## Clinical Context This is an Rh-negative unsensitised primigravida at 34 weeks with negative ICT and low antibody titres (<1:8). She requires antenatal anti-D prophylaxis to prevent isoimmunisation. ## Management Rationale **Key Point:** Unsensitised Rh-negative pregnant women require anti-D immunoglobulin at 28 weeks and again at 34 weeks (or as a single 500 IU dose at 34 weeks in some protocols) to prevent primary sensitisation during pregnancy. **High-Yield:** The standard antenatal anti-D prophylaxis schedule in India and most guidelines: - 500 IU (100 µg) IM at 28 weeks, OR - 500 IU IM at both 28 and 34 weeks (some centres) - Repeat antibody titres 4–6 weeks after each dose to confirm no sensitisation has occurred **Clinical Pearl:** A negative ICT and low antibody titre (<1:8) indicate the woman is still unsensitised. Anti-D must be given before sensitisation occurs — it is preventive, not therapeutic. ## Why This Approach | Feature | Unsensitised (This Case) | Sensitised | | --- | --- | --- | | ICT | Negative | Positive | | Antibody titre | <1:8 or absent | ≥1:8 | | Management | Anti-D prophylaxis | Fetal monitoring (amniocentesis/cordocentesis) | | Delivery timing | Term (unless other indications) | Planned early delivery based on severity | **Mnemonic: ANTI-D UNSENSITISED** — **A**ntenatal prophylaxis at 28 & 34 weeks, **N**egative ICT, **T**itre <1:8, **I**mmunoglobulin 500 IU IM, **D**ose repeated, **U**nsensitised status maintained. ## Explanation of Correct Answer At 34 weeks, an unsensitised Rh-negative woman receives 500 IU anti-D IM. Antibody titres are rechecked 4–6 weeks later (around 38–40 weeks) to ensure no sensitisation has occurred during pregnancy. This is standard antenatal prophylaxis.
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