PREVENTION OF RhD ALLOIMMUNIZATION IN RhD NEGATIVE WOMEN

Abstract

Background. Despite the introduction of anti-D prophylaxis into clinical practice, RhD alloimmunization still presents a problem to date. The actual incidence of RhD alloimmunization in pregnant women remains unknown in most countries. Anti-D immunoglobulin is administered to RhD negative women at a fixed dose and in much greater amounts than is actually necessary. On the other hand, it is not possible to diagnose cases where greater doses are needed. To optimize the prevention of RhD alloimmunization in RhD negative women, it is important to diagnose conditions that lead to fetomaternal hemorrhage (FMH), precisely determine the volume and subsequently administer the appropriate dose of anti-D immunoglobulin. The possibility to accurately detect FMH and precisely determine its volume would enable more effective and less costly prevention of RhD alloimmunization. Anti-D immunoglobulin could be administered only in indicated cases and only in doses essentially necessary for prevention of RhD alloimmunization.Methods and results. The Cochrane and UpToDate databases of systematic reviews, as well as national guidelines, were reviewed.Conclusions. Due to the medical significance and indispensable economic costs associated with prevention of RhD alloimmunization, it would be appropriate to establish exact methodical guidelines. The text itself should be limited to a list of potentially sensitising events during which anti-D immunoglobulin should be administered to RhD negative women if anti-D antibodies are not already present. Following each potentially sensitising event, the minimal dose of anti-D immunoglobulin necessary for prevention of RhD alloimmunization should be determined. After 20 weeks of gestation, the volume of FMH should also be determined to specify the necessary dose of anti-D immunoglobulin.

Rhesus Negative Woman Transfused With Rhesus Positive Blood: Subsequent Normal Pregnancy Without Anti D Production

“…17 With regards to its immunogenicity and volume needed to cause sensitization, the D antigen is very immunogenic and parenteral administration of Rh D positive RBC volumes as little as 0.1ml is capable of causing sensitization in Rh D negative individuals. 18 Hence the about 220ml Rh D positive RBCs received by Madam VD was enough to cause sensitization.…”

Fetomaternal hemorrhage in normal vaginal delivery and in delivery by cesarean section

“…A number of countries therefore recommend assessing the volume of FMH after delivery to specify the dose of IgG anti‐D necessary to prevent D alloimmunization of the mother (Australia, Canada, United States, Great Britain, France, Ireland, Czech Republic) 5‐10 . After delivery, the volume of FMH should be assessed.…”

“…If the volume of fetomaternal hemorrhage (FMH) is not assessed, usually an IgG anti‐D dose of 100 to 300 µg is administered intramuscularly. The effectiveness of administering a standard dose of more than 100 µg to all women has not been demonstrated 1‐10 . The goal of further studies should be establishing optimal doses of IgG anti‐D.…”

Anti-D Antibodies in Pregnant D Variant Antigen Carriers Initially Typed as RhD+

“…Conversely, women with partial D should be classified as D- considering their prenatal management and RhD immunoprophylaxis [13,14]. In Europe, anti-D reagents are selected to deliberately type pregnant DVI carriers as D- to ensure that such mothers would receive RhD immunoprophylaxis in their second trimester and/or postpartum.…”