Assessment of fetal circulation in patients with retrochorionic hematoma during the first trimester of pregnancy

Objective To assess early fetal circulation in cases of first-trimester thr eatened abortion with living embryo and sonographically evident retrochorio nic hematoma. Methods A prospective cross-sectional study was performed in 52 consecutive patients (mean age 30.3 years; SD 4.4; range 24-40 years) with first-trime ster threatened abortion (mean gestational age 8.8 weeks; SD 2.1; range 6.0 -12.6 weeks), and sonographically demonstrated retrochorionic hematoma usin g transvaginal pulsed Doppler ultrasonography combined with color velocity imaging for color blood flow codification. The umbilical artery, abdominal aorta and cerebral vessels were assessed. The pulsatility index (PI) was me asured in each vessel. A total of 184 patients (mean age 29.9 years; SD 3.8 ; range 15-41 years) with normally developing first-trimester pregnancies ( mean gestational age 9.1; SD 1.9; range 6.0-12.6 weeks) were used as contro ls. Results In normal pregnancies, a significant and progressive decrease in PI in the umbilical artery (R-2 = -0.29; p < 0.0001), abdominal aorta (R-2 = -0.15; P < 0.0001) and cerebral vessels (R-2 = -0.32; p < 0.0001) was found . Ten (19.2%) out of the 52 patients with retrochorionic hematoma ultimatel y aborted. The mean volume of retrochorionic hematoma was 4.8 mi (SD 10.3; 95% CI 0.60-7.48). Most hematomas were localized marginally. No differences were found in any parameter assessed between patients with retrochorionic hematoma (including those whose pregnancies ended in spontaneous abortion) and controls. Conclusions Our results indicate that early fetal circulation is not affect ed by the presence of retrochorionic hematoma, although this could be expla ined by the fact that, in our series, most hematomas were smart and margina l, not substantially affecting the chorion frondosum.