A 44-year-old woman comes to the emergency department with severe epigastric pain that radiates to her back. The pain was sudden in onset and has remained steady for the past several hours. She has associated nausea and vomiting. Past medical history is notable for a surgically repaired femoral hernia and appendectomy as a child. The patient takes no medications and does not use tobacco, alcohol, or recreational drugs. Temperature is 37.2 C (98.9 F), blood pressure is 112/70 mm Hg, pulse is 98/min, and respirations are 18/min. BMI is 35 kg/m². Examination shows an agitated woman who sits leaning forward on the bed. Her skin has no evidence of icterus or excoriations. Lungs are clear to auscultation and heart sounds are normal. There is moderate tenderness in the epigastrium but no guarding, rebound tenderness, or hepatosplenomegaly. Bowel sounds are normal. Laboratory results are as follows: Which of the following is the best next step in evaluating the underlying etiology for this patient's acute condition?

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11ec25c8_d8d6_430c_bc81_e9234a78cc15_MD0003_00 This patient has pancreatitis given her epigastric abdominal pain radiating to the back and the amylase/lipase levels >3 times the upper limit of normal (ULN). Gallstone pancreatitis is most likely as she does not use alcohol, takes no medications, has normal triglyceride and calcium levels, and has had no recent major illness. Her high BMI, alanine aminotransferase >150 U/L, and elevated alkaline phosphatase also suggest gallstone pancreatitis. A right upper-quadrant ultrasound is advised for all patients with suspected gallstone pancreatitis as it provides the most accurate information regarding the presence of gallstones. If the ultrasound is nondiagnostic and there is high clinical suspicion for common bile duct disease, endoscopic retrograde cholangiopancreatography (ERCP) may be performed to better visualize the biliary tree. (Choices A and C) CT scan is not required to diagnose pancreatitis in patients (such as this one) with typical abdominal pain and amylase/lipase levels >3 times ULN. It can be used to confirm the diagnosis and identify complications (eg, pancreatic hemorrhage or necrosis) in patients without these classic findings (eg, atypical abdominal symptoms, amylase/lipase elevation <3 times ULN). However, CT is not as sensitive as ultrasound for detecting gallstones. Plain radiographs also have a very low sensitivity for gallstones. (Choice B) Hepatobiliary iminodiacetic acid (HIDA) scan (cholescintigraphy) is used to diagnose acute cholecystitis if ultrasound does not provide a clear diagnosis. It is not routinely used to evaluate pancreatitis. (Choice E) Viruses (eg, hepatitis B, cytomegalovirus, varicella-zoster, HIV) are a less likely cause of pancreatitis in this patient. Serologic studies can be deferred unless standard testing does not identify the cause. (Choice F) Stool elastase is a marker for pancreatic exocrine function. Low levels would be seen in chronic, rather than acute, pancreatitis. Educational objective: Gallstones and chronic alcohol abuse are the most common causes of acute pancreatitis. Abdominal ultrasound is the most sensitive and specific imaging study to detect gallstones and should be performed in all patients with suspected gallstone-induced pancreatitis. References: New diagnostic criteria of acute pancreatitis. (http://www.ncbi.nlm.nih.gov/pubmed/20012328) Classification of acute pancreatitis--2012: revision of the Atlanta classification and definitions by international consensus. (http://www.ncbi.nlm.nih.gov/pubmed/23100216)

A 44-Year-Old Woman Comes to the Emergency Department with Severe