Manual reduction in minimally invasive management of obturator hernia: a retrospective study

Abstract

Background

Incarcerated obturator hernias, rare but serious, often require emergency surgery in elderly patients having poor health. In recent years, several studies have reported that manual reduction under imaging guidance may facilitate less invasive, elective laparoscopic repair. However, the clinical significance of successful manual reduction in terms of surgical strategy and postoperative outcomes remains unclear.

Methods

We retrospectively reviewed 35 incarcerated obturator hernia cases treated at our institution between 2016 and 2025. Ultrasound-guided manual reduction was attempted in all cases. The success of reduction was confirmed using post-reduction computed tomography (CT) imaging. Patients were then classified into two groups: the reduction success group (n = 14) and the failure group (n = 21). We compared the patients’ backgrounds, surgical approaches, bowel resections, mesh usage, and postoperative outcomes between the groups.

Results

Laparoscopic repair was more frequent in success group (43% vs. 5%, P = 0.04). Bowel resection was not required for success group patients but was necessitated in 53% of failure group patients (P = 0.02). Mesh usage was higher in success group (100% vs. 29%, P = 0.001). No manual reduction-related complications were noted. Severe postoperative complications (Clavien–Dindo ≥ grade III) were more frequent in failure group (29% vs. 0%).

Conclusions

Ultrasound-guided manual reduction appeared safe in our cohort and was associated with a higher feasibility of elective surgery and laparoscopic mesh repair, with lower rates of bowel resection and severe postoperative complications. Reduction success may serve as a practical marker to guide surgical planning, although causal inference is limited by the retrospective design.

Introduction

An obturator hernia is a rare condition that can be life-threatening. It frequently requires emergency surgical intervention, especially in elderly patients who have poor general health. It often presents with vague symptoms and has a delayed diagnosis, increasing the risks of bowel incarceration and necrosis [1, 2].

Recent reports have presented a minimally invasive approach involving ultrasound‑guided manual reduction with subsequent elective laparoscopic surgery [3–5]. However, the clinical significance of successful versus unsuccessful manual reduction on the surgical strategy and patient outcomes remains unclear [6, 7]. We performed a retrospective study to evaluate the clinical significance of successful ultrasound-guided manual reduction by comparing surgical strategy (elective vs. emergency surgery, laparoscopic vs. open approach, mesh use, and bowel resection) and postoperative outcomes between reduction-success and reduction-failure cases.

Methods

In this retrospective study, we reviewed 35 patients diagnosed with incarcerated obturator hernia who were treated at the Japanese Red Cross Ishinomaki Hospital between 2016 and 2025. In all cases, ultrasound‑guided manual reduction was attempted. Manual reduction was performed under ultrasound guidance with the patient in a supine position, the affected leg abducted, flexed, and externally rotated. The surgeon identified the incarcerated bowel anterior to the adductor longus muscle using ultrasound. Reduction was achieved by manually compressing the posterior side of the adductor longus and the lateral labium majora until the hypoechoic mass disappeared [6, 7]. Procedure success was confirmed by post‑reduction CT (Fig. 1) [6, 7]. The patients were then categorized into “success” (n = 14) and “failure” groups (n = 21). After successful reduction, the decision between delayed elective repair and watchful waiting was made through shared decision-making and was primarily based on patient and family preference. Surgical procedures included laparoscopic transabdominal preperitoneal (TAPP) repair or anterior open repair. The surgical approach was determined based on anticipated bowel viability, the degree of proximal bowel dilatation due to obstruction, and the overall condition of the patient. Mesh repair was generally performed unless gross contamination or bowel resection was present.

Fig. 1.

Computed tomography (CT) images acquired before and after manual reduction. a CT scan showing an incarcerated small intestine (arrows) before manual reduction. b After the procedure, the incarcerated small intestine is resolved (arrows)

We compared the time from symptom onset to hospital visit, surgical approach (laparoscopic vs. open), timing (elective vs. emergency), bowel resection, mesh usage, and postoperative outcomes between the groups. Laboratory values [white blood cells (WBC), C-reactive protein (CRP), base excess, and lactate] upon admission were also assessed. Postoperative complications were classified according to the Clavien–Dindo classification (grades I–V) [8].

The institutional ethics committee or review board approved the study protocol (accession no. 25–04). Written informed consent was waived because of the retrospective design, and participation was offered on an opt-out basis through public disclosure.

Statistical analysis

Statistical analyses were performed using JMP Pro version 17 (SAS Institute, Cary, NC, USA). All tests were two-sided. Continuous variables are presented as mean (SD) and were compared using Student’s t-test. Categorical variables are presented as counts (percentages) and were compared using Fisher’s exact test. A P value < 0.05 was considered statistically significant. Given the small sample size and sparse cells, the results should be interpreted cautiously and are presented primarily as descriptive comparisons with P values.

Results

The patient outcome flowchart is shown in Fig. 2. Altogether, manual reduction was performed in 35 patients, including success and failure cases (Table 1). In 14 cases, manual reduction was successful. Seven patients opted for vigilant observation, and seven underwent elective surgery. Most watchful-waiting patients were promptly referred back to their primary/referring institutions after symptom resolution; therefore, long-term outcomes (including recurrence) could not be consistently ascertained in this subgroup. Among the patients who were scheduled for delayed elective surgery after successful reduction, the average waiting period before surgery was 32 days (SD: 31.2). Patients scheduled for delayed elective surgery were typically observed in hospital for approximately 5 days after successful reduction and then followed closely as outpatients until repair. No emergent complications were observed during this waiting period. A total of 21 patients had an unsuccessful manual reduction. The average time from symptom onset to the hospital visit tended to be shorter for patients in the success group than those in the failure group (38.9 vs. 51.8 h). There were no significant differences in preoperative laboratory values (WBC, CRP, base excess, or lactate) between the groups. Table 2 shows the surgical and clinical outcomes of surgically treated patients in the success and failure groups. Laparoscopic transabdominal preperitoneal repair was significantly more common for patients in the success group (43% vs. 5%, P = 0.04) (Fig. 3). Bowel resection was not necessary in any of the patients in the success group but was required in 53% of patients in the failure group (P = 0.02). Mesh was used in all patients in the success group and in 29% of patients in the failure group (P = 0.001). No complications related to manual reduction (e.g., bowel perforation) were observed. Clavien–Dindo grade III or higher postoperative complications were reported in 29% of patients in the failure group but were not reported for any patients in the success group. Postoperative complications included: (1) sputum retention (Clavien–Dindo IIIa), (2) anastomotic leakage (IIIb), (3) disseminated intravascular coagulation (V), (4) pneumonia (IV), (5) cholecystitis (IIIa), and (6) recurrent obturator hernia requiring reoperation (IIIb), which occurred in a patient who underwent patch repair without mesh.

Fig. 2.

Flowchart of patient outcomes. A total of 35 patients underwent manual reduction. The procedure was successful for 14 patients, of whom seven opted for watchful waiting. Of the 14 patients, seven underwent elective surgery. In total, 21 patients failed manual reduction and underwent emergency surgery

Table 1.

Patient characteristics of the success and failure cases

Clinicopathological features	Success (n = 14) (%)		Failure (n = 21) (%)		P-value
Age (years)†	87.6	(5.7)	86.7	(9.7)	0.76
Gender
Male	0	(0)	0	(0)	1.00
Female	14	(100)	21	(100)
Time from onset (hours)†	38.9	(66.7)	51.8	(58.6)	0.55
Laboratory findings
White blood cells†	7643	(3412)	8519	(3390)	0.46
C-reactive protein (mg/dL)†	0.6	(1.0)	2.2	(4.2)	0.17
Base excess (mmol/L)†	−1.3	(4.6)	−1.1	(6.2)	0.97
Lactate (mmol/L)†	1.3	(0.6)	2.4	(0.2)	0.17
†values are mean (SD)

^†Values are mean (SD)

*Indicates statistical significance. Student’s t-test was used to assess age, time to symptom onset, and laboratory findings. Fisher’s exact test was utilized to assess gender. Values in parentheses are percentages unless indicated otherwise

Table 2.

Surgical and clinical outcomes of surgically treated patients in the manual reduction success and failure groups

Clinicopathological features	Success (n = 7) (%)		Failure (n = 21) (%)		P-value
Surgical procedure
Open	4	(57)	20	(95)	0.04*
Laparoscopic	3	(43)	1	(5)
Postoperative complications
Absent	7	(100)	15	(71)	0.29
Present	0	(0)	6	(29)
Bowel resection
No	7	(100)	10	(47)	0.02*
Yes	0	(0)	11	(53)
Mesh repair
No	0	(0)	15	(71)	0.001*
Yes	7	(100)	6	(29)

†Values are mean (SD)

*Indicates statistical significance. Fisher’s exact test was performed. Values in parentheses are percentages unless indicated otherwise

Fig. 3.

Intraoperative findings during laparoscopic repair. a Distant view of obturator hernia (arrows). b Close view of obturator hernia. The hernia sac is inverted and not ligated (arrows). c A ULTRAPRO mesh was placed to reinforce the obturator foramen. d A 3D MAX light mesh was positioned to cover the myopectineal orifice (dashed line). Mesh repair was generally performed unless gross contamination or bowel resection was present

Discussion

This study shows that ultrasound-guided manual reduction is a safe and effective first-line treatment for incarcerated obturator hernia [6, 7, 9]. Successful reduction enabled elective surgery in all cases and was associated with a higher laparoscopic mesh repair rate, lower bowel resection incidence, and fewer severe postoperative complications.

Our findings are consistent with earlier studies suggesting that early intervention and successful non-invasive reduction may improve surgical outcomes [5, 10, 11]. Recently, ultrasound-guided manual reduction has been reported to be associated with a reduced need for bowel resection and improved recovery profiles in patients with obturator hernias [11]. Laparoscopic surgery has been reported to be feasible even in emergency settings, but elective surgery following successful reduction may further facilitate its safe application [12].

Because groups were defined retrospectively by reduction success, the observed associations should not be interpreted as causal. Reduction success likely reflects earlier presentation and less advanced ischemia, and may therefore serve as a marker of disease severity rather than the direct cause of better outcomes.

In our cohort, patients with failed manual reduction had longer intervals between the onset of their symptoms and hospital visit, possibly contributing to increased bowel ischemia [13]. This is consistent with a previous report that indicated that delayed presentation and unsuccessful reduction are predictive of bowel non-viability [14]. The large variability in time from symptom onset likely reflects nonspecific symptoms and delayed presentation, which are characteristic of obturator hernia. Although not statistically significant, lactate levels were numerically higher in the failure group, which may be clinically relevant and warrants validation in larger cohorts.

The waiting period before elective repair varied widely. In selected patients, delaying repair allowed improvement of proximal bowel dilatation after obstruction, which may facilitate safer minimally invasive handling. In addition, scheduling constraints during the COVID-19 era likely contributed to prolonged intervals in some cases. Importantly, no emergent complications were observed among patients scheduled for elective surgery during the waiting period.

Notably, no adverse events occurred during manual reduction, supporting that this technique is safe when performed under image guidance [6, 7, 9]. Based on these results, ultrasound-guided manual reduction should be regarded a valuable initial management option in suspected incarcerated obturator hernia cases.

The limitations of this study include its retrospective nature, small sample size, and single-center design, which limit statistical power and preclude causal inference. In addition, ultrasound-guided manual reduction is operator-dependent and outcomes may vary with surgeon experience. Finally, long-term recurrence outcomes were not consistently available, particularly for watchful-waiting patients who were promptly referred back to their primary institutions. Further prospective multicenter studies are warranted to validate these findings and to establish standardized selection criteria and reduction techniques.

Conclusion

Ultrasound-guided manual reduction for incarcerated obturator hernia appeared safe in our cohort and was associated with the feasibility of delayed elective surgery, a higher use of laparoscopic techniques and mesh repair, and lower rates of bowel resection and severe postoperative complications. Because reduction success may reflect disease severity and timing of presentation, it should be interpreted as a clinical marker that can guide surgical planning rather than proof of causality. Further multicenter prospective studies are needed to establish standardized protocols and clarify the prognostic value of reduction success, including long-term outcomes in conservatively managed patients.

Authors’ contributions

Y.G. designed the study, analyzed the data, and drafted the manuscript. R.N. reviewed and verified the surgical findings. Y.S., K.M., S.H., W.K., K.T., S.N., T.Y., H.T., K.S., K.S., J.T., F.S., Y.S., K.F., M.O., and H.I. critically reviewed and approved the final manuscript. All authors contributed to the supervision and final approval of the manuscript.

Funding

No funding was received for this research.

Data availability

The datasets analyzed during the current study are available from the corresponding author.

Declarations

Ethical approval and consent to participate

All procedures involving human participants were conducted in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study protocol was approved by the Institutional Review Board of the Japanese Red Cross Ishinomaki Hospital (approval no. 25–04). In accordance with the institutional policy for retrospective studies, the requirement for written informed consent was waived, and an opt-out approach was used. Information regarding the study was disclosed publicly, and patients were provided the opportunity to decline participation.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.