[Risk factors of evolution of postpartum hemorrhage towards severe postpartum hemorrhage: A case-control study]. / Factores de riesgo de la evolución de la hemorragia posparto a hemorragia posparto severa: estudio de casos y controles.

OBJECTIVE: To describe the incidence and risk factors for evolution of postpartum haemorrhage towards severe. MATERIAL AND METHODS: Epidemiologic, observational, analytical, case-control study was done from total data of deliveries in Complexo Hospitalario de Ourénse between January 1st 2004 and June 30th 2014. Mann-Whitney U test was used to determine the differences between cases and controls. The statistical analyses were made with the informatic programs Spss 15.0 y Epidat 3.0. We considered statistical significance for p < 0.05. RESULTS: The initial size of the sample was 17,116 deliveries from which we selected 150 patients with the diagnosis of postpartum haemorrhage. The incidence for HPSe form all deliveries was 3.3% reaching 36% of the total of postpartum haemorrhages. 79.63% of HPSe showed symptoms withing the first 24h postpartum, but we found that 20.37% debuted as secondary postpartum haemorrhages. BMI ≥ 35, hypertensive gestational manifestations, labor's second phase ≥ 120 minutes and weight at birth > 4000 g presented statistical significance as risk factor for evolution to severe postpartum haemhorrage. The relative risk for evolution towards HPSe was 2.81 for instrumental delivery and 3.55 for cesarean section. The most prevalent etiology was uterine atony. CONCLUSION: The incidence of HPSe in our hospital is low, as well as secondary maternal mortality. The major risk factor for the appearance of the clinical symptoms is cesarean section, followed, in less proportion by instrumental delivery. It is possible for the HPSe to make its appearance delayed after delivery, usually secondary to infrequent and non well-known clinical presentations.