Pitfalls in the diagnosis of gallbladder disease in clinically severe obesity

Cholelithiasis affects 10-20% of the USA population, with higher incidence in certain ethnic groups. Obesity is associated with an increase in gallstone formation, reported in up to 45% of morbidly obese patients. Ultrasound is the best diagnostic tool, although its accuracy is less in this particular population. This paper discusses false negative sonographic findings in morbid obesity.

Retrospective review of 5257 patients submitted to bariatric surgery. Cholecystectomy had previously been performed in 16%. Gallbladder ultrasound was obtained in the remaining group, and cholecystectomy was done based on this information and/or intraoperative observations. Radiology results and surgical findings were correlated with pathology reports. Misread films were reviewed by a radiologist blind to these reports.

The series consisted of 88% females. Mean age, weight and percentage overweight were 37 years, 125 kg and 105%, respectively. Cholecystectomy was performed in 3084 patients (59%). Discrepancies between radiological and pathological findings were found in 35 cases (1.1%). Five correct diagnosis of lithiasis also had gallbladder hydrops. Four 'inconclusive' and 20 'negative' studies showed definitive pathology. In six cases of 'non/poor visualization', lithiasis was encountered.

Preoperative gallbladder ultrasound is mandatory in bariatric surgery. Results are accurate and false-negative reports rare if sonographers and radiologists are experienced. Non/poor visualization is usually due to technical problems or gallbladder pathology, not due to the patient's size. False-negative results are commonly caused by soft stones, microlithiasis or polypoid cholesterolosis. Single calculus impacted in the cystic duct can produce hydrops, resulting in a negative sonogram.