgery for primary unilateral inguinal hernia are based on data from overseas studies, as there are no reports from Japan. Systematic reviews from the United Kingdom and the United States have shown that laparoscopic surgery provides a higher quality of life, assessed by quality‐adjusted life years (QALYs) [333], because of earlier return to social activities and reduced pain and infection risk. However, laparoscopic surgery is associated with higher operative and facility costs, and the cost difference decreases over the long term.

In a UK study [147], the initial cost of laparoscopic surgery was 300–350 pounds higher than that of the Lichtenstein repair. However, when productivity loss due to time away from work was taken into account, the cost difference disappeared because of earlier return to work. In a US study [334], laparoscopic surgery was the most cost‐effective option, followed by anterior open mesh repair and then non‐mesh repair. However, if the facility‐related costs of laparoscopic surgery exceed a certain threshold, its cost‐effectiveness is lost.

Overall, laparoscopic surgery is at least equivalent to, and possibly superior to, anterior open mesh repair in terms of cost‐effectiveness. However, careful judgment is required in severe cases and recurrent cases. At present, data from Japan are insufficient, and further studies are needed to establish a recommendation.

CQ23‐1 Is follow‐up investigation possible in case registration?

In Japan, case registration for groin hernia using the National Clinical Database (NCD) began in April 2021, and accumulation of detailed data is expected. Overseas, several major registries are in operation, including AHSQC [335], CH [336], DHDB [153, 337, 338], EuraHS, Herniamed [339, 340, 341, 342, 343], and SHR [344, 345]. Follow‐up methods and registration systems differ among countries.

In particular, the Danish Hernia Database (DHDB) is a nationally operated system with mandatory registration and is the only system that enables follow‐up of all cases using a social security number. The Swedish Hernia Register (SHR) is also publicly funded and maintains a follow‐up rate of more than 90%. In Herniamed and CH, follow‐up registration is performed by questionnaire at 1, 2, and 5 years after surgery, and the follow‐up rate exceeds 85% [346].

In Japan, because groin hernia is a benign disease and the duration of outpatient follow‐up is short, long‐term follow‐up is challenging. However, based on experience in other disease fields, follow‐up investigation is considered feasible with appropriate methodological modifications. In the future, it is desirable to establish follow‐up methods suited to the Japanese healthcare system by utilizing the NCD.

CQ24‐1 What outcomes are required for the evaluation of inguinal hernia surgery?

For the evaluation of inguinal hernia surgery, major outcomes include operative time, blood loss, complications, conversion rate, postoperative pain, urinary retention, sensory disturbance, length of hospital stay, time to return to daily activities/work, recurrence, chronic pain, and patient satisfaction [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39]. For postoperative QOL assessment, the SF‐36 [18, 19, 22, 25, 32, 36] and its short form, the SF‐12 [21, 347], are widely used. In addition, the Carolinas Comfort Scale (CCS) [348] is available as a hernia‐specific instrument and comprehensively assesses pain, foreign body sensation, and movement limitation [16, 25, 34]. The CCS is used internationally and more accurately reflects QOL in patients with hernia [349]. Furthermore, the COMI [350] and EuraHS‐QoL [351] are also useful as multidimensional assessment tools [38, 352]. For the evaluation of chronic pain, the Inguinal Pain Questionnaire [353] is used, and for postoperative activity, the Activities Assessment Scale and other instruments are used [354, 355]. The use of patient‐reported outcomes (PROs) combining these measures has been expanding [356]. In addition, cost analyses, including operative cost [32], hospitalization cost [15], readmission cost due to recurrence or complications [357], and societal cost, are also important evaluation items [358]. Overall, integrated evaluation of surgery‐related indicators and patient‐reported outcomes is indispensable for the objective comparison of surgical outcomes.

CQ24‐2 What types of data accumulation regarding groin hernia are currently being conducted?

Data accumulation regarding groin hernia has progressed mainly in Europe and North America, and the first report was the Swedish Hernia Register [40], initiated in 1992. This registry covers approximately 98% of hernia operations throughout Sweden and enables long‐term follow‐up through use of personal identification numbers [37]. Subsequently, in 1998, the Danish Hernia Database (DHDB) was established in Denmark and prospectively registers adult cases nationwide, maintaining an accuracy of more than 90% through annual linkage with the National Hospital Register [359]. In 2009, Herniamed was launched in three German‐speaking countries (Germany, Austria, and Switzerland), tracking detailed data including operative technique, mesh information, and postoperative pain for 10 years [360]. In the United States, the Americas Hernia Society Quality Collaborative Database (AHSQC) [361] was initiated in 2013; it uses a format in which both surgeons and patients enter data, and by 2019 more than 45 000 cases had been registered [362]. In addition, the French Club Hernie and the EuraHS operated by the European Hernia Society are also in operation [346]. In Japan, a nationwide data collection initiative using the National Clinical Database (NCD), led by the Japanese Hernia Society, began in 2021; however, establishment of a postoperative follow‐up system remains a future challenge.

2. Discussion

This article summarizes the recommendations of the JHS GL 2024 [6] and provides an English version in a form that can be shared internationally. In this process, it is also true that there are areas in which the recommendations differ from those of the IG [1], which serve as the international standard, particularly the 2023 update [2]. Some explanatory texts refer to differences from the IG, but one reason for such differences, especially where largely overlapping references were consulted, is considered to be differences in the manner in which recommendations are presented and in the role expected of the guidelines. The JHS GL 2024 clearly adopts a cautious position, faithfully organizing the scientific evidence based on the existing literature and refraining from strong recommendations in areas where evidence has not been sufficiently established. This may be interpreted as reflecting the role of a domestic guideline intended to present standards that can be safely applied nationwide, taking into account the Japanese healthcare delivery system, health insurance system, and technical diversity among institutions. In contrast, the IG may be considered to have a more implementation‐oriented character, placing emphasis on supporting decision‐making in actual clinical practice and presenting more assertive recommendations even in situations where differences in the evidence are small.

Adding specific considerations regarding the principal items, first, for the open repair technique in CQ7‐2, the IG recommends the Lichtenstein technique, whereas the JHS states that the operative method with which the surgeon is most proficient is preferable. This is considered to reflect a careful judgment of the scientific evidence based on the existing literature while also taking Japanese clinical circumstances into consideration.

In addition, although the 2023 update of the IG preceded the JHS GL 2024 in terms of publication timing, it is noteworthy that it incorporated more recent literature regarding mesh weight and organized its recommendations accordingly. In the JHS GL 2024, CQ12‐1 did not reach a definitive conclusion regarding the superiority of lightweight mesh versus heavyweight mesh, and individualized selection based on case background and surgeon experience was considered appropriate. In contrast, the IG update, based on new evidence, provides more specific procedure‐based recommendations, recommending lightweight mesh for the Lichtenstein technique and heavyweight mesh for laparo‐endoscopic repair, particularly for large direct hernias. More recently, a 2025 nationwide Danish database study reported that a mesh weight of 45–65 g/m² was associated with the lowest risk of reoperation for recurrence after laparoscopic inguinal hernia repair, whereas both lighter (< 45 g/m²) and heavier (> 65 g/m²) meshes were associated with higher risks of reoperation for recurrence [363]. These findings suggest that the relationship between mesh weight and recurrence after laparoscopic repair may be more complex than can be explained by a simple lightweight‐versus‐heavyweight distinction. However, because this was an observational registry‐based study, the potential influence of confounding factors should be considered when interpreting the findings. Further studies are therefore needed to clarify the optimal mesh characteristics for laparoscopic inguinal hernia repair. These emerging data do not alter the conclusions of the JHS GL 2024 but may provide relevant evidence for future guideline updates.

Regarding the prevention of chronic postoperative inguinal pain (CPIP) in CQ17‐2, the JHS GL 2024 identifies non‐fixation of an onlay mesh or the use of fibrin glue as potentially effective preventive approaches, although no formal recommendation is issued because of the limited evidence. The international HerniaSurge guidelines also address CPIP prevention through recommendations concerning operative technique, mesh selection, and fixation methods. Although both guidelines emphasize the importance of minimizing the risk of chronic pain, their approaches to structuring recommendations differ, and a directly corresponding recommendation to the JHS CQ17‐2 formulation is not provided in the IG.

In contrast, CQ17‐3 addresses the management of established CPIP. The JHS GL 2024 acknowledges that surgical treatment may be effective but does not issue a formal recommendation because of the insufficient level of evidence. The 2023 update of the IG, however, provides more specific guidance, suggesting a tailored surgical approach to CPIP, including neurectomy, open mesh removal, or a combination of these procedures, depending on the original repair method, surgeon experience, pain distribution and symptoms, physical findings, and imaging findings. The IG also strongly recommends centralizing the evaluation and treatment of CPIP in specialist centres with an experienced multidisciplinary team. Thus, although both guidelines recognize the limited evidence regarding surgical treatment of established CPIP, the IG provides more specific guidance for its clinical management.

From the above, many of the differences in recommendations observed between the JHS GL 2024 and the IG can be positioned not as denying the validity of either, but as arising from differences in the objectives of the guidelines and in the healthcare environments for which they are intended. It is strongly hoped that the English summary presented in this article will promote international understanding of the JHS GL 2024 and contribute to constructive comparison and future revision among domestic and international guidelines.

Future priorities include prospective multicenter studies, further analyses of national registry data with standardized long‐term and patient‐reported outcomes, and international collaborative studies. These efforts should help strengthen the evidence base in areas where current recommendations remain uncertain and support future comparison and harmonization of domestic and international guidelines.

Author Contributions

Hitoshi Idani: conceptualization, writing – original draft, writing – review and editing. Gen Shimada: conceptualization, writing – original draft, writing – review and editing. Katsuhito Suwa: conceptualization, writing – original draft, writing – review and editing. Yoshiko Honda: conceptualization, writing – original draft, writing – review and editing. Yuji Konishi: conceptualization, writing – original draft, writing – review and editing. Itsuro Nagae: conceptualization, writing – original draft, writing – review and editing. Kenta Saito: conceptualization, writing – original draft, writing – review and editing. Takafumi Tamura: conceptualization, writing – original draft, writing – review and editing. Satoshi Nagayama: writing – review and editing. Chie Tanaka: writing – review and editing. Seiko Hirono: writing – review and editing.

Funding

The authors have nothing to report.

Disclosure

Permission to reproduce copyrighted material has been obtained from the copyright holder.

Ethics Statement

The authors have nothing to report.

Consent

The authors have nothing to report.

Conflicts of Interest

Satoshi Nagayama and Seiko Hirono are Editorial Board Members of Annals of Gastroenterological Surgery. They are not involved in the editorial evaluation or decision‐making process for this article. The other authors declare no conflicts of interest.

Idani H., Shimada G., Suwa K., et al., “The Japanese Hernia Society (JHS) Guidelines for Adult Groin Hernia Management 2024,” Annals of Gastroenterological Surgery (2026): 1–28, 10.1002/ags3.70295.

Data Availability Statement

Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.