Safety of chorionic villus sampling in the presence of asymptomatic subchorionic hematoma.

OBJECTIVE: According to our knowledge the safety of chorionic villus sampling (CVS) has not been studied in the presence of subchorionic hematoma (SCH). Our study aimed to evaluate the effects of CVS on the procedure-related fetal loss rate in patients with SCH.

METHOD: Fifty-six patients with asymptomatic SCH (cases) and 986 controls in whom there was no hematoma underwent elective CVS for a prenatal diagnosis of beta-thalassemia and were entered into a prospective study. Mean gestational age (+/-SD) at diagnosis for the case and control groups were 11.07 weeks (+/-0.95, range 10-13 weeks) and 11.51 weeks (+/-1.04, range 10-13 weeks), respectively. Procedural fetal loss rates were evaluated in these groups after follow-up until 28 weeks of gestation.

RESULTS: The average hematoma volume (+/-SD) was 1.83 ml (+/-1.57, range 0.3-10.0 ml). Post-CVS early fetal loss was seen in 3.57% (2/56) of patients in the case group and 1.62% (16/986) of patients in the control group. Late fetal loss (up to the 28th week) in the case and control groups was 8.16% (4/49) and 3.76% (29/771), respectively. Post-CVS early fetal loss was seen in 2.44% (1/41) of patients with small-sized SCH (<20% of gestational sac circumference) and in 6.67% (1/15) of patients with medium-sized SCH (20-50% of gestational sac circumference). Comparison of procedure-related early and late fetal loss in the case and control groups using Fisher's exact test demonstrated no statistically significant difference (p value = 0.252, p value = 0.128). Difference in CVS-related early fetal loss in small- and medium-sized hematoma groups (6.67 vs. 2.44%) was not significant either (p value = 0.468).

CONCLUSION: We were unable to detect any statistically significant difference in fetal loss rate after performing CVS in patients with SCH in comparison to the control group. However, it seems that fetal loss rate may be higher in the presence of medium-sized (20-50% of gestational sac circumference) SCH and further cases are necessary to evaluate the safety of doing CVS in this group.