Faculty Bibliography

The present study of 466 consecutive liveborn preterm singleton deliveries included 238 cases of spontaneous preterm labor and delivery, 175 cases with premature rupture of membranes, 13 cases of nonhypertensive abruption, 18 cases of preeclampsia, and 22 cases of placenta previa. Placental infarction, chronic villitis, and decidual pathologic processes showed different associations with fetal growth, depending on the clinical circumstances. Placental infarction was associated with decreased growth in all groups except placenta previa; in cases of placenta previa, placental infarction was associated with heavier infants. Chronic villitis was related to decreased growth in spontaneous rupture of membranes and preterm labor cases but was related to increased growth in cases of preeclampsia

Placental examination was carried out in 128 consecutive cases of idiopathic intrauterine growth retardation (IUGR) at term and the findings were compared with those of 179 gestational age-matched cases with normal growth. Mean pregnancy weight and mean maternal weight gain during pregnancy of IUGR cases were both significantly lower than for non-IUGR cases. There was a higher frequency of a history of previous growth-retarded infants between IUGR cases (18 of 128, or 14%) compared with non-IUGR cases (7 of 179, or 3.9%). The studied placental lesions were placental infarction, chronic villitis, hemorrhagic endovasculitis, and placental vascular thromboses. One or more of these lesions were present in 71 of 128 (55%) of IUGR cases, and 58/179 (32%) of non-IUGR cases. Thirty-eight of 72 (53%) cases with chronic villitis were IUGR (30% of all IUGR cases). Thirty-one of 49 cases (63%) with placental infarction were IUGR cases (24% of all IUGR cases). Nineteen of 32 cases (59%) with hemorrhagic endovasculitis were IUGR cases (15% of all IUGR cases). Twelve of 17 cases (71% with placental vascular thromboses were IUGR (9% of all IUGR cases). Relationships of all placental lesions to IUGR were independent of each other. IUGR infants more frequently had multiple types of lesions in their placentas. Chronic villitis and hemorrhagic endovasculitis tended to occur in the same placentas. There were no significant relationships between maternal characteristics and placental lesions, except for an association between low pregravid weight and increased incidence of placental infarction. Decreased birth length was associated only with placental infarction (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

A recent report by FitzSimmons et al. demonstrated a greater frequency of upper- versus lower-extremity shortening in autopsies of second-trimester fetuses with trisomy 21. We undertook this study to determine whether this upper-limb shortening could be detected by prenatal ultrasonography in the second trimester and therefore identify fetuses at risk for trisomy 21. A retrospective review of all prenatal sonograms preceding genetic amniocentesis was conducted. Between 1987 and 1990 11 consecutive fetuses between 15 and 22 weeks' gestation with trisomy 21 were identified by genetic amniocentesis. Femur and humerus lengths were plotted on growth curves created from 1470 normal patients between 12 and 26 weeks. Gestational age was confirmed by last menstrual period and biparietal diameter. In fetuses with trisomy 21, seven of 11 humeri were less than 5th percentile, for a sensitivity of 64%, whereas only two of 11 femurs were less than 5th percentile, for a sensitivity of 18%. Biparietal diameter/femur length and biparietal diameter/humerus length ratios were also tested to predict Down syndrome. In only 2 of 11 cases was the biparietal diameter/femur length ratio greater than 95th percentile, whereas the biparietal diameter/humerus length ratio was greater than 95th percentile in 7 of 11. Since all seven were identified by shortened humerus alone, we conclude that humerus length versus gestational age is the simplest and most effective screen. The positive predictive value of an abnormally short humerus length in detecting Down syndrome was 6.8% in our population where the prevalence of Down syndrome was 1 of 173. The present study supports the observations of FitzSimmons et al. that shortened humerus length has a greater sensitivity than femur length in cases of trisomy 21. We conclude that in fetuses at risk for trisomy 21 humerus length should be determined, because it may, if shortened, aid in the prenatal diagnosis.

The relationship between peak-systolic/end-diastolic ratio of the umbilical artery waveform and fetal biometry was studied in 127 uncomplicated pregnancies with established dates between 20 and 40 weeks' gestation. At each ultrasonographic examination fetal biometry included measurement of the biparietal diameter, head circumference, abdominal circumference, and femur length. The peak-systolic/end-diastolic ratio was measured by either a continuous or a pulsed-wave method. There were significant linear negative correlations between all the biometric parameters, as well as between the ultrasonographically estimated fetal weight and peak-systolic/end-diastolic ratio. Of the individual ultrasonographic parameters the femur length (for gestations less than 30 weeks) and the abdominal circumference (for gestations greater than or equal to 30 weeks) were found to be best correlated with the peak-systolic/end-diastolic ratio. Regression curves, including the 10th and the 90th percentile, were developed between each biometric parameter (biparietal diameter, head circumference, abdominal circumference, and femur length), as well as between estimated fetal weight and peak-systolic/end-diastolic ratio. The estimated fetal weight nomogram had the best sensitivity (48%) in predicting intrauterine growth retardation. These nomograms should prove most useful in assessing downstream placental vascular resistance in high-risk patients with unknown dates.

In a prospective study of 62 patients undergoing cesarean delivery before the onset of labor, fetal biophysical assessment and umbilical artery systolic-diastolic ratios (S/Ds) were performed within 3 hours of delivery. There was a significant relationship between the fetal biophysical profile score and cord arterial as well as cord venous pH. However, there was no identifiable relationship between S/D and cord arterial or venous pH. The efficacies of the biophysical components alone (nonstress test [NST] and fetal biophysical profile) and in combination with S/D to predict fetal acidosis were determined. The NST had the best sensitivity (100%) and negative predictive value (100%). The fetal biophysical profile had the best specificity (91%), positive predictive value (62%), and overall efficiency (90%). The S/D had the lowest sensitivity (66%), specificity (42%), positive predictive value (16%), negative predictive value (88%), and overall efficiency (45%). The addition of S/D to the NST or fetal biophysical profile did not improve diagnostic accuracy. These data suggest that the NST should be used as a primary test for the antepartum detection of fetal acidosis, whereas the fetal biophysical profile is a reasonable adjunct test. The umbilical artery S/D, as determined by continuous-wave Doppler velocimetry, has no value as a primary method or an adjunct in the antepartum detection of fetal acidosis.

Previous studies have presented conflicting evidence on the association between intrauterine growth retardation (IUGR) and placenta previa, with some groups reporting rates of IUGR as high as 16-19%. However, most of these studies failed to include a control population, included patients with other factors known to be associated with IUGR (eg, chronic hypertension, fetal anomalies, pregnancy-induced hypertension, insulin-dependent diabetes mellitus, etc), and/or did not confirm the patient's estimated gestational age. During the study period of January 1, 1980 through June 30, 1990, 54,969 deliveries occurred at the three affiliated hospitals of the Maternal-Fetal Medicine Division of the University of Connecticut Health Center. Review of the delivery records revealed 179 singleton pregnancies with documented placenta previa and without the above exclusion factors. One hundred seventy-one of these 179 study patients were compared with 171 women without placenta previa matched for confirmed gestational age, race, parity, and fetal sex. The incidence of small for gestational age (SGA) infants was 4.1% (seven of 171) in the study group and 5.8% (ten of 171) in the control group. Mean birth weights were 2559 and 2476 g, respectively. Neither difference was statistically significant. These results suggest that the prenatal diagnosis of an SGA fetus in a pregnancy complicated by placenta previa should not simply be attributed to abnormal placental implantation. Furthermore, routine ultrasonic examinations for growth in pregnancies complicated by placenta previa are not indicated.

In a prospective study of 162 patients, measurements of the transverse cerebellar diameter (TCD) and abdominal circumference (AC) were obtained between 15-38 weeks' gestation. A ratio between the TCD and AC was calculated after each examination. This ratio remained constant during gestation. The mean ratio was 13.7% (fifth and 95th percentiles of 11.9 and 15.9%, respectively); the median ratio was 13.6%. Forty-two patients had repeat measurements and the ratio did not change. This ratio is gestational age-independent; however, further investigation is needed to determine its application in the assessment of fetal growth abnormalities.