title: Relationship between crown-rump length and early detection of cardiac activity.
abstract: OBJECTIVE
  To investigate whether improvements in sonographic technology would allow detection of embryonic demise at a crown-rump length (CRL) < 5 mm.
  
  
  METHODS
  A prospectively collected, computerized ultrasound database was queried for singleton gestations with CRL < or = 5 mm from January 2000 to February 2003. Embryonic viability was determined by repeat ultrasound examination after 6 weeks'gestation confirming cardiac activity or by documentation of an ongoing pregnancy. Viability rates in the presence or absence of cardiac activity were calculated for CRL of 2.0-2.9, 3.0-3.4, 3.5-3.9, 4.0-4.4, 4.5-4.9 and 5.0 mm. Sensitivity, specificity, positive predictive value and negative predictive value for embryonic demise were calculated, with a subanalysis based on the presence of vaginal bleeding.
  
  
  RESULTS
  Outcome was available for 179 of 195 gestations meeting inclusion criteria. The absence of cardiac activity at CRL > or = 3.5 mm had 100% positive predictive value and specificity. The presence of vaginal bleeding did not affect this cutoff.
  
  
  CONCLUSIONS
  Improved sonographic technology permits diagnosis of embryonic demise at a CRL > or = 3.5 mm under ideal conditions. Vaginal bleeding increases the likelihood of demise, but does not alter test performance. Further investigation is warranted, as our data suggest a limit closer to 3 mm.
authors.affiliation: Division of Gynecologic Oncology, Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, 101 Manning Drive, CB 7570, Chapel Hill, NC 27599-7570, USA. labaid@med.unc.edu
authors.forename: Lisa N
authors.initials: LN
authors.lastname: Abaid
authors.forename: Sawsan
authors.initials: S
authors.lastname: As-Sanie
authors.forename: Honor M
authors.initials: HM
authors.lastname: Wolfe
mesh_terms: D000328:Adult; D018568:Crown-Rump Length; D016208:Databases, Factual; D005260:Female; D005313:Fetal Death / Q000000981:diagnostic imaging*; D005318:Fetal Heart / Q000000981:diagnostic imaging*; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal