Ultrasound strategy excludes DVT in pregnant women

By Stephanie Leveene, medwireNews Reporter

Serial compression ultrasonography with iliac vein visualization can reliably exclude deep vein thrombosis (DVT) in symptomatic pregnant women, according to results from an 8-year prospective cohort study published in the Canadian Medical Association Journal.

Consequently, "it is likely safe to withhold anticoagulation in women with negative

imaging results," write Wee-Shian Chan (McMaster University, Hamilton, Ontario, Canada) and colleagues.

In total, 221 pregnant women with suspected DVT were given compression ultrasonography and iliac vein visualization. Sixteen (7.2%) cases of DVT were found with the first use of these tests, and these patients were treated with anticoagulants. Anticoagulation therapy was then withheld from the other 205 women and they were retested at days 2-4 and 6-8. No additional cases of DVT were detected during that time.

Six additional patients out of the group of 205 developed DVT and/or pulmonary embolism symptoms during the subsequent follow-up period of 3 months or more, but there was only one confirmed case. This translates to a follow-up incidence rate of 0.49% and an overall study prevalence rate of 7.7%. The sensitivity of both the initial and serial compression ultrasonographic studies and iliac vein visualization was 94.1%.

The majority (82%) of DVT diagnoses were made in the left leg. Of the 17 cases of DVT, 11 (65%) involved the iliac vein. As the authors explain, the thrombosis can then move into the femoral vein or the inferior vena cava. This is different from how DVT presents in men and nonpregnant women; in those groups, isolated iliac DVT is rare.

The current standard method of diagnosing DVT in symptomatic pregnant women is compression ultrasonography, with iliac vein visualization recommended if the results are negative. Previously, there had been no specific prospective studies validating the use of this diagnostic approach.

The authors conclude: "Our strategy… appears to reliably exclude clinically important deep vein thrombosis. Because all of our cases of deep vein thrombosis were identified by initial imaging with compression ultrasonography and Doppler studies, it is unclear whether serial testing over a 7-day period is necessary."

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