There is no worldwide agreement on the definitions of postpartum haemorrhage and major postpartum haemorrhage. Some define postpartum haemorrhage as blood loss exceeding 500 ml and major postpartum haemorrhage as blood loss exceeding 1000 ml. Others define postpartum haemorrhage as blood loss exceeding 500 ml in vaginal deliveries and exceeding 1000 ml at caesarean section. The limitation of all these definitions is the difficulty in quantifying blood loss accurately, particularly in vaginal deliveries. Collector bags can be used for this purpose, but blood frequently falls outside; amniotic fluid and urine may be collected and both will affect quantification. Weighing of swabs is routinely performed in some centres, but the practice is time-consuming and not widely disseminated, and similar inaccuracies to those referred for collector bags may occur. The most widely used alternative is visual estimation of blood loss, but this has well-known limitations, although improved accuracy may be achieved with visual aids, where the appearance of different blood quantity losses is depicted on photographs/drawings (Fig. 6.1). An additional problem arises from the fact that small women and those with pre-existing anaemia may decompensate with lesser quantities of blood loss.

Another definition of postpartum haemorrhage is a reduction in the haematocrit exceeding 10 %, but routine blood analysis before and after birth is rarely practised in low-risk labours, where the majority of complications occur. The need for blood transfusion is an alternative criterion, but it is used mainly in research settings, it leaves out less severe cases of haemorrhage, and transfusion criteria may vary between centres.

From a clinical point of view, the most important factor to define postpartum haemorrhage is the one that should trigger a response from the healthcare team. In the majority of situations, this occurs because profuse and/or persistent genital bleeding is witnessed to occur spontaneously after birth or when uterine massage is performed. Bleeding may be mild and rapidly reversible, so it is important to separate the concept of major postpartum haemorrhage, where more complex interventions need to be considered. Blood loss exceeding 1000 ml or a heart rate approaching the systolic blood pressure is probably the most useful criteria, from a clinical point of view. The “shock index”, defined as the heart rate divided by systolic blood pressure, is used in other areas of Medicine and has recently been applied to postpartum haemorrhage. It is considered abnormal when exceeding 0.9.

The three major causes of early postpartum haemorrhage are uterine atony, which is responsible for about 70–80 % of cases, genital tract lesions accounting for 10–15 % of cases and retained placental tissue. Partial placental retention is usually associated with recurring uterine atony and haemorrhage. Abnormally adherent placenta (accreta, increta and percreta) is normally associated with haemorrhage when attempts are made to remove the placenta, and its incidence has been increasing in some parts of the world because of escalating caesarean section rates. Rarer causes of postpartum haemorrhage are uterine inversion, uterine rupture and maternal bleeding disorders. Uterine inversion is thought to be caused mainly by mismanagement of the third stage of labour, namely by excessive pressure on the uterine fundus, premature traction on the umbilical cord or excess traction during manual removal of an abnormally adherent placenta. Less frequently it occurs after an episode of coughing or vomiting during the third stage of labour.

The incidence of early postpartum haemorrhage varies widely, depending on the criteria used for the diagnosis, the population studied and the methods used for prevention, but it is reported to occur in 2–10 % of all deliveries. The most important risk factors are listed in Table 6.1, but many cases occur in women where these are not present.

Postpartum haemorrhage can be defined as profuse and/or persistent genital bleeding occurring spontaneously after birth or when uterine massage is performed. The diagnosis may be triggered by routine clinical re-evaluation, maternal complaints of dizziness and loss of vision, maternal paleness or by the detection of tachycardia or hypotension. The main clinical usefulness of this definition is that it constitutes a trigger for action from the healthcare team.

The diagnosis of major postpartum haemorrhage implies the same findings, but in addition blood loss exceeds 1000 ml (by quantification or visual estimation) or maternal heart rate approaches systolic blood pressure (the shock index exceeds 0.9).

Management of postpartum haemorrhage involves two major components – support of maternal circulation/oxygenation and treatment of the underlying cause. When an anaesthetist and an obstetrician are present in the room, the responsibility for these two aspects is usually divided among them. In the remaining situations, the person in charge needs to take care of both.