Contralateral groin management during unilateral hernia repair is controversial. Approximately 10% of these patients will develop MCIH later on with the need to have a second operation and anesthesia. Contralateral groin exploration is frequently used to detect CPPV, but it carries the risk of operative complications, and closing the processus vaginalis will be useless [11]. This will help the surgeon decide whether to explore the contralateral groin if the US could accurately predict the presence of CPPV. Our study measured the WLIR during rest, and we used > 4 mm to diagnose PPV (patent processus vaginalis). Chen et al. [4], Chou et al. [12], and Kervancioglu et al. [13] accepted the same values for diagnoses. All patients underwent a contralateral side laparoscopic exploration, which showed a 36.6% CPPV incidence, 42.1% with a right-sided hernia, and 27.3% with a left-sided hernia. CPPV incidence in our series is similar to Shehata et al. (35.8%) [14] and lower than Zhoa et al. (51%) [15]. At laparoscopy, Zhoa et al. [15] and Schier et al. [16] reported a higher CPPV incidence in left-sided hernia compared to right-sided hernia (53.4% vs. 50.2% and 23% vs. 22% respectively). Our study revealed a higher CPPV incidence in patients who presented with a right-sided OIH and this may be because of the small sample size.

In our study, the preoperative US diagnosis and the contralateral side laparoscopic diagnosis were concordant in 19 (63.3%) patients and discordant in 11 (36.6%) patients. US showed a sensitivity of 50.00%, specificity of 72.22%, and accuracy of 63.3% in diagnosing CPPV. Chou et al. [12] examined the US values in the preoperative CPPV detection, wherein 179 patients underwent a US examination and contralateral side surgical exploration. They reported a sensitivity of 92.3%, a specificity of 93.7%, and a diagnostic accuracy of 93.2%. Chen et al. [4] explored only the contralateral side with positive US findings and revealed that the US accuracy in both symptomatic and asymptomatic sides based on the width of the internal ring was 95%. Kervancioglu et al. [13] revealed that the sensitivity, specificity, and accuracy of US were 95.4%, 85.7%, and 94.9%, respectively. In contrast to our study, they included both the presenting and contralateral sides and also explored only groins with positive findings.

Meanwhile, Lawrenz et al. [17] reported a 65% diagnostic accuracy, 78% sensitivity, and 20% specificity. These figures were reached by prospectively comparing the US finding (maximum diameter of the inguinal canal) and operative findings in both groins of 23 infants presenting with a unilateral inguinal hernia. Namgoong et al. [18] reported a 20.5% sensitivity, 95.2% specificity, 75% PPV, and 63.2% NPV, with 64.5% accuracy. These figures were reached by retrospectively comparing the US (abnormal shading) and laparoscopic findings of the contralateral side of 107 infants who presented with a unilateral inguinal hernia.

These differences in sensitivity, specificity, and accuracy of US in predicting CPPV may be explained using different sonographic criteria for PPV diagnosis in these reports. Additionally, some reports explored only the contralateral side with positive US findings. Further, we found WLIR as a problematic criterion because the internal ring is funnel-shaped, and a more precise point should be considered as a guideline for the examiner.

Our study had limitations. First, our sample size is small. Second, we only measured WLIR during rest to preoperatively diagnose CPPV.

Therefore, future studies should be conducted to determine the effect of increasing intra-abdominal pressure (straining or valsalva) on the accuracy of measuring WLIR to diagnose CPPV and compare WLIR measurement to other sonographic findings, including mid-canal width, PPV as a cyst at the internal ring, widened PPV with increases in abdominal pressure, and the PPV that contains moving fluid.