title: Anterior placentation as a risk factor for massive hemorrhage during cesarean section in patients with placenta previa.
abstract: OBJECTIVE
  In placenta previa (PP), anterior placentation, compared with posterior placentation, is reported to more frequently cause massive hemorrhage during cesarean section (CS). Whether this is due to the high incidence of placenta accreta, previous CS, or a transplacental approach in anterior placenta is unclear. We attempted to clarify this issue.
  
  
  METHODS
  We retrospectively analyzed the relation between the bleeding amount during CS for PP and various factors that may cause massive hemorrhage (>2400 mL) (n = 205) in a tertiary center. If the preoperatively ultrasound-measured distance from the internal cervical ostium to the placental edge was longer in the uterine anterior wall than in the posterior wall, we defined it as anterior previa, and vice versa.
  
  
  RESULTS
  Patients with accreta, previous CS, total previa, and anterior placentation bled significantly more than their counterparts. Multivariate logistic regression analysis showed that accreta (odds ratio [OR] 12.6), previous CS (OR 4.7), total previa (OR 4.1), and anterior placentation (OR 3.5) were independent risk factors of massive hemorrhage.
  
  
  CONCLUSIONS
  Anterior placentation, namely, the placenta with a longer os-placental edge distance in the anterior wall than in the posterior wall, was a risk of massive hemorrhage during CS for PP.
authors.affiliation: Department of Obstetrics and Gynecology, Jichi Medical University, Tochigi, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Baba
authors.forename: Shigeki
authors.initials: S
authors.lastname: Matsubara
authors.forename: Akihide
authors.initials: A
authors.lastname: Ohkuchi
authors.forename: Rie
authors.initials: R
authors.lastname: Usui
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kuwata
authors.forename: Hirotada
authors.initials: H
authors.lastname: Suzuki
authors.forename: Hironori
authors.initials: H
authors.lastname: Takahashi
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Suzuki
mesh_terms: D000328:Adult; D016063:Blood Loss, Surgical; D002585:Cesarean Section / Q000009:adverse effects*; D005260:Female; D006801:Humans; D016015:Logistic Models; D010923:Placenta Previa / Q000503:physiopathology*; D010929:Placentation; D006473:Postpartum Hemorrhage / Q000209:etiology; D011247:Pregnancy; D012189:Retrospective Studies; D012307:Risk Factors
keywords: anterior placentation; cesarean section; massive hemorrhage; placenta accreta; placenta previa