What are the key diagnostic criteria for intrahepatic cholestasis of pregnancy (ICP) in a patient presenting with pruritus?

In a patient presenting with pruritus suggestive of intrahepatic cholestasis of pregnancy (ICP), the key diagnostic criteria include the presence of unexplained pruritus, particularly on the palms and soles, accompanied by elevated maternal serum bile acid concentrations and abnormal liver function tests (LFTs) such as raised transaminases and gamma-glutamyl transferase. Diagnosis requires exclusion of other hepatic or systemic causes of liver dysfunction, including pre-eclampsia, fatty liver of pregnancy, viral hepatitis (A, B, C), Epstein-Barr virus, cytomegalovirus, and autoimmune liver diseases like primary biliary cirrhosis. Serum bile acid measurement is essential, as elevated bile acids are the hallmark biochemical marker supporting the diagnosis. If bile acids and LFTs are normal but pruritus persists, weekly monitoring is recommended until resolution or further specialist assessment if symptoms worsen. Liver ultrasound and viral and autoimmune screening may be performed to exclude differential diagnoses. The diagnosis is confirmed when pruritus is associated with raised bile acids and/or abnormal LFTs in the absence of other causes. Postnatally, liver function should be reassessed to confirm resolution, as persistent abnormalities may indicate alternative diagnoses. This integrated approach aligns with UK clinical guidelines and is supported by recent literature emphasizing the central role of bile acid measurement and exclusion of other causes in diagnosing ICP NICE CKS Walker et al. 2020Abdul Waheed et al. 2024.