Solo Ultrasound for DVT Enough in Pregnancy

It appears to be safe to use a single complete compression ultrasound scan to rule out deep vein thrombosis (DVT) in pregnant women and those who have recently given birth, researchers found.

Among women with a negative sonographic scan, just 1.1% developed a confirmed DVT through 3 months of follow-up, Gre'goire Le Gal, MD, PhD, of the Centre Hospitalier Universitaire de la Cavale Blanche in Brest, France, and colleagues reported online in BMJ.

That rate was consistent with the rate following a normal phlebography - the reference test - in nonpregnant individuals, they noted.

"These data suggest that a negative single complete compression ultrasonography result may safely exclude the diagnosis of deep vein thrombosis in this setting," they wrote.

Diagnosing DVT during pregnancy, and the immediate postpartum period, can be challenging because pregnancy is a risk factor for venous thromboembolism. Also, some symptoms, including pain, tenderness, and swelling of the legs, occur in both the settings of pregnancy and DVT.

Phlebography is the reference method for diagnosing DVT, but in recent years, compression ultrasonography has become widely used in clinical practice. The technique has been shown to safely rule out DVT in nonpregnant individuals, although it had not been prospectively evaluated during and shortly after pregnancy.

Arteries have thin muscles within their walls to be able to withstand the pressure of the heart pumping blood to the far reaches of the body. Veins don't have a significant muscle lining, and there is nothing pumping blood back to the heart except physiology. Blood returns to the heart because the body's large muscles squeeze the veins as they contract in their normal activity of moving the body. The normal activities of moving the body returns the blood back to the heart.

There are two types of veins in the leg; superficial veins and deep veins. Superficial veins lie just below the skin and are easily seen on the surface. Deep veins, as their name implies, are located deep within the muscles of the leg. Blood flows from the superficial veins into the deep venous system through small perforator veins. Superficial and perforator veins have one-way valves within them that allow blood to flow only in the direction of the heart when the veins are squeezed.

A blood clot (thrombus) in the deep venous system of the leg is not dangerous in itself. The situation becomes life-threatening when a piece of the blood clot breaks off (embolus, pleural=emboli), travels downstream through the heart into the pulmonary circulation system, and becomes lodged in the lung. Diagnosis and treatment of a deep venous thrombosis (DVT) is meant to prevent pulmonary embolism.

Clots in the superficial veins do not pose a danger of causing pulmonary emboli because the perforator vein valves act as a sieve to prevent clots from entering the deep venous system. They are usually not at risk of causing pulmonary embolism.