Successful management of maternal anti‐PP1Pk alloimmunization in pregnancy with therapeutic plasma exchange and intravenous immunoglobulin

Anti‐PP1P K alloimmunization is rare given ubiquitous P1PK expression. Prevention of recurrent miscarriages and hemolytic disease of the fetus and newborn (HDFN) in pregnant individuals with anti‐PP1P K antibodies has relied upon individual reports. Here, we demonstrate the successful management of maternal anti‐PP1P K alloimmunization in a 23‐year‐old, G2P0010, with therapeutic plasma exchange (TPE), intravenous immunoglobulin (IVIG), and monitoring of anti‐PP1P k titers. Twice‐weekly TPE (1.5 plasma volume [PV], 5% albumin replacement) with weekly titers and IVIG (1 g/kg) was initiated at 9 weeks of gestation (WG). The threshold titer was ≥16. Weekly middle cerebral artery‐peak systolic velocities (MCA‐PSV) for fetal anemia monitoring was initiated at 16 WG. PVs were adjusted throughout pregnancy based on treatment schedule, titers, and available albumin. Antigen‐negative, ABO‐compatible RBCs were obtained through the rare donor program and directed donation. An autologous blood autotransfusion system was reserved for delivery. Titers decreased from 128 to 8 by 10 WG. MCA‐PSV remained stable. At 24 WG, TPE decreased to once weekly. After titers increased to 32, twice‐weekly TPE resumed at 27 WG. Induction of labor was scheduled at 38 WG. Vaginal delivery of a 2950 g neonate (APGAR score: 9, 9) occurred without complication (Cord blood: 1+ IgG DAT; Anti‐PP1P k eluted). Newborn hemoglobin and bilirubin were unremarkable. Discharge occurred postpartum day 2. Anti‐PP1P k alloimmunization is rare but associated with recurrent miscarriages and HDFN. With multidisciplinary care, a successful pregnancy is possible with IVIG and TPE adjusted to PV and titers. We also propose a patient registry and comprehensive management plan.