Uteroplacental Doppler flow velocity waveforms in the second trimester. A complex circulation.
Continuous wave Doppler ultrasound was used to examine the uteroplacental circulation of an unselected group of 977 [corrected] women between 16 and 24 weeks gestation. Reference ranges for resistance index (RI) were determined and throughout this gestation range there was a significant fall in RI with increasing gestation. The RI was lower from placental than non-placental sites and from distal 'arcuate' than proximal 'uterine' sites. There is a need to define fixed standardized sites for sampling and for normal ranges to account for variables such as placental site.
Bewley
S
S
Department of Obstetrics and Gynaecology, King's College Hospital, Denmark Hill, London.
Campbell
S
S
Cooper
D
D
D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D010920:Placenta / Q000098:blood supply*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012016:Reference Values; D014463:Ultrasonography; D014599:Uterus / Q000098:blood supply*