Evaluation of Pulmonary Artery Acceleration/Ejection Time Ratio (PATET) and the AST-to-Platelet Ratio Index (APRI) in Intrahepatic Cholestasis of Pregnancy

Objective: To evaluate fetal pulmonary artery hemodynamics (PAAT, PAET, PATET) in pregnancies complicated by intrahepatic cholestasis of pregnancy (ICP) and to investigate their association with the aspartate aminotransferase-to-platelet ratio index (APRI). Methods: In this prospective study, 64 ICP cases and 64 healthy pregnancies are included. Doppler measurements of the fetal main pulmonary artery, umbilical artery (UAPI), and middle cerebral artery (MCAPI) were performed by a single operator, and all biochemical analyses were conducted in the same laboratory. APRI was calculated using the standard formula. Results: Doppler evaluation demonstrated significantly higher PAAT, PAET, PATET, UAPI, and MCAPI values in the ICP group (all p < 0.05). AST, ALT, and APRI levels were markedly elevated in ICP pregnancies (all p < 0.001). No significant correlation was observed between PATET and APRI (p = 0.368) or fasting bile acid levels (FBA) (p = 0.116), whereas APRI showed a weak positive correlation with FBA (r = 0.308; p = 0.013). Doppler parameters and APRI values did not differ significantly according to cholestasis severity (10–39/≥40/≥100 μmol/L; all p > 0.05). Conclusions: In ICP, fetal pulmonary artery Doppler indices (PAAT, PAET, PATET) and fetoplacental Doppler parameters are increased; the elevation in PATET is consistent with lower—rather than higher—fetal pulmonary vascular resistance, potentially reflecting accelerated fetal lung maturation or a hemodynamic adaptation to ICP-related physiological perturbations. Despite elevated APRI levels, these biochemical changes do not parallel fetal hemodynamic indicators. These findings suggest that fetal hemodynamic effects in ICP may be independent of biochemical disease severity. PATET is best conceptualized as a hemodynamic monitoring variable complementing bile acid assessment in fetal surveillance, not as a standalone screening or prognostic tool.