Faculty Bibliography

OBJECTIVE: To determine the sensitivity of using a complete anatomic sonographic survey in detecting fetal abnormalities via correlation with perinatal autopsy results. METHODS: All perinatal autopsies (1994-2001) with positive findings for at least 1 fetal abnormality and performed by a single perinatal pathologist at our institution were retrospectively reviewed. From these cases, singleton fetuses who received prenatal sonography solely in our unit were identified. The sensitivity of sonography in detecting anomalous fetuses as well as fetal abnormalities and abnormalities by organ system was determined. Abnormalities were classified as major or minor In addition, findings from sonography and autopsy were compared, and their correlation was assigned to 1 of 3 categories. RESULTS: Of 88 fetuses identified, 85 had 1 or more abnormal structural sonographic findings (sensitivity for fetuses with anomalies, 97%). A total of 372 separate abnormalities were found on autopsy; of the 299 major and 73 minor abnormalities, prenatal sonography showed 224 (75%) and 13 (18%), respectively. There was either complete agreement or only minor differences between sonographic and autopsy findings in 57 (65%) of 88. The sensitivity of sonography in identifying abnormalities was greater than 70% in these systems: central nervous system, cardiac system, urinary system, extremities, genitalia, ribs, and hydrops. CONCLUSIONS: In experienced hands, sonography has 97% sensitivity in detecting anomalous fetuses when compared with perinatal autopsy results. Although the sensitivity of sonography in detecting major fetal abnormalities is 75%, the sensitivity for minor abnormalities is poor, even when using a complete anatomic sonographic survey. Although it has limitations, this type of survey is invaluable for both patients and physicians in diagnosing fetal abnormalities

OBJECTIVE:To determine whether the decision of the general obstetrician-gynecologist to refer high-risk obstetric patients depends on the type of practice of the maternal-fetal medicine (MFM) specialist. METHODS:A questionnaire was mailed to 935 general obstetrician-gynecologists who were asked whether the MFM specialist's practice characteristics would influence their decision to refer their high-risk obstetric patients. Potential MFM practice components presented in the survey included: MFM, high-risk obstetrics, low-risk obstetrics or general obstetrics and gynecology. RESULTS:A total of 140 (15%) general obstetrician-gynecologists responded, 110 of whom were practicing obstetrics. Of the practicing responders, 77% stated that they were more likely to refer their high-risk obstetric patients if the MFM specialist practiced only MFM and high-risk obstetrics; 69% were less likely to refer their patients when the MFM specialist, in addition to MFM, practiced general obstetrics; and 75% were less likely to refer their patients when the MFM specialist also practiced general obstetrics and gynecology. The MFM practice setting (university vs. community hospital vs. private practice), as well as the geographic location and years of practice of the respondents, did not influence the general obstetrician-gynecologists' decision to refer their high-risk obstetric patients. CONCLUSION/CONCLUSIONS:General obstetrician-gynecologists are more likely to refer high-risk obstetric patients if the MFM specialist practiced only MFM and high-risk obstetrics.

The authors performed a population-based epidemiologic study to evaluate and contrast risk factor profiles for placental abruption among singleton and twin gestations. Data were derived from linked US birth/infant death files for 1995 and 1996, comprising 7,465,858 singleton births and 193,266 twin births. The authors also evaluated effect modification between smoking and hypertension and the effect of a dose-response relation with number of cigarettes smoked daily on abruption risk. Abruption was recorded in 5.9 per 1,000 singleton births and 12.2 per 1,000 twin births. Risk factors for abruption among singleton and twin births, respectively, included preterm premature rupture of membranes (adjusted relative risks (RRs) = 4.89 and 2.01), eclampsia (RRs = 3.58 and 1.67), anemia (RRs = 2.23 and 2.33), hydramnios (RRs = 2.04 and 1.66), renal disorders (RRs = 1.54 and 2.56), and intrapartum fever (>100 degrees F) (RRs = 1.17 and 1.69). Chronic hypertension (RR = 2.38) and pregnancy-induced hypertension (RR = 2.34) were risk factors for abruption in singleton births but not in twin births. Number of cigarettes smoked daily demonstrated a dose-response trend for abruption risk in singletons and twins. Abruption was more likely to occur among smokers with chronic hypertension (RRs = 4.66 and 3.15) and eclampsia (RRs = 6.28 and 5.08). The authors conclude that abruption is twice as likely to occur in twins as in singletons with differing risk factor profiles. This suggests that abruption in twins may result from different pathophysiologic processes.

Uterine rupture can occur at any time throughout gestation. We present a woman with a previous Cesarean section followed by an abdominal pregnancy. In her next pregnancy, complete uterine rupture resulted in an emergency laparotomy. This case is unique in that it gives insight into the variable presentations of uterine rupture and the risks associated with prior Cesarean sections.

OBJECTIVE:To compare the genetic risk assessment of the referring obstetrician to the risk assessment of the genetic counselor. STUDY DESIGN/METHODS:All patients evaluated between January 1, 1999, and March 31, 1999, and who required genetic counseling were retrospectively reviewed. The genetic risk assessment of the referring obstetrician was compared to the genetic risk assessment following counseling by a genetic counselor who used a questionnaire and a three-generation pedigree. The number of patients with additional genetic risk factors identified by the genetic counselor were recorded and compared by using the McNemar chi-square test. Group demographics and characteristics were evaluated. RESULTS:Among the 145 patients evaluated, 38% (n = 55) had additional genetic risk factors detected by the genetic counselor (P =.01). The maternal demographics and characteristics did not differ between the two groups. CONCLUSION/CONCLUSIONS:The practice of referring high-risk obstetric patients for genetic counseling improves the detection of identifiable genetic risk factors.

OBJECTIVE:To compare the frequency of visualization of echogenic intracardiac foci in different cardiac views. METHODS:Women having ultrasonographic examinations between October 1997 and July 1998 were prospectively evaluated if a fetal echogenic intracardiac focus was seen in either ventricle. RESULTS:Echogenic intracardiac foci were seen in 89 fetuses in whom both the apical and lateral 4-chamber heart views were obtained. Eight-six fetuses (97%) had a single focus (83 in the left ventricle and 3 in the right ventricle), and 3 (3%) had 2 foci. Echogenic intracardiac foci were seen in the apical 4-chamber view in 89 (100%) and in the lateral 4-chamber view in only 26 (29%; P = .001). CONCLUSIONS:Echogenic intracardiac foci are not easily seen in the lateral 4-chamber view. Studies that suggest an increased risk of aneuploidy when echogenic foci are seen should specify the orientation of the 4-chamber view used.

OBJECTIVE:To describe gestational age-dependent and -independent nomograms for fetal thyroid size. METHODS:Two hundred fetuses were evaluated between 16 and 37 weeks' gestation in this cross-sectional study. RESULTS:Nomograms of fetal thyroid size were created by using the 5th, 10th, 50th, 90th, and 95th percentiles based on biparietal diameter and gestational age. A second-order polynomial fit for biparietal diameter and a linear fit for gestational age best described thyroid circumference measurements. Variations in thyroid circumference measurements increased with both larger biparietal diameter and advancing gestational age. There was no intraobserver or interobserver variability in thyroid circumference measurements (P > .20). CONCLUSIONS:Both biparietal diameter and gestational age serve as good predictors of fetal thyroid circumference. When the biparietal diameter is difficult to measure, gestational age can be used to assess thyroid size.

OBJECTIVE:To examine the independent contributions of prematurity and fetal growth restriction to low birth weight among women with placenta previa. METHODS:A population-based, retrospective cohort study of singleton live births in New Jersey (1989-93) was performed. Mother-infant pairs (n = 544,734) were identified from linked birth certificate and maternal and infant hospital discharge summary data. Women diagnosed with previa were included only if they were delivered by cesarean. Fetal growth, defined as gestational age-specific observed-to-expected mean birth weight, and preterm delivery (before 37 completed weeks) were examined in relation to previa. Severe and moderate categories of fetal smallness and large for gestational age were defined as observed-to-expected birth weight ratios below 0.75, 0.75-0.85, and over 1.15, respectively, all of which were compared with appropriately grown infants (observed-to-expected birth weight ratio 0.86-1.15). RESULTS:Placenta previa was recorded in 5.0 per 1000 pregnancies (n = 2744). After controlling for maternal age, education, parity, smoking, alcohol and illicit drug use, adequacy of prenatal care, maternal race, as well as obstetric complications, previa was associated with severe (odds ratio [OR] 1.37, 95% confidence interval [CI] 1.25, 1.50) and moderate fetal smallness (OR 1.24, 95% CI 1.17, 1.32) births. Preterm delivery was also more common among women with previa. Adjusted OR of delivery between 20-23 weeks was 1.81 (95% CI 1.24, 2.63), and 2.90 (95% CI 2.46, 3.42) for delivery between 24-27 weeks. OR for delivery by each week between 28 and 36 weeks ranged between 2.7 and 4.0. Approximately 12% of preterm delivery and 3.7% of growth restriction were attributable to placenta previa. CONCLUSION/CONCLUSIONS:The association between low birth weight and placenta previa is chiefly due to preterm delivery and to a lesser extent with fetal growth restriction. The risk of fetal smallness is increased slightly among women with previa, but this association may be of little clinical significance.

OBJECTIVE:The purpose of this study was to determine how frequently general obstetricians refer pregnant patients to maternal-fetal medicine specialists in the presence of the clinical indications specified as appropriate for referral or consultation by the 1996 statement of the Society of Perinatal Obstetricians. STUDY DESIGN/METHODS:A questionnaire was mailed to 400 randomly selected general obstetricians across the United States. The obstetricians were asked how often they refer their high-risk pregnant patients to maternal-fetal medicine specialists in the presence of (1) a need for diagnostic or therapeutic procedures, (2) medical/surgical disorders, (3) healthy gravid women with high-risk fetuses, and (4) conditions that necessitate admission for reasons other than delivery. Response categories for each individual procedure/high-risk condition included "always," "frequently," "infrequently," "never," and "not applicable." RESULTS:Overall, 55% of the responses indicated referral (always or frequently) to maternal-fetal medicine specialists for procedures or in the presence of high-risk conditions. More than 75% of the obstetricians always or frequently refer to maternal-fetal medicine specialists for most diagnostic/therapeutic procedures and for the following high-risk conditions: acute fatty liver, portal hypertension, pulmonary hypertension, transplantations, fetal hydrops, fetal anomaly/cytogenetic abnormality, fetal supraventricular tachycardia or congenital heart block, isoimmunization, and twin-to-twin transfusion syndrome. CONCLUSION/CONCLUSIONS:Most of the conditions for which >75% of the obstetricians refer to maternal-fetal medicine are rarely seen in practice. Comprehensive ultrasound examination is the only commonly encountered clinical situation that >75% of the general obstetricians refer to maternal-fetal medicine specialists.