title: The incidence of large fetomaternal hemorrhage and the Kleihauer-Betke test.
abstract: OBJECTIVE
  To assess the frequency of large fetomaternal hemorrhage and to estimate its incidence in cesarean compared with vaginal deliveries.
  
  
  METHODS
  In this prospective cohort study, the study group was composed of 313 women who underwent cesarean delivery. Control subjects were 253 women who delivered vaginally and were matched for age, parity, ethnic origin, and gestational age. Ninety-six pregnant women at term, but before delivery (prelabor group), were also included to determine whether delivery itself is the cause of fetomaternal hemorrhage. Fetomaternal hemorrhage was measured by using the Kleihauer-Betke test.
  
  
  RESULTS
  Twenty women (6.4%) in the study group and 17 (6.7%) in the control group had a large fetomaternal hemorrhage (Kleihauer-Betke test > 0.4%). Five women (5.2%) in the prelabor group had a large fetomaternal hemorrhage. The differences were not significant. A large fetomaternal hemorrhage occurred in 14 of 146 (9.6%) women who underwent emergency cesarean, compared with 6 of 167 (3.5%) who delivered by elective cesarean (P = .04). In deliveries complicated by oligohydramnios, cord around the neck, or low birth weight, a higher rate of large fetomaternal hemorrhage was seen.
  
  
  CONCLUSIONS
  Our results indicate a rate of large fetomaternal hemorrhage that is substantially higher than previously reported, with no difference between vaginal and cesarean deliveries. This may reflect inaccuracies with the current method used to estimate the degree of fetomaternal hemorrhage.
authors.affiliation: Department of Obstetrics and Gynecology, Ha'Emek Medical Center, Afula, Israel.
authors.forename: Raed
authors.initials: R
authors.lastname: Salim
authors.forename: Izhar
authors.initials: I
authors.lastname: Ben-Shlomo
authors.forename: Zohar
authors.initials: Z
authors.lastname: Nachum
authors.forename: Rivka
authors.initials: R
authors.lastname: Mader
authors.forename: Eliezer
authors.initials: E
authors.lastname: Shalev
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002585:Cesarean Section / Q000379:methods / Q000706:statistics & numerical data*; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005331:Fetomaternal Transfusion / Q000175:diagnosis* / Q000453:epidemiology*; D005500:Follow-Up Studies; D005865:Gestational Age; D006403:Hematologic Tests; D006801:Humans; D015994:Incidence; D008423:Maternal Age; D009321:Natural Childbirth / Q000706:statistics & numerical data; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome; D011336:Probability; D011446:Prospective Studies; D018570:Risk Assessment