Abstract: Ten studies including 5056 participants met the inclusion criteria for this review and assessed the diagnostic accuracy of the index tests in people presenting to the emergency department with acute abdominal pain. The risk of bias was unclear or high for all of the included studies. The study that contributed approximately two-thirds of the participants included in this review was excluded from the results of the analysis presented below due to major concerns about the participants included in the study. We have presented only the results where at least two studies were included in the analysis. Serum amylase, serum lipase, and urinary trypsinogen-2 at the standard threshold levels of more than three times normal for serum amylase and serum lipase, and a threshold of 50 ng/mL for urinary trypsinogen-2 appear to have similar sensitivities (0.72 (95% CI 0.59 to 0.82); 0.79 (95% CI 0.54 to 0.92); and 0.72 (95% CI 0.56 to 0.84), respectively) and specificities (0.93 (95% CI 0.66 to 0.99); 0.89 (95% CI 0.46 to 0.99); and 0.90 (95% CI 0.85 to 0.93), respectively). At the median prevalence of 22.6% of acute pancreatitis in the studies, out of 100 people with positive test, serum amylase (more than three times normal), serum lipase (more than three times normal), and urinary trypsinogen (more than 50 ng/mL), 74 (95% CI 33 to 94); 68 (95% CI 21 to 94); and 67 (95% CI 57 to 76) people have acute pancreatitis, respectively; out of 100 people with negative test, serum amylase (more than three times normal), serum lipase (more than three times normal), and urinary trypsinogen (more than 50 ng/mL), 8 (95% CI 5 to 12); 7 (95% CI 3 to 15); and 8 (95% CI 5 to 13) people have acute pancreatitis, respectively. We were not able to compare these tests formally because of sparse data. As about a quarter of people with acute pancreatitis fail to be diagnosed as having acute pancreatitis with the evaluated tests, one should have a low threshold to admit the patient and treat them for acute pancreatitis if the symptoms are suggestive of acute pancreatitis, even if these tests are normal. About 1 in 10 patients without acute pancreatitis may be wrongly diagnosed as having acute pancreatitis with these tests, therefore it is important to consider other conditions that require urgent surgical intervention, such as perforated viscus, even if these tests are abnormal. The diagnostic performance of these tests decreases even further with the progression of time, and one should have an even lower threshold to perform additional investigations if the symptoms are suggestive of acute pancreatitis.

Plain-language summary: We identified 10 studies reporting information on 5056 people with abdominal pain that started suddenly. The studies included pancreatitis due to all causes. All of the studies were of unclear or low methodological quality, which may result in arriving at false conclusions. We excluded the study that contributed approximately two-thirds of the participants included in this review from the results of the analysis presented below due to concerns about whether the participants included in the study are typical of those seen in the emergency department. The accuracy of serum amylase, serum lipase, and urinary trypsinogen-2 in making the diagnosis of acute pancreatitis was similar. About a quarter of people with acute pancreatitis fail to be diagnosed as having acute pancreatitis with these tests. The patient should be admitted and treated as having acute pancreatitis, even if these tests are normal, if there is a suspicion of acute pancreatitis. As about 1 in 10 patients without acute pancreatitis may be wrongly diagnosed as having acute pancreatitis with these tests, it is important to consider other conditions that require urgent surgery, even if these tests are abnormal. The diagnostic performance of these tests decreases even further with the progression of time, and additional investigations should be performed if there is a suspicion of acute pancreatitis.