Increased severity of fetal hemolytic disease with known rhesus alloimmunization after first-trimester transcervical chorionic villus biopsy.

Fetomaternal hemorrhage secondary to chorionic villus biopsy has the potential to accelerate fetal hemolytic disease in the pregnant patient previously sensitized to red cell antigens. A case of poor fetal outcome after first-trimester transcervical chorionic villus sampling in an alloimmunized patient is reported. An increase in antibody titers was associated with the demise of a hydropic fetus early in the second trimester. Maternal red cell alloimmunization is suggested as an absolute contraindication for chorionic villus sampling performed for genetic indications.