Venous Thromboembolism in Pregnancy: Challenges and Solutions

Figures & data

Figure 1 Convergence of Virchow’s triad during pregnancy —endothelial trauma, venous stasis, and hypercoagulability—as well as postpartum. Coagulation is gradually activated to prepare the mother for delivery. The anticoagulant activity of protein S is reduced, and activated protein C resistance rises. A higher concentration of fibrinogen, factors V, IX, X, and VIII, enhances procoagulant activity, leading to increased thrombin production, as demonstrated by an increase in soluble fibrin and prothrombin levels. Reduced fibrinolysis results from increased plasminogen activator inhibitor type 1 and 2 and decreased tissue plasminogen activator (tPA) activity. Endothelial damage to the pelvic vessels results from mechanical stress during normal, induced, or operative vaginal delivery. Venous stasis occurs due to the combination of estrogen-induced venodilation, pelvic venous compression, and compression of the left iliac vein by the right iliac artery.

Table 1 Risk Factors Associated with Pregnancy-Associated VTE

Antepartum Risk Factors	Adjusted OR
Immobilization
BMI < 25 kg/ m	7.7 (3.2–19)
BMI > 25 kg/ m	62.3 (11.5–337)
Smoking	2.1 (1.3–3.4)
Twins	2.6 (1.1–6.2)
Assisted reproduction	4.3 (2–9.4)
IBD	2.1 (1.7–2.7)
Diabetes	3.5 (1.1–11)
Varicose veins	2.2 (1.6–4.8)
Hyperemesis	2.5 (1.4–4.5)
Postpartum Risk factors
Cesarean Delivery (non-emergent)	1.3 (0.7 −2.2)
Cesarean Delivery (emergent)	2.7 (1.8–4.1)
Postpartum infection	20.2 (6.4–63.5)
Immobilization
BMI< 25 kg /m2	10.8 (4–28)
BMI > 25 kg/m2	40.1 (8–201)
Postpartum bleeding	4.1 (2.3–7.3)
Preeclampsia	3.1 (1.8–5.3)
Smoking	3.4 (2–5.5)
IBD	2.6 1.8–3.7
Varicose veins	3.9 2.6–5.9

Note: Data from^79,96

Table 2 The Table Shows How the Following Clinical Criteria Would Perform in 1000 Women, of Whom 65 Had PE as per the DiPEP study

Scores	Sensitivity	Specificity	PPV	NPV
Primary consensus^a	0.615	0.585	0.093	0.956
Sensitive consensus^a	0.954	0.035	0.065	0.916
Specific consensus^a	0.354	0.783	0.102	0.946
PERC^b	0.677	0.519	0.089	0.958
Simplified Revised Geneva	0.446	0.636	0.079	0.943
Well’s (permissive)	0.490	0.617	0.082	0.946
Well’s (strict)	0.376	0.895	0.196	0.952
D-dimer (conventional threshold)	0.877	0.088	0.063	0.911
D-dimer (pregnancy-specific threshold)^c	0.692	0.325	0.066	0.939

Notes: ^aPrimary consensus, Sensitive Consensus, and Specific consensus are clinical criteria developed earlier in the DiPEP study to guide advanced imaging decisions for pulmonary embolism in pregnancy and the postpartum period.^{103 c}Previous studies had suggested that using a higher threshold could improve specificity without compromising sensitivity.¹¹⁴ Data from ^99,103,114

Abbreviation: ^bPERC, Pulmonary embolism Rule-out Criteria.

Table 3 Diagnostic Accuracy of Presenting Features as Calculated in the Study Population of DiPEP

Symptom/ Sign	Sensitivity	Specificity	PPV	NPV
Presenting feature: Pleuritic chest pain	0.519	0.471	0.407	0.584
Presenting feature: Non-pleuritic chest pain	0.210	0.819	0.447	0.597
Presenting feature: SOB	0.536	0.394	0.382	0.548
Presenting feature: Hemoptysis	0.072	0.961	0.565	0.597
Presenting feature: Cough	0.088	0.911	0.410	0.589
Presenting feature: Syncope	0.050	0.973	0.563	0.594
Presenting feature: Palpitations	0.133	0.884	0.444	0.593
Temperature> 37.5	0.077	0.973	0.667	0.601
Diastolic Pressure < 50 mmHg	0.022	0.992	0.667	0.592
Systolic pressure < 90 mmHg	0.017	0.996	0.750	0.592
O2 saturation <94%	0.149	0.961	0.730	0.618
RR > 24 / min	0.099	0.903	0.419	0.589
Heart rate > 100/min (110/min third trimester)	0.304	0.722	0.433	0.597
Clinical signs of DVT	0.127	0.911	0.500	0.599

Note: Data from Goodacre S, Horspool K, Nelson-Piercy C, et al. The DiPEP study: an observational study of the diagnostic accuracy of clinical assessment, D-dimer and chest x-ray for suspected pulmonary embolism in pregnancy and postpartum. BJOG. 2019;126(3):383–392.⁹⁹

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