A prospective, blinded comparison of laparoscopic ultrasound with transabdominal ultrasound for the detection of gallbladder pathology in morbidly obese patients

Background: Transabdominal ultrasound (TAU) is the gold standard for detecting cholelithiasis. Morbid obesity can inhibit detection of gallbladder pathology due to increased subcutaneous and visceral fat. Laparoscopic ultrasound (LUS) has the potential to overcome these technical challenges. We hypothesized that LUS would have a sensitivity and specificity similar to TAU for detecting cholelithiasis and polyps in morbidly obese patients presenting for laparoscopic Roux-en-Y gastric bypass. Study Design: After Institutional Review Board approval, patients underwent preoperative TAU and intraoperative LUS during laparoscopic Roux-en-Y gastric bypass. Certified ultrasonographers performed all TAUs. Surgeons, blinded to TAU results, performed the LUS. Presence of cholelithiasis or polyps and common bile duct diameter was evaluated. Statistical analysis included chi-square and McNemar's test. Results: Two hundred and fifty-three patients were prospectively enrolled during a 6-year period. Seventy-six percent were female, mean age and preoperative body mass index (calculated as kg/m²) were 43.5 years and 48, respectively. Mean time to complete the LUS was 4 minutes. Mean common bile duct diameter measured 3.7 mm via LUS and 4.0 mm via TAU. Transabdominal ultrasound and LUS identified 61 and 60 patients with cholelithiasis, respectively (p = 0.763). The sensitivity and specificity of LUS for cholelithiasis was 90.2% and 97.4%. Laparoscopic ultrasound identified polyps in 41 patients, and TAU identified polyps in 6 patients, 5 of which had polyps identified on LUS as well (p < 0.001). Sensitivity and specificity of LUS for polyps was 83.3% and 85.4%. Conclusions: Laparoscopic ultrasound is equivalent to TAU in detecting cholelithiasis, however, LUS detected significantly more polyps. Intraoperative LUS is an appropriate alternative to TAU in patients undergoing laparoscopic Roux-en-Y gastric bypass.