Friday, January 16, 2009

0.5% risk of deep vein thrombosis with cesarean delivery

A new North American study by Winnie Siaa et al, 'The incidence of deep vein thrombosis in women undergoing cesarean delivery', set out to determine the incidence of deep vein thrombosis (DVT) post cesarean delivery since venous thromboembolism (VTE) is one of the leading causes of maternal mortality in the United States and Canada, and cesarean delivery is a known risk factor.

The autors found an incidence proportion of DVT post cesarean delivery of 0.5% and say this is the largest study to date that uses Doppler compression ultrasound to diagnose DVT in women after cesarean deliveries.

Study highlights
The research is certainly worth a read, but I've highlighted some of the interesting points made by the researchers in the 'Comment' section of their presentation:

*A Swedish prospective study found an incidence of DVT post cesarean delivery at 1.8% using impedance plethysmography, which is known to have high false positive rate compared to Doppler ultrasound. However, four other studies using Doppler ultrasound did not find any DVT in their cesarean delivery population... [many more studies are cited]

*This incidence of post cesarean delivery DVT is much lower than that reported among general surgical patients... This disparity between general surgical patients and patients undergoing CD may be due to many factors. First, patients undergoing CD are generally younger. This is still true even though 20% of our population would be described as “advanced maternal age” for being over 35 years old. Age is both an independent risk factor of VTE and is associated with increased likelihood of co-morbidities. Second, most cesarean deliveries are now performed under regional anesthesia, which is known to have a lower risk of postoperative DVT compared with general anesthesia. Third, postpartum mothers are more likely to be out of bed early and frequently (because of the needs of their newborn) as compared to patients who have undergone other abdominal surgeries.

*It is interesting to note that while our study population appears to have few VTE risk factors, 78% would have warranted thromboprophylaxis after cesarean delivery per RCOG guideline. The preeclampsia rate of nearly 10% in our study is higher than that of the general obstetric population likely because preeclampsia increases the risk of cesarean delivery and our participants all had cesarean deliveries.

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