Uterine venous blood flow in normal and complicated pregnancies: a methodological study.

OBJECTIVE.: Finding of venous congestion at histopathological examination of placenta indicates the importance of abnormal placenta-maternal venous return. The present descriptive study investigates the possibility of recording Doppler flow signals from maternal uterine veins. MATERIAL AND METHODS.: Transabdominal Doppler ultrasound examinations of uterine veins on both sides of uterus were performed. The uterine vein (UtV) was identified using colour Doppler and the flow velocity signals of UtV and uterine artery (UtA) were recorded. 40 normal and 44 high-risk singleton pregnancies were examined at 23 to 39 gestational weeks. Morphological examination of the placenta was carried out in 45 of pregnancies. RESULTS.: Flow velocity signals of the uterine veins were recorded from at least one side of the uterus in all patients (success rate 81 % and 89 % for the right and left UtV, respectively). Three types of flow velocity pattern were identified: continuous non-pulsatile flow (type I, n=70), pulsatile flow with a notch touching the zero line (type II, n=6), and pulsatile flow with absent flow signals for a part of the heart cycle (type III. n=8).The UtA pulsatility index was significantly higher in women with UtV types II and III than in those with UtV type I (p=0.039). Similarly, the UtV types II and III were more often found in pregnancies with bilateral UtA notch (p=0.013) and with uterine artery score (UAS) 3-4 (p=0.024) than in cases with normal UtA. No statistical significant association was found between the UtV flow pattern and abnormal histopathological findings in placenta, and between the UtV and umbilical artery findings. CONCLUSION.: It is possible to record Doppler signals from the uterine veins in the second and third trimester pregnancies. The abnormal flow velocity patterns of the uterine veins were associated with abnormal Doppler findings in the uterine artery. Copyright (c) 2010 ISUOG. Published by John Wiley & Sons, Ltd