title: Patient selection for later delivery timing with suspected previa-accreta.
abstract: BACKGROUND
  We identified patients with previa and suspected accreta who are at lowest risk of unscheduled delivery or major morbidity with planned delivery beyond 34 weeks' gestation.
  
  
  METHODS
  This was a retrospective cohort study of patients who had reached 34.0 weeks' gestational age with a suspected previa-accreta. We evaluated rates of unscheduled and emergent delivery based on known risk factors for premature birth. In a second analysis, we stratified patients based on level of preoperative morbidity concern and evaluated rates of major transfusion and Intensive Care Unit admission by delivery week (34 weeks, 35 weeks or 36 weeks and beyond).
  
  
  RESULTS
  Of 84 available patients, we classified 31 patients as low risk for unscheduled delivery and 52 as high risk. The low risk group was scheduled later (36.6 vs. 36.0 weeks; p < 0.01), but demonstrated lower rates of unscheduled delivery prior to 36 weeks (3% vs. 19%, p = 0.05). Of the patients with no prior cesarean section, only one (7%) experienced massive blood loss even though 36% had unscheduled deliveries. We observed no significant increase in major transfusion or massive blood loss with advancing gestational age, likely due to selection of the most concerning patients for early, scheduled delivery.
  
  
  CONCLUSIONS
  Patients with suspected previa-accreta and no risk factors for preterm birth are at low risk for an unscheduled delivery prior to 36 weeks. Those with no concern for percreta or increta or no prior cesarean section may also be candidates for later delivery.
authors.affiliation: Harvard Medical School, Boston, MA, USA.
authors.forename: Nicola C
authors.initials: NC
authors.lastname: Perlman
authors.affiliation: Harvard Medical School, Boston, MA, USA.|Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Little
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Ann
authors.initials: A
authors.lastname: Thomas
authors.affiliation: Harvard Medical School, Boston, MA, USA.|Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Cantonwine
authors.affiliation: Harvard Medical School, Boston, MA, USA.|Department of Obstetrics, Gynecology, and Reproductive Biology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Daniela A
authors.identifier: http://orcid.org/0000-0002-6263-8224
authors.initials: DA
authors.lastname: Carusi
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003661:Decision Support Techniques; D036861:Delivery, Obstetric; D005260:Female; D005865:Gestational Age; D006801:Humans; D008875:Middle Aged; D018579:Patient Selection; D010921:Placenta Accreta / Q000000981:diagnostic imaging*; D010923:Placenta Previa / Q000000981:diagnostic imaging*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular; D047928:Premature Birth / Q000401:mortality / Q000517:prevention & control*; D012189:Retrospective Studies; D012307:Risk Factors; D016216:Ultrasonography, Prenatal; D055815:Young Adult
keywords: Placenta accreta; placenta previa; preterm delivery