[IS ANTI-THROMBOTIC PROPHYLAXIS WARRANTED IN FERTILITY AND IN-VITRO FERTILIZATION TREATMENTS?].

Introduction: Assisted reproductive technology (ART) treatments are potential risk factors for thromboembolism (TE) due to excessive estrogen levels. Recently, several studies have shed new light on this matter.

Aims: To review the literature to assess the risk for TE during ART and to establish guidelines regarding thrombophylaxis.

Methods: A search was conducted of PubMed, Medline, Cochrane and clinicaltrials.gov. The search terms were fertility, assisted reproductive technology, IVF, thromboembolism, thrombosis and anticoagulation. Case reports and reviews were excluded.

Results: Three cohort studies and one cross-sectional study were included; one examined the effect of ART on TE risk after cycles not resulting in pregnancy. The others evaluated TE risk if pregnancy was achieved. The rate of TE for 75,141 cycles not resulting in pregnancy was not higher than controls in the general population. The three studies which compared TE risk when pregnancies were achieved found that ART increased the risk for TE primarily during the first trimester. If ovarian hyperstimulation syndrome (OHSS) was present the risk increased further. The risk for TE after frozen embryo replacement cycles was not increased.

Conclusions: ART posed a risk factor for TE during pregnancy, but not during ovarian stimulation or in cycles not resulting in pregnancy. Thrombophylaxis is not indicated for all women undergoing ART. Women with OHSS should be given thrombophylaxis during the acute episode and throughout the first trimester. Caution is advised for patients with combined risk factors and treatment should be individualized. Guidelines for thromboprophylaxis are provided.