Paper I — 2021 December (Supplementary) (2010 Scheme) — Q2
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Paper I
2021 December (Supplementary) (2010 Scheme) · 40 marks · 120 min
Question
A 30 years old pregnant woman attended to hospital with a complaint of sudden onset
of swelling of right leg and tenderness over calf. Venous Doppler of right leg suggestive
of presence of a large thrombus in leg veins.
(a) Classify anticoagulants 2 mark(s)
(b) Choose the ideal drug for this patient, write its mechanism of action and adverse 2 mark(s)
(c) What are advantages of low molecular weight heparins 2 mark(s)
Q26 marksEssays
Answer
This clinical picture (sudden calf swelling/tenderness with a large thrombus on Doppler in a pregnant woman) is consistent with deep vein thrombosis (DVT).
Oral: Vitamin K antagonists (Warfarin), Direct oral anticoagulants (Rivaroxaban, Apixaban, Dabigatran)
(b) Ideal drug, mechanism, and adverse effects
Ideal drug: Low molecular weight heparin (e.g., Enoxaparin) — since warfarin and DOACs are contraindicated/avoided in pregnancy (warfarin is teratogenic; DOACs lack established pregnancy safety data), while heparin/LMWH does not cross the placenta and is the anticoagulant of choice in pregnancy
Mechanism: Predominantly inhibits factor Xa via antithrombin III, preventing further thrombus propagation
Adverse effects: Bleeding, heparin-induced thrombocytopenia (lower risk than unfractionated heparin), osteoporosis with prolonged use
(c) Advantages of LMWH
Better bioavailability and predictable anticoagulant response — allows fixed/weight-based dosing without routine coagulation monitoring
Longer duration of action — once/twice-daily subcutaneous dosing (vs. continuous IV infusion for unfractionated heparin)
Lower risk of heparin-induced thrombocytopenia and osteoporosis
