What are the key diagnostic criteria for Primary Sclerosing Cholangitis (PSC) in adults?

Key diagnostic criteria for primary sclerosing cholangitis (PSC) in adults include a combination of clinical, biochemical, and imaging findings. Diagnosis is primarily based on cholestatic liver biochemistry with persistently elevated alkaline phosphatase levels, alongside characteristic cholangiographic features showing multifocal strictures and segmental dilatations of the intrahepatic and/or extrahepatic bile ducts on magnetic resonance cholangiopancreatography (MRCP) or endoscopic retrograde cholangiopancreatography (ERCP).

Typical imaging findings are essential to distinguish PSC from other causes of cholestasis, with MRCP preferred as a non-invasive first-line modality. Liver biopsy is not routinely required but may be used when imaging is inconclusive or to assess for overlap syndromes or small-duct PSC.

Exclusion of secondary causes of sclerosing cholangitis, such as bile duct injury, IgG4-related disease, or cholangiocarcinoma, is critical before confirming PSC diagnosis. The presence of associated inflammatory bowel disease, especially ulcerative colitis, supports the diagnosis but is not mandatory.

Recent 2024 diagnostic criteria emphasize the importance of typical cholangiographic findings combined with biochemical cholestasis and exclusion of mimics, reflecting advances in imaging and understanding of disease heterogeneity (Naitoh et al., 2025). UK clinical practice aligns with these principles, recommending MRCP as the initial diagnostic imaging and reserving ERCP for therapeutic or diagnostic uncertainty cases ⁵.