Women undergoing termination of pregnancy before 15 weeks gestation do not need thromboprophylaxis unless they have factors that put them at high risk, new guidance published in the British Journal of Haematology advises.

It comes after a Canadian study found that while women have twice the risk of venous thromboembolism (VTE) after a medical or surgical termination compared with women who are not pregnant, the risk is a fifth of that seen in women who deliver at full term.

The risk was also found to be the same in women who had an abortion as pregnant women at the same stage of gestation, the research had shown.

Professor Beverley Hunt a co-author of the guideline and consultant in haemostasis and thrombosis at King’s College London told the limbic that the Canadian paper showed there was much less risk in this group of patients than people had thought prompting the British Society of Haematology Obstetric Haematology Special Interest Group to put together a consensus.

“It was suggested that the termination procedure doesn’t increase risk of VTE up to 15 weeks so we have produced some guidance with a scoring system which suggests you don’t need to give so much low molecular weight heparin to women if they have a termination.”

She added that using the modified standard scoring system enables healthcare professionals to take into account other risk factors that women may have including age, weight, or other conditions. The recommendations also apply to women having a miscarriage in the first trimester.

Women with four or more points should receive LMWH for seven days post-procedure as per the RCOG risk assessment tool, the guidance states.

“But for many women who are not older or not overweight or don’t have underlying problems you wouldn’t give thromboprophylaxis with low molecular weight heparin,” said Professor Hunt

The recommendations, which are pointed out that lack of evidence meant NICE guidance published in 2019 was only able to provide the advice that women considered to be at increased risk of VTE should receive seven days of thromboprophylaxis following the termination of pregnancy.

After 15 weeks women should be treated the same as those post-partum, the recommendations state.