Pulsed Doppler umbilical artery waveforms: significance of elevated umbilical artery systolic/diastolic ratios in the normally grown fetus

Article Abstract:

In fetal life, blood leaves the fetus en route to the placenta through the umbilical artery, and elevated resistance in this artery is correlated with the birth of infants who are small for their gestational age (SGA, having a low birth weight for a given age in the womb). Resistance in the umbilical artery is determined by calculating the ratio between the blood pressure during systole (S, the active phase of fetal heart contraction) and diastole (D, the pressure during the heart's resting phase). Blood pressure is monitored with a form of ultrasound called Doppler ultrasound. Although the association between elevated S/D ratios and SGA infants is well established, less is known about other abnormalities that might be found in non-SGA fetuses with high S/D ratios. To learn more about this, investigators evaluated the results of 373 Doppler ultrasound examinations of 256 patients. Non-SGA infants were delivered to 32 women with S/D ratios of 4.5 or more. S/D ratios from the umbilical arteries of these fetuses were compared with those from 200 non-SGA infants who had had normal Doppler results, and from 24 SGA infants. Structural defects, amniotic fluid volume (the fluid that surrounds the fetus), and pregnancy outcome were monitored for all subjects. Results showed that 31 percent of the non-SGA infants with abnormal waveforms had structural abnormalities (birth defects), most commonly of the central nervous system. This was a greater percentage than for the non-SGA group with normal Doppler results (18 percent). Moreover, the rate of stillbirth and termination of pregnancy for lethal abnormalities was five times higher in non-SGA infants with abnormal waveforms than in the non-SGA infants with normal S/D ratios. SGA infants tended to have less amniotic fluid, while the non-SGA group with abnormal waveforms had elevated fluid volumes. No differences were noted among the groups with respect to the frequency of cesarean deliveries. The results indicate that abnormal results from Doppler ultrasound of the fetal umbilical artery are associated with important structural malformations and increased mortality, as well as with low birth weight. (Consumer Summary produced by Reliance Medical Information, Inc.)

Fetus, Birth defects, Blood pressure, Blood pressure measurement, Prenatal ultrasonography, Umbilical arteries

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Doppler systolic-diastolic ratios in pregnancies complicated by syphilis

Article Abstract:

Doppler ultrasonography is a noninvasive method that allows the evaluation of maternal and fetal blood flow patterns in pregnancy; it is also useful for studying complications of pregnancy. Pregnant women who are infected with syphilis can transmit the infection to the fetus, leading to vasculitis (inflammation of blood vessels) of the placenta and uterus. However, these conditions are difficult to diagnose in the fetus. Although treatment with benzathine penicillin before delivery prevents infection of the newborn in more than 97 percent of cases, the treatment is unsuccessful in as many as one-third of the cases of congenital syphilis. It is possible that Doppler velocity waveform studies could identify fetuses who are infected with syphilis. To test this possibility, the method was used to study 41 pregnancies in women diagnosed with syphilis in the third trimester. A control group of women with normal pregnancies was also studied. The ratio of blood flow during systole (when the fetal heart actively pumps) to flow during diastole (when the heart rests), the S/D ratio, was calculated. S/D ratios for the uterine and umbilical arteries were significantly elevated in pregnancies complicated by syphilis. This abnormality indicates a greater increase in resistance to blood flow through the placenta. The elevation was greater in the subgroup of 26 infected patients in whom spirochetes (the organism that causes syphilis) could be observed in the amniotic fluid (in which the fetus floats). Of the 37 cases that were followed-up, 8 women delivered prematurely (4 at 36 weeks' gestation) and 7 low-birth-weight infants were born. Two premature infants had congenital disease and died during labor. The results suggest that infection with syphilis is associated with heightened resistance to blood circulation in the placenta, probably because of syphilitic placental vasculitis. Whether the Doppler measurements were useful in predicting the effectiveness of treatment was not clear from the study's outcome. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Syphilis, Congenital, hereditary, and infantile, Congenital syphilis

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Is pulsed Doppler velocimetry useful in the management of multiple-gestation pregnancies?

Article Abstract:

Doppler velocimetry is a technique that is used to measure blood flow, and it has been used to identify abnormalities in blood flow in the umbilical cord. Previous studies have reported that some infants who are small for their gestational age (SGA) at birth have abnormal Doppler velocimetry test results, indicating that blood flow in the umbilical cord is abnormal. Other studies have reported that this technique does not predict abnormal outcome in twin pregnancies that involve the twin transfusion syndrome. This syndrome occurs when one fetus receives less blood and amniotic fluid (the fluid that surrounds the developing fetus) than the other, which can cause the fetus to be SGA at birth. To determine if Doppler velocimetry can be used in multiple-gestation pregnancies (pregnancies involving two or more fetuses) to identify fetuses at risk for low-birth-weight and birth defects, 94 pairs of twin fetuses and seven sets of triplets were examined. Doppler velocimetry was performed during pregnancy and these test results were compared with the outcome of each pregnancy. Eight percent of the fetuses examined had abnormal Doppler test results, and all of them were born prematurely. Of the infants with abnormal Doppler test results, 77 percent weighed less than 3.3 pounds at birth, 12 percent had birth defects, and 12 percent were stillbirths. There were six cases of twin transfusion syndrome resulting in fetal growth retardation, and Doppler test results were abnormal in four of the cases. It is concluded that fetuses with abnormal Doppler velocimetry test results have higher rates of infant morbidity and mortality. (Consumer Summary produced by Reliance Medical Information, Inc.)

Blood flow, Blood flow measurement, Fetofetal transfusion, Pregnancy, Complications of, Pregnancy complications, Pregnancy, Multiple, Multiple pregnancy, Laser Doppler blood flowmetry, Laser Doppler flowmetry, Laser Doppler velocimeter, Laser Doppler velocimeters

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