Ultrasound shows that fetal venous catheter A-wave reversal is usually abnormal, mostly suggesting that the fetus has a high risk of recent hypoxia, and the fetus has a high possibility of chromosomal anomalies and congenital heart disease. A-wave is one of the three major waves in the venous spectrum of venous catheterization. A-wave is the wave of atrial contraction, and reversal of A-wave in venous catheterization is usually indicative of cardiac disease, which may lead to overloading of the right side of the fetal heart, or cardiac malfunction. Due to the abnormal blood flow in the fetal period, the blood from umbilical vein rich in oxygen and various nutrients cannot be delivered to the whole body of the fetus, which can lead to fetal hypoxia, thus affecting the growth and development of the fetus, and fetal venous catheterization flow A wave reverse flow suggests a poor prognosis. If the ultrasound shows that the A-wave of the fetal venous catheter is reversed, it is recommended to consult a doctor in time, complete the relevant examinations under the doctor’s guidance, clarify the cause of the disease, and take the corresponding treatment measures.