Hemorragia Post Parto: Epidemiologia y Factores De Riesgo, Causas

CLINICAL OBSTETRICS AND GYNECOLOGY Volume 53, Number 1, 147–156 r 2010, Lippincott Williams & Wilkins

Postpartum Hemorrhage: Epidemiology, Risk Factors, and Causes
YINKA OYELESE, MD* and CANDE V. ANANTH, PHD, MPHw * Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Tennessee Institute of Fetal Maternal and Infant Health, University of Tennessee Health SciencesCenter, Memphis, TN; and w Division of Epidemiology and Biostatistics, Department of Obstetrics, Gynecology, and Reproductive Sciences, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey

Abstract: Postpartum hemorrhage (PPH) is a leading cause of death and morbidity relating to pregnancy. Uterine atony is the leading cause of PPH, and trauma, including iatrogenic trauma, increasesthe risk for postpartum hemorrhage. Women with PPH in a pregnancy are at increased risk of PPH in a subsequent pregnancy. Awareness of these facts, and anticipation and prevention of uterine atony, as well as avoiding unnecessary cesareans, episiotomies, and other genital tract trauma have the potential to significantly reduce the mortality and morbidity from postpartum hemorrhage. Theepidemiology of postpartum hemorrhage, including the incidence and temporal trends as well as the causes and risk factors associated with it are presented. Key words: postpartum hemorrhage, uterine atony, epidemiology

Introduction
Postpartum hemorrhage (PPH) is considered the leading cause of pregnancyrelated deaths worldwide,1 with an estimated 140,000 women dying annually from this complication,2equating to 1 every 4 minutes.3 Although deaths from PPH in the Western world have dropped precipitously in recent years, it remains one of the leading causes of pregnancyassociated death even in the United States, France,4 and the United Kingdom.5 Besides death, PPH also is an important cause of pregnancy-related morbidity. Unfortunately, although several risk factors exist, often PPH occurs withoutwarning.3 Efforts to determine the incidence of PPH are hampered by 2 issues: lack of a universal definition of the condition and the inaccuracy in clinical estimates of
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Correspondence: Yinka Oyelese, MD, Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Tennessee Institute of Fetal Maternal and Infant Health, 853 Jefferson Ave,Suite E102, University of Tennessee Health Sciences Center, Memphis, TN. E-mail: yinkamd@aol.com, Bob.silver@hsc.utah.edu
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Oyelese and Ananth observation that blood loss is typically underestimated. These authors also found the prevalence of SPPH (defined as blood loss >1000 mL) to be 1.86% (95% CI, 1.82-1.90). Again, theprevalence was almost doubled when the blood loss was measured objectively (3.04%; 95% CI, 2.90-3.17). Interestingly, these authors found that PPH was more common in rural than in urban settings. They also found that the rates of PPH were highest in Africa, and attributed this partly to a lack of adequately skilled delivery personnel. Magann and colleagues,11 in a study that defined PPH as bloodloss in excess of 1000 mL, a need for transfusion, or hemodynamic instability, found that PPH occurred in 714 (5.2%) of 13,868 women who delivered vaginally. Combs and coworkers,12 in a case-control study of 9598 vaginal deliveries at Moffitt Hospital in San Francisco, found a rate of PPH (defined as a hematocrit drop of 10 points or more) of 2.8% (374 cases). These authors excluded patients fromtheir study who had experienced antenatal bleeding during their pregnancies. In another study by the same authors,14 limited to women who underwent cesarean delivery, 196 of 3052 eligible deliveries were complicated by PPH, yielding a rate of 5.9%. In a prospective cohort study of 11,323 vaginal births in two Latin-American countries (Uruguay and Argentina), Sosa and coinvestigators15 found that...