C-section may increase risk of blood clot in vein: study

Women are four times more likely to suffer from blood clots in veins after a cesarean-section delivery compared to a vaginal birth, according to a new study.
Following any birth, women are at an increased risk for a venous thromboembolism (VTE), however it is believed that cesarean-section (CS) leaves women more vulnerable to VTE, or blood clots in veins, than vaginal delivery (VD).
The study determined that there is a link between CS and an increased absolute risk of VTE, including pulmonary embolism and deep vein thrombosis.
Investigators found that CS was associated with a higher rate of overall VTE risk, with emergency CS associated with the greatest risk.

The new analysis systematically reviewed 60 authoritative studies related to postpartum VTE outcomes. Investigators found that CS carries a four-fold greater VTE risk than VD.
"We found that CS is an important independent risk factor for the development of VTE in the postpartum period and that approximately three VTE will occur for everything 1,000 CS performed, with greater risks for nonscheduled emergency CS," said lead investigator Marc Blondon, from Geneva University Hospitals in Switzerland.

These risks were largely independent of other factors like maternal age and body mass index.
Pregnant women become more susceptible to VTE due to a variety of factors, including venous stasis and trauma associated to delivery, researchers said.

Hemostatic changes drive increases in some coagulation factors, while decreasing bleeding inhibitors, but for some reason these changes seem to be worse for women who deliver via CS.
"In the postpartum period specifically, women following CS exhibit greater activation of coagulation than women following VD, as reflected by greater D-dimer levels," said Blondon.
D-dimer levels indicate that blood clots may be forming or breaking down in the body.
"This outcome may be a result of the conditions leading to the CS or to the procedure itself, similar to the increased VTE risk following non-obstetric surgery.
"Furthermore, physical activity is reduced following CS compared with following VD, with delayed recovery of mobility occurring in the first two days following delivery," said Blondon.

The research was published in the journal CHEST.