Positive predictive value of ultrasound in correctly identifying an inguinal hernia: a single-centered retrospective pilot study

Objectives: To determine the clinical utility of preoperative ultrasound imaging for predicting an inguinal hernia in need of surgery. In addition, we aimed to identify factors associated with false positive (FP) ultrasound examinations. Methods: In this retrospective pilot study, we included all 175 patients who underwent inguinal hernia surgery in our hospital in 2019 and of whom a positive preoperative ultrasound examination of the groin area was available. The positive predictive value (PPV) of the ultrasound examination was determined using inguinal hernia detected during surgery (yes/no) as golden standard. To identify possible predictive factors, we compared the characteristics of patients with a FP ultrasound with patients with a true positive (TP) ultrasound. Results: PPV of ultrasound examinations to identify an inguinal hernia in need of surgery correctly was 90.9% (159/175). The patients with a FP ultrasound examination had a significantly higher body mass index (BMI) than the patients with a TP ultrasound examination (27.6 ± 4.2 vs 25.8 ± 2.3, p = 0.043). Conclusions: With a false positive percentage of 9.1%, there is still room for improvement of preoperative diagnostic imaging. Studies with larger cohorts are necessary to establish prediction models that have the potential to reduce FP ultrasound results.