title: Effect of an increase of the hematocrit on middle cerebral artery peak and umbilical vein maximum velocities in anemic fetuses.
abstract: OBJECTIVE
  To measure the effects of acute large increases of the hematocrit on fetal peak arterial and maximum venous blood flow velocities.
  
  
  METHODS
  Middle cerebral artery peak flow velocities and umbilical vein maximum flow velocities were measured before, immediately after, and 12-24 h after intrauterine transfusions. All measurements were standardized for gestational age.
  
  
  RESULTS
  Complete measurements were obtained at 60 intrauterine transfusions. The mean hematocrit before intrauterine transfusion was 0.19 l/l and after 0.40 l/l. The middle cerebral artery peak flow velocity decreased immediately after transfusion in 59 of the 60 cases. There was a rise in umbilical vein maximum flow velocity immediately after intrauterine transfusion in 37 of the 60 cases. The sensitivity of middle cerebral artery peak flow velocity for severe anemia before intrauterine transfusion was 54% and the specificity 57%. The sensitivity of umbilical vein maximum flow velocity for severe anemia before intrauterine transfusion was 67% and the specificity 57%.
  
  
  CONCLUSIONS
  An acute large increase of the fetal hematocrit significantly decreases middle cerebral artery peak flow velocity. The effect on umbilical vein maximum velocity is, however, unpredictable.
authors.affiliation: Department of Obstetrics and Gynecology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Esther
authors.initials: E
authors.lastname: Sikkel
authors.forename: Frank P H A
authors.initials: FP
authors.lastname: Vandenbussche
authors.forename: Dick
authors.initials: D
authors.lastname: Oepkes
authors.forename: Frans J C M
authors.initials: FJ
authors.lastname: Klumper
authors.forename: Katinka A K
authors.initials: KA
authors.lastname: Teunissen
authors.forename: Robertjan H
authors.initials: RH
authors.lastname: Meerman
authors.forename: Saskia
authors.initials: S
authors.lastname: Le Cessie
authors.forename: Humphrey H H
authors.initials: HH
authors.lastname: Kanhai
mesh_terms: D000704:Analysis of Variance; D000740:Anemia / Q000097:blood* / Q000503:physiopathology / Q000628:therapy*; D001783:Blood Flow Velocity / Q000502:physiology; D001805:Blood Transfusion, Intrauterine / Q000379:methods*; D005260:Female; D005315:Fetal Diseases / Q000503:physiopathology / Q000628:therapy*; D006400:Hematocrit / Q000379:methods; D006801:Humans; D020768:Middle Cerebral Artery / Q000502:physiology*; D011247:Pregnancy; D018608:Ultrasonography, Doppler / Q000379:methods; D014471:Umbilical Veins / Q000502:physiology*