A single complete compression ultrasound study may safely exclude the diagnosis of deep vein thrombosis (DVT) in pregnant and postpartum women, according to a study published in the May issue of British Medical Journal. However, the authors suggested additional confirmatory data are needed.

Pregnancy is a risk factor for venous thromboembolism, yet diagnosis in this population can be challenging. Phlebography is invasive and costly and exposes the fetus to radiation. The clinical utility of D-dimer measurements is reduced in pregnant women. Serial impedance plethysmography is safe during pregnancy, but less accurate than compression ultrasonography, which has emerged as the primary diagnostic exam for suspected DVT. However, the exam had not been prospectively evaluated in pregnant and postpartum women.

Gregoire Le Gal, MD, professor of internal medicine at Centre Hospitalier Universitaire de la Cavale Blanche in Brest, France, and colleagues conducted a prospective study to exam the safety of using a single complete compression ultrasound exam to rule out DVT in pregnant and postpartum women.

The study sample included 210 women who presented to two tertiary care centers and 18 private practices in France and Switzerland with suspected DVT between January 2006 and June 2009. All women underwent venous ultrasonography and women with negative results were followed up for a three-month period.

DVT was diagnosed in 22 women, wrote Le Gal and colleagues. Of the remaining women, 10 received therapeutic anticoagulant treatment and one was lost to follow-up, leaving 177 women available for analysis.

After follow-up, the researchers observed a three-month thromboembolic rate in patients left untreated based on a negative ultrasound result of 1.1 percent. “This result is in line with what was reported after a normal phlebography—the reference test—in non-pregnant patients and with the data obtained in a retrospective cohort study assessing the safety of a single complete compression ultrasonography in pregnant and postpartum women with DVT.”

The authors admitted that the 4 percent upper bound of the 95 percent confidence interval is higher than the 3 percent limit suggested by others, which prevented them from making a firm conclusion. They suggested additional, larger studies be undertaken to provide narrower estimates of the failure rate.

“Further investigations should aim at confirming these results and evaluating the use of compression ultrasonography in a sequential diagnostic strategy including assessment of clinical probability and D-dimer measurement,” they wrote.