MCQs on Anti-Coagulation

Written by Dr. Daniel Fraser (MBBS, FRACP) – Physician

Question 1

A 65-year-old woman underwent an emergency surgery for a strangulated femoral hernia 2 days ago. She was on warfarin that was ceased before the surgery and fresh frozen plasma was given. Which one of the following is the most appropriate action to take regarding resuming anticoagulation?

A) Start the patient on LMWH
B) Start the patient on unfractionated heparin
C) Resume warfarin
D) Resume warfarin and start LMWH
E) Resume warfarin after one week

Correct Answer: D) Resume warfarin and start LMWH

For patients whose warfarin therapy is stopped before major surgery, it is recommended to resume warfarin within 12-24 hours after surgery, alongside starting a prophylactic dose of low molecular weight heparin (LMWH) simultaneously.

This bridging therapy with LMWH is essential because warfarin initially increases the risk of thromboembolism due to early reduction of protein C and S before adequate anticoagulation is achieved.

Unfractionated heparin (UFH) is a second-line option if LMWH is contraindicated, but requires careful monitoring of APTT and should be given by slow infusion, not bolus.
LMWH or UFH should be continued for at least 5 days and stopped 48 hours after the INR reaches therapeutic levels (around 1.8 or above).
Simply resuming warfarin alone or delaying its resumption (Options C and E) without bridging increases the risk of thrombosis.
Starting LMWH alone (Option A) without warfarin does not address the patient’s long-term anticoagulation needs.

Therefore, the best approach is to resume warfarin and start LMWH concurrently.

Question 2

A 55-year-old man has been on warfarin for atrial fibrillation for the past 3 months. He presented with an incarcerated inguinal hernia and was booked for emergent surgery. Warfarin was stopped and fresh frozen plasma was given. Which one of the following is the time to resume warfarin therapy?

A) 12 hours post-op
B) 48 hours post-op
C) Immediately after recovery from anesthesia
D) 5 days post-op
E) When INR is less than 1.8 again

Correct Answer: A) 12 hours post-op

For patients who have had warfarin stopped before major surgery, it is recommended to resume the previous maintenance dose of warfarin on the night of surgery, generally 12 to 24 hours postoperatively.

At the same time, prophylactic low molecular weight heparin (LMWH) or unfractionated heparin (UFH) should be started to provide anticoagulation coverage until the warfarin reaches therapeutic levels. UFH requires careful monitoring of activated partial thromboplastin time (APTT) to maintain a target of about 1.5 times normal.

Heparin or LMWH is continued for at least 5 days and discontinued 48 hours after the INR reaches therapeutic levels (around 1.8 or above).

Delaying warfarin resumption beyond 12-24 hours or waiting for INR to drop before restarting (Options B, C, D, E) may increase the risk of thromboembolic complications.

Question 3

A 56-year-old woman is brought to the emergency department with sudden-onset severe epigastric pain. On examination, she has a blood pressure of 90/55 mmHg, heart rate of 110 bpm, and respiratory rate of 22 breaths per minute. There is abdominal guarding and rigidity, as well as marked tenderness and rebound tenderness over the epigastric area. A chest X-ray reveals free air under the right hemi-diaphragm. Based on clinical findings, a perforated peptic ulcer is diagnosed and the patient is planned for emergency laparotomy. She is on warfarin due to deep vein thrombosis (DVT) that developed 2 weeks ago. Which one of the following is the most appropriate next step in management?

A) Stop warfarin, give vitamin K and do the surgery.
B) Proceed with the surgery.
C) Give fresh frozen plasma (FFP) and proceed with the surgery.
D) Add intravenous heparin and perform the surgery.
E) Stop warfarin, give her heparin and proceed with the surgery.

Correct Answer: C) Give fresh frozen plasma (FFP) and proceed with the surgery.

This patient requires emergency life-saving surgery for a perforated peptic ulcer with peritonitis. In emergency surgeries where delaying the procedure is not possible, the effects of warfarin must be reversed immediately to reduce bleeding risk. This is best achieved by administering prothrombin complex concentrate (PCC) (e.g., Prothrombinex-VF®), or if unavailable, fresh frozen plasma (FFP), regardless of potential risks from temporarily stopping warfarin.

Option A (stop warfarin and give vitamin K alone) is inadequate here because vitamin K takes time to reverse warfarin and is suitable only if surgery can be delayed at least 24 hours.
Option B (proceed without reversal) carries a significant risk of severe bleeding and is not recommended.
Option D (adding heparin) increases bleeding risk unnecessarily.
Option E (stop warfarin and start heparin) is a bridging strategy used for elective surgeries, not emergency ones.

Following surgery, warfarin can be resumed with careful monitoring once bleeding risk decreases.

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6. Hematology Module

6.1 Anemia

6.2 Thrombocytopenia

6.3 Thromboembolism

6.4 Anti-Coagulation

6.5 Lymphomas

6.6 Other Hematological Disorders

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