Question:medium
36 weeks pregnant female on warfarin with mitral stenosis. What should we do?
36 weeks pregnant female on warfarin with mitral stenosis. What should we do?
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Consider which anticoagulant does not cross the placenta and is therefore safe for the fetus near term.
Updated On: Jun 23, 2026
- Shift to LMW Heparin
- Warfarin
- Switch to Aspirin
- Aspirin + Heparin
Show Solution
The Correct Option is A
Solution and Explanation
Core pharmacology principle: Warfarin is a small molecule that freely crosses the placental barrier. At 36 weeks (near term), it places the fetus at high risk of $\textbf{intracranial haemorrhage}$ during labour and delivery due to compression of the fetal head in the birth canal.
$\text{LMWH}$ (Low Molecular Weight Heparin) is a large polysaccharide that does $\textbf{NOT}$ cross the placenta, making it safe for the fetus while providing adequate anticoagulation for the mother with mitral stenosis.
Anticoagulation in pregnancy timeline (for prosthetic valves/mitral stenosis):
- Weeks 1-12: LMWH preferred (avoids warfarin embryopathy)
- Weeks 13-35: Warfarin acceptable with dose monitoring
- $\geq$ 36 weeks: Switch back to LMWH until delivery
Aspirin is an antiplatelet agent, not an anticoagulant, and is insufficient for mitral stenosis thromboprophylaxis.
\[\boxed{\text{Shift to LMWH}}\]
$\text{LMWH}$ (Low Molecular Weight Heparin) is a large polysaccharide that does $\textbf{NOT}$ cross the placenta, making it safe for the fetus while providing adequate anticoagulation for the mother with mitral stenosis.
Anticoagulation in pregnancy timeline (for prosthetic valves/mitral stenosis):
- Weeks 1-12: LMWH preferred (avoids warfarin embryopathy)
- Weeks 13-35: Warfarin acceptable with dose monitoring
- $\geq$ 36 weeks: Switch back to LMWH until delivery
Aspirin is an antiplatelet agent, not an anticoagulant, and is insufficient for mitral stenosis thromboprophylaxis.
\[\boxed{\text{Shift to LMWH}}\]
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