What is the best initial imaging study for a 41-year-old female with a 3-month history of steatorrhea (floating stool) and a slightly positive Murphy's sign, who is concerned about early pancreatic cancer?

Gallbladder Ultrasound is the Appropriate Initial Imaging Study

For a 41-year-old female with a slightly positive Murphy's sign and 3-month history of floating stools, order a right upper quadrant ultrasound to evaluate for cholecystitis and biliary pathology first, as this is the most likely diagnosis and ultrasound is the investigation of choice for suspected gallbladder disease. 1

Clinical Reasoning

Murphy's Sign Points to Gallbladder Disease

• A positive Murphy's sign is a specific clinical finding for acute cholecystitis and should be evaluated with ultrasound as the first-line imaging modality 1
• Ultrasound can detect gallstones, pericholecystic fluid, distended gallbladder, edematous gallbladder wall, and can elicit Murphy's sign during the examination itself 1
• The combination of right upper quadrant symptoms with Murphy's sign makes cholecystitis far more likely than pancreatic cancer in this clinical scenario 1

Steatorrhea (Floating Stools) Can Be Explained by Biliary Obstruction

• Chronic gallbladder disease with intermittent biliary obstruction can cause fat malabsorption and steatorrhea over months 1
• This is a more common explanation than pancreatic insufficiency in a 41-year-old with Murphy's sign 1

Why Not Jump to Pancreatic Cancer Workup?

• This patient lacks high-risk features for pancreatic cancer screening: She has no family history mentioned, no genetic mutations (BRCA1/2, PALB2, ATM, CDKN2A, STK11), and is not in a high-risk category that would warrant pancreatic surveillance 1, 2
• Pancreatic cancer screening with MRI/MRCP or EUS is reserved for high-risk individuals with genetic predisposition and family history, typically starting at age 45-50 1, 2
• At age 41 without risk factors, the pre-test probability of pancreatic cancer is extremely low 1
• Pancreatic cancer typically presents with painless jaundice (for head lesions), severe abdominal or back pain, weight loss, or new-onset diabetes in patients over 50—not with Murphy's sign 1, 3

Diagnostic Algorithm

Step 1: Right Upper Quadrant Ultrasound

• Order this immediately as the first-line test 1
• Look for: gallstones, gallbladder wall thickening (>3mm), pericholecystic fluid, dilated bile ducts, and sonographic Murphy's sign 1

Step 2: If Ultrasound Shows Cholecystitis

• Proceed with appropriate management: early laparoscopic cholecystectomy (within 7-10 days) for uncomplicated cases 1
• Consider antibiotic therapy if surgery is delayed 1

Step 3: If Ultrasound Shows Dilated Bile Ducts or Is Inconclusive

• Consider MRCP to evaluate for common bile duct stones or other biliary pathology 1
• MRCP is superior to CT for evaluating the biliary tree and pancreatic duct 1

Step 4: If Biliary Pathology Is Ruled Out AND Steatorrhea Persists

• Only then consider pancreatic evaluation with contrast-enhanced CT or MRI/MRCP to assess for chronic pancreatitis or other pancreatic pathology 1, 4
• Check fecal elastase to confirm pancreatic insufficiency if suspected 4

Common Pitfalls to Avoid

Don't Skip the Obvious Diagnosis

• Murphy's sign has high specificity for cholecystitis—don't be distracted by the patient's cancer anxiety 1
• Floating stools alone do not indicate pancreatic cancer; they indicate fat malabsorption which has many causes, most commonly biliary 1

Don't Order Advanced Imaging Prematurely

• Starting with MRI/MRCP or CT for suspected gallbladder disease wastes resources and exposes the patient to unnecessary testing 1
• Ultrasound is more sensitive than CT for detecting gallstones and is the guideline-recommended first test 1

Don't Perform ERCP for Diagnosis

• ERCP should only be used therapeutically to relieve bile duct obstruction, not for initial diagnosis 1
• Preoperative biliary stenting increases serious complications and should only be done if surgery cannot be performed expeditiously 1

Addressing the Patient's Cancer Concern

Reassurance Based on Risk Stratification

• At age 41 without family history or genetic risk factors, this patient does not meet criteria for pancreatic cancer screening 1, 2
• The clinical presentation (Murphy's sign) strongly suggests benign gallbladder disease rather than malignancy 1
• If gallbladder pathology is confirmed and treated, and symptoms resolve, no further pancreatic evaluation is needed 1

When to Escalate Concern for Pancreatic Pathology

• New-onset diabetes in a patient over 50 with weight loss would warrant pancreatic evaluation 3
• Pancreatic duct dilation ≥5mm on any imaging would require MRI/MRCP for further characterization 3
• Unexplained acute pancreatitis would necessitate investigation for underlying pancreatic lesions 3, 4
• Persistent symptoms after appropriate treatment of biliary disease would warrant pancreatic imaging 4