Indiana University School of Medicine Indianapolis, Indiana, United States
Background/Case Studies: Alloimmunization can occur in Rh-negative female patients via exposure to Rhesus (Rh) antigen due to prior transfusions or pregnancies. The consequential anti-D, IgG antibody is known for its potential to cause hemolytic transfusion reaction (HTR) and hemolytic disease of the fetus and newborn (HDFN). Exposure to blood through needle sharing in intravenous drug abuse (IVDA), during pregnancy resulting in alloimmunization has been rarely reported. In this case report we present a challenging case of high antibody titers in a Rh-negative pregnant female who received appropriate pre- and post-natal care in her previous pregnancy.
Study
Design/Methods: Review of relevant patient history, transfusion history, routine prenatal screening to include a type/screen, and antibody identification workup.
Results/Findings: We present the case of a 29-year-old G2P1001 female presenting at 7 weeks gestation to establish prenatal care. The patient has a history of a full-term uncomplicated delivery followed by RhIG administration 14 years ago, no history of previous transfusion, and history of IVDA. Her current workup was remarkable for a positive antibody screen for alloantibodies to the C and D antigens, with an anti-C titer of 128 and an anti-D titer of 16384. It was also noted that there was a possibility complex anti-G antibody, however further testing is needed to verify. Our findings were discussed with the clinician regarding the significance of her highly elevated titers and the potential risk for HTR and HDFN. An interdisciplinary discussion between transfusion medicine and her prenatal team took place to educate on the need for cross-match compatible blood products in the event of transfusion need. Conclusions: This case highlights the potentially overlooked risk of alloimmunization in individuals who have a history of IVDA. While unknown pregnancies with subsequent loss could also lead to alloimmunization the history of IVDA is significant as a potential exposure to blood. Considering the receipt of RhIG following her previous pregnancy several years ago, it is highly probable that patient’s elevated alloantibody titers against the D and C antigens are related to repeated exposures to blood and not due to current exposure to a D or C antigen positive fetus. This case emphasizes the importance of being aware of alloimmunization risk in patients with a history of IVDA and taking appropriate preventative measures. Further information on the phenotype of the fetus and frequency of IVDA could help support the cause of elevated anti-D titers.
Importance of research: This case emphasizes the importance of considering IVDA as a potential source of exposure to Rh antigens and implementing preventative measures especially in pregnancy. Further research on the relationship between IVDA and alloimmunization could provide crucial insight into managing high-risk pregnancies.
