Medical Sonography

Biography

Biography: Mohammed Elmetwally

Abstract

Sheep represents an appropriate animal model to study the uterine blood perfusion in women, because the similarities of uterine vascularization and existence of pelvic anastomoses of non pregnant sheep with that in women (1,2). The objective of the present study was to characterize blood flow in the maternal and fetal blood flow changes during pregnancy in sheep. Herein 18 pregnant sheep were used in the present study. The blood flow indices includes  blood flow volume (BFV), Time averaged maximum velocity (TAMV), resistance index (RI), pulsatility index (PI), Time averaged mean velocity, impedance of blood flow (AB or S/D ratio), peak velocity of blood flow (PV) and blood flow acceleration (Accel). Non-invasive Color Doppler Ultrasound examinations were started 2 weeks (wk) after breeding, and continued at 2-wk intervals until parturition. Blood flow volume, TAMV, PS as well as PV were increased (P<0.0001) continuously until parturition. Also, TAMEAN increased with advancing pregnancy (P<0.0001) and decreased (P<0.0001) after wk. 18. The uterine artery RI, PI and S/D were progressively decreased until parturition. On the other hand, the blood flow acceleration velocity was increased until wk. 16 in sheep begin to decrease until birth. For umbilical blood flow significant increases (P<0.001) of BFV, TAMV and TAMEAN were recognized until W 19 of pregnancy in sheep foeti and then decreased (P<0.001) until parturition. Conversely, UM-PI, RI and PS/ED were decreased significantly ((P<0.002-0.01) until W 19 and then increased (P<0.01-0.0001 resp.). The umbilical artery BFV increased (P<0.0001) during the pregnancy from 7.27±0.82 ml/min at W 6 of gestation to 700.51±31.05 ml/min at W 19 and then significantly (P<0.0001) decreased to 350.561±72.15 ml/min at W 20. Absence of end diastolic velocity (EDV) of umbilical blood flow is recognized in in all examined fetuses between Week 4 and Week 12. In conclusion, the obtained results may guide the state of intrauterine fetal growth retardation in abnormal pregnancies.