Intrahepatic cholestasis of pregnancy explained

Q. A 34-year-old G2P1 presents with diffuse itching involving her abdomen and upper extremities at 34 weeks' gestation. What are the leading causes of itching in pregnancy? How should this patient be evaluated?

A. For an obstetrical patient who presents with itching (pruritus), the initial evaluation includes a detailed history of the patient's symptoms and a physical exam. The differential diagnosis of pruritus includes systemic, dermatological, and gastrointestinal disorders as well as etiologies that are more common in, or unique to, pregnancy.

Elevation of bile acids confirms the diagnosis of ICP. Although some clinicians use a cutoff point of more than 10 µmol/L to define abnormal levels, proposed cutoffs range from 6 µmol/L to 20 µmol/L.^1-3 Of patients with ICP, 20% to 60% will have transaminase elevation, and 20% will have mildly increased direct bilirubin levels.⁴ Because women with hepatitis C have an increased incidence of ICP (6% to 16%), clinical and serum screening for this viral illness has been suggested.^5,6 Pruritus with normal bile acids but abnormal liver function tests can indicate biliary obstruction or hepatitis, so further evaluation of these patients is indicated. In the rare case in which symptoms and laboratory abnormalities do not normalize after pregnancy, primary biliary cirrhosis should be considered.

What are the complications of intrahepatic cholestasis of pregnancy?

ICP is of particular importance to obstetricians because it has been connected to an increased risk of fetal complications. ICP is associated with an increased risk of preterm delivery, meconium passage, intrapartum fetal heart rate abnormalities, and fetal death.^2,7 The risk of fetal death usually is reported as less than 5%, although higher frequencies have been noted. In addition to being diagnostic for ICP, bile acid levels have prognostic value. In a population-based study from Sweden, pregnancy outcomes from more than 500 women with ICP were stratified by bile acid levels. Approximately 80% of women had bile acid levels between 10 µmol/L and 40 µmol/L, and the remaining 20% had bile acid levels greater than 40 µmol/L. Women with bile acids between 10 µmol/L and 40 µmol/L had similar outcomes compared with patients with uncomplicated pregnancies. However, women with bile acid levels greater than 40 µmol/L were at increased risk for preterm birth, meconium-stained fluid, operative delivery, Apgar score less than 7 at 5 minutes, and umbilical artery pH less than 7.05. No conclusions could be made regarding the association between intrauterine fetal death and bile acid levels.² Based on this and other data, bile acid level greater than 40 µmol/L is considered consistent with severe ICP. In another study, in which all patients were delivered by 37 weeks, none of these morbidities were seen except for an increase in meconium passage.⁸