title: Development of quantitative Doppler indices for uteroplacental and fetal blood flow during the third trimester.
abstract: The aim of our study was to describe the development of uteroplacental and fetal blood flow during the third trimester. Doppler examination was carried out on 393 uncomplicated pregnancies with uncomplicated term delivery. Using a pulsed color Doppler, we calculated the maximum systolic, mean and maximum end-diastolic velocity after correcting the angle of insonation. Patients under tocolysis or other medication influencing blood flow parameters were excluded from this cross-sectional study. Summarizing the results gained by Doppler ultrasound investigation of the uteroplacental and fetal blood vessels, we created quantiles as quantitative Doppler indices for the maximum systolic, mean (TAMX = time averaged maximum velocity) and maximum end-diastolic velocity. The following conclusions could be drawn: (1) resistance to the blood flow in the maternal portion of the placenta does not change during the third trimester; (2) resistance to the blood flow on the fetal side of the placenta decreases up to week 42 of gestation; (3) cerebral vascular resistance decreases constantly up to gestational week 42; and (4) vascular resistance to the blood flow of the kidney decreases only slightly during the third trimester. This study offers clinically important values for quantitative Doppler flow velocimetry for the first time. We hope that our findings improve the usefulness of Doppler ultrasound as a diagnostic tool in obstetrical management.
authors.affiliation: Department of Obstetrics and Gynaecology, Technical University of Aachen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Joern
authors.forename: A
authors.initials: A
authors.lastname: Funk
authors.forename: M
authors.initials: M
authors.lastname: Goetz
authors.forename: H
authors.initials: H
authors.lastname: Kuehlwein
authors.forename: A
authors.initials: A
authors.lastname: Klein
authors.forename: H
authors.initials: H
authors.lastname: Fendel
mesh_terms: D001783:Blood Flow Velocity; D002536:Cerebral Arteries / Q000502:physiology; D003430:Cross-Sectional Studies; D003971:Diastole; D005260:Female; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D021041:Placental Circulation; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D012016:Reference Values; D012077:Renal Artery / Q000502:physiology; D013599:Systole; D018608:Ultrasonography, Doppler; D014469:Umbilical Arteries / Q000502:physiology; D014599:Uterus / Q000098:blood supply; D014655:Vascular Resistance