Nasal bone length throughout gestation: normal ranges based on 3537 fetal ultrasound measurements.

OBJECTIVE: To establish normal ranges for nasal bone length measurements throughout gestation and to compare measurements in two subsets of patients of different race (African-American vs. Caucasian) to determine whether a different normal range should be used in these populations. METHOD: Normal nasal bone length reference ranges were generated using prenatal measurements by a standardized technique in 3537 fetuses. RESULTS: The nasal bone lengths were found to correlate positively with advancing gestation (R(2) = 0.77, second-order polynomial). No statistical difference was found between African-American and Caucasian subjects. CONCLUSION: These reference ranges may prove to be useful in prenatal screening and diagnosis of syndromes known to be associated with nasal hypoplasia. Different normal ranges for African-American and Caucasian women are not required.

Nasal bone hypoplasia in trisomy 21 at 15-22 weeks' gestation.

OBJECTIVE: To investigate the potential value of ultrasound examination of the fetal profile for present/hypoplastic fetal nasal bone at 15-22 weeks' gestation as a marker for trisomy 21. METHODS: This was an observational ultrasound study in 1046 singleton pregnancies undergoing amniocentesis for fetal karyotyping at 15-22 (median, 17) weeks' gestation. Immediately before amniocentesis the fetal profile was examined to determine if the nasal bone was present or hypoplastic (absent or shorter than 2.5 mm). The incidence of nasal hypoplasia in the trisomy 21 and the chromosomally normal fetuses was determined and the likelihood ratio for trisomy 21 for nasal hypoplasia was calculated. RESULTS: All fetuses were successfully examined for the presence of the nasal bone. The nasal bone was hypoplastic in 21/34 (61.8%) fetuses with trisomy 21, in 12/982 (1.2%) chromosomally normal fetuses and in 1/30 (3.3%) fetuses with other chromosomal defects. In 3/21 (14.3%) trisomy 21 fetuses with nasal hypoplasia there were no other abnormal ultrasound findings. In the chromosomally normal group hypoplastic nasal bone was found in 0.5% of Caucasians and in 8.8% of Afro-Caribbeans. The likelihood ratio for trisomy 21 for hypoplastic nasal bone was 50.5 (95% CI 27.1-92.7) and for present nasal bone it was 0.38 (95% CI 0.24-0.56). CONCLUSION: Nasal bone hypoplasia at the 15-22-week scan is associated with a high risk for trisomy 21 and it is a highly sensitive and specific marker for this chromosomal abnormality.

Can fetal biophysical observations anticipate outcome in preterm labor or preterm rupture of membranes?

OBJECTIVE: To evaluate fetal biophysical testing as a predictor of preterm delivery after preterm labor or preterm rupture of the membranes (PROM). METHODS: We studied 50 women with suspected preterm labor and intact membranes and 25 women with PROM but not in labor between 28 and 36 weeks' gestation. Before treatment, each subject had cervical Bishop scoring and 1-hour ultrasound observation of fetal heart rate, breathing, body movements, and flexion-extensions. Data were compared with t tests, chi 2 tests, or receiver operating curves. RESULTS: The mean gestational age at entry was similar in both groups. Twenty (80%) PROM and ten (18%) preterm labor patients delivered within 72 hours of admission; two (8%) PROM and 38 (76%) preterm labor patients delivered more than 7 days after admission. Absent breathing and body movements had high positive predictive values (100%) but moderate sensitivities (less than 55%) for predicting delivery within 72 hours or 7 days in the PROM and preterm labor groups. These sensitivities increased to nearly 70% with the addition of Bishop scores. The optimal diagnostic cutoffs for delivery within 72 hours or 7 days were a breathing incidence below 1% for the PROM group and a body movement incidence below 1% for the preterm labor group, and a breathing incidence of at most 5%. CONCLUSIONS: Complete absence of one biophysical variable confers limited sensitivity but high positive predictive value for early delivery in patients with preterm labor or PROM. The use of cutoff percentages for the incidence of individual variables improved sensitivity for both conditions. Cervical scoring added to biophysical monitoring by improving the sensitivity for early delivery of patients in preterm labor.

Fetal biophysical activities in third-trimester pregnancies complicated by diabetes mellitus.

OBJECTIVE: Our purpose was to compare third-trimester fetal biophysical activities in normal and well-controlled insulin-dependent diabetic pregnancies. STUDY DESIGN: We performed serial bimonthly fetal biophysical studies from 30 to 38 weeks in 18 normal and 18 well-controlled insulin-dependent diabetic pregnancies (White classes B through D). Each study contained 60 minutes of simultaneous ultrasonographic recordings of fetal breathing movements and rates, baseline heart rate, and body movements. Mean daily blood glucose levels of diabetic patients were determined from home monitors; HbA1c was determined every 6 weeks and ultrasonographic fetal growth rates every 3 weeks. Data were compared with t tests, analysis of variance with repeated measures, and chi 2 tests. RESULTS: Women in the diabetic group maintained good glycemic control and were delivered of normal infants of weights similar to those of nondiabetic gravidas. Their fetuses had higher mean incidences of fetal breathing movement, fetal heart rates, and fetal breathing rates but lower fetal movements and fetal heart rate acceleration counts than did controls throughout the study. Neither short- nor long-term maternal glycemic levels correlated well with fetal biophysical performance. CONCLUSIONS: In spite of good maternal glycemic control fetuses of diabetic women behaved differently from those of nondiabetic women. Modulation of their biophysical activities may be affected by maternal glycemic status before the last trimester. Different standards might need to be applied to interpret their tests.

The prediction of "controlled" uterine rupture by the use of intrauterine pressure catheters.

OBJECTIVE: To determine whether uterine activity, assessed by either fluid-filled or solid pressure catheters, changes with uterine incision at cesarean delivery. METHODS: Uterine activity was recorded continuously during low transverse cesarean delivery in ten parturients using fluid-filled pressure catheters and in ten women with solid pressure catheters. Visual analyses were performed of the last 30 minutes of uterine recording before uterine incision and of the period after incision; the analyses were then compared within and between the catheter groups for mean uterine tone and contraction amplitude, frequency, and duration. Oxytocin use, anesthesia method, mean gestational age, birth weight, length of labor, duration of monitoring, and uterine incision-to-delivery time were compared between the groups. RESULTS: All obstetric end points were similar in both catheter groups except for a higher mean birth weight in the solid-catheter group. The mean (+/- standard deviation) duration of post-incision monitoring was 4.7 +/- 0.94 minutes. After uterine incision, mean tone and contraction amplitude were unchanged, whereas mean contraction frequency and duration decreased significantly. CONCLUSIONS: Though intrauterine monitoring was brief, this model allows a unique view of "controlled" uterine rupture. Spontaneous uterine rupture may evolve more gradually; however, neither catheter type would be likely to aid its early recognition.

Do semiquantitative amniotic fluid indexes reflect actual volume?

OBJECTIVE: Our objective was to determine how well semiquantitative ultrasonographic measures of amniotic fluid, i.e., maximal amniotic fluid vertical pocket and amniotic fluid index, reflect actual amniotic fluid volumes in 50 near-term patients whose amniotic fluid volume estimates were normal by visual inspection. STUDY DESIGN: Before amniocentesis for fetal lung maturity, each patient had visual amniotic fluid volume estimates, maximal amniotic fluid vertical pocket, and amniotic fluid index performed by the same examiner, and then each received intraamniotic injection of a 10% paraaminohippurate solution. Amniotic fluid volume was quantitated by spectrophotometric assay of paraaminohippurate concentration. Oligohydramnios and polyhydramnios were defined as < 300 and > 2000 ml, respectively. RESULTS: Quantitative amniotic fluid volume was positively related to both amniotic fluid index and maximal amniotic fluid vertical pocket (r = 0.75 and 0.60, respectively). True-positive rates for oligohydramnios (amniotic fluid index < 5 cm or maximal amniotic fluid vertical pocket < 2 cm) were 100% and 0%, respectively; false-positive rates with either method were 0%. True-positive rates for polyhydramnios (amniotic fluid index > 20 cm and maximal amniotic fluid vertical pocket > 8 cm) were 0%; false-positive rates were 16% and 24%, respectively. CONCLUSIONS: Amniotic fluid index appears to be slightly better than maximal amniotic fluid vertical pocket for reflecting actual amniotic fluid volume. Both indirect methods tend to overestimate actual amniotic fluid volume at the upper end of its extremes.

Culturing tubal pregnancies for Chlamydia trachomatis: is it beneficial?

Chronic Chlamydia trachomatis infection has been demonstrated in the fallopian tubes of asymptomatic infertile women. These women have a significantly increased risk of ectopic pregnancies. The purpose of our study was to determine the efficacy of culturing the ectopic site for C. trachomatis, the likely cause of asymptomatic salpingitis in association with a tubal pregnancy. We cultured the fallopian tubes of 21 patients undergoing surgery for tubal pregnancy, all 21 cultures were negative for C. trachomatis. Although infection with this organism is one of the causes of ectopic pregnancy, we were unable to demonstrate the presence of a concomitant chlamydial infection at the time of surgery. Combining chlamydial cultures with nonculture techniques may be more beneficial in further attempts to demonstrate such an association.

Chronic asymptomatic Chlamydia trachomatis colonization of the fallopian tubes during the peripartum period.

Antepartum cervical Chlamydia trachomatis infection is associated with an increased risk of peripartum maternal and neonatal morbidity. Chronic chlamydial salpingitis has been described in asymptomatic women. We studied the incidence of asymptomatic chlamydial colonization of the fallopian tubes during pregnancy, and the influence of such infection on the patients' clinical course, by culturing the fallopian tubes of 53 asymptomatic women who underwent tubal ligation in the immediate postpartum period. One patient had a positive chlamydial culture in one of her tubes, and two others had histologic evidence of acute and chronic salpingitis. These patients had no infectious morbidity during the antepartum, intrapartum, or postpartum periods. Our findings suggest that asymptomatic chlamydial colonization and inflammatory processes may exist in the fallopian tubes during the peripartum period.

Cytogenetic study of amniotic fluid in the evaluation of fetal death.

Cytogenetic study is an important part of the evaluation of intrauterine fetal death. Many tissue cultures fail to grow because of maceration and autolysis of the fetal tissues. We evaluated eight amniotic fluid cytogenetic cultures from patients whose fetus had died. All patients had sonographic evidence of Spalding's sign. In four patients, urea and PGF2 alpha were simultaneously injected into the amniotic cavity. Seven amniotic cultures, gestational age 19 to 33 weeks, grew successfully, even when a tissue culture obtained after delivery failed to grow. One culture, gestational age 36.5 weeks, failed to grow and could not be analyzed. The use of amniotic fluid culture for cytogenetic evaluation of fetal death, obtained at the time of diagnosis, is superior to culture of fetal tissue obtained after delivery. The amniocentesis may also serve for intra-amniotic induction of labor.