Sonographic estimates of fetal weight in the intrauterine growth retardation population.

The efficacy of different methods of fetal weight estimation using sonographic measurements of the abdominal circumference (AC), biparietal diameter (BPD), and femur length (FL), either alone or in combination, was evaluated in the fetus with intrauterine growth retardation (IUGR). Eighty-one patients, referred with a clinical suspicion of IUGR, were studied. All patients had sonographic measurements within 7 days of delivery. Four regression equations were used to estimate fetal weight: AC (Hadlock), BPD-AC (Shepard), AC-FL (Hadlock), BPD-AC-FL (Hadlock). For the total study group, as well as for the infants who were found to be IUGR at birth, 75% of the estimates of fetal weight using the BPD-AC-FL method were within 10% of the actual birthweight. Nearly comparable results were obtained using the AC-FL method. In the fetus with IUGR, estimates of fetal weight that incorporated the FL correlated best with the actual birthweight.

Discordant twins--a prospective study of the diagnostic value of real-time ultrasonography combined with umbilical artery velocimetry.

This study was undertaken to evaluate the role of Doppler velocimetry combined with intertwin differences in ultrasonographically derived estimated fetal weight, biparietal diameter, abdominal circumference, and femur length as a comprehensive test for the prediction of discordancy. The following cutoff values were used to indicate abnormal test results: delta biparietal diameter greater than 6 mm, delta abdominal circumference greater than 20 mm, delta femur length greater than 5 mm, delta estimated fetal weight greater than 15%, and delta systolic/diastolic ratio greater than 15%. Discordancy was identified when the birth weight difference exceeded 15%. The study population consisted of 58 consecutively evaluated third-trimester twin gestations. Eighteen sets of twins were discordant. None of these tests was uniformally successful in identifying twin discordancy; in three instances, all test results were normal. The diagnostic accuracy provided by ultrasonography was not significantly different from that provided by Doppler velocimetry. Overall the best predictor appeared to be the presence of either delta systolic/diastolic ratio greater than 15% or delta estimated fetal weights greater than 15%, which correctly identified 14 of the 18 discordant twins and misclassified only five of the 40 concordant pairs. This combination also had the highest positive and negative predictive values (73% and 90%, respectively).

Postdate fetal surveillance: is 41 weeks too early?

During an 18-month period, 293 patients had a nonstress test and ultrasonographic evaluation of amniotic fluid volume twice weekly beginning at 41 weeks' gestation. Patients were admitted for induction of labor for either an abnormal nonstress test result or oligohydramnios. A control population consisted of 59 low-risk patients who were delivered between 39 and 41 weeks' gestation and had antepartum testing within 4 days of delivery. Study patients who were delivered between 41 and 42 weeks' gestation had a significantly increased incidence of abnormal nonstress tests, oligohydramnios, cesarean sections for fetal distress, and admissions to the neonatal intensive care unit compared with control patients. The abnormal fetal testing and adverse perinatal outcome associated with pregnancies over 42 weeks were also found in pregnancies between 41 and 42 weeks' gestation. These data support the concept that postdate fetal testing should begin at 41 weeks of gestation.

Intrauterine growth retardation--a prospective study of the diagnostic value of real-time sonography combined with umbilical artery flow velocimetry.

This study was undertaken to evaluate the role of umbilical artery flow velocimetry combined with sonographic estimation of fetal weight, head circumference to abdominal circumference ratio, femur length to abdominal circumference ratio, and qualitative determination of amniotic fluid volume as a comprehensive test for the detection of intrauterine growth retardation (IUGR). The following cutoff values were used to indicate abnormal test results: 1) umbilical artery peak systolic to end-diastolic ratio (S/D) above 3, 2) estimated fetal weight below the tenth percentile for gestational age, 3) head circumference to abdominal circumference ratio more than 2 SD above the mean for gestational age, 4) femur length to abdominal circumference ratio above 23.5%, and 5) qualitative amniotic fluid volume less than 2 cm. The study population consisted of 127 patients referred with a clinical suspicion of IUGR. Forty-five infants (35%) were small for gestational age. None of these five tests were uniformly successful in identifying growth-retarded infants. Overall, the best predictor appeared to be estimated fetal weight below the tenth percentile for gestational age, which correctly identified 39 of the 45 IUGR infants (sensitivity 87%, specificity 87%). The sensitivity of this test was nearly twice that of any other test. All indices performed similarly in predicting the non-IUGR infant (range of specificities 87-98%).

Intrapartum vibratory acoustic stimulation of the human fetus during episodes of decreased heart rate variability.

The effects of intrapartum vibratory acoustic stimulation during periods of decreased fetal heart rate variability were studied in 25 healthy term fetuses. Fetal monitoring and real-time ultrasound scanning were used simultaneously to detect fetal response. Vibratory acoustic stimulation was provided by an artificial larynx generating a signal at 85 dB and 85 Hz. This stimulus was applied for 5 seconds on the maternal abdomen over the fetal head after a 20-minute period of decreased fetal heart rate variability. All fetuses reacted with an immediate fetal heart rate acceleration of at least 10 bpm (range: 10 to 35 bpm, mean +/- SD = 18.4 +/- 7.0), and 19 fetuses also had sudden fetal body movement. A deceleration of the fetal heart rate after the initial acceleration was observed in nine fetuses (range: 15 to 70 bpm, mean +/- SD = 45.5 +/- 16.5). The implications of these findings are discussed in relation to the possible use of fetal vibratory acoustic stimulation for intrapartum surveillance.

Fetal umbilical artery flow velocimetry in postdate pregnancies.

This study prospectively examined the use of umbilical artery flow velocimetry for monitoring fetal health in postdate pregnancies. Forty-six patients with well-established dates were evaluated with semiweekly biophysical profiles and umbilical artery flow velocimetry (characterized by the ratio of the peak systolic to end-diastolic velocity). Their labor records were reviewed, and neonates were examined for signs of postmaturity. Twenty neonates had an abnormal test result or outcome (identified as an abnormal nonstress test, oligohydramnios, meconium, intrapartum fetal distress, or a 5-minute Apgar score less than 7). Nine neonates had a physical examination consistent with the postmaturity syndrome. Twenty-one neonates were entirely normal. Comparisons of the mean systolic/diastolic ratios for neonates with and without the complications associated with postdatism showed no significant differences. In addition, all systolic/diastolic ratios were within the normal range. Therefore, umbilical artery flow velocimetry is unlikely to be useful for the routine antenatal assessment of the postdate fetus.