Postpartum hemorrhage is the leading cause of maternal death worldwide, with an estimated mortality rate of 140 000 per year, or one maternal death every four minutes. PPH occurs in five per cent of all deliveries and is responsible for a major part of maternal mortality. The majority of these deaths occur within four hours of delivery, which indicates that they are a consequence of the third stage of labour. Nonfatal PPH results in further interventions, such as uterine exploration, evacuation or surgical procedures. Other implications include: iron deficiency anemia, exposure to blood products, coagulopathy, and organ damage with associated hypotension and shock which has the potential to jeopardize future fertility (Leduc et al. 2018).
Despite the use of uterotonics and active management of third stage of labour to prevent PPH, increases in PPH rates have been reported from high income countries, including Canada, the United States, the United Kingdom and Australia. Rates of severe PPH and of transfusion for treatment also appear to be rising. Rates of postpartum hemorrhage and severe postpartum hemorrhage continued to increase in Canada between 2003 and 2010 [from 3.9 per cent in 2003 to 5.0 per cent in 2010] and occurred in most provinces and territories. The increase could not be explained by maternal, fetal, or obstetric factors. Routine audits of severe postpartum hemorrhage are recommended for ensuring optimal management and patient safety (Mehrabadi et al. 2014).
Primary Postpartum Hemorrhage (PPH) is defined as excessive bleeding that occurs within the first 24 hours after delivery. Traditionally the definition of PPH has been blood loss in excess of 500 mL after vaginal delivery and in excess of 1000 mL after abdominal delivery. For clinical purposes, any blood loss that has the potential to produce hemodynamic instability should be considered PPH. The amount of blood loss required to cause hemodynamic instability will depend on the pre-existing condition of the woman. Hemodynamic compromise is more likely to occur when conditions such as anemia (e.g., iron deficiency, thalassemia) or volume-contracted states (e.g., dehydration, gestational hypertension with proteinuria) (Leduc et al. 2018) are present.
PPH is one of the few obstetric complications with an effective preventive intervention and it is generally assumed that by preventing and treating PPH, most PPH-associated deaths could be avoided (Mathai et al. 2007; WHO 2012). Specifically, 54-93% of maternal deaths due to obstetric hemorrhage may be prevented. Imprecise healthcare provider estimation of actual blood loss during birth and the immediate postpartum period is the leading cause of delayed response to hemorrhage (The American College of Obstetricians and Gynecologists 2019). Blood loss is difficult to estimate and is frequently underestimated when volumes are high and overestimated when volumes are low (The American College of Obstetricians and Gynecologists 2019; Lyndon et al. 2015).
There are several possible reasons for severe bleeding during and after the third stage of labour, often referred to as the four
Tone or uterine atony: abnormalities of uterine contraction;
Tissue: retained placenta, products of conception;
Trauma of the genital tract: lacerations of the cervix, vagina or perineum; uterine rupture; uterine inversion; and
Thrombin: abnormalities of coagulation due to pre-existing states such as haemophilia A and von Willebrand's Disease, or acquired in pregnancy such as Immune Thrombocytopenic Purpura (ITP) or Disseminated Intravascular Coagulation (DIC) (Leduc, et al. 2018).
Secondary PPH is defined as excessive vaginal bleeding from 24 hours after delivery, to up to six weeks postpartum. Most cases of secondary PPH are due to retained products of conception, infection, subinvolution of the placental site and inherited coagulation defects such as von Willebrand (The American College of Obstetricians and Gynecologist 2017).
Instrumentation and Caesarean Section: Some obstetrical interventions are found to consistently be associated with higher rates of blood loss at the time of delivery thus predisposing patients to developing PPH. Included interventions are instrumental deliveries, episiotomy and caesarean sections, with emergency caesarean sections associated with higher rates of blood loss. It is important to note that more recent studies suggest that some obstetrical interventions increase the likelihood of PPH in a subsequent pregnancy, and that the recent increase in PPH in developed countries, which cannot seem to be wholly explained by factors related to the current pregnancy and delivery, may be due to more distal contributory factors (Roberts et al. 2009; Briley et al. 2014).
To prevent obstetrical hemorrhage from the pelvic area, genital tract, or perineum following vaginal delivery and from surgical incision after an instrument-assisted delivery or Caesarean section.
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