Faculty Bibliography

OBJECTIVES: To determine whether intertwin discordant abdominal circumference, femur length, head circumference, and estimated fetal weight sonographic measurements in early second-trimester monochorionic diamniotic twins predict adverse obstetric and neonatal outcomes. METHODS: We conducted a multicenter retrospective cohort study involving 9 regional perinatal centers in the United States. We examined the records of all monochorionic diamniotic twin pregnancies with two live fetuses at the 16- to 18-week sonographic examination who had serial follow-up sonography until delivery. The intertwin discordance in abdominal circumference, femur length, head circumference, and estimated fetal weight was calculated as the difference between the two fetuses, expressed as a percentage of the larger using the 16- to 18-week sonographic measurements. An adverse composite obstetric outcome was defined as the occurrence of 1 or more of the following in either fetus: intrauterine growth restriction, twin-twin transfusion syndrome, intrauterine fetal death, abnormal growth discordance (>/=20% difference), and very preterm birth at or before 28 weeks. An adverse composite neonatal outcome was defined as the occurrence of 1 or more of the following: respiratory distress syndrome, any stage of intraventricular hemorrhage, 5-minute Apgar score less than 7, necrotizing enterocolitis, culture-proven early-onset sepsis, and neonatal death. Receiver operating characteristic and logistic regression-with-generalized estimating equation analyses were constructed. RESULTS: Among the 177 monochorionic diamniotic twin pregnancies analyzed, intertwin abdominal circumference and estimated fetal weight discordances were only predictive of adverse composite obstetric outcomes (areas under the curve, 79% and 80%, respectively). Receiver operating characteristic curves showed that intertwin discordances in abdominal circumference, femur length, head circumference, and estimated fetal weight were not acceptable predictors of twin-twin transfusion syndrome or adverse neonatal outcomes. CONCLUSIONS: In our cohort, only second-trimester abdominal circumference and estimated fetal weight discordances in monochorionic diamniotic twin pregnancies were predictive of adverse composite obstetric outcomes. Twin-twin transfusion syndrome and adverse neonatal outcomes were not predicted by any of the intertwin discordances measured.

BACKGROUND: The incidence of cesarean scar pregnancy (CSP) is rising due to the increasing numbers of cesarean deliveries in the United States. However, little is known with respect to epidemiology, best screening methodologies, and treatment options. CASES: Three patients in their first trimester of pregnancy presented with a history of cesarean delivery and were diagnosed by pelvic ultrasound as having CSP. Methods of treatment included definitive surgery with hysterectomy or conservative management with methotrexate and lidocaine injection into the gestational sac. CONCLUSION: In patients with prior cesarean delivery, careful attention to all possible ultrasound signs of CSP during routine first trimester ultrasound is important for an early diagnosis, which can allow for various treatment options.

Ischemic placental disease is characterized by one or more of the clinical manifestations of preeclampsia, fetal growth restriction, and/or placental abruption, resulting in indicated preterm delivery. Since over half of the indicated preterm deliveries are due to ischemic placental disease, accurate early prediction of the disease is of paramount importance in developing prevention strategies. This review article focuses on studies that have used the first trimester aneuploidy screening timing window to predict those patients who later develop ischemic placental disease. Emphasis was given to studies originating from the Fetal Medicine Foundation because of their uniformity in definitions and expertise of the personnel who performed the ultrasound screening exams.

In medicine in general, and in obstetrics in particular, it is common practice to use arbitrary cutoffs in expressing continuous variables. However, the dichotomy of continuous data is associated with loss of statistical power, which may result in inaccurate estimates in clinical prognosis or prediction of outcomes and, consequently, may lead to incorrect inferences. If the predictor is a continuous variable, arbitrary percentile-based categorizations without clinical justification is an anathema (Greek word meaning "curse") and should be discouraged. Instead, the clinical outcome of interest should be defined first and then a receiver operating characteristic curve analysis or other appropriate statistical techniques should be employed to determine the most optimal cutoff of the predictor. The next step should be to validate the cutoff in a different population before introducing it to clinical use or interventional trials.

The traditional statistical analyses with adjustment for confounders in observational studies assume that there is perfect similarity in the already-provided medical management between the comparison groups. However, variations in medical management frequently exist because of differences in circumstances of health care. We propose that to minimize the selection bias of observational studies, the degree of similarity or dissimilarity of the comparison groups regarding the circumstances of health care should be considered. Circumstances of health care include the geographic setting, health care setting, type of health care providers, and likelihood in having confounding introduced by differences in the medical management between comparison groups. We propose a comparability scoring system of circumstances of care and provide examples of the application of this system, using recent literature to assess comparability among study groups. In our examples, the presupposed statistical associations disappeared once the analyses accounted for the differences in circumstances of care. Authors of submitted manuscripts using an observational study design may consider incorporating our scoring system or an equivalent in their methods and in reporting of the results. The comparability score should be factored during statistical analysis so that the appropriate analysis can correct for differences in circumstances of care. The use of a comparability scoring system can provide important insights for reviewers and readers that will improve the interpretation of this type of research study.