Umbilical artery blood velocity waveforms were recorded by a pulsed Doppler system in the third trimester of pregnancy in 16 diabetic women (12 class B, 1 class C, 3 class D) and the waveforms were analysed for resistance index (RI = peak systolic velocity minus end diastolic velocity/peak systolic velocity). There was no significant correlation between the RI values and either serum glucose (r = 0.385) or fructosamine levels (r = 0.380). However, the RI values were raised in two cases with serum glucose levels of over 300 mg/dl. With a fall in serum glucose levels, the RI values returned to the normal range. No abnormal umbilical artery velocity waveforms were found when the serum glucose level was below 200 mg/dl.
In 40 twin pregnancies, the evaluation of hemodynamics by ultrasound was performed during the period January 1986 through September 1991. The blood flow velocities' waveforms in the umbilical artery, umbilical vein and tricuspid valve, and the total cardiac dimension, were obtained by ultrasonography in conjunction with 3.5 MHz pulsed Doppler ultrasound. Six patients with twin pregnancies were identified as having twin-to-twin transfusion syndrome (TTS), on the basis of like-sex twins with monochorionic diamniotic placentation, vascular anastomosis in the placenta, and umbilical cord venous blood hemoglobin difference exceeding 5 gldl at delivery. No distinctive -findings for TTS were revealed by the measurement of umbilical artery blood flow velocity waveforms. However, cardiomegaly in 5 recipient fetuses and tricuspid regurgitation and biphasic umbilical vein waveforms in 3 recipient fetuses constituted characteristic features of TTS. Ultrasonography and a Doppler study might be beneficial in diagnosing TTS and evaluating the hemodynamics in a recipient fetus.
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