Clinical and ultrasonographic predictors of biliopancreatic malignancy in patients with biliary obstruction and an unclear diagnosis

Abstract

BACKGROUND: The ability to distinguish benign vs malignant causes of biliary obstruction using clinical and/or ultrasonographic features is of interest, especially with the advent of MRCP and ERCP. AIM: We prospectively followed patients at intermediate risk of having biliary obstruction after ultrasonography (US) and clinical exam, undergoing ERCP or MRCP for further investigation to evaluate clinical/ultrasonographic predictors of a malignant cause of obstruction. METHODS: Over 24 months, 162 patients with suspected biliary obstruction, whose clinical examination coupled to initial US did not make a definitive diagnosis as to the cause of the obstruction, randomly underwent either ERCP (n=80) or MRCP (n=82). The diagnoses made at the time of MlERCP were categorized as malignant or benign and subsequent information gained from clinical follow-up (at 3, 6, and 12 mos) or interval investigations was used to confirm or refute the diagnosis. Univariate and multivariate analyses were performed to look at the following predictors of malignant obstruction: Age, gender, weight loss, clinical jaundice, palpable mass, right upper quadrant pain, previous cholecystectomy, gallstone on ultrasound, hemoglobin, INR, ALT, alkaline phosphatase (ALP), bilirubin, amylase, and 4 US findings (common bile duct dilatation (CBDD), intrahepatic duct dilatation (IHDD), pancreatic duct dilatation (PDD), and level of obstruction). RESULTS: A diagnosis of malignancy was made in 4.9% of patients in the study population. Of the 8 malignancies, there were 3 patients with cholangiocarcinoma, 3 with pancreatic cancer, and 2 with metastatic disease. Of these, 7 (87.5%, 95%CI: [59.8,115] required a therapeutic ERCP. In univariate analysis, only the following US features were predictive of malignancy (OR; [95%CI]): level of obstruction within the CBD (16.2; [3.4,77]), CBDD (8.6; [1.7,45]), IHDD (28.5; [3.5,234]), PDD (13.1; [2.5,68]), and US suspicion of malignancy (75.2; [10.6,534]). Other clinical variables did not reach statistical significance. In multivariate analysis, an US suspicion of malignancy was the only factor independently predictive of a malignant diagnosis. CONCLUSIONS: In patients in whom no clear diagnosis exists after history, physical exam and ultrasound, I) clinical factors are not helpful in distinguishing benign and malignant causes of biliary obstruction and 2) even a weak suspicion of malignancy on US is an important predictor.