Patient's question:
I'll be 22 weeks pregnant soon. The doctor said my umbilical cord blood flow ratio is high. What is the normal standard for this?Doctor's answer:
The umbilical blood flow ratio is used to measure the fetal blood supply and oxygenation status, and it can also determine placental function or whether there are any abnormalities. Specifically, it is the ratio of the maximum systolic blood flow velocity in the fetal umbilical artery to the end-diastolic blood flow velocity. It is related to fetal blood supply, and when placental function is poor or there are umbilical cord abnormalities, this ratio becomes abnormal. In normal pregnancy, as gestational age increases, the fetus requires more blood, leading to a decrease in S and an increase in D, which results in a lower ratio. The SD value varies at different gestational ages. Near term pregnancy, the SD is less than 3. High SD values are commonly seen in conditions such as fetal growth restriction, preeclampsia, umbilical cord abnormalities, and gestational diabetes.