Advances in the Treatment of Postpartum Hemorrhage

Alison M El Ayadi; Nuriya Robinson; Stacie Geller; Suellen Miller

Disclosures

Expert Rev of Obstet Gynecol. 2013;8(6):525-537. 

In This Article

Epidemiology

Postpartum hemorrhage (PPH) is the leading contributor to maternal mortality globally, responsible for approximately 25% of the nearly 300,000 maternal deaths estimated to occur each year.[1,2] It is a major contributor to maternal morbidity, such as anemia.[3] While low-resource countries experience a much higher burden of PPH, it is also a significant cause of maternal death in the developed world.[4] Death from PPH occurs in about 1 per 1000 deliveries in low-resource countries compared with 1 in 100,000 deliveries in higher-resource countries.[5] PPH has traditionally been defined as blood loss ≥500ml within the 24 h following childbirth, with severe PPH defined as blood loss ≥1000ml.[6] Other definitions specified PPH as blood loss >15% of total blood volume, or 10% measured peripartum decline in hemoglobin levels.[7] Recent definitions pay greater attention to symptoms (e.g., lightheadedness, weakness, palpitations, diaphoresis, restlessness, confusion, air hunger and/or syncope) and signs of hypovolemia (e.g., hypotension, tachycardia, oliguria, low oxygen saturation). Most healthy women do not exhibit signs or symptoms of hemodynamic instability until blood loss of 1200 ml. However, some PPH may not be recognized prior to onset of hypovolemia because blood loss is often underestimated,[8] bleeding may occur intra-abdominally[9] and less blood loss is sufficient for PPH development when women are compromised by anemia, preeclampsia or another co-morbidity. Provider awareness of blood loss and monitoring of vital signs is important to trigger the initiation of resuscitation measures and to determine response to resuscitation.

PPH is estimated to occur in between 1 and 5% of deliveries,[10,11] but incidence estimates vary by definition. Globally, Calvert et al. reported PPH prevalence at 10.8% (95% CI: 9.6–12.1) in a recent systematic review and meta-analysis, with wide regional variation ranging from 7.2% (95% CI: 6.3–8.1) in Oceana to 25.7% (95% CI: 13.9–39.7) in Africa.[12] Severe PPH was lower, at 2.8% (95% CI: 2.4–3.2), with similar regional patterning from 1.9% (95% CI: 1.2–2.8) in Asia to 5.1% (95% CI: 0.3–15.3) in Africa. Variability in PPH prevalence was reported by blood loss measurement method (objective vs subjective), management of third stage of labor (active vs expectant), and region. Trend data from the past decade suggest an increasing prevalence of PPH, evidenced by research based in Australia, Canada, USA and UK.[13] Joseph et al. report the observed increase in Canada was mediated by an increase in uterine atony despite temporal adjustment for risk factors.[14] Wu et al. describe a temporal increase in the incidence of placenta accreta over the past several decades, concurrent with increases in cesarean delivery.[15]

Etiologies of PPH are traditionally referred to as the '4 Ts': tone, trauma, tissue and thrombin. 'Tone' describes uterine atony, failure of the uterus to adequately contract. It is the primary cause of PPH, responsible for approximately 70% of cases.[16] Genital tract or uterine 'trauma' is responsible for about 20% of PPH, and comprises perineal, cervical and vaginal lacerations as well as spontaneous or iatrogenic uterine rupture due to surgical or instrumental delivery.[16] 'Tissue' etiologies including retained placenta and abnormal placentation are responsible for 10% of cases.[16] Such etiologies operate via three primary mechanisms of action: uterine atony due to retained tissue prohibiting the uterus from effectively contracting, placental misplacement in less contractile tissue of the lower uterus, or invasive placental implantation with varying levels of attachment to the myometrium and potential extension to other organs (e.g., rectum or bladder).[17] 'Thrombin' refers to inherited or acquired coagulation disorders including dysfunctions of the clotting cascade or platelets, and disseminated intravascular coagulopathy (DIC), which cause approximately 1% of PPH.[16,18]

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