title: Ectopic pregnancy diagnosis and the pseudo-sac.
abstract: OBJECTIVE
  To evaluate the impact of an ultrasound finding of a pseudo-sac (PS), a uterine sac without a double decidual ring or a yolk sac, on the management of cases with possible ectopic pregnancy.
  
  
  METHODS
  A retrospective review of a series of cases.
  
  
  METHODS
  A general hospital.
  
  
  METHODS
  Seventy-seven patients who had a diagnostic laparoscopy over a period of 3 years for suspected ectopic pregnancy.
  
  
  METHODS
  A logistic regression analysis was conducted to evaluate the effect of the ultrasound finding of a PS on predicting a negative finding at laparoscopy.
  
  
  RESULTS
  The report of a PS is significantly associated with a false-positive diagnosis of ectopic pregnancy.
  
  
  CONCLUSIONS
  A diagnosis of PS should not be interpreted as indicative of an ectopic pregnancy because radiological differentiation between an early intrauterine pregnancy failure and an ectopic pregnancy is not possible.
authors.affiliation: Medical Research Council, Biostatistics Unit, Institute of Public Health, University Forvite Site, Cambridge, United Kingdom. aaa42@cam.ac.uk
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Ahmed
authors.forename: Brian D M
authors.initials: BD
authors.lastname: Tom
authors.forename: Peter
authors.initials: P
authors.lastname: Calabrese
mesh_terms: D005189:False Positive Reactions; D005260:Female; D001556:Hexachlorocyclohexane / Q000097:blood; D006801:Humans; D016015:Logistic Models; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000175:diagnosis*; D012189:Retrospective Studies; D014463:Ultrasonography; D014599:Uterus / Q000000981:diagnostic imaging*
chemical_list: D001556:Hexachlorocyclohexane; C023888:beta-hexachlorocyclohexane