What are the first-line investigations for a patient with yellow stool, elevated bilirubin (hyperbilirubinemia), without diarrhea, nausea, vomiting, or abdominal pain, and is fractionated bilirubin the same as conjugated bilirubin?

From the Guidelines

For a patient with yellow stool, elevated bilirubin, and absence of diarrhea, nausea, vomiting, or abdominal pain, the first-line investigations should include liver function tests (ALT, AST, ALP, GGT), complete blood count, abdominal ultrasound, and fractionated bilirubin. Fractionated bilirubin is not exactly the same as conjugated bilirubin testing, although they are often used interchangeably in clinical practice, as noted in 1. This test separates total bilirubin into its direct (conjugated) and indirect (unconjugated) components, which is crucial in determining the origin of hyperbilirubinemia as pre-hepatic, hepatic, or post-hepatic. Yellow stool with elevated bilirubin suggests potential biliary obstruction or liver dysfunction. The ultrasound can identify biliary dilation, gallstones, or liver abnormalities, as recommended in 1 and 1. If these initial tests suggest obstruction, further imaging like MRCP or ERCP may be needed, as suggested in 1 and 1. If they suggest hepatocellular disease, viral hepatitis serology, autoimmune markers, and other specialized tests would be appropriate next steps. The absence of pain doesn't rule out serious pathology, as some conditions like pancreatic cancer can present with painless jaundice, making prompt investigation essential, as discussed in 1. Key points to consider in the investigation and management of such a patient include:

• The importance of differentiating between conjugated and unconjugated hyperbilirubinemia to guide further investigation and management.
• The role of imaging studies, particularly ultrasound, in identifying potential causes of biliary obstruction or liver dysfunction.
• The need for a comprehensive approach that includes laboratory tests, imaging, and potentially specialized tests to determine the underlying cause of jaundice and to guide management. Given the most recent and highest quality evidence from 1, which provides recommendations for imaging in patients with abnormal liver function tests, including those with hyperbilirubinemia, the initial imaging approach should include ultrasound and potentially other modalities like CT or MRI, depending on the specific clinical scenario and laboratory findings.

From the Research

Initial Investigations

If a patient presents with yellow stool, raised bilirubin, and no symptoms of diarrhea, nausea, vomiting, or abdominal pain, the initial investigations should include:

• A comprehensive medical history, review of systems, and physical examination to differentiate potential causes of jaundice, such as alcoholic liver disease, biliary strictures, choledocholithiasis, drug-induced liver injury, hemolysis, or hepatitis 2
• Laboratory evaluation, including:
  • Bilirubin (total and fractionated) to determine whether the hyperbilirubinemia is conjugated or unconjugated 2, 3
  • Complete blood cell count
  • Aspartate transaminase
  • Alanine transaminase
  • Gamma-glutamyltransferase
  • Alkaline phosphatase
  • Albumin
  • Prothrombin time
  • International normalized ratio

Fractionated Bilirubin and Conjugated Bilirubin

Fractionated bilirubin is not exactly the same as conjugated bilirubin, but rather it refers to the measurement of both conjugated and unconjugated bilirubin levels in the blood. Conjugated bilirubin is a subset of fractionated bilirubin, and an elevated level of conjugated bilirubin implies hepatocellular disease or biliary obstruction in most settings 3. Measuring fractionated bilirubin allows for the determination of whether the hyperbilirubinemia is conjugated or unconjugated, which can help guide further evaluation and diagnosis 2.

Imaging Studies

First-line options for imaging studies in patients presenting with jaundice include:

• Ultrasonography of the abdomen
• Computed tomography with intravenous contrast media
• Magnetic resonance cholangiopancreatography, depending on the suspected underlying etiology 2