Letters to the EditorRe: Alanine transaminase rather than abdominal ultrasound alone is an important investigation to justify cholecystectomy in patients presenting with acute pancreatitis

I write with reference to the informative study by Anderson and colleagues on the use of alanine transaminase (ALT) as an indicator of gallstone pancreatitis, published in a recent edition of this journal.1 Alkaline phosphatase (ALP) and γ-glutamyl transferase (GGT) have been shown to be sensitive indicators for the presence of common bile duct stones and cholangitis;2,3 however, ALT is a more sensitive, but less specific, parameter. We read with interest Anderson et al.'s description of the role of ALT in the treatment of acute pancreatitis1 and would like to resolve our subsequent queries and offer several comments. What was the reference standard for the diagnosis of gallstones? Did any patients with negative initial ultrasound (US) undergo a repeat interval US? Once the episode of acute pancreatitis has resolved, repeat US should become as sensitive for detecting gallstones as it is in subjects without pancreatitis (92–98%).4,5 We would disagree with the statement that a negative US should be interpreted as a reason not to proceed to cholecystectomy. In our practice, patients with a negative initial US undergo subsequent US either prior to discharge or at the first outpatient review. This eliminates the difficulty involved in interpreting the US scan when ileus is present and increases sensitivity. When two US scans are negative, the patient does not drink significant amounts of alcohol and rare causes are excluded, we would discuss cholecystectomy and cholangiography with any patient fit for surgery. Investigations with low risk for morbidity that are designed to identify the main risk factor are imperfect, whereas those with a higher sensitivity carry costs and risks for morbidity that are not much lower than those of cholecystectomy and cholangiography. According to Anderson et al.,1 patients with alcoholic pancreatitis were excluded on the basis of history of alcohol consumption (>40 units of alcohol per week) and no US evidence of gallstones. This is contradictory, as the authors state that the sensitivity of US to detect gallstones in the setting of acute pancreatitis falls. Furthermore, patients with alcoholic pancreatitis may have incidental gallstones, whereas patients with gallstone pancreatitis may drink moderate amounts of alcohol. We perform US in patients with pancreatitis not only to find gallstones, but to image the pancreatic head, liver texture and, most importantly, the biliary tree. For patients with common bile duct stones, endoscopic retrograde cholangiopancreatography (ERCP) may represent the initial step in a management strategy. Other centres perform cholecystectomy with transcystic exploration of the bile duct (laparoscopic or open).6,7 In both instances, preoperative US is an integral step. Furthermore, some patients with pancreatitis, who are not suitable for cholecystectomy, may benefit from ERCP or sphincterotomy, neither of which is performed without prior US.