Thromboembolic (TE) disease remains the leading direct cause of maternal death in the UK and caesarean section increases TE risk. Women are assessed for their TE risk and may receive thromboprophylaxis. From a single blood sample thromboelastography(®) (TEG(®)) allows a test of coagulation. Blood samples from women undergoing elective caesarean sections were collected at specific stages: antenatally, following overnight 'nil-by-mouth', immediately after surgery, four hours post-delivery and 24 hours post-delivery. Analyses of the R time (time taken for blood to clot) and maximum amplitude (MA) (overall clot strength) were performed. Analyses of the high and moderate risks cohorts were performed and compared to the low risk group. Fifty-four women were recruited. A reduction in the R time was demonstrated following pre-operative fluid restriction and a further reduction in R time occurred after surgery. The R time increased 24 hours after surgery and became comparable to pre-operative levels. The MA changed similarly due to pre-operative fluid restriction. Analysis also showed that pre-operatively, the combined high and moderate risk groups' R time was shorter than the low risk group. The high and moderate risk group, having received thromboprophylaxis, had similar R times 24 hours postoperatively compared to the low risk group. TEG(®) demonstrates that following pre-operative fluid restriction and surgery women become hypercoagulable but by 24 hours coagulation has returned to third trimester levels. Sub-group analysis suggests the relative pre-operative hypercoagulability of high and moderate risk women compared to low risk women, becoming comparable after 24 hours following thromboprophylaxis.
Keywords: caesarean section; haematology; maternal mortality; pregnancy; thromboelastography; thromboembolic disease.