Rh testing or immunoglobulin administration following induced first-trimester abortion not necessary: JAMA

Rh testing and therapy are not indicated before to 12 weeks' gestation since induced first-trimester abortion is not a risk factor for Rh sensitization, says an article published in the Journal of American Medical Association.

Rh immunoglobulin is not essential until 12 weeks of pregnancy, according to population-level statistics, however there is little clinical support for this idea. As a result, recommendations change, leaving the dangers and advantages of Rh testing and therapy unclear. This study by Sarah Horvath and colleagues assessed how frequently maternal exposure to fetal red blood cells (fRBCs) in induced first-trimester abortion surpasses the most conservative reported threshold for Rh sensitization.

High-throughput flow cytometry was used to identify circulating fRBCs in matched maternal blood samples taken before and after an induced first-trimester abortion (either medically or surgically). Before 12 weeks and 0 days of gestation, those who had an induced first-trimester abortion were included. 506 patients who experienced either a medical (n = 319 [63.0%]) or procedural (n = 187 [37.0%]) abortion were able to provide paired blood samples. The percentage of subjects with fRBC counts over the sensitization threshold (125 fRBCs/5 million total RBCs) following an induced first-trimester abortion served as the main outcome.