Occurs primarily in the late 2nd and 3rd trimesters (typically >30 weeks GA).
Pathophysiology: ICP is intrahepatic and non-obstructive. High levels of estrogen and progesterone metabolites inhibit the canalicular Bile Salt Export Pump (BSEP) in genetically susceptible patients.
Resolves rapidly postpartum.
Risk factors:
Personal or family history of ICP (strong genetic component).
Multifetal gestation.
Advanced maternal age (AMA) >35.
History of gallstones or HCV.
Clinical Features
Intense pruritus:
Characteristically starts/worst on palms and soles, then generalizes.
Typically worse at night.
No primary rash:
Skin examination reveals only secondary excoriations from scratching.
Systemic signs (rare, <10%):
Mild jaundice.
Right upper quadrant (RUQ) abdominal pain.
Dark urine and pale stools.
Diagnosis
Initial & Best Diagnostic Test: ↑ Total serum bile acids (TBA) (≥10 µmol/L is diagnostic).
TBA >40 µmol/L associated with increased fetal risk.
TBA ≥100 µmol/L indicates severe disease (critical threshold for fetal mortality).
Key Labs:
↑ LFTs (ALT and AST can be mildly elevated up to 10x ULN).
↑ Direct bilirubin (mildly elevated in <20% of cases).
Normal to minimally increased GGT (helps differentiate from other biliary pathologies).
Imaging: RUQ US not required for diagnosis, but done if biliary colic/cholecystitis is suspected.
Differential Diagnostics
Pruritic Urticarial Papules and Plaques of Pregnancy (PUPPP):
Diff: Presents with an intense pruritic rash (erythematous papules/plaques) starting within abdominal striae with periumbilical sparing. Normal LFTs and TBA.
Atopic Eruption of Pregnancy (AEP):
Diff: Presents with eczematous or papular lesions on trunk/limbs. Normal TBA.
Diff: Characterized by hemolysis (schistocytes, ↑ LDH), elevated liver enzymes, and low platelets (<100,000), usually associated with preeclampsia. No isolated severe pruritus.
Management
Medical Therapy:
First-line: Ursodeoxycholic acid (UDCA).
Mechanism: Increases bile flow, decreases serum bile acid concentration, and relieves maternal pruritus.
Weekly or biweekly Nonstress Test (NST) and/or Biophysical Profile (BPP) starting at diagnosis or 32 weeks GA.
Timing of Delivery (to prevent stillbirth):
TBA <100 µmol/L: Scheduled delivery at 36 0/7 to 39 0/7 weeks GA.
TBA ≥100 µmol/L: Scheduled delivery at 36 0/7 weeks GA (or earlier if additional complications arise).
Complications
Maternal:
Minimal risk except for severe sleep deprivation (due to pruritus) and increased risk of future gallstones/recurrence in subsequent pregnancies (up to 90%).
Fetal (driven by toxic bile acid transfer across placenta):