Effect of placenta penetration during cordocentesis at mid-pregnancy on fetal outcomes.

OBJECTIVES: To compare the rates of fetal loss, low birth weight, and preterm birth between pregnancies undergoing cordocentesis at mid-pregnancy with placenta penetration and those without it.

METHODS: Consecutive cases of cordocenteses were prospectively recorded. The inclusion criteria for analysis were: (1) singleton pregnancies, (2) no fetal abnormalities, (3) gestational age of 18-22 weeks, and (4) procedures performed by experienced operators. The primary outcome was fetal loss rate, and the secondary outcomes were rates of failed procedures, low birth weight, and preterm birth.

RESULTS: Of 6147 cordocenteses recorded, 2829 met the inclusion criteria with complete data for analysis. Of these, 654 procedures were further excluded because the puncture site was at cord insertion. The remaining 2175 cases, consisting of 615 procedures with placenta penetration and 1560 cases with no penetration, were analyzed. Cordocenteses with placenta penetration had a significantly higher rate of fetal loss (3.6% vs 1.3%, p = 0.01) as well as of low birth weight and preterm birth.

CONCLUSION: Cordocentesis with placenta penetration carries a higher risk for fetal loss, preterm birth, and low birth weight. This information may be helpful in prenatal diagnosis counseling, and it may encourage performers to avoid placenta penetration, if possible.