Risk of Placenta Accreta Spectrum With Early Pregnancy Subchorionic Hematoma Location and Size in Hormone Replacement Cycles

To study whether subchorionic hematoma (SCH) location and size in early pregnancy affect placenta accreta spectrum (PAS) risk in hormone replacement cycles (HRC).

Retrospective cohort study of 685 singleton live births following frozen-thawed embryo transfer in HRC (November 2018-September 2023) at a single fertility clinic. SCH location (cervical-side, mid-cavity, or fundal-side) and size (< 10% or > 50% of gestational sac), assessed by first-trimester ultrasound, were evaluated for association with PAS.

The presence of SCH showed a trend toward increased PAS frequency (adjusted Risk Ratio (RR) 1.56, 95% Confidence Interval (CI) 0.87-2.80). Location-specific analysis revealed that cervical-side SCH conferred significantly elevated PAS risk compared to those without cervical-side SCH (adjusted RR 2.21, 95% CI 1.18-4.15), whereas mid-cavity SCH (adjusted RR 1.74, 95% CI 0.94-3.22) and fundal-side SCH (adjusted RR 0.59, 95% CI 0.20-1.76) showed no significant association. Regarding SCH size, larger hematomas (> 50% of gestational sac) were not associated with increased PAS risk compared to smaller hematomas (< 10%) (adjusted RR 0.59, 95% CI 0.16-2.13).

Cervical-side SCH, but not mid-cavity or fundal-side hematomas, was associated with increased PAS risk in HRC pregnancies. These findings suggest that SCH location may serve as a key prognostic marker in HRC.