Health Advice



Doctors debate use of blood thinners to prevent clots in women after C-sections

Harris Meyer, Kaiser Health News on

Published in Health & Fitness

Nearly all women who deliver babies through cesarean section at Columbia University Irving Medical Center in New York City receive injections of the blood thinner heparin for weeks after the procedure, to prevent potentially life-threatening blood clots.

Obstetric leaders there say that’s good medical practice because the formation of those clots, called venous thromboembolism or VTE, though uncommon, is a leading cause of maternal death after delivery, particularly C-section delivery. Broad use of heparin has been shown to be effective and safe in the United Kingdom in reducing that risk and should be adopted in the U.S., they argue.

But there’s sharp debate among physicians about whether wide use of heparin is effective, worth the cost and safe, since it carries the risk of bleeding. Last year, the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine recommended heparin only for women at elevated risk of VTE, citing a lack of evidence supporting near-universal use.

The controversy illustrates a classic dilemma for physicians: whether and how to adopt promising new treatments before studies have proven their safety and effectiveness. There also are questions about keeping drug company funding from influencing clinical recommendations around the drug.

The Columbia doctors were lead authors of 2016 guidelines from the National Partnership for Maternal Safety — a multidisciplinary group of medical experts — encouraging doctors to give heparin shots to all women after C-sections, except patients with specific risks. Previously, only a small percentage of mothers received them. Nearly 1.2 million U.S. women deliver via C-section each year.

Other U.S. physician groups generally promote heparin use only for women with a personal or family history of deep vein thrombosis or blood clots in the lungs, called pulmonary embolism, or other high-risk factors. They are estimated to make up less than 5% of pregnant or postpartum women.


Despite gaps in evidence, experts said, the use of heparin has increased across the U.S. since the 2016 guidelines came out, though practices vary widely among doctors and hospitals. One reason for the rise is that more women giving birth have risk factors for VTE, such as obesity and older age.

“We have to make sure we’re doing everything possible to reduce preventable maternal death,” said Dr. Mary D’Alton, chairperson of obstetrics and gynecology at Columbia University and lead author of the 2016 guidelines. She called heparin treatment “very reasonable” after a cesarean delivery.

One of her co-authors has had second thoughts, however.

“I’d have to agree with some of the critics that there isn’t solid evidence we should be giving heparin to as many patients as we do here at Columbia,” said Dr. Richard Smiley, an anesthesiologist. “I’d probably want to take a step back. But physicians are willing to be a little more aggressive on this because maternal death is so traumatizing.”


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