“Provoked” feto-maternal hemorrhage may represent insensible cell exchange in pregnancies from 6 to 22 weeks gestational age

Commentary: No-test medication abortion: A sample protocol for increasing access during a pandemic and beyond

“…Recent research has suggested that the risk of Rh sensitization after early abortion is negligible [34][35][36]. Consequently, the National Abortion Federation has concluded that forgoing Rh typing and administration of anti-D immunoglobulin is reasonable for Rh-negative patients having aspiration abortion before 56 days of gestation and may be considered for all patients having MA at less than 70 days [16,37].…”

Anti-D prophylaxis for rhesus D (RhD)-negative women having an abortion of a pregnancy up to 13+6weeks’ gestation: a systematic review and new NICE consensus guidelines

“…The committee were reassured by recent work using flow cytometry, using a method able to differentiate between fetal red cells and maternal F cells, which showed that fetal red cells were at a level well below the threshold for sensitisation following surgical evacuation at up to 12 weeks’ gestation (personal communication S Hovarth 2019). Some fetal cells are present in the maternal circulation when no procedure is performed, and analysis in 110 patients with a mean gestational age of 18 weeks showed that the magnitude of exposure was similar following invasive procedures compared with measurements prior to these procedures 21. The realisation that silent fetomaternal haemorrhage is common, yet sensitisation is rare, would infer that the prevention of sensitisation by using anti-D may be less important than has been previously assumed.…”

Can We Safely Stop Administering Anti-D Immune Globulin to First Trimester Rh-Negative Mothers Undergoing Abortion? A Systematic Review and Meta-Analysis

“…Hollenbach et al also described a cohort of patients receiving a surgical abortion between 6 to 22 weeks. Two-thirds of the subjects demonstrated fetal cells in the maternal circulation after instrumentation [11], but the majority also demonstrated this prior to the abortion procedure, raising the possibility of insensible cell exchange resulting in the presence of fetal cells in the circulation. Visscher RD and Visscher HC conducted a randomized controlled study to determine Rh-sensitization with or without RhID [12].…”

“…The practice of administering RhIG after first trimester abortion is based on expert opinion and is largely extrapolated from data on fetomaternal hemorrhage in late pregnancy. However, the evidence indicates that there is not adequate fetomaternal hemorrhage in first trimester to cause sensitization [9][10][11]27]. Therefore, the recommendation to administer RhIG in the first trimester should depend on resource availability, cost, values, preferences, equity, acceptability and feasibility.…”