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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.

Expectant management of prolonged pregnancy is predicated on reassuring biophysical testing. However, even the combination of a reactive nonstress test and normal amniotic fluid volume may not prevent subsequent morbidity. To test the hypothesis that diminished cord Wharton's jelly incurs risk of peripartum cord compression in addition to decreased amniotic fluid, 68 patients with confirmed gestational age greater than or equal to 41 weeks were evaluated prospectively with semiweekly nonstress tests and weekly ultrasound examinations. Amniotic fluid volume was assessed, and umbilical cord diameter was measured and then correlated with the quantity of Wharton's jelly at delivery, determined by cord circumference. A significant correlation between cord circumference and umbilical cord diameter was observed, even in those patients with decreased amniotic fluid volume. Either an amniotic fluid volume less than 3.8 cm or an umbilical cord diameter less than 1.6 cm was associated with significant cord compression patterns. Peripartum morbidity was greatest in the presence of a smaller cord and decreased fluid, suggesting a synergism between these two factors for the risk of cord compression in prolonged pregnancy.

Ten fetuses underwent ultrasound scanning at 7-10 weeks gestational (postmenstrual) age. In all cases, an echogenic mass measuring 0.5-1.0 cm was demonstrated within the base of the umbilical cord at its insertion into the fetal abdomen. No area with echogenicity characteristic of the small bowel was identified within the lower part of the fetal abdomen. All fetuses were reexamined 4-12 weeks later, at which time the mass in the umbilical cord was no longer seen, and normal fetal bowel was visualized in the lower abdominal cavity of the fetus. This sequence of findings appears to represent the sonographic demonstration of normal fetal bowel migration early in gestation and should not be confused with defects of the abdominal wall such as omphalocele or gastroschisis.

We report two cases in which the umbilical cords of fetuses were large on prenatal ultrasound scans. The pregnancies terminated uneventfully, however, and the babies were healthy at birth and on follow-up visits. We discuss the various etiologies of a large umbilical cord and conclude that, although a large cord may suggest the presence of an underlying abnormality, in some instances it may represent a normal finding.

Abdominal and obstetric applications of a dynamically focused phased array real time ultrasonic system are described. This work was performed utilising both the Thaumascan (two-dimensional, high resolution, actual time, ultrasound, multi-element array scanner) and the first commercial unit based on this system, the Grumman RT-400. Examples of normal and pathological anatomy are presented from over 300 examinations performed to date, including a series of 28 abdominal aortic aneurysms studied with the RT-400. Following electronic alterations in the Thaumascan with resultant improvement in the grey scale, prospective analyses in 86 obstetric and 23 abdominal examinations were undertaken. These studies indicate that fetal, intra-uterine, and abdominal structures can be rapidly and consistently imaged. The value of real time ultrasonic scanning in obstetric and abdominal examinations is illustrated. The principles of dynamically focused phased arrays are described, and the merits and limitations of these systems are discussed.