Standard haemostatic tests following major obstetric haemorrhage

Postpartum haemorrhage is an important cause of maternal morbidity and mortality. It is associated with haemostatic impairment which may exacerbate bleeding.

All deliveries over a 3-year period in a large UK unit were reviewed and cases of haemorrhage of 1500 mL or more identified. Laboratory records were reviewed and the lowest value for haemoglobin, platelet count and fibrinogen, and longest value for prothrombin time and activated partial thromboplastin time within 24h of delivery were recorded.

Of 18,501 deliveries there were 456 bleeds of 1500 mL or more (2.5%). Fibrinogen levels correlated best with blood loss (r -0.48 P<0.01) and fell progressively as volume increased. Activated partial thromboplastin time was less sensitive (r 0.4 P<0.01) to increasing blood loss. Prothrombin time did not correlate with blood loss (r 0.01). Activated partial thromboplastin time and prothrombin time remained within the normal range in most women despite large bleeds. Similar results were observed in women who received four or more units of red blood cells. Haemoglobin level was adequately maintained irrespective of blood loss. Based on UK national guidelines only 13 of 456 (3%) women should have received fresh frozen plasma, although it was given to 45; despite this, fibrinogen levels below the pregnancy-related normal range were observed in most cases.

Fibrinogen level was the parameter that best correlated with increasing volume of haemorrhage and was the most useful marker of developing haemostatic impairment. Guidelines for fresh frozen plasma use in major postpartum haemorrhage were rarely followed and should be reviewed.