Blood loss and blood transfusion at caesarean section: a prospective observational study covering 30 years

Attitudes to acute blood loss and transfusion have changed during the last 40 years. This study observed the trends in blood loss and transfusion rates at caesarean section during that period to identify any trends between 1976 and 2006.

Prospective analysis of clinical notes of women delivered by caesarean sections in a major district hospital obstetric unit in the UK, delivering around 6000 annually during four 12-month periods every 10 years from 1976 to 2006. Details including demographic, pregnancy, delivery, blood loss, transfusion, and puerperal observations were recorded.

3222 of 22,998 women were delivered by caesarean section during the four study years, increasing from 7.2% in 1976 to 23.4% in 2006 (P<0.001). The median recorded blood loss was 500ml, which did not change significantly over the study years. The rate of excess blood loss however increased in low-risk cases in 2006 compared with 1996 (P<0.001); this increase followed the recommended restricted intra-operative oxytocin dose. Transfusion rates declined significantly from 22% in 1976 to 4-5% in 1996 and 2006 (P<0.001).

Median blood loss remained steady for each of the study years but with an increase in excess blood loss cases in the last study year compared with the two previous study years. The explanation for this is presently uncertain, but was possibly influenced by the 2001 recommendation for a reduced dose of oxytocin at delivery. Transfusion rates declined, probably precipitated by anxieties over infections associated blood products. There was no indication of increased morbidity with the reduced transfusion rates accessed by the surrogate of post-delivery discharge times.