Department of Pathology, University of Pittsburgh Medical Center Pittsburgh, Pennsylvania, United States
Background/Case Studies: The anti-PP1PK antibody is associated with recurrent miscarriages, hemolytic disease of the newborn (HDN), and hemolytic transfusion reactions. However, the p phenotype and anti-PP1PK antibody are exceedingly rare since the P1PK antigens are ubiquitous. As such, therapeutic protocols for anti-PP1PK-positive pregnant individuals have relied on case reports and lack clinical validation/consensus. Here – with maternal-fetal and bloodless medicine - we demonstrate the successful management of fetomaternal anti-PP1PK alloimmunization identified after her first miscarriage in a 23-year-old, G2P0010, female with biweekly plasma exchange (TPE) and weekly intravenous immunoglobulin (IVIG) starting in the first trimester of her second pregnancy.
Study
Design/Methods: Utilizing an adapted strategy, we implemented biweekly TPE (1.0 plasma volumes (PV) with albumin replacement) with weekly titers and IVIG (1g/kg) starting at 9 weeks of gestation (WG). Titers of 16 or higher were considered critical. Weekly middle cerebral artery-peak systolic velocities (MCA-PSV) for fetal anemia were followed starting at 16 WG. PV was increased to 1.5 in the second trimester to account for increased PV during pregnancy. Antigen-negative RBCs were obtained for the mother and newborn in advance through the rare donor program and directed donation from an ABO-compatible PP1PK-negative relative.
Results/Findings: Initial antibody titers were 128 and decreased to 8 with therapy (Figure A). The patient’s anemia was optimized with iron and vitamin B12. At 24 WG, TPE was decreased to once weekly with 1.5 PV. However, titers increased to 32, and twice-weekly TPE was resumed. MCA-PSV remained stable throughout (Figure A). At 38 WG, induction of labor was scheduled. Intraoperative blood salvage, tranexamic acid, and compatible blood were reserved for obstetric hemorrhage. Vaginal delivery of a 2950 g female neonate (APGAR score: 9, 9) occurred without complication. Cord blood and antibody identification panel were positive (1+, anti-PP1Pk). Newborn hemoglobin and total bilirubin were stable; hospital discharge occurred on day two without intervention. Conclusions: Alloimmunization with anti-PP1Pk is rare but associated with recurrent miscarriages and HDN. With multidisciplinary care and monitoring, a successful pregnancy is possible with weekly IVIG and biweekly TPE adjusted to rising PV and antibody titers in pregnancy.
Importance of research: The anti-PP1PK antibody is associated with recurrent miscarriage and hemolytic disease of the newborn. However, Anti-PP1PK antibodies are rare since P1PK antigens are ubiquitous. Protocols for anti-PP1Pk alloimmunization and management during pregnancy are scarce ( < 15) and lack consensus. Here, we demonstrate the successful management of fetomaternal anti-PP1Pk alloimmunization, provide a well-documented therapeutic plan, and lend further validation/clinical considerations for this rare entity.
