What is the rate of uterine blood flow at term in a primigravida?
At term, uterine blood flow represents about 10% of the cardiac output, or 600-700 mL/min (compared with 50 mL/min in the nonpregnant uterus). Eighty percent of uterine blood flow normally supplies the placenta; the remainder goes to the myometrium. Pregnancy maximally dilates the uterine vasculature, so that autoregulation is absent, but the uterine vasculature remains sensitive to -adrenergic agonists. Also know: Uterine blood flow is not usually significantly affected by respiratory gas tensions, but extreme hypocapnia (PaCO2 Three major factors decrease uterine blood flow during pregnancy: (1) systemic hypotension, (2) uterine vasoconstriction, and (3) uterine contractions. Ref: Butterwoh IV J.F., Mackey D.C., Wasnick J.D. (2013). Chapter 40. Maternal & Fetal Physiology & Anesthesia. In J.F. Butterwoh IV, D.C. Mackey, J.D. Wasnick (Eds), Morgan & Mikhail's Clinical Anesthesiology, 5e.
50-75 ml/min
150-200 ml/min
350-400 ml/min
>500 ml/min