Use of thromboelastography to assess the combined role of pregnancy and obesity on coagulation: a prospective study.

BACKGROUND

Thromboelastography (TEG®) is a point of care monitor of whole blood coagulation and has previously demonstrated hypercoagulability in both pregnant and obese populations. However, the individual and combined contribution of pregnancy and obesity on coagulation status has not been defined. We carried out a study to assess the effect of both pregnancy and body mass index (BMI) on blood coagulation using laboratory tests of coagulation and thromboelastography.

METHODS

This was a prospective study of 96 women divided into four equal groups; non-pregnant lean (NPL) BMI <25kg/m(2), pregnant lean (PL) BMI <25kg/m(2), non-pregnant obese (NPO) BMI >35kg/m(2) and pregnant obese (PO) BMI >35kg/m(2). Women were of either >36weeks of gestation presenting for elective caesarean delivery; non-pregnant women with BMI >35kg/m(2) presenting for bariatric surgery; or non-pregnant volunteers with BMI <25kg/m(2). Eligible women were then allocated to a group based on BMI and pregnancy status. TEG® analysis, full blood count and coagulation profiles were performed on all patients. The main outcome measures were TEG® profile (including r time, k time, α angle, maximum amplitude and coagulation index), platelet count, activated partial thromboplastin time, prothrombin time, and fibrinogen levels.

RESULTS

The coagulation index was significantly higher in the obese patient groups compared with the lean groups (NPL -4.5 vs. NPO 1.9, P<0.001; PL -4.3 vs. PO 2.5, P<0.001). However, comparisons between the pregnant and non-pregnant groups when matched for BMI demonstrated no significant difference in coagulation.

CONCLUSIONS

The combined effect of pregnancy and obesity on coagulation has not previously been investigated. Thromboelastographic comparison of pregnant and non-pregnant females separated into low or high BMI cohorts in the current study suggests that obesity correlates more with a hypercoagulable state than with pregnancy, particularly in pregnant patients at the extremes of low and high body weight.