title: Pitfalls in diagnosis of interstitial pregnancy.
abstract: BACKGROUND
  To determine the incidence and reasons for misdiagnosis in interstitial ectopic pregnancy.
  
  
  METHODS
  We conducted a retrospective study from 1990 to 2001. Women with interstitial pregnancy were identified and their case records retrieved and reviewed. Reasons for delay in diagnosis and associated morbidity were recorded.
  
  
  RESULTS
  Thirty-six women were diagnosed as having interstitial pregnancy during the study period. Initial diagnosis was incorrect in 15 cases (41.7%). In 14 cases, the interstitial pregnancies were mistaken as intrauterine pregnancy. These misdiagnoses resulted in six inappropriate surgical procedures (evacuation of uterus) being performed and led to rupture of interstitial pregnancy in eight women. In two women, the interstitial pregnancy was mistaken as normal intrauterine pregnancy while the uterus itself was thought to be a cervical fibroid. In both cases, the interstitial pregnancies ruptured at 18-20 weeks of gestation.
  
  
  CONCLUSIONS
  Despite advances in sonographic skills and equipment and the availability of beta-human chorionic gonadotropin (hCG) monitoring, misdiagnosis of interstitial pregnancy still occurs frequently. Clinicians should be aware of the limitations of various investigations and maintain a high index of suspicion.
authors.affiliation: Department of Obstetrics and Gynecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong. lyschan@cuhk.edu.hk
authors.forename: Louis Yik-Si
authors.initials: LY
authors.lastname: Chan
authors.forename: Wing Yee
authors.initials: WY
authors.lastname: Fok
authors.forename: Pong Mo
authors.initials: PM
authors.lastname: Yuen
mesh_terms: D000328:Adult; D003951:Diagnostic Errors / Q000009:adverse effects*; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008499:Medical Records; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D011296:Prenatal Diagnosis; D012189:Retrospective Studies; D014597:Uterine Rupture / Q000209:etiology*