Circulating cell-free fetal DNA for the detection of RHD status and sex using reflex fetal identifiers

OBJECTIVE

To determine the sensitivity and specificity of circulating cell-free fetal DNA in determining the fetal RHD status and fetal sex.

METHODS

Maternal blood was collected in each trimester of pregnancy from RhD negative nonalloimmunized women. Whole blood was centrifuged, separated into plasma and buffy coat, and frozen at -80°C. DNA analysis was conducted via allele-specific primer extensions for exons 4, 5, and 7 of the RHD gene and for a 37-base pair insertion in exon 4 (RHD pseudogene; psi) three Y-chromosome sequences (SRY, DBY, and TTY2), and an extraction control (TGIFL-like X/Y). RhD serotyping on cord blood and gender assessment of the newborns were entered into a Web-based database.

RESULTS

One hundred twenty women were enrolled. The median gestational age at the first venipuncture was 12.4 (range: 10.6-13.9) weeks with 120 samples drawn; 118 samples were drawn at 17.6 (16-20.9) weeks; and 113 samples at 28.7 (27.9-33.9) weeks. Overall accuracy for RHD was 99.1%, 99.1%, and 98.1% for each trimester and was 99.1%, 99.1%, and 100% for fetal sex determination.

CONCLUSIONS

Fetal RHD genotyping and sex can be very accurately determined in all three trimesters using circulating cell-free fetal DNA in the maternal circulation.

Maintaining quality assurance for sonographic nuchal translucency measurement: lessons from the FASTER Trial

OBJECTIVE

To evaluate nuchal translucency measurement quality assurance techniques in a large-scale study.

METHODS

From 1999 to 2001, unselected patients with singleton gestations between 10 + 3 weeks and 13 + 6 weeks were recruited from 15 centers. Sonographic nuchal translucency measurement was performed by trained technicians. Four levels of quality assurance were employed: (1) a standardized protocol utilized by each sonographer; (2) local-image review by a second sonographer; (3) central-image scoring by a single physician; and (4) epidemiological monitoring of all accepted nuchal translucency measurements cross-sectionally and over time.

RESULTS

Detailed quality assessment was available for 37 018 patients. Nuchal translucency measurement was successful in 96.3% of women. Local reviewers rejected 0.8% of images, and the single central physician reviewer rejected a further 2.9%. Multivariate analysis indicated that higher body mass index, earlier gestational age and transvaginal probe use were predictors of failure of nuchal translucency measurement and central image rejection (P = 0.001). Epidemiological monitoring identified a drift in measurements over time.

CONCLUSION

Despite initial training and continuous image review, changes in nuchal translucency measurements occur over time. To maintain screening accuracy, ongoing quality assessment is needed.

First- and second-trimester Down syndrome screening markers in pregnancies achieved through assisted reproductive technologies (ART): a FASTER trial study

OBJECTIVE

To determine whether first- and second-trimester Down syndrome screening markers and screen-positive rates are altered in pregnancies conceived using assisted reproductive technologies (ARTs).

METHODS

ART pregnancies in the multicenter FASTER trial were identified. Marker levels were evaluated for five types of ART: in vitro fertilization with ovulation induction (IVF-OI), IVF with OI and egg donation (IVF-OI-ED), IVF with ED (IVF-ED), and intrauterine insemination with OI (IUI-OI) or without OI (IUI). Each group was compared to non-ART controls using Mann-Whitney U analysis.

RESULTS

First-trimester marker levels were not significantly different between ART and control pregnancies, with the exception of reduced PAPP-A levels in the IUI-OI group. In contrast, second-trimester inhibin A levels were increased in all ART pregnancies, estriol was reduced and human chorionic gonadotropin (hCG) was increased in IVF and IUI pregnancies without ED, and alpha-fetoprotein (AFP) was increased in ED pregnancies. Second-trimester screen-positive rates were significantly higher than expected for ART pregnancies, except when ED was used.

CONCLUSIONS

These data show that ART significantly impacts second-, but not first-, trimester markers and screen-positive rates. The type of adjustment needed in second-trimester screening depends on the particular type of ART used.

The impact of maternal obesity on midtrimester sonographic visualization of fetal cardiac and craniospinal structures

OBJECTIVE

To examine the impact of maternal obesity on the rate of suboptimal ultrasound visualization (SUV) of fetal anatomy and determine the optimal timing of prenatal ultrasound examination for the obese gravida.

METHODS

A computerized ultrasound database was used to identify ultrasound examinations for singleton gestations performed between 14(0/7) and 23(6/7) weeks at a tertiary care, university-based hospital. Patients were divided into four groups and categorized based on body mass index (BMI): nonobese (BMI <30 kg/m2), class I obesity (30< or =BMI<35 kg/m2), class II obesity (35< or =BMI<40 kg/m2), and extreme obesity (BMI > or =40 kg/m2). The rates of SUV for fetal cardiac and craniospinal structures were calculated for each group and compared.

RESULTS

A total of 11,019 pregnancies were studied, of which 38.6% of the patients were obese. Overall, the rate of SUV of the fetal structures was higher for obese compared to nonobese women for both cardiac (37.3 [1723/4200] vs 18.7% [1275/6819]; P<0.0001) and craniospinal structures (42.8 [1798/4200] vs 29.5% [2012/6819]; P<0.0001). Increased severity of maternal obesity was associated with SUV rate for both the cardiac (nonobese 18.7% [1275/6819], class I 29.6% [599/2022], class II 39.0% [472/1123], and extreme obesity 49.3% [580/1055]; P<0.0001) and for the craniospinal structures: (nonobese 29.5% [2012/6819], class I 36.8% [744/2022], class II 43.3% [486/1123], and extreme obesity 53.4% [563/1055]; P<0.0001). With increasing gestational age at examination, the rate of SUV decreased for both obese and nonobese women. However, for obese women there was minimal improvement in visualization after 18-20 weeks. Even after adjustment for gestational age and the type of ultrasound machine, obese women (class I, class II, and extreme obesity) were still associated with increased odds for SUV of the fetal cardiac and craniospinal structures compared to nonobese women.

CONCLUSION

Maternal obesity increases the rate of SUV for the fetal cardiac structures by 49.8% and for the craniospinal structures by 31%. The optimal gestational age for visualization of fetal cardiac and craniospinal anatomy in obese patients may be after 18-20 weeks.

Relationship between fetal pulmonary maturity assessment and neonatal outcome in premature rupture of the membranes at 32-34 weeks' gestation

The absence of fetal pulmonary maturity in patients with preterm premature rupture of the membranes (PPROM) is often considered an indication for conservative management. The purpose of this study was to examine the value of biochemical pulmonary maturity assessment for the prediction of neonatal outcome in patients with PPROM between 32 and 34 weeks' gestation. Pregnancies complicated by PPROM at 32 to 34 weeks' gestation that delivered from January 1995 to May 2000 and had biochemical pulmonary maturity assessment were reviewed. Patients with medical disorders, multiple gestations, fetal growth restriction or structural anomalies, or evidence of intra-amniotic infection were excluded. Neonatal outcome measures were compared between patients with mature and immature pulmonary indices. During this time period, 244 patients with PPROM at 32-34 weeks' gestation were delivered; 78 patients met inclusion criteria (n = 41 patients with mature indices and n = 37 patients with immature indices). There were no cases of perinatal death or sepsis. There was no difference in major neonatal morbidities including need for mechanical ventilation, grade 2 or 3 necrotizing enterocolitis, grade 3 or 4 intraventricular hemorrhage, or seizures. After controlling for confounding factors including gestational age at PPROM and delivery, latency period, group B streptococcus (GBS) vaginal colonization, corticosteroid therapy, neonatal sex, mode of delivery, fetal indications for delivery, and umbilical cord pH, biochemical pulmonary maturity was not predictive of major neonatal morbidity. In our population, biochemical pulmonary maturity status does not appear to be predictive of neonatal morbidity in pregnancies complicated by PPROM at 32-34 weeks' gestation.

Nucleated red blood cell counts in term neonates with umbilical artery pH < or = 7.00

The purpose of this study was to determine whether nucleated red blood cell (NRBC) counts are elevated in term neonates who have severe fetal acidemia at birth. The neonatal NRBC counts of term (gestational age > or = 37 weeks) neonates with pathological acidemia were compared with those from control neonates who met the following criteria: gestational age > or = 37 weeks, birth weight > or = 2800 g, umbilical artery pH > or = 7.25, and a 5-minute APGAR > 7. Pathological acidemia was defined as an umbilical artery pH < or = 7.0 and a base excess > -12 mEq/L. Twenty-six neonates met all inclusion criteria and were compared to 78 controls. The mean NRBC/100 WBC was 11.9 +/- 13.5 (range 0 to 45) for acidemic neonates compared to 3.9 +/- 2.9 NRBC/100 WBC (range 0 to 11) for control neonates [p <0.001]. Our findings suggest that the onset of hypoxia-ischemia in pregnancies complicated by severe fetal acidemia often begins prior to the intrapartum period.

Meconium staining and meconium aspiration syndrome. Is there seasonal variation?

OBJECTIVE

To determine whether the incidence of pregnancies complicated by meconium-stained amniotic fluid (MSAF) or meconium aspiration syndrome (MAS) differs with seasonal changes.

METHODS

An established perinatal database was used to identify all term (> or = 37 weeks) singleton gestations resulting in a live birth from January 1, 1997 to December 31, 1999. Patients were divided into groups based on the season of delivery: winter (December-February), spring (March-May), summer (June-August), and fall (September-November). Rates of MSAF (%MSAF/total deliveries) and MAS (%MAS/total deliveries) were calculated and compared among seasons. Local climatic data (average monthly temperature and monthly precipitation) were obtained from the National Weather Service. Multiple logistic regression analysis was performed to control for the effects of confounding variables and odds ratio (OR) with 95% confidence intervals (CI) were calculated. p < 0.05 was considered significant.

RESULTS

Over the 3-year study period there were a total of 14,888 deliveries meeting the criteria. MSAF occurred in 3,206 (21.5%) deliveries and MAS developed in 92 (0.6% of total, 2.9% of MSAF). There were no differences in the rate of MSAF (p = 0.2) or MAS (p = 0.6) between seasons. By logistic regression neither season, temperature, nor precipitation were associated with MSAF or MAS.

CONCLUSIONS

Our findings suggest that over the period examined there were no significant seasonal variations in the incidence of MSAF or MAS.

Relationship between the sonographic pattern of intrauterine growth restriction and acid-base status at the time of cordocentensis

OBJECTIVE

To determine whether there is a difference in acid-base status at the time of cordocentesis between fetuses with symmetric and asymmetric intrauterine growth restriction (IUGR).

STUDY DESIGN

Non-anomalous singleton fetuses with IUGR who underwent fetal blood sampling for rapid karyotype analysis from 1992-1995 were retrospectively identified. Cases with gestational age <24 weeks, abnormal karyotype, or evidence of congenital infection were excluded. Fetuses were divided into two groups based on Head Circumference/ Abdominal Circumference Ratio (HC/AC). The asymmetric-IUGR group had HC/AC > or = 95% tile for GA, and the symmetric-IUGR group had HC/AC <95% tile. GA adjusted values of umbilical venous pH, pCO2, pO2, HCO3, hemoglobin and reticulocyte count were calculated by subtracting the mean values for GA from the observed and compared between groups.

RESULTS

Both symmetric-IUGR (n = 7) and asymmetric-IUGR (n = 9) had umbilical venous pH and pO2, levels lower than GA normative values. However, there were no differences between groups for any of the parameters studied.

CONCLUSIONS

Fetuses with symmetric and asymmetric IUGR due to UPI display a similar degree of acid-base impairment.

Vaginal birth after cesarean in the diabetic gravida

OBJECTIVE

To compare the delivery outcomes in term diabetic patients without a prior cesarean delivery to those attempting vaginal birth after cesarean (VBAC).

STUDY DESIGN

A retrospective chart review study was performed of singleton pregnancies complicated by class A-2-R diabetes who delivered at > or = 37 weeks from 1991 to 1997. Exclusion criteria were prior classical or low vertical cesarean, more than one prior cesarean delivery, fetal structural defects or any contraindications to labor. Outcome measures were compared for patients without prior cesarean (group 1) to those with a VBAC attempt (group 2).

RESULTS

One hundred fifty-nine patients, 127 patients without a prior cesarean delivery and 32 patients with a VBAC attempt, met all the study criteria. The cesarean delivery rate was 26.3% (34/127) in group 1 and 56.3% (18/32) in group 2 (VBAC success rate, 43.7%). There were no cases of uterine rupture. There were no differences in the frequency of endometritis rates or neonatal intensive care unit admission, whether vaginal or cesarean delivery occurred.

CONCLUSION

VBAC success rates appeared to be lower for diabetic gravidas as compared to those for nondiabetic women reported in the literature. Although maternal and neonatal complication rates were low, further studies are necessary to determine the safety of VBAC in this population.

Influence of maternal-fetal medicine subspecialization on the frequency of trial of labor in term pregnancies with breech presentation

OBJECTIVE

To investigate the role of subspecialization in maternal-fetal medicine (MFM) on the frequency of a trial of labor in term pregnancies with breech presentation.

METHODS

We conducted a retrospective study of 332 singleton pregnancies > or =37 weeks with nonfootling breech presentation that delivered over a 6-year period (1994-1998) at a university-based, tertiary care hospital. Patients were divided into two groups based on whether the delivery was attended by an MFM or non-MFM obstetrician-gynecologist. Demographic and clinical data were compared between groups and outcome variables included whether the patient had an attempt at vaginal delivery, cesarean delivery after a labor attempt, or vaginal breech delivery.

RESULTS

The frequency of labor attempt (OR 1.4, 95% CI 0.9-2.3), vaginal breech success rate (OR 0.6, 95% CI 0.3-1.5), and overall cesarean rates (OR 0.9, 95% CI 0.5-1.7) were similar between groups. Using discriminant function analysis, only nulliparity (R2 = 1.6%, F = 6.0, P = 0.005) and birthweight (R2 = 2.0% F = 6.4, P = 0.01) were associated with trial of vaginal delivery.

CONCLUSIONS

Subspecialization in MFM had no impact on the frequency of trial of labor in the term pregnancy with a breech presentation.

Benefits associated with harmonic tissue imaging in the obstetric patient

OBJECTIVE

We sought to determine the impact of harmonic tissue imaging on image resolution and visualization of fetal structures during obstetric ultrasonography.

STUDY DESIGN

Patients with singleton second- or third-trimester fetuses were recruited. Prospective comparisons of conventional fundamental imaging and harmonic tissue imaging were made. Visualization rates and frequencies of improvement in resolution were calculated. Discriminate function analysis evaluated determinants of improved visualization.

RESULTS

Harmonic tissue imaging improved resolution of at least one fetal structure in 51.4% of patients studied. Differences were most marked for 4-chamber views of the heart with improvement in resolution in 30.5% of patients and change in ability to visualize in 9.5%. Maternal weight and gestational age had a significant influence on whether improvements were noted with harmonic tissue imaging, accounting for 27% of the variance.

CONCLUSIONS

Harmonic tissue imaging offers significant improvements over fundamental imaging in image resolution and structure visualization in obese patients during the second trimester of pregnancy.

The relationship between nucleated red blood cell counts and early-onset neonatal seizures

OBJECTIVE

This study was undertaken to better define the timing of neurologic insult in neonates with early-onset seizures through evaluation of neonatal nucleated red blood cell levels.

STUDY DESIGN

Medical records and the International Classification of Diseases, Ninth Revision codes were used to identify all term neonates with neonatal convulsions who were delivered at our institution (January 1, 1990-December 31, 1995). Each neonate with early-onset seizures was matched to the next 3 neonates who met the following criteria: gestational age > or =37 weeks, no early-onset seizures, birth weight > or =800 g, umbilical artery pH > or =7.25, and a 5-minute Apgar score >7. Demographic characteristics, clinical factors, and mean initial nucleated red blood cell counts were compared between groups.

RESULTS

During the 6-year study period, there were a total of 36, 490 singleton term deliveries of infants who were alive at birth. Forty-five (0.1%) of these neonates had early-onset seizures. Thirty neonates with early-onset seizures met the inclusion criteria. Mean nucleated red blood cell counts (number of nucleated red blood cells per 100 white blood cells) for neonates with early-onset seizures were significantly increased compared with those of control neonates (18.4 +/- 22.0 vs 4.6 +/- 4.5; P <.0008).

CONCLUSIONS

Our findings are suggestive of the hypothesis that neurologic injury leading to early-onset seizures often occurs before the intrapartum period.

Patients with an ultrasonographic cervical length < or =15 mm have nearly a 50% risk of early spontaneous preterm delivery

OBJECTIVE

The aim of this study was to determine the value in the prediction of spontaneous preterm delivery of ultrasonographically measured cervical length measured between 14 and 24 weeks' gestation.

STUDY DESIGN

A retrospective cohort study examined cervical length by means of a two-stage procedure, transabdominal ultrasonography followed by transvaginal ultrasonography if cervical length was <30 mm.

RESULTS

A total of 6877 patients met inclusion criteria. Mean cervical length was 37.5 mm. Odds ratios for early preterm delivery (< or =32 weeks' gestation) for patients with cervical lengths < or =10, < or =15, < or = 20, < or =25, and < or =30 mm were, respectively, 29.3 (95% confidence interval, 11.3-75.8), 24.3 (95% confidence interval, 12. 9-45.9), 18.3 (95% confidence interval, 10.8-31.0), 13.4 (95% confidence interval, 8.8-20.6), and 3.2 (95% confidence interval, 2. 4-4.4). For early preterm delivery a cervical length of < or =15 mm had a positive predictive value of 47.6%, a negative predictive value of 96.7%, a sensitivity of 8.2%, and a specificity of 99.7%.

CONCLUSIONS

A short cervix seen on a second-trimester sonogram was a powerful predictor of early spontaneous preterm delivery (< or =32 weeks' gestation). Nearly 50% of patients with a cervical length < or =15 mm had an early spontaneous preterm delivery, which suggests that clinical trials of interventions (eg, cerclage) in this population are urgently needed.

Delivery of the marginally preterm infant: what are the minor morbidities?

OBJECTIVE

We sought to determine frequencies of minor morbidities associated with delivery between 32 and 36 weeks' gestation.

STUDY DESIGN

The study population consisted of all infants delivered between 32 and 36 weeks' gestation at a tertiary care hospital during 1997. Maternal and neonatal charts were abstracted for maternal history, pregnancy complications, and neonatal demographics comparing complications present at each gestational week. The Student t test, chi(2) analysis, and stepwise regression analysis were used to assess statistical significance. Odds ratios were calculated.

RESULTS

There were 553 patients eligible for study. There was increased risk of neonatal intensive care unit admission with delivery before 34 weeks' gestation (P <.04). An increased incidence of feeding difficulties was present before 35 weeks' gestation (P <.001). Hypothermia remained more frequent until 35 weeks' gestation (P <.05). Delivery at 35 weeks' gestation did not increase the mean number of neonatal hospital days.

CONCLUSION

Although the incidences of major morbidities decline after 32 weeks' gestation, minor morbidities continue up to 35 to 36 weeks' gestation and may lengthen neonatal hospitalization.

The apparently isolated choroid plexus cyst: importance of minor abnormalities in predicting the risk for aneuploidy

OBJECTIVES

To assess the risk of aneuploidy in cases of isolated choroid plexus cysts (CPCs) and to compare the risk when associated with minor or major anomalies.

METHODS

All fetuses with CPCs and known karyotype were identified. CPCs were categorized as 'isolated' or associated with minor or major sonographic anomalies. Preexisting risk factors for aneuploidy were compared between groups. The frequency of aneuploidy was compared between fetuses with isolated CPCs and those with CPCs associated with minor or major anomalies. Continuous and categorical variables were analyzed using one-way analysis of variance or chi-square as appropriate with p < 0.05 considered significant.

RESULTS

One hundred and forty-nine fetuses with CPCs diagnosed at a mean gestational age of 19 weeks were identified. No significant differences in the frequency of preexisting risk factors for aneuploidy were identified between groups. Eighteen of 149 (12%) fetuses with CPCs had other sonographic anomalies; in 10 they were minor, and 2 of the 10 had abnormal karyotypes. Four of 8 fetuses with major anomalies were aneuploid. All 131 fetuses with isolated CPCs had normal karyotypes, and all aneuploid fetuses had additional anomalies.

CONCLUSIONS

The overall rate of aneuploidy in patients with CPCs was 4% with no abnormal karyotypes among isolated CPCs. The presence of even minor sonographic abnormalities substantially increased the risk of aneuploidy. Isolated CPCs identified sonographically may not place the patient at risk of aneuploidy, but should prompt a diligent search for other minor or major anomalies. The finding of any other anomaly warrants consideration for karyotypic evaluation.

Telemedicine and fetal ultrasonography: assessment of technical performance and clinical feasibility

OBJECTIVE

Our aim was to determine the performance and clinical feasibility of telesonography for the interpretation of fetal anatomic scans sent from a remote location compared with those obtained at a tertiary care prenatal ultrasonography center.

STUDY DESIGN

Routine ultrasonographic studies from 35 patients were remotely interpreted. Evaluation included a blinded comparison of the sonographer's assessment of 38 fetal structures with that of the physician at the tertiary care center. Technical evaluation included system reliability and the number of digital telephone lines required for adequate real-time visualization.

RESULTS

The mean gestational age at the time of the ultrasonography was 25.84 +/- 6.8 weeks (range 14 to 38). There was complete consistency of interpretation for 25 of 38 (66%) fetal structures. Thirteen structures had discrepancies in visualization, reflecting a difference in the adequacy of visualization, not the normalcy or identity of the structures. Three digital (integrated switching digital network, ISDN) telephone lines were required for real-time visualization.

CONCLUSION

Our preliminary experience supports telesonography as a clinically useful tool for remote interpretation of fetal ultrasonographic examinations. Further studies are warranted for the continued evaluation of this emerging technology.

Limited clinical utility of midtrimester fetal morphometric percentile rankings in screening for birth weight abnormalities

OBJECTIVE

Our purpose was to determine whether midtrimester fetal ultrasonographic morphometric percentile rankings are sensitive screening tests for preterm labor or birth weight abnormalities.

STUDY DESIGN

Stepwise multiple regression and chi 2 analysis were used to identify midtrimester fetal measurements predicting birth weight and gestational age. Receiver-operator characteristics curves were used to evaluate abdominal circumference percentiles as a test for large-for-gestational-age and small-for-gestational-age infants.

RESULTS

Extremes in abdominal circumference and head measurement percentiles were associated with large- and small-for gestational-age infants but not with preterm delivery. Abdominal circumference predicted birth weight in regression analysis; however, receiver-operator characteristic curves showed abdominal circumference percentiles to be poor screening tests for large- or small-for-gestational-age infants. The positive predictive value of 10th and 90th abdominal circumference percentiles for small- and large-for-gestational-age infants was < 20%.

CONCLUSION

Midtrimester percentile rankings offer no clear benefit in targeting fetuses with potential birth weight abnormalities or risk of preterm delivery and may provide clinically misleading information.

Differences in measurements of the atria of the lateral ventricle: does gender matter?

OBJECTIVE

To evaluate possible differences in measurements of the width of atria of the lateral cerebral ventricles of male and female fetuses.

STUDY DESIGN

A prospectively entered database was reviewed to identify patients undergoing ultrasound examination at > 13 weeks between July 1, 1994 and June 30, 1995. Inclusion criteria included identification of fetal gender, measurement of the atria, and the absence of fetal anomalies.

RESULTS

The atrial width of the lateral ventricles was statistically greater in male than in female fetuses (7.1 vs. 7.0 mm, p < 0.001).

CONCLUSION

Although statistically significant, the difference between genders in the measurement of the ventricular atria is too small to be of clinical utility.

Maternal thrombocytopenia. Predicting neonatal thrombocytopenia with cordocentesis

OBJECTIVE

To evaluate the efficacy of cordocentesis for predicting fetal thrombocytopenia in the presence of maternal thrombocytopenia.

STUDY DESIGN

We studied platelet counts obtained by cordocentesis from 42 consecutive immune thrombocytopenia purpura patients. Platelet counts were obtained on 36 neonates, and the statistical analysis included only these infants. Presence of maternal antiplatelet antibodies, interval from fetal sampling to delivery, neonatal platelet counts and outcome were evaluated. Thrombocytopenia was defined as a platelet count < or = 150,000/microL, with < or = 50,000 microL considered severe.

RESULTS

No procedure-related complications occurred. A moderate correlation existed between fetal and neonatal platelet counts (r = .48, P = .003), unrelated to the interval between sampling and delivery. Eight of 36 fetuses had thrombocytopenia, and 4 were confirmed at delivery. Two neonates had thrombocytopenia at birth but not at cordocentesis. Two neonatal thrombocytopenia cases were severe. Neither was categorized as severe antenatally. The sensitivity, specificity, and positive and negative value for predicting severe neonatal thrombocytopenia were 0%, 100%, 0%, and 94%, respectively. Grade 1 intraventricular hemorrhages occurred in two neonates delivered at 35 weeks' with normal platelet counts.

CONCLUSION

Cordocentesis was not reliable in predicting severe neonatal thrombocytopenia; however, the high negative predictive value was reassuring. The clinical utility of the technique and the population in which it should be used remain to be defined.

Neonatal outcome following methadone exposure in utero

To examine the relationship between maternal methadone exposure and neonatal head circumference and abstinence syndrome, we examined the records of 172 opiate-addicted gravidas enrolled in a methadone maintenance program in an urban hospital over a 2-year period. Higher doses of methadone in the third trimester were associated with increased head circumference reflecting both increased gestational duration and improved overall growth. Neonatal withdrawal was positively correlated with gestational age at delivery and race, with nonblack infants exhibiting higher neonatal abstinence scores than blacks following adjustment for maternal dose and gestational age at delivery. Selection of optimal methadone dosage is a complex problem in which the favorable neurobehavioral outcome associated with increased growth and gestational age must be weighed against the risks associated with more severe neonatal withdrawal. Our findings of improved overall fetal growth and gestational duration associated with higher methadone doses suggest that more liberal methadone dosing in pregnancy may improve long-term neonatal outcome.

Prenatal cytogenetic abnormalities: correlations of structural rearrangements and ultrasonographically detected fetal anomalies

OBJECTIVE

Our purpose was to determine the distribution of karyotypic abnormalities detected at prenatal diagnosis, fetal anomalies, and ability for fluorescent in situ hybridization detection.

STUDY DESIGN

Our cytogenetic database from January 1988 to April 1994 was categorized according to type and potential detection by current standard fluorescent in situ hybridization probes. Fetal anomalies and cytogenetic aberrations were compared.

RESULTS

A total of 664 cases of abnormal fetal karyotypes were identified from 12,454 prenatal cytogenetic cases (7529 amniocenteses and 4925 chorionic villus sampling) and were classified as autosomal aneuploidy (331), sex aneuploidy (103), polyploidy (38), marker aneuploidy (19) and structural rearrangements (173). Standard fluorescent in situ hybridization probes would have missed 31% of the abnormal cases: 90 aneuploidy, 14 de novo marker aneuploidy, and 65 de novo structural aberrant cases. The 134 cases of structural chromosomal rearrangements with complete ultrasonographic records were further classified as polymorphism (42), familial (43), or de novo (49). Frequency of fetal anomaly detection by ultrasonography in de novo cases (22/49) was higher than other rearrangements (chi 2 7.4, p = 0.006).

CONCLUSION

The contribution of unusual aneuploidies (16%) and structural chromosomal rearrangements (26%) in prenatal diagnostic practice is significant. Fetal anomalies were detected by ultrasonography in 45% of the de novo rearrangement cases. Fluorescent in situ hybridization would miss 31% of the abnormal cases.

Prenatal diagnosis of sirenomelus with color Doppler ultrasonography

Sirenomelus is an invariably lethal congenital anomaly characterized by complete or nearly complete fusion of the lower extremities that occurs in 1 of 60,000 births. In about 50% of cases this condition cannot be diagnosed prenatally because of the associated oligohydramnios that precludes a detailed examination of the fetus. We present a case of sirenomelus in which prenatal diagnosis was aided by color Doppler ultrasonography; visualization of the vitelline artery as a single, large intraabdominal vessel that did not branch in the fetal pelvis but rather coursed ventrally into the umbilical cord proved to be diagnostic of this rare condition. Color Doppler flow ultrasonography is a valuable tool for the prenatal diagnosis of sirenomelus.

Trends in sonographic fetal organ visualization

In order to assess changes in sonographic visualization over the last 6 years, 7092 second- and third-trimester ultrasound examinations from separate pregnancies in three individual years (1451 in 1985, 3016 in 1988, and 2625 in 1991) were compared. Overall, visualization across all gestational ages improved from 63.9% (1985) to 85.8% (1988) to 87.3% (1991), with the year in which the scan was performed explaining 19.6% of the variance in visualization. Maternal size (as determined by body mass index) remained the major determinant of ultrasound visualization in 1991 (r(2) = 11.2%), with gestational age explaining only 5.2% additional variance. Overall organ visualization was maximal at 21-23 weeks' gestation, with the decline in later gestation primarily accounted for by worsened visualization of fetal extremities and spine. Improved fetal visualization earlier in the second trimester and the advent of embryonic visualization in the first trimester may allow a continuum of prenatal sonographic diagnosis.

The sonographically thick placenta: a predictor of increased perinatal morbidity and mortality

In order to determine the prevalence and significance of sonographically thick placentas, we reviewed the computerized records of 18 827 viable, singleton pregnancies. Of these, 116 (0.6%) had thick placentas diagnosed by ultrasound examination. Perinatal mortality was markedly increased among pregnancies with thick placentas (odds ratio = 13.1, 95% confidence limits (CL) = 8.3-20.8), accounting for 6.2%; of the total. The rates of abruptio placentae (odds ratio = 2.9, CL = 1.1-8.1), neonatal intensive care unit admissions (odds ratio = 4.6, CL = 3.1-6.9) and anomalies (odds ratio = 8.4, CL = 4.9-14.4) were also significantly increased among the thick placenta cohort compared to controls. The 106 liveborn neonates with thick placentas had lower Apgar scores, were delivered at an earlier gestational age, and weighed less than controls. Anomalies, hydrops fetalis and abruptio placentae complicated 16 of the 24 cases of perinatal mortalities. Sonographically thick placentas should alert the clinician to the possibility of compromised perinatal outcome.

Neonatal morphometry. Relation to obstetric, pediatric, and menstrual estimates of gestational age

OBJECTIVE

To determine gestational age-dependent neonatal morphometrics based on last menstrual periods (LMPs), Ballard examinations, and obstetric estimates of gestational age.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional survey of 38,818 live-born neonates at a tertiary care center in Detroit, Mich.

SELECTION PROCEDURES

Consecutive sample of all viable, structurally normal, singleton neonates delivered at Hutzel Hospital from 1984 through 1991.

MEASUREMENTS/MAIN RESULTS

Neonatal weights, lengths, and head circumferences were recorded at birth. Gestational age-dependent morphometrics were based solely on LMPs and compared with those based on obstetric estimates (using LMPs corrected by fetal ultrasound). Ballard examination had an 85.4% concurrence (within 14 days) with obstetric estimates of gestational age, but only a 69.9% (P less than .0001) agreement with LMP. Dating only by LMP significantly overestimated the prevalence of prematurity (odds ratio [OR], 1.3; 99% confidence interval [CI], 1.3 to 1.4) and postmaturity (OR, 5.0; 99% CI, 4.6 to 5.4), distorting apparent growth patterns, especially for preterm neonates. In contrast to previous studies based solely on LMPs, morphometric measurements increased beyond 40 weeks when dated by obstetric estimates.

CONCLUSIONS

Gestational age-dependent neonatal morphometrics should not be based solely on LMPs.

Biparietal diameter and femur length discrepancies: are maternal characteristics important?

We examined whether gestational age, maternal race or height can be used to explain discrepancies between biparietal diameter- and femur length-derived gestational ages by analyzing ultrasound scans from 8041 consecutively scanned, singleton pregnancies, using multiple regression analysis. While a consistent association was noted between differences of more than 3 weeks and less than 3 weeks and advancing gestational age, neither maternal height nor race were significantly related. We conclude that, first, discrepancies between gestational age by biparietal diameter and femur length are rare (5%) and, second, the presence of discrepancies should not be dismissed on the basis of maternal stature or race and should alert the clinician to possible abnormal fetal growth or development.

Ultrasound findings in gestations destined for unanticipated fetal demise

There are few reports of ultrasound findings in the second and third trimesters preceding intrauterine fetal demise. To describe these findings, the ultrasound assessments of 36 structurally normal singleton fetuses with subsequent intrauterine fetal demise were compared to gestational age-matched controls. Compared to controls, it was found that biparietal diameter, head circumference, femur length and estimated fetal weight were all decreased, abnormalities of amniotic fluid volume were more frequent, but the cephalic index was not different. Upon delivery, the group with subsequent intrauterine fetal demise was not found to have any major anomalies, but had a high incidence of abnormal umbilical cord position, abruptio placentae, chorioamnionitis and meconium aspiration.

The clinical utility of maternal body mass index in pregnancy

To describe maternal body mass index and to compare the use of maternal weight and body mass index for risk assessment at the initial prenatal visit, 6270 gravid women who were consecutively delivered of infants were studied. Body mass index increased with advancing maternal age, parity, and advancing gestational age and was significantly greater in black women than in nonblack women. Risks for the development of adverse outcome associated with maternal obesity, including development of gestational diabetes, preeclampsia, fetal macrosomia, and shoulder dystocia, were comparably predicted by either maternal weight or body mass index greater than 90th percentile. Maternal weight was as predictive of preeclampsia, macrosomia, and shoulder dystocia as was body mass index when these factors were analyzed as continuous variables, whereas increasing body mass index was more predictive of gestational diabetes. The prediction of factors associated with low maternal weights, small-for-gestational-age birth, prematurity, low birth weight, and perinatal death was equivalent for maternal weight and body mass index that was less than 10th percentile. This study indicates that in the initial risk assessment of outcomes related to maternal weight, the calculation of maternal body mass index offers no advantage over simply weighing the patient. This finding contrasts with results in nonpregnant women.

Cocaine abuse is associated with abruptio placentae and decreased birth weight, but not shorter labor

Many of our patients report having ingested cocaine hoping to decrease the duration of labor. We reviewed the computerized records of 592 women who abused cocaine. Compared with 4687 controls, women who ingested cocaine were older and had higher parity. Birth weight, birth weight percentile, and gestational age at delivery were significantly decreased among their neonates, and the incidence of abruptio placentae was nearly doubled among these women. Although these factors tend to shorten labor, the total duration of labor was not significantly different between the two groups. These data add to the accumulating evidence that cocaine abuse is associated with increased obstetric morbidity, but do not support the belief that cocaine shortens labor.

Maternal obesity: a potential source of error in sonographic prenatal diagnosis

Sonograms from 1622 consecutively scanned singleton pregnancies at a mean gestational age of 28.5 weeks were analyzed to determine whether maternal obesity affected visualization of fetal anatomy. Fetal head (cerebral ventricles), heart (four-chamber view), stomach, kidneys, bladder, diaphragm, intestines, spinal column, extremities, and umbilical cord were classified as visualized or suboptimally visualized. Maternal body mass index was used as a measure of relative leanness. No significant impairment of ultrasound visualization was noted until a body mass index above the 90th percentile, when visualization fell by an average of 14.5%. Reduction in visualization was most marked for the fetal heart, umbilical cord, and spine. Among non-obese women, advancing gestation and decreasing body mass index were the most important determinants of visualization. However, among obese women, body mass index was the best predictor of visualization, with no improvement seen with advancing gestation or duration of examination.

Correlation of commonly used measures of intrauterine growth with estimated neonatal body fat

Several morphometric measures have been used to identify infants at greatest risk from aberrant intrauterine growth. 119 near-term infants were studied to answer the more basic question of how well measures, such as birthweight percentile, ponderal index, the body mass index and the weight/length ratio reflect body fat in the neonate. Skinfold thicknesses were measured as an estimate of fat stores. Multiple regression analysis revealed that the weight/length ratio showed the strongest correlation with relative adiposity, explaining 52% of the variance. Further, sequential exponentiation of the crown-heel length in body mass index and ponderal index decreased the correlation with estimates of body fat. The simple weight/length ratio, exhibiting both a close correlation with body fat and independence of gestational age, race and sex, in near-term infants may be the best morphometric measure of the nutritional component of intrauterine growth in the neonate.

Increased neonatal urinary ammonia: a marker for in utero caloric deprivation?

The decline in the urinary urea to ammonia ratio represents a simple measure of nutritional status in the adult. We examined the relationship of this ratio to nutrient-related fetal growth retardation. Levels of ammonia and urea nitrogen were measured in the first voided urine and cord blood from 15 term infants exhibiting a wide range of growth. Analysis by multiple regression with neonatal ponderal index as the primary dependent variable revealed a significant correlation between lowered ponderal index and decreased urinary urea and ammonia. The correlation was primarily a function of increasing ammonia levels, with no relationship between fetal leanness and urinary urea. Comparable cord artery and vein ammonia suggest that placental ammoniagenesis was not a major determinant of observed elevations in urinary ammonia. Confirmation of the striking correlation between increased urinary ammonia and lowered neonatal ponderal index may afford a simple test for the identification of nutrient-related growth retardation.

Determinants of morbidity in obese women delivered by cesarean

Studies examining the increased surgical morbidity among obese gravidas have focused mainly on differences in outcome between obese and nonobese mothers. Little is known, however, about the cause for worsened operative outcome in obese mothers or the potential impact of perioperative interventions. To define more precisely the clinical determinants of postoperative morbidity, multivariate analysis was used to relate antepartum and intrapartum variables to three measures of morbidity in 107 consecutively delivered obese women undergoing cesarean. Although obesity is clearly an operative risk factor, this study suggested that among obese gravidas, varying degrees of maternal obesity and accompanying medical complications, such as diabetes and hypertension, were not associated with greater operative morbidity. Furthermore, neither choice of skin incision nor type of anesthesia appeared to be related to operative morbidity. However, two factors potentially under the control of the clinician, increased length of surgery and operative blood loss, were associated significantly with measures of operative morbidity. A finding of worsened outcome with prophylactic antibiotics and heparin requires further study.

Fetal hemorrhage from umbilical cord hemangioma

Hemangiomas of the umbilical cord are rare. In this case, an acute, massive fetal hemorrhage from a ruptured umbilical hemangioma occurred after spontaneous rupture of membranes. Ectopic small intestinal mucosa covered the proximal surface of the umbilical cord. Fetal anomalies included a patent vitellointestinal duct remnant and distal ileal atresia. Fetal hemorrhage appears to be another previously unreported and potentially life-threatening complication of umbilical hemangiomas.

Recurrent small for gestational age birth: perinatal risks and outcomes

The risk of recurrent small for gestational age birth, as well as maternal and fetal-neonatal characteristics associated with recurrence, was examined in 174 mothers of consecutively delivered small for gestational age infants followed through an additional 240 livebirths. There was a twofold and fourfold increase in the risk for small for gestational age birth after one and two small for gestational age births, respectively. Although an intervening average for gestational age birth decreased the risk of recurrence, these women remained at increased risk over the general population. Given the history of a previous small for gestational age birth, perinatal risks and outcomes considered individually would not improve the prediction of recurrence. However, the significantly higher frequency of these variables, considered as a group, among mothers with recurrent small for gestational age birth suggests an association with underlying maternal disease, for example, chronic hypertension, substance use and abuse, more severe fetal-neonatal compromise, and recurrent small for gestational age birth. Recurrent small for gestational age birth should initiate a search for persistent, underlying maternal disease.