What is the most appropriate management for a 40-year-old primigravida with a Body Mass Index (BMI) of 31 and no history of previous Deep Vein Thrombosis (DVT)?

Management of VTE Prophylaxis in a 40-Year-Old Primigravida with BMI 31

For this 40-year-old primigravida with BMI 31 and no history of DVT, early ambulation with compression stockings is the most appropriate management, with pharmacologic prophylaxis reserved only if she undergoes cesarean delivery or develops additional risk factors. 1

Risk Stratification

This patient presents with two minor risk factors according to the American College of Chest Physicians criteria: age >35 years and obesity (BMI >30). 1

• Age >35 years is classified as a minor risk factor for VTE in pregnancy 1
• BMI 31 (obesity) is classified as a minor risk factor 1
• She has no history of previous VTE, which would be a major risk factor 1
• She is not undergoing cesarean delivery based on the question stem 1

Evidence-Based Recommendations by Mode of Delivery

For Vaginal Delivery (Current Scenario)

The American College of Chest Physicians recommends that women without risk factors or with only minor risk factors planning vaginal delivery receive early mobilization only, without pharmacologic prophylaxis. 1

• The Royal College of Obstetricians and Gynaecologists classifies this patient as low-risk (two minor factors without cesarean delivery during labor), recommending early mobilization and avoidance of dehydration 1
• Mechanical prophylaxis with compression stockings is reasonable and safe, though not mandated for vaginal delivery with only minor risk factors 1

If Cesarean Delivery Occurs

If this patient requires cesarean delivery, she would then meet criteria for pharmacologic prophylaxis with LMWH. 1

• The American College of Chest Physicians suggests LMWH prophylaxis when 1 minor risk factor is present in the setting of emergent cesarean delivery 1
• For elective cesarean delivery with 2 or more minor risk factors (age >35 + obesity), LMWH prophylaxis is suggested 1
• Sequential compression devices should be used for all women undergoing cesarean delivery, starting before surgery and continuing until fully ambulatory 1

Important Clinical Context

Number Needed to Treat vs Number Needed to Harm

The evidence reveals a critical safety consideration: 1

• Number needed to treat (NNT) to prevent one VTE episode ranges from 640 to 4,000 in high-risk postpartum women 1
• Number needed to harm (NNH) with pharmacologic prophylaxis is as low as 200, primarily from wound complications (separation, hematomas) 1
• The NNH may be lower than the NNT in scenarios with minor risk factors only, making routine pharmacologic prophylaxis potentially more harmful than beneficial 1

Why Not Aspirin?

Aspirin is not recommended for VTE prophylaxis in pregnancy. 1

• Current guidelines from the American College of Chest Physicians and Royal College of Obstetricians and Gynaecologists do not include aspirin as an option for VTE prophylaxis 1
• When pharmacologic prophylaxis is indicated, LMWH is the agent of choice in pregnancy 1, 2

Why Not Routine LMWH Now?

LMWH with compression stockings (Option D) would be excessive for this clinical scenario: 1

• She has no major risk factors (no previous VTE, no high-risk thrombophilia, no immobility) 1
• She has only two minor risk factors without cesarean delivery 1
• The risk of bleeding complications and wound issues may outweigh the modest VTE risk reduction 1

Specific Management Algorithm

For this patient planning vaginal delivery:

1. Recommend early and frequent ambulation starting immediately postpartum 1
2. Consider graduated compression stockings (20-30 mmHg) for comfort and modest VTE reduction 1
3. Ensure adequate hydration 1
4. Reassess if clinical situation changes: 1
   • If cesarean delivery becomes necessary → initiate LMWH prophylaxis
   • If prolonged immobility occurs (>1 week antepartum) → initiate LMWH prophylaxis
   • If additional risk factors develop (preeclampsia, postpartum hemorrhage, infection) → consider LMWH prophylaxis

Common Pitfalls to Avoid

• Do not routinely prescribe LMWH based solely on age >35 and BMI >30 without cesarean delivery or other major risk factors, as this may cause more harm than benefit 1
• Do not use aspirin for VTE prophylaxis in pregnancy 1
• Do not withhold compression devices if cesarean delivery occurs—they should be standard for all cesarean deliveries 1
• Do not forget to reassess risk if clinical circumstances change during labor or postpartum 1

Answer: C. Early ambulation only (with consideration for compression stockings as an adjunct)