Effect of vacuum extraction on umbilical cord blood acid-base measurements.

The objective of this study was to determine whether vacuum extraction is associated with umbilical cord blood acid-base changes when used electively or in the presence of suspected fetal distress. Data from 1,428 patients from a previously published randomized trial of intrapartum electronic fetal heart rate monitoring versus intermittent auscultation were analyzed to identify differences in umbilical cord blood acid-base measurements associated with the elective use of vacuum extraction (patients with duration of second stage of labor 60 min or less) and also in the presence of suspected fetal distress during the second stage of labor. When used electively, vacuum extraction was associated with lower pH (in both umbilical cord artery and vein), lower venous base excess, and higher venous carbon dioxide tension (PCO2), as compared to normal spontaneous vaginal delivery. After correcting for duration of second stage of labor, elective vacuum delivery was significantly associated only with a decrease in cord venous pH and increase in venous PCO2. However, these cord blood acid-base changes were not accompanied by any differences in perinatal morbidity and mortality or in the number of neonates born with acidemia (cord arterial pH < 7.15 or < 7.10). In cases of suspected fetal distress, the use of vacuum extraction was not associated with any detectable cord blood acid-base changes as compared to normal spontaneous vaginal delivery. These data support the continued use of vacuum extraction, especially in cases of suspected fetal distress during the second stage of labor.

Comparison of intrapartum electronic fetal heart rate monitoring versus intermittent auscultation in detecting fetal acidemia at birth.

OBJECTIVE: Our purpose was to compare continuous intrapartum electronic fetal heart rate monitoring with intermittent auscultation for detecting fetal acidemia at birth. STUDY DESIGN: Data from a previously published randomized trial of electronic fetal heart rate monitoring versus intermittent auscultation were analyzed to identify any differences between the two methods in detecting fetal acidemia at birth. Fetal acidemia at birth was defined as the presence of cord blood arterial pH < 7.15. RESULTS: A total of 1419 patients with umbilical cord blood acid-base measurements were identified, 739 in the electronic FHR monitoring group and 680 in the auscultation group. Electronic FHR monitoring had significantly better sensitivity (97% vs 34%, p < 0.001), lower specificity (84% vs 91%, p < 0.001), higher positive predictive value (37% vs 22%, p < 0.05), and higher negative predictive value (99.5% vs 95%, p < 0.001) in detecting fetal acidemia at birth. In addition, electronic FHR monitoring was significantly better in detecting all types of acidemia: metabolic (95.5% vs 26.5%, p < 0.001), mixed (95% vs 37.5%, p < 0.001), and respiratory (100% vs 41.5%, p < 0.001). CONCLUSION: These data suggest that electronic FHR monitoring is superior to intermittent auscultation in detecting fetal acidemia at birth.

Intrapartum electronic fetal heart rate monitoring versus intermittent auscultation: a meta-analysis.

OBJECTIVE: To use a meta-analysis of all published randomized trials to determine whether the use of continuous electronic fetal heart rate monitoring (EFM) as the main method of intrapartum fetal surveillance is associated with improved pregnancy outcome compared to intermittent auscultation. DATA SOURCES: We used the MEDLINE data base and reference lists of articles to identify all published randomized trials of EFM versus intermittent auscultation. METHODS OF STUDY SELECTION: A total of nine randomized trials published in peer-review journals were identified. The selection criterion was the use of EFM or intermittent auscultation as the main intrapartum fetal surveillance technique. DATA EXTRACTION AND SYNTHESIS: A total of 18,561 patients were included in the nine published randomized trials, 9398 in the EFM group and 9163 in the auscultation group. Measures of pregnancy outcome included cesarean delivery, cesarean for suspected fetal distress, overall use of forceps or vacuum, use of forceps or vacuum for suspected fetal distress, overall perinatal mortality, and perinatal mortality due to fetal hypoxia (intrapartum or early neonatal death) attributable to the method of intrapartum monitoring. The meta-analysis showed that the patients monitored electronically had a significantly higher overall cesarean rate (odds ratio [OR] 1.53, 95% confidence interval [CI] 1.17-2.01), higher cesarean rate for fetal distress (OR 2.55, 95% CI 1.81-3.53), overall increased use of forceps or vacuum (OR 1.23, 95% CI 1.02-1.49), increased use of forceps or vacuum for suspected fetal distress (OR 2.50, 95% CI 1.97-3.18), and decreased perinatal mortality due to fetal hypoxia (OR 0.41, 95% CI 0.17-0.98). CONCLUSION: Electronic fetal monitoring is associated with increased rates of surgical intervention and decreased perinatal mortality due to fetal hypoxia.

Intrauterine fetal growth in discordant twin gestations.

Twenty-five discordant twin pairs were assessed ultrasonically in a longitudinal fashion and were compared with a group of 60 concordant twin pairs. The growth parameters of the larger fetus of the discordant pair did not differ significantly from the concordant twins, while the smaller of the discordant pair exhibited a slower rate of intrauterine growth as early as 23 to 24 weeks. We conclude that (1) twins who ultimately become discordant exhibit demonstrable differences as early as 23 to 24 weeks; (2) the smaller twin in a discordant pair has a much slower rate of growth between 33 to 37 weeks; and (3) using estimated fetal weight to predict concordancy and discordancy by Shepard's and Hadlock's tables are equally efficacious, although Hadlock's table can be used more often because biparietal diameter cannot be obtained as often as femur length.

Intrauterine fetal growth in concordant twin gestations.

We longitudinally assessed intrauterine ultrasonic growth parameters (biparietal diameter, head circumference, abdominal circumference, and femur length) in 60 pairs of concordant twins. Head circumference to abdominal circumference and femur length to abdominal circumference ratios were calculated. Estimated fetal weight curves were created with the formula of Shepard et al., incorporating biparietal diameter and abdominal circumference, as well as that of Hadlock et al., incorporating femur length and abdominal circumference. Biparietal diameter was obtained in only 79% of fetuses, whereas femur length and abdominal circumference were obtained in 96% and 99% of fetuses, respectively. The intrauterine growth of abdominal circumference appears to be linear between 18 and 40 weeks, fitting the simple equation abdominal circumference = -4.5 + 0.97 gestational age (gestational age in weeks). The mean femur length to abdominal circumference ratio is 22.4 +/- 1.5 and appears to be gestational age independent between 20 and 40 weeks. The head circumference to abdominal circumference ratio decreases as gestational age advances in a linear fashion. Estimated fetal weight curves by the formulas of both Shepard et al. and Hadlock et al. fit second-order polynomial equations. Neither formula appears to be superior in estimating fetal weight in twin gestations, although that of Hadlock et al. can be used more frequently since biparietal diameter cannot always be obtained in both twins.

Comparison of six different ultrasonographic methods for predicting lethal fetal pulmonary hypoplasia.

Nomograms of six different ultrasonographic fetal parameters were established by studying uncomplicated, singleton pregnancies, with well-established dates, between 16 and 40 weeks of gestation. The studied parameters could reflect fetal lung mass and included the following: chest circumference (CC), chest area (CA), chest area minus heart area (CA - HA), chest circumference/abdominal circumference ratio (CC X 100/AC), chest area/heart area ratio (CA/HA), and chest area minus heart area divided by chest area ratio [(CA - HA) X 100/CA]. The effect of ruptured membranes on these six ultrasonographic parameters was assessed by studying patients who had premature rupture of the membranes of less than 1 week's duration. It was found that premature rupture of the membranes is associated with increased frequency of CC, CA, and CA - HA measurements at or below the 5th percentile. However, in patients with premature rupture of the membranes all measurements were within the normal range for the three ratios. The efficacy of each of the six parameters was determined by studying 13 fetuses at high risk for development of lethal pulmonary hypoplasia. The (CA - HA) X 100/CA parameter had the best diagnostic accuracy (sensitivity 85%, specificity 85%, positive predictive value 83%, and negative predictive value 85%).

Neonatal survival rates based on estimated fetal weights in extremely premature infants.

With the increasing survival rates of the extremely premature infants, counseling patients as to the potential outcome of the pregnancy is difficult. Traditional methods of basing survival rates on gestational age and actual birthweights have limitations. This study compares survival rates based on ultrasonically estimated fetal weights to those of actual birthweights and demonstrates an excellent correlation at this institution. It is suggested that individual institutions should construct their own neonatal survival rates based on estimated fetal weights for the extremely premature fetus to counsel better patients at risk for early delivery.

Heart rate cyclicity during labor in healthy term fetuses.

Fifty-four intrapartum fetal heart rate (FHR) tracing were subjected to retrospective analysis of the presence, length, and frequency of cyclic changes in long-term variability (cyclicity). All patients had spontaneous uncomplicated labor and received no narcotics or analgesics. The following cycles were identified according the difference in long-term variability in terms of amplitude range: cycle A, 0 to 2.5 beats/min; cycle B, 3 to 5 beats/min; cycle C, 6 to 10 beats/min; and cycle D, 11 to 20 beats/min. The frequency and length of FHR cycles was established in the latent, active phases and second stage of labor. Periods of diminished variability should be followed by fetal acid-base assessment only if their duration exceeds the established norms.

Use of the fetal biophysical profile in severe oligohydramnios after preterm premature rupture of the membranes.

A protocol of expectant management using daily fetal biophysical assessment was applied to 23 consecutive women with severe oligohydramnios after preterm premature rupture of the membranes. A persistently low biophysical score (less than or equal to 6 on two examinations two hours apart) in the presence of a nonreactive nonstress test and absence of fetal breathing was used as an indication for delivery. The pregnancy outcome in this group was compared to that in a historic control group managed similarly except that an abnormal biophysical assessment was not an indication for delivery. The results suggest that the management of women with severe oligohydramnios after preterm premature rupture of the membranes with daily fetal biophysical profiles decreases the incidence of low five-minute Apgar scores as well as that of maternal and neonatal infection.

A comparison of two different ultrasound methods for estimating fetal weight in preterm gestations.

A prospective study was conducted to evaluate the estimation of fetal weight in preterm pregnancies by use of ultrasound measurements. Two equations for estimating fetal weight, one proposed by Shepard and associates and the other by Hadlock and associates, were evaluated. The ability to estimate fetal weight accurately was evaluated with respect to birth weight and menstrual age. Shepard's equation is associated with a lower mean signed percent error than Hadlock's, when the birth weight is less than 1500 g (4% vs 12%) or when the menstrual age is between 23 weeks to 30 weeks (2% vs 10%). However when the birth weight is between 1500 g and 3500 g, or the menstrual age is between 31 weeks to 36 weeks, Hadlock's equation has a lower mean signed percent error: 1% vs -4% for the birth weight category and 2% vs -3% for the menstrual age category. In preterm gestations both equations estimate fetal age weight with a low mean signed percent error--Shephard's -0.4% versus Hadlock's 6.0%.

Spontaneous resolution of fetal cystic hygroma in Down's syndrome.

We describe a case of spontaneous resolution of a cystic hygroma between 14-16 weeks' gestation in a fetus with trisomy 21 who, at termination at 19 weeks, revealed only mild webbing of the neck. Redundant nuchal skin folds are among the most common features of trisomy 21. Our case supports the hypothesis that this redundant skin of the fetal neck represents early cystic hygromas, which resolve in utero before 16 weeks' gestation.

Fetal jejunoileal atresia with persistent omphalomesenteric duct.

A case of fetal jejunoileal atresia in association with persistent omphalomesenteric duct is presented. The dilated stomach and proximal and distal duodenum produced a multiple bubble sign on the prenatal sonogram. The neonate underwent exploratory laparotomy, excision of the persistent omphalomesenteric duct, gastrotomy, and colostomy. Possible causes of jejunoileal atresia are presented.

Antenatal diagnosis and management of monoamniotic twins.

Double survival of monoamniotic twins is rare. Three consecutive cases in which double survival occurred are presented. Accurate antenatal diagnosis, intensive fetal surveillance, and operative delivery should improve neonatal outcome.

The relationships among the fetal biophysical profile, umbilical cord pH, and Apgar scores.

The relationships among the fetal biophysical profile, umbilical cord blood pH, and Apgar scores were investigated in 124 patients undergoing cesarean section before the onset of labor. Based on a standard for the diagnosis of fetal acidosis of an umbilical cord arterial pH less than 7.20, the sensitivity, specificity, and positive and negative predictive values of the fetal biophysical profile score were 90%, 96%, 82%, and 98%, respectively. When the combination of a nonreactive nonstress test and absent fetal breathing was used as the "abnormal test," the sensitivity, specificity, and positive and negative predictive values were 100%, 92%, 71%, and 100%, respectively. The efficacy of the fetal biophysical profile to indicate fetal acidosis was found to be superior to the 1- and 5-minute Apgar scores in sensitivity and positive predictive value. These data suggest that the biophysical profile is very accurate in the identification of the fetus with acidemia. The first manifestations of fetal acidosis are nonreactive nonstress testing and loss of fetal breathing; in advanced acidemia fetal movements and fetal tone are compromised. A new protocol of antepartum fetal evaluation is suggested based on individual biophysical components rather than the score alone.

Fetal malignant melanoma: ultrasound presentation and review of the literature.

Malignant melanoma is an infrequently described type of congenital neoplasm. We report a case of primary fetal malignant melanoma. A review of the literature yielded six previous cases, four of which were due to metastasis from advanced maternal disease, and two of which were fetal (primary) in origin. Recommendations are discussed for management of this rare fetal malignancy.

The use of fetal biophysical profile improves pregnancy outcome in premature rupture of the membranes.

A protocol using daily fetal biophysical assessment was applied in 73 consecutive patients with premature rupture of the membranes and no clinical signs of infection or labor. A persistently low biophysical score (7 or less on two examinations 2 hours apart) in the presence of a nonreactive nonstress test and absence of fetal breathing was used as an indication for delivery. Measures of pregnancy outcome included the presence of amnionitis or neonatal infection. The outcome of pregnancy in this group of patients was compared with the outcomes of two historic groups: one managed conservatively (control group) and the other managed with amniocentesis on admission to the hospital (amniocentesis group). Infection outcome, maternal as well as neonatal, and low 5-minute Apgar scores were significantly less in the study than in the control group. The frequency of neonatal sepsis was significantly less in the study than in the amniocentesis group. These data suggest that management of premature rupture of the membranes with daily fetal biophysical profiles improves pregnancy outcome by reducing the incidence of maternal and neonatal infection.

Fetal weight estimation formulas with head, abdominal, femur, and thigh circumference measurements.

Most current sonographic techniques for estimating fetal weight involve measurements of the head, abdomen, and femur length both alone and in combination. The value of the fetal thigh circumference measurement in addition to the head, abdominal, and femur length measurements has not been investigated previously. Eighty-nine patients were scanned within 72 hours of delivery, and the following ultrasonic fetal parameters were obtained in all fetuses: biparietal diameter, head circumference, abdominal circumference, femur length, and thigh circumference. With multiple stepwise regression analysis, the best-fit formulas were developed with one, two, three, four, and five parameters, respectively. The best results were obtained by combining measurements of all five parameters: biparietal diameter, head circumference, abdominal circumference, femur length, and thigh circumference. The mean error of this formula was 6%, the mean deviation 0.3%, and the SD 7.8%. These data suggest that the addition of thigh circumference to measurements of the head, abdomen, and femur length improves the accuracy of fetal weight estimates.

The relationship between fetal biophysical profile and cord pH in patients undergoing cesarean section before the onset of labor.

In a prospective study of 124 patients undergoing cesarean section before the onset of labor, the fetal biophysical profile was found to have a significant relationship with umbilical cord blood pH (artery and vein). Using cord arterial pH less than 7.20 as a standard for the diagnosis of fetal acidosis, the sensitivity, specificity, and positive and negative predictive values of the fetal biophysical profile score were 90, 96, 82, and 98%, respectively. When the combination of nonreactive nonstress test and absent fetal breathing was used as the "abnormal test," the sensitivity, specificity, and positive and negative predictive values were 100, 92, 71, and 100%, respectively. The first manifestations of fetal acidosis are nonreactive nonstress testing and loss of fetal breathing; in advanced acidemia, fetal movements and fetal tone are compromised. A protocol of antepartum fetal evaluation is suggested based upon the individual biophysical components rather than the score alone.

Preterm premature rupture of the membranes: a risk factor for the development of abruptio placentae.

A retrospective study of 298 patients with preterm premature rupture of the membranes managed expectantly during a 3-year period investigated the association between preterm premature rupture of the membranes and abruptio placentae. Expectant management was associated with the development of abruptio placentae in 19 of these 298 patients (6.3%). The prevalence of abruptio placentae in the entire population during the same 3-year period was 2.7%, whereas in patients without preterm premature rupture of the membranes it was 2%. None of the patients developed clinical or laboratory evidence of disseminated intravascular coagulation and no infection (maternal or neonatal) was noted among the patients who had abruptio placentae. Patients with preterm premature rupture of the membranes and severe oligohydramnios (largest pocket less than 1 cm) seem to be at particular risk for developing this complication. These data suggest that abruptio placentae should be considered as one of the possible risks of expectant management in preterm premature rupture of the membranes.

Antenatal evaluation and management of ultrasonically detected fetal anomalies.

With the advent of improved ultrasound imaging, it is now possible to make an intrauterine diagnosis of many fetal anomalies. The key to an accurate antenatal diagnosis is careful scanning of the fetus and knowledge of the abnormalities that may be associated with a particular anomaly. In the presence of fetal anomalies known to be associated with increased frequency of chromosome abnormalities, fetal karyotyping is indicated, using either amniocentesis or fetal blood sampling, depending upon the urgency of the diagnosis. Fetal echocardiography is mandatory when the ultrasonically detected fetal anomaly is one that is known to be associated frequently with cardiac disease. Based on the antenatal findings, the parents should receive appropriate genetic and perinatal counseling. The management plan should always take into consideration the parents' wishes. Management plans for the most common ultrasonically detected fetal anomalies are presented, based upon review of the literature and authors' experience.