From the Guidelines
For a patient with yellow stools, elevated bilirubin, and absence of diarrhea, nausea, vomiting, or abdominal pain, the first-line investigations should include liver function tests (LFTs), complete blood count (CBC), and abdominal ultrasound. These tests will help evaluate for obstructive jaundice, which is suggested by the yellow stools (indicating excess bile pigment) and elevated bilirubin. The LFTs should include alkaline phosphatase, gamma-glutamyl transferase, AST, ALT, and fractionated bilirubin to distinguish between conjugated and unconjugated hyperbilirubinemia, as recommended by the American College of Radiology 1.
The pattern of elevation can help differentiate between hepatocellular and cholestatic causes. CBC may reveal anemia if there's chronic liver disease or hemolysis contributing to the hyperbilirubinemia. Abdominal ultrasound is crucial to visualize the biliary tree, assess for bile duct dilation, gallstones, or masses that might be causing obstruction, with a specificity ranging between 71% to 97% for confirming the absence of mechanical obstruction 1.
The absence of pain, nausea, and vomiting suggests a gradual rather than acute process, potentially indicating conditions like painless jaundice from pancreatic cancer, primary biliary cholangitis, or medication-induced cholestasis. If these initial tests are inconclusive, further investigations like MRCP, ERCP, or liver biopsy may be warranted based on the preliminary findings, as suggested by the ACR Appropriateness Criteria for abnormal liver function tests 1.
Some key points to consider in the initial evaluation include:
- The clinical presentation and laboratory findings to categorize the type of jaundice 1
- The use of abdominal ultrasound as the initial imaging modality to evaluate the biliary tree and assess for obstruction 1
- The consideration of further imaging or invasive tests based on the initial findings and clinical suspicion 1
From the Research
Initial Investigations
To approach a patient with yellow stool, raised bilirubin, and no symptoms of diarrhea, nausea, vomiting, or abdominal pain, the following initial investigations can be considered:
- Fractionation of total bilirubin to direct and indirect bilirubin fractions to determine if the elevation is due to conjugated or unconjugated bilirubin 2
- Assessment of liver chemistries, including serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase to determine the pattern of liver injury (hepatocellular or cholestatic) 2
- Testing for viral hepatitis A, B, and C, as well as screening for nonalcoholic fatty liver disease and alcoholic liver disease 2
- Evaluation for hereditary hemochromatosis, autoimmune hepatitis, Wilson's disease, and alpha-1 antitrypsin deficiency 2
- Review of prescribed and over-the-counter medications that may be contributing to the liver chemistry abnormalities 2
Further Evaluation
If the initial investigations suggest a cholestatic pattern of injury, further testing for primary biliary cholangitis and primary sclerosing cholangitis may be warranted 2 If the diagnosis remains unclear after serologic testing and imaging, a liver biopsy may be considered to stage a condition or to evaluate for multiple possible diagnoses 2