The sensitivity of ultrasound in the clinical diagnosis of inguinal hernias in adults: a comparative study

Abstract

Objective

Ultrasonography (US) is a non-invasive, non-ionizing radiation modality highly successful at diagnosing inguinal hernia. The aim of this study is to demonstrate the accuracy of ultrasound in evaluating defects of fascia in inguinal hernias and compare with surgical findings.

Material and methods

A total of 33 patients with a sonographic diagnosis of an inguinal hernia are included to study. After US, all patients underwent a blinded surgery and the surgical findings are compared with the US results.

Results

The sensitivity of US was found to be 100% and 80% for indirect and direct types, respectively. The mean size of the defect was found to be 22 mm (max: 70 mm, min: 6 mm) with US; and 27 mm (max: 50 mm, min: 4 mm) at surgery. The size of defects at US and in surgery were correlated with each other (p = 0.001).

Introduction

An inguinal hernia is defined as displacement of organs from the abdominal cavity through the inguinal floor. It encompasses direct and indirect subtypes. A direct inguinal hernia arises from protrusion of abdominal viscera through a weakness of the posterior wall of the inguinal canal medial to the inferior epigastric vessels. An indirect inguinal hernia arises lateral and superior to the course of the inferior epigastric vessels, lateral to Hesselbach's triangle, and then protrude through the deep or internal inguinal ring into the inguinal canal.

Most patients were clinically diagnosed. However, in some patients the inguinal hernia may not be clinically apparent (nonpalpable, no lump after valsalva maneura etc.). Computed tomography (CT) and magnetic resonance imaging (MRI) are highly accurate imaging modalities for diagnosing both the presence and the type of inguinal hernia. The sensitivities, specificities, and accuracies are approaching 100% with these modalities [1, 2]. Ultrasonography (US) is an alternative diagnostic method to CT and MRI for diagnosing inguinal hernia [3]. Unlike CT and MRI, it is a readily available, accessible, and less expensive technique. It also allows for a dynamic assessment and has no ionizing radiation. Recent studies have shown high accuracy of US in the detection of both the presence and the type of groin hernias [2, 4]. To the best of our knowledge, there is no study that measures the fascia defects in inguinal hernia. In this study, the fascia defects of inguinal hernias were measured by US and intraoperatively and results were compared.

Material and methods

This study was approved by Health Sciences University Kartal Dr Lütfi Kırdar City Hospital, Istanbul, Turkey University Institutional Ethics Committee (Protocol number: 514/196/1-24.02.2021). An informed consent was obtained from each participant. All patients referred for US examination for suspected inguinal hernia in our institution from September 2020 and January 2021 were included in the study. Patients with previous inguinal surgery were excluded from the study. The height and weight of the patients were recorded; body mass index (BMI) was calculated. All US examinations were performed by the same musculoskeletal radiologist. The patients were placed in the supine position. Sonographic examination of inguinal hernia was performed by a Toshiba Aplio 500 device (Toshiba Medical Systems Corporation, Tokyo, Japan) using a 12 MHz linear transducer. The transducer position was placed in the transverse-oblique plane and the inferior epigastric artery was identified. Valsalva maneuver was performed. The deep inguinal ring and fascia defect were evaluated on the inguinal region (Fig. 1). The maximum transverse diameter of the defect was measured during the Valsalva maneuver. The presence of omentum and bowel in the hernia sac was evaluated. An inguinal hernia was diagnosed by identifying a hernia sac communicating with the peritoneal cavity containing fat or the bowel protruding though a fascial defect. If a hernia sac was located medial to the inferior epigastric artery, it was defined a direct inguinal hernia; if the sac was located lateral to the inferior epigastric artery, it was defined an indirect inguinal hernia. US images were archived digitally. The patients who were diagnosed with an inguinal hernia by US were referred for surgery. The surgeon was blind to the types of inguinal hernias and size of fascia defects (Fig. 2). All the surgeries were performed by the same General Surgery team. The surgery was performed laparoscopically (Transabdominal Preperitoneal technique). The type of hernia and hernia sac (fat or bowel contents) were evaluated. The maximum transverse diameter of the fascia defect was measured with measuring tape. Finally, sonographic and surgical results were compared. A single radiologist and a single surgeon took measurements independently of each other. Therefore, the interobserver did not share variability for the study.

Fig. 1.

A 54-year-old man with a right inguinal hernia: There was a fascia defect of the inguinal floor on US and protrusion of the omental fat tissue to the inguinal canal with Valsalva maneuver. The maximum diameter of the fascia was measured on US (points)

Fig. 2.

The same patient’s image at the time of operation. The maximum transverse diameter of the fascia defect was measured with measuring tape during laparoscopic surgery

Statistical analysis

IBM SPSS 21.0 (Statistical Package for the Social Sciences version 21, SPSS Inc., Chicago, IL, USA) for windows statistical package program was used for the statistical evaluation of our research data. Descriptive methods were used for the evaluation of the data, one-way analysis of variance for comparison between groups, independent t-test of the two groups and chi-square test for qualitative comparison. p < 0.05 was found to be significant.

Results

Fifty patients who presented to the General Surgery clinic with complaints of inguinal pain and had suspicious inguinal hernia on physical examination were included in the study. Fifty patients were evaluated by US. Thirty-three (29 men, 4 women) patients were diagnosed with inguinal hernia by US and all of them underwent surgery. The demographic results of the patients are given in the Table 1.

Table 1.

Patients characteristics (n = 33)

n =  33	Mean	Maximum	Minimum
Age	53	84	26
Weight (kg)	78	94	62
Height (cm)	174	182	165
BMI (kg/m2)	26	30	21

Thirty-two patients were found to have indirect type hernia and one patient was found to have direct type hernia with US. During surgery, Twenty-two patients were found to have only indirect type, four patients had only direct type, and seven patients had direct and indirect type hernias. The mean size of the defect was found to be 22 mm (max: 70 mm, min: 6 mm) with US and it was found to be 27 mm (max: 50 mm, min: 4 mm) during surgery. The size of the defects with US and in surgery were correlated with each other (p = 0.001) (p < 0.05).

Discussion

An inguinal hernia is a frequently diagnosed condition with an important impact on daily activities. There is a predominance in the age range between 50 and 69 years [1, 4]. The typical complaints and/or physical examination were accurate to identify inguinal hernias [5]. Nevertheless, if a hernia is not detected clinically, the patient may not be offered curative surgery. The patients must be referred to imaging modalities [6]. The first method described was herniography; described for the first time in 1967. It is an invasive technique, involving the use of intraperitoneal contrast injection. It is not preferred in daily practices because of radiation, the risk of complications and because it lacks the visualization of adjacent soft tissue structures [7]. CT and MRI are additional options for the diagnosis of inguinal hernias. They can clearly show the location of the anatomic site of the hernial sac and its contents. CT has been useful in occult or atypical hernias, with sensitivity of CT and specificity of 67–83% [8]. Furthermore, CT can depict occlusive bowel complications caused by incarceration or strangulation in patients with acute symptoms. The sensitivity and specificity of MRI are around 94 and 96%, respectively. Van Den Berg et al. found that US and MRI showed similar sensitivity and specificity of 92.7, 81.5 and 94.5, 96.3% against a surgical outcome for inguinal hernias respectively [9]. Although these imaging modalities have good sensitivity and specificity, both of them are expensive techniques and not easily available. US, has excellent inherent soft tissue contrast and resolution for groin evaluation. It is a costeffective, noninvasive, reliable and without radiation (unlike herniography and CT) diagnostic method that allows for real-time examination with provocative Valsalva maneuver. It is also helpful at the time to differentiate other pathologies such as incisional hernia, femoral hernia, lipoma, nuck cyst, varicocele, hydrocele, lymph node enlargement, endometriosis, sebaceous cysts, abscesses etc. [8]. On the other hand, it has the limitation of operator-dependence [9]. So, it is important for sonographers to use a technique that maximizes the diagnostic accuracy of this examination [10]. Mathews et al. proposed that in patients with normal or doubtful clinical examination, the US can be considered valid for diagnostic clarification [11]. Mike Bradley et al. agreed that US diagnoses all the hernias (sensitivity and specificity 100%) and correctly differentiates the types of inguinal hernias [7, 12]. Babkova and Bozhko also demonstrated a sensitivity of 84.3% and 71.1% for indirect and direct hernias respectively [13]. In the present study, the sensitivity of US was found to be 100% and 80% for indirect and direct types respectively. To the best of our knowledge, this is the first study to evaluate the defects of fascia and deep inguinal ring on both US and surgery in inguinal hernias. We showed and agreed that the size of the defects with US and in surgery were correlated with each other (p = 0.001) (p < 0.05).

Laparoscopic or open surgical repair are the standard treatment methods for inguinal hernia patients. In surgical planning, the size of the defect is directly related to the difficulty of the operation and surgical success [14]. This study has several limitations. First, the sample size was small. Second, evaluation of the inguinal region was performed by a single radiologist and by the same surgical team.

Conclusion

US is a helpful imaging modality used to evaluate the inguinal region and has high accuracy compared between surgery results. It needs to be studied further with larger sample sizes and also including a control group in the future.

Author contributions

Concept: MAG; Design: MAG, MTK; Supervision: AKB, Funding: MAG, AKB; Materials: MAG, AKB; Data Collection and/or Processing: MAG, AKB; Analysis and/or Interpretation: AKB, MTK; Literature Review: MTK; Writer: MAG, AKB, MTK; Critical Review: MTK.

Funding

The authors declared that this study has received no financial support.

Declarations

Conflict of interest

No conflict of interest was declared by the authors.

Ethical approval

This study was approved by Health Sciences University Kartal Dr Lütfi Kırdar City Hospital Institutional Ethics Committee (Protocol number: 514/196/1- 24.02.2021).

Informed consent

Written informed consent was obtained from patient who participated in this study.