title: Decidual cyst: endovaginal sonographic sign of ectopic pregnancy.
abstract: OBJECTIVE
  To determine the prevalence of decidual cysts in patients with ectopic pregnancy and assess the value of endovaginal sonographic demonstration of decidual cysts in predicting ectopic pregnancy.
  
  
  METHODS
  A series of 288 proved ectopic pregnancies was reviewed, and a series of 179 patients with pregnancies of less than 8 weeks menstrual age was prospectively examined.
  
  
  RESULTS
  Decidual cysts were identified in 30 (14.4%) of 208 ectopic pregnancies. In 12 patients a decidual cyst was the first sonographic sign of ectopic pregnancy, and in six patients it was the only abnormal sonographic finding. Four of five patients with decidual cysts had an ectopic pregnancy. Decidual cysts had a sensitivity of 21%, specificity of 92%, positive predictive value of 80%, and negative predictive value of 42% in the diagnosis of ectopic pregnancy.
  
  
  CONCLUSIONS
  Patients with decidual cysts are at high risk for ectopic pregnancy and should be monitored or treated appropriately, depending on the clinical findings.
authors.affiliation: Section of Ultrasound, Health Sciences Centre, Winnipeg, Manitoba, Canada.
authors.forename: T E
authors.initials: TE
authors.lastname: Ackerman
authors.forename: C S
authors.initials: CS
authors.lastname: Levi
authors.forename: E A
authors.initials: EA
authors.lastname: Lyons
authors.forename: S M
authors.initials: SM
authors.lastname: Dashefsky
authors.forename: D J
authors.initials: DJ
authors.lastname: Lindsay
authors.forename: S C
authors.initials: SC
authors.lastname: Holt
mesh_terms: D000328:Adult; D003656:Decidua / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D015994:Incidence; D011237:Predictive Value of Tests; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000000981:diagnostic imaging* / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D014463:Ultrasonography