Use of Therapeutic Plasma Exchange and Intravenous Immunoglobulin to Prevent Complications in a K+ Sensitized Pregnancy.

The K antigen is a major cause of hemolytic disease of the fetus and newborn (HDFN). K-HDFN is unique in that it can result in destruction of not just mature erythrocytes but fetal erythrocyte progenitors, causing severe fetal anemia earlier in pregnancy than other antigens. This poses a danger to fetal health as intrauterine transfusion (IUT), the preferred method of managing HDFN, becomes riskier earlier in pregnancy. This report follows a K-negative mother managed with an alternative treatment, designed to delay the need for IUT.  The patient is a 32-year-old K-negative female, G2P1001, sensitized against K by her previous pregnancy with a 256 anti-K antibody titer. To prevent HDFN, she opted for preventative treatment to lower her immune response. She received three rounds of therapeutic plasma exchange, which lowered her titer to 64, followed by weekly IVIG administration at a dosage of 1g/kg body weight. Fetal anemia was monitored via middle cerebral artery Doppler imaging. The fetus did require two IUTs; however, they were not required until the third trimester. A healthy baby was delivered at 36 weeks with mild anemia and a positive direct antiglobulin test. The standard of care for K-sensitized pregnancies involves watchful waiting and correction of anemia with IUT. However, K-HDFN, if untreated, can cause severe anemia in early pregnancy when IUT is less viable. This case study joins a handful of others in reported literature where a K-sensitized pregnancy was treated prophylactically with immune-modulating therapies and argues that these treatments deserve further recognition and study.