OG12.8 | Iso-Immunization in Pregnancy — Summary & Reflection

KEY TAKEAWAYS

Rh iso-immunization results from sensitisation of an Rh-negative mother to D antigen on fetal red cells via fetomaternal haemorrhage, typically at delivery or a sensitising event. The primary response (IgM) does not cross the placenta; the secondary response (IgG) does — causing fetal red cell haemolysis, anaemia, and hydrops in subsequent pregnancies. Prevention: anti-D immunoglobulin 300 µg IM at 28 weeks gestation (routine), within 72 hours of any sensitising event, and within 72 h of delivery of an Rh-positive baby; Kleihauer-Betke test determines if additional doses are needed for large FMH. Diagnosis: ICT at booking (detects circulating anti-D in maternal serum); ICT titre ≥1:16 = critical titre. Monitoring in sensitised pregnancies: MCA-PSV Doppler — >1.5 MoM indicates moderate-severe fetal anaemia. Management: if MCA-PSV >1.5 MoM → cordocentesis ± IUT (18–34 weeks); >34 weeks → delivery. Neonatal: jaundice within 24 h, positive DCT → phototherapy; exchange transfusion if bilirubin >20 mg/dL or rapidly rising. Anti-D is INEFFECTIVE once sensitisation has occurred.

REFLECT

Consider the preventable nature of Rh haemolytic disease. Every case of iso-immunization that occurs today in India does so because either: the woman was not tested for her Rh status, or she was not given anti-D after a sensitising event, or she was given anti-D but the dose was inadequate. Reflect on the systemic vulnerabilities: which events are most likely to be missed in the Indian healthcare setting? After a home delivery? After a first-trimester miscarriage at a primary health centre? After an emergency caesarean at a district hospital overnight? What would an ideal system look like, and what is the minimum standard that every woman deserves? Now apply Kolb's cycle: what would you personally do differently — as the admitting doctor, the surgical registrar, or the ANM — to ensure that every Rh-negative woman at every sensitising event in your institution receives timely anti-D?