Venous drainage of the human uterus: respiratory gas studies in normal and fetal growth-retarded pregnancies.
OBJECTIVE
To determine respiratory gas relationships between the uterine veins and umbilical vein in normal and pregnancies complicated by intrauterine growth retardation.


METHODS
Respiratory gases were measured in both uterine veins and the umbilical vein in eight normal and 13 pregnancies with intrauterine growth retardation.


RESULTS
No significant differences were found in the placental versus nonplacental uterine veins. There was a significant correlation for umbilical and uterine venous values of PO2 (p less than 0.002) and PCO2 (p less than 0.004) in appropriate-for-gestational-age pregnancies, umbilical venous PO2 was always less than uterine venous PO2, and PCO2 always greater than uterine. The transplacental gradient was significantly higher in intrauterine growth retarded than appropriate-for-gestational-age pregnancies for both POC2 and PCO2. There was a lower uterine oxygen extraction in intrauterine growth retarded pregnancies (p less than 0.05).


CONCLUSIONS
There is no consistent relationship between placental venous drainage in each uterine vein and placental location. The human placenta simulates a relatively inefficient venous equilibrator and the larger transplacental gradients in intrauterine growth retarded pregnancies may reflect differences in both perfusion pattern and placental structure.
Pardi
G
G
Department of Obstetrics and Gynecology, San Paolo Institute of Biomedical Sciences, University of Milan, Italy.
Cetin
I
I
Marconi
A M
AM
Bozzetti
P
P
Buscaglia
M
M
Makowski
E L
EL
Battaglia
F C
FC
D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005317:Fetal Growth Retardation / Q000097:blood / Q000503:physiopathology*; D006801:Humans; D016018:Least-Squares Analysis; D010100:Oxygen / Q000097:blood*; D010920:Placenta / Q000098:blood supply; D011247:Pregnancy / Q000097:blood / Q000502:physiology*; D012039:Regional Blood Flow; D012044:Regression Analysis; D014471:Umbilical Veins; D014599:Uterus / Q000098:blood supply*; D014680:Veins / Q000502:physiology / Q000503:physiopathology
D002245:Carbon Dioxide; D010100:Oxygen