From the Guidelines
A total serum bile acid level of >10 mmol/L is diagnostic for intrahepatic cholestasis of pregnancy (ICP). This threshold represents the upper limit of normal during pregnancy, with levels above this indicating cholestasis 1. Many clinicians consider levels above 40 mmol/L to represent severe disease, which carries higher risks for adverse fetal outcomes. Bile acid testing should be performed in pregnant women presenting with pruritus, particularly if it affects the palms and soles and worsens at night. The test should ideally be drawn after fasting, as postprandial levels can be transiently elevated. It's essential to note that bile acid levels may fluctuate during pregnancy, and a single normal result does not exclude the diagnosis if clinical suspicion remains high. Repeat testing is recommended in such cases. Elevated bile acids occur because pregnancy hormones, particularly estrogen, impair bile flow through the liver, leading to accumulation of bile acids in the bloodstream, which causes the characteristic itching and can pose risks to the fetus, including preterm birth and stillbirth.
Some key points to consider in the diagnosis and management of ICP include:
- The diagnosis of ICP is based on a serum bile acid level >10 mmol/L in the setting of pruritus, typically during the second or third trimester 1.
- Treatment should be offered with oral ursodeoxycholic acid in a total daily dose of 10–15 mg/kg 1.
- Serum bile acid levels correlate with the risk of intrauterine fetal demise, with the highest risk in patients with levels >100 mmol/L 1.
- Delivery is advised to be based on serum total bile acid levels, with delivery at 36 weeks or at diagnosis if after 36 weeks for levels >100 mmol/L, and delivery at 36 or 39 weeks of gestation if diagnosed later for levels <100 mmol/L 1.
It's crucial to prioritize the management of ICP to minimize the risks of adverse fetal outcomes and to improve maternal symptoms. The use of ursodeoxycholic acid has been shown to improve pruritus, serum bile acid levels, and serum alanine aminotransferase levels, and may decrease adverse outcomes, including preterm birth and stillbirth 1.
From the Research
Diagnostic Criteria for Intrahepatic Cholestasis of Pregnancy
- The diagnostic criteria for intrahepatic cholestasis of pregnancy (ICP) include increased total bile acid levels, enhanced cholic acid percentage, and decreased glycine/taurine bile acid ratio 2.
- Specifically, a total bile acid level above 11.0 micromol/L is considered predictive and accurate for the diagnosis of ICP 2.
Bile Acid Values and ICP Diagnosis
- Elevated bile acid levels are a key diagnostic marker for ICP, with levels above 11.0 micromol/L indicating a high risk of ICP 2.
- Other studies have also highlighted the importance of bile acid levels in diagnosing ICP, although they do not provide a specific cutoff value 3, 4, 5.
- However, one study found that bile acid concentrations less than 40 μmol/l may not respond to treatment with ursodeoxycholic acid (UDCA) 6.
Clinical Implications
- The diagnosis of ICP is based on symptoms of pruritus, elevated bile acid levels, and other liver function tests such as alanine aminotransferase and aspartate aminotransferase 3.
- Fetal risks associated with ICP include increased risk of preterm birth, meconium-stained amniotic fluid, respiratory distress syndrome, or stillbirth, which may be related to increased bile acid levels 3, 4, 5.