A randomised double-blind placebo controlled trial of low molecular weight heparin as prophylaxis in preventing venous thrombolic events after caesarean section: a pilot study

Objective To pilot a protocol for a national multicentre randomised trial in which a low molecular weight heparin will be compared with placebo for prevention of venous thrombotic events occurring within six weeks after caesarean section. Design Double-blind randomised controlled trial. Setting Tertiary care centre. Participants Seventy-six women having had a caesarean section, 37 in the control group and 39 in the Dalteparin group. Methods Consenting patients having had an emergency or elective caesarean section were commenced on study medication 6-24 hours post-operatively. The study medication, dalteparin 2500iu or saline, was oriven subcutaneously once daily for four or five days post-operatively depending on the patient's length of stay. Patients were reviewed in hospital for operative outcomes and contacted at two and six weeks post-operatively. Results Of the 141 women given information about the trial, 76 (54%) consented to participate. Follow up to six weeks was achieved in all women who were recruited. More women in the placebo arm had general anaesthesia, but otherwise the two groups had similar characteristics at randomisation. There was only one occurrence of a deep vein thrombosis during the study. This patient was in the treatment arm and the thrombosis occurred between two and six weeks post-operatively. All other outcomes were similar in the two groups. Conclusion Our experience of a 26% recruitment rate, the thrombosis rate of 1.3% (95% CI 0.03-7.1%) and the contactability of all participants two and six weeks post-operatively, indicates that this study is feasible.