(P-TS-114) Use of RhIG in Pregnancy During National Shortage

The United States is facing a critical shortage of Rho(D) immune globulin (RhIg), a medication essential for preventing Rh alloimmunization in RhD-negative pregnant patients. RhD alloimmunization can lead to severe anemia and even death in a fetus or newborn.

In this study, we determined the distribution of indications for RhIG during pregnancy at two hospitals at a quaternary academic medical center, with the goal of identifying ways to save RhIG doses considering the national shortage.

Study

Design/Methods:

This single center, retrospective study reviewed records of patients who received RhIG during pregnancy over a 3-year period, January 1, 2021 – December 31, 2023. This included both inpatients and outpatients, and RhIG doses issued by the Blood Bank/Transfusion Service as well as by the pharmacy. Individual patient indications for RhIG were analyzed and grouped.

Results/Findings:

In total, 1145 RhIG doses were administered to RhD-negative pregnant individuals during this 3-year period. The majority (655, 57.2%) were issued to inpatients, while 490 (42.8%) doses were administered in the outpatient setting. The most common indication for RhIG during pregnancy was delivery of an Rh-D positive infant (39.2%), followed by prophylactic prevention of RhD alloimmunization at around 28 weeks gestation (26.2%), first trimester bleeding/spotting (9.7%), second or third trimester bleeding or other reasons (10.0%), and procedures including CVS and amniocentesis (8.2%). For the remaining 6.7%, the RhIG indication was unknown.

It is estimated that 60-70% of RhD-negative pregnant individuals deliver an RhD-positive infant and require RhD. In other words, 30-40% of RhD-negative individuals do not require RhIG at the time of delivery, for prophylaxis, or for any procedures or possible bleeding during the pregnancy. Non-invasive prenatal diagnosis for fetal RHD genotyping is widely used in Europe and is available in the US. If an estimated 65% of RhD-negative pregnant individuals deliver an RhD-positive infant and require RhD and 35% deliver an RhD-negative infant and no not require RhIG, then cell-free fetal DNA screening of RHD genotype would result in a reduced need for RhD immunoprophylaxis, saving approximately 15.5% of doses (or 178 doses over 3 years) at our academic hospital.

Conclusions:

With RhIg supplies limited, prenatal cell-free DNA screening for RHD could be more widely performed in the first trimester at 10 weeks gestational age to determine fetal RhD-antigen status and save subsequent RhIG doses during the pregnancy if the fetus is RhD-negative.