Blood Clot Searching During Pregnancy

Deep vein thrombosis in pregnant women can be detected with ultrasound Doppler imaging

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Pregnant women are at higher risk for blood clots, which can be fatal. Doctors use ultrasound tests to look for clots, but it's not clear whether those tests are good enough.

Symptomatic women are therefore often given blood thinners to be on the safe side. But blood thinners also have risks.

Therefore researchers conducted a study to see how effective the ultrasound testing was on women who had symptoms of blood clots.

The researchers used multiple ultrasound scans over a period of one week with a technique called Doppler imaging.

They found that this method was effective in discovering blood clots in women and did not have a high rate of failure in not finding clots.

"Attend all prenatal visits."

The study was led by Wee-Shian Chan, MD, of the Department of Medicine at McMaster University in Ontario, Canada. It involved 221 women who were suspected of having deep vein thrombosis - a condition characterized by blood clots in the legs which can eventually dislodge into the lungs or heart.

None of the women were given blood thinners, also called anticoagulants. Blood thinners are the most common treatment when someone is known to have a blood clot because the medication helps break up the clot.

Each woman received an ultrasound assessment using Doppler imaging of her legs. Blood clots most often form in the legs first and then travel up the body.

Women whose tests showed no blood clots received two additional ultrasound tests over the next week after the first test.

Only 16 of the women (7.2 percent) were diagnosed at the time of the ultrasound with deep vein thrombosis, but none of those women had blood clots on later tests. One woman had normal tests during all the ultrasounds but had a pulmonary embolism (blood clot in the lungs) 7 weeks later.

Overall, 17 of the 221 women with symptoms of deep vein thrombosis had any blood clots at all.

The researchers concluded that repeated ultrasound scans with Doppler imaging was effective in diagnosing deep vein thrombosis (blood clots) in pregnant women.

They acknowledged that repetition of the testing may not be necessary over 7 days because a single scan appeared sufficient for excluding the possibility that a woman had blood clots.

Serial (multiple) scans are more expensive, and women are less likely to return for later tests, the researchers noted, so they plan to do another study to see if single scans are safe enough on their own.

The study was published January 14 in the Canadian Medical Association Journal. The research was funded by Heart and Stroke Ontario.

One author has received consultancy, lecture or travel payments from Bayer, Amgen, Sanofi and Covidien. Another has received grants from Pfizer, Boehringer Ingelheim, GTC Therapeutics, bioMérieux and LEO Pharma. A third author has consulted for Boehringer Ingelheim, Bayer, Bristol-Myers Squibb and Pfizer. No other disclosures were noted.

Reviewed by: 
Review Date: 
January 14, 2013
Last Updated:
January 15, 2013