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Overview

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., 2009) are present. Blood loss is difficult to estimate, and is frequently underestimated (Lyndon et al., 2015). Healthy women can compensate for significant blood loss before exhibiting marked signs and symptoms. This underscores the importance of clinical vigilance to manage patients who experience PPH and to ensure the development and implementation of protocols and practices to actively manage the third stage of labour (the period following the completed delivery of the newborn until the completed delivery of the placenta) to prevent PPH (WHO, 2012; Lyndon et al., 2015). 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).

There are several possible reasons for severe bleeding during and after the third stage of labour, often referred to as the four T's:

  • 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., 2009).

Tone or "uterine atony" is the leading cause of immediate PPH (75 to 90 per cent) (Koh et al., 2009).

Secondary PPH is defined as excessive vaginal bleeding from 24 hours after delivery, to up to six weeks postpartum. Most cases of delayed PPH are due to retained products of conception, choriocarcinoma, infection, and subinvolution of the placental implantation site. Other causes include, lower genital tract lacerations/hematoma, surgical injury, dehiscence of Caesarean section scar, fibroids and arteriovenous malformation and coagulopathies (Alexander, Thoas, Sanghera, 2002; ACOG, 2006; Aiken, Mehasseb, Prentice, 2012).

Instrumentation and C-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).

Risk Factors for PPH

Table 3 of the SOGC Clinical Practice Guideline "Active Management of the Third Stage of Labour: Prevention and Treatment of Postpartum Hemorrhage" (Leduc et al., 2009) lists multiple risk factors associated postpartum hemorrhage (PPH). The California Maternal Quality Care Collaborative (CMQCC) Obstetric Hemorrha ge Toolkit (Lyndon et al., 2015), offers guidance on assessing for risk factors on admission as well as during labour and postpartum (see details of risk factors listed below).

Table 1: Pregnancy/Admission Risk Factors (Lyndon et al., 2015)

Low Medium High
No previous uterine incisionPrior Caesarean birth(s) or uterine surgeryPlacenta previa, low lying placenta
Singleton pregnancyMultiple gestationSuspected placenta accreta, percreta, increta
≤ 4 previous vaginal births> 4 previous vaginal birthsHematocrit < 30 AND other risk factors
No known bleeding disorderChorioamnionitisPlatelets < 100,000
No history of postpartum hemorrhageHistory of previous postpartum hemorrhageActive bleeding
 Large uterine fibroidsKnown coagulopathy

Additional risk factors that may develop in labour include:

  • Prolonged second stage.
  • Prolonged oxytocin use.
  • Active bleeding.
  • Chorioamnionitis.
  • Magnesium Sulfate treatment.

Additional third stage/postpartum risk factors for hemorrhage stemming from the birth process include:

  • Vacuum- or forceps-assisted birth.
  • Caesarean birth (especially urgent/emergent Caesarean).
  • Retained placenta.

Implications

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, 2009).

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).

Goal

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.