A 32-year-old Rh-negative multigravida (G3P2) presents at 20 weeks gestation with a history of intrauterine fetal death (IUFD) in her previous pregnancy due to severe haemolytic disease. Indirect Coombs test is positive (titre 1:32). Regarding the management of this case, all of the following are appropriate EXCEPT:

Explanation

## Management of Rh Isoimmunisation in a Sensitised Pregnancy ### Clinical Context: Already Sensitised Mother **Key Point:** This mother is ALREADY SENSITISED (positive indirect Coombs test with detectable antibody titre). She is not a candidate for anti-D prophylaxis — anti-D is for PREVENTION of sensitisation in non-sensitised mothers, not treatment of established sensitisation. **Clinical Pearl:** Once a mother is sensitised (antibody titre > 1:16 or positive indirect Coombs), anti-D immunoglobulin is ineffective and is NOT indicated. The focus shifts to monitoring and treating fetal haemolytic disease. ### Management Algorithm for Sensitised Pregnancy ```mermaid flowchart TD A[Rh-negative mother with positive indirect Coombs]:::outcome --> B{Antibody titre & gestation}:::decision B -->|Titre ≤ 1:16, gestation ≥ 20 weeks| C[Serial ultrasound every 2-4 weeks]:::action B -->|Titre > 1:16 or signs of anaemia| D[Doppler assessment: MCA-PSV]:::action C --> E{MCA-PSV normal?}:::decision E -->|Yes| F[Continue surveillance]:::action E -->|No| G[MCA-PSV > 1.5 MoM]:::outcome D --> G G --> H[Intrauterine transfusion]:::action H --> I[Repeat IUT as needed until term]:::action I --> J[Delivery at 37-38 weeks]:::action ``` ### Fetal Assessment in Sensitised Pregnancy **High-Yield:** The gold standard for detecting fetal anaemia is **middle cerebral artery peak systolic velocity (MCA-PSV)** measured by Doppler ultrasound: - **MCA-PSV < 1.5 MoM:** Low risk of anaemia; continue surveillance - **MCA-PSV 1.5–1.95 MoM:** Moderate risk; repeat in 1–2 weeks or consider cordocentesis - **MCA-PSV > 1.95 MoM:** High risk of moderate-to-severe anaemia; intrauterine transfusion indicated **Clinical Pearl:** Cordocentesis with fetal blood sampling and direct antiglobulin test (DAT) can confirm fetal anaemia and guide IUT volume, but is now reserved for cases where MCA-PSV is borderline or non-reassuring. ### Intrauterine Transfusion (IUT) **Key Point:** IUT is the definitive treatment for severe fetal anaemia in isoimmunised pregnancies: - Performed under ultrasound guidance via cordocentesis (umbilical vein) or intraperitoneal transfusion - Uses O-negative, Rh-negative, cytomegalovirus (CMV)-negative blood - Repeated at 2–3 week intervals until fetal maturity (≥37 weeks) - Success rate > 95% with modern techniques ### Maternal Interventions: IVIG and Plasma Exchange **High-Yield:** Maternal IVIG and plasma exchange are **adjunctive** therapies in some centres, used to reduce antibody titre and complement-mediated fetal haemolysis: - IVIG 400 mg/kg IV weekly or fortnightly (mechanism: blocks Fc receptors on maternal macrophages) - Plasma exchange: removes circulating antibodies - Evidence is mixed; not universally recommended as first-line - May be considered in severe cases or as an adjunct to IUT **Warning:** These interventions do NOT replace IUT — they are supportive measures, not definitive treatment. ### Why Anti-D is Contraindicated Here **Key Point:** Anti-D prophylaxis is ONLY for non-sensitised mothers to prevent initial sensitisation. Once sensitisation has occurred (positive Coombs, detectable antibody titre), anti-D: - Is ineffective at reducing existing antibodies - May worsen haemolytic disease by adding more anti-D - Is contraindicated and should NOT be given The correct management is surveillance, Doppler assessment, and IUT if needed — NOT anti-D.