Ramon A. Castillo

The nonstress test as a diagnostic test: A critical reappraisal

In the past decade the nonstress test has become a major method of assessing high-risk pregnancy. Although many studies have been published, there has been a lack of rigorous adherence to the standard criteria for diagnostic testing, that is, presentation of test specificity, sensitivity, predictive value, and the prevalence of abnormal outcomes in the populations studied. Furthermore, the populations studied vary widely in composition, testing conditions, methods of test interpretation, and clinical management. The authors undertake a review of these studies, with a focus on these issues, in an attempt to indicate potential problems involved in current test usage and to suggest avenues for needed clinical investigation.

Nonimmune hydrops fetalis: Clinical experience and factors related to a poor outcome

Twenty-one cases of nonimmune hydrops fetalis diagnosed at the Medical College of Georgia during a 2-year period are presented. All fetuses satisfied strict diagnostic criteria and were evaluated according to a standard protocol. The corrected mortality rate was 95% with pulmonary hypoplasia being the most common cause of perinatal death. The mean gestational age at diagnosis was 24.8 weeks; in 57% of the cases the cause of nonimmune hydrops fetalis was identified. Fifteen fetuses had serial ultrasound assessment and in 19 cases postnatal evaluation was performed. Two factors that consistently conveyed a poor perinatal outcome were ultrasonographic evidence of malformation and/or the presence of persistent pleural effusions. A method for the quantification of fetal pleural effusions is presented and its clinical relevance is discussed.

Pleural effusions and pulmonary hypoplasia

Nine cases of fetuses with pleural effusions are presented in which the diagnosis was made by ultrasound before the thirtieth week of gestation. A ratio of lung span to hemithorax diameter was calculated and ranged from 0.44 to 0.77 (mean 0.60). At autopsy, pulmonary hypoplasia was confirmed in all cases by criteria based on the ratio of lung weight to total body weight. Because pleural effusions occurring in the midtrimester can be detected and may lead to pulmonary hypoplasia, consideration should be given to definitive in utero therapy when no other major fetal abnormality is detected.

Fetal biophysical activities in third-trimester pregnancies complicated by diabetes mellitus

OBJECTIVE Our purpose was to compare third-trimester fetal biophysical activities in normal and well-controlled insulin-dependent diabetic pregnancies. STUDY DESIGN We performed serial bimonthly fetal biophysical studies from 30 to 38 weeks in 18 normal and 18 well-controlled insulin-dependent diabetic pregnancies (White classes B through D). Each study contained 60 minutes of simultaneous ultrasonographic recordings of fetal breathing movements and rates, baseline heart rate, and body movements. Mean daily blood glucose levels of diabetic patients were determined from home monitors; HbA1c was determined every 6 weeks and ultrasonographic fetal growth rates every 3 weeks. Data were compared with t tests, analysis of variance with repeated measures, and chi 2 tests. RESULTS Women in the diabetic group maintained good glycemic control and were delivered of normal infants of weights similar to those of nondiabetic gravidas. Their fetuses had higher mean incidences of fetal breathing movement, fetal heart rates, and fetal breathing rates but lower fetal movements and fetal heart rate acceleration counts than did controls throughout the study. Neither short- nor long-term maternal glycemic levels correlated well with fetal biophysical performance. CONCLUSIONS In spite of good maternal glycemic control fetuses of diabetic women behaved differently from those of nondiabetic women. Modulation of their biophysical activities may be affected by maternal glycemic status before the last trimester. Different standards might need to be applied to interpret their tests.

Alcohol and reproductive function: a review.

This article reviews the effects of alcohol on male and female gonads and hormonal levels; it further discusses the use of ethanol during pregnancy and its teratogenic effect on the fetus. Impotence is a common result of acute alcoholism, and testicular atrophy, infertility, and decreased libido are associated with alcoholism 70-80% of the time. In addition, alcohol consumption produces significant spermatozoal morphological changes involving breakage of the sperm head, distention of the midsection, and curling of its tail. Seminiferous tubules are filled mostly with spermatids that undergo degeneration and result in aspermia. Acute ethanol intoxication is accompanied by decreased plasma testosterone levels and a surge of luteinizing hormone. Ethanol appears to have a dual effect: locally on the gonads and centrally on the hypothalamus-pituitary axis, causing an adverse effect on spermatogenesis. Less is known about the effects of alcohol on the female reproductive function; however, inhibition of ovulation and a significant reduction of plasma estradiol and progesterone levels has been noted in rats following ethanol administration. Alcohol consumption during pregnancy is the most frequent known teratogenic cause of mental retardation. Infants most severely affected by maternal alcohol abuse during gestation possess a number of dysmorphic anomalies termed fetal alcohol syndrome. The abnormalities most typically associated with alcohol teratogenicity can be grouped into 4 categories: growth deficiencies, central nervous system dysfunctions, craniofacial abnormalities, and other major and minor malformations. The effects of maternal alcohol consumption on the fetus are independent of maternal nutritional status and smoking history. Alcohol abuse during pregnancy occurs in 2-13% of US women, and these women have a 50-70% chance of delivering an infant with a serious abnormality.

Maternal dietary substrates and human fetal biophysical activity. I. The effects of tryptophan and glucose on fetal breathing movements

To study the effects of L-tryptophan and glucose on fetal breathing activity, we examined 40 women with normal term pregnancies, randomly assigned to four equal groups who either continued fasting (group C), received 1 gm of oral tryptophan (group T), received 100 gm of oral glucose (group G), or received both substrates (group T + G). Studies lasted 210 minutes, during which fetal breathing movements were observed with real-time ultrasonography and entered and analyzed for incidence, rate, and variability on a microcomputer. Plasma glucose and tryptophan levels were determined every 30 minutes. The incidence of fetal breathing movements declined in group C and rose significantly in the other groups. Breathing rates were unchanged in groups C and T but rose significantly in groups G and T + G during peak breathing intervals. Breath interval variability did not change significantly in any study group. Maternal administration of tryptophan is associated with an alteration in fetal breathing activity but to a lesser degree than that observed after maternal glucose loading.

Computer-assisted assessment of the fetal biophysical profile

The biophysical profile assesses fetal heart rate, breathing movements, fetal body movements, amniotic fluid volume, and fetal tone. In the past, these data have been scored by an arbitrary, unweighted system. While this approach is useful in detecting major anomalies and oligohydramnios, both static observations, the dynamic variables (fetal heart rate, fetal breathing movements, and fetal body movements) have added little information beyond that of an extended nonstress test alone. We have evaluated an alternative biophysical assessment system, modeled after extended physiologic studies, which not only acquires dynamic fetal variables simultaneously but, with computer assistance, quantifies the biophysical information. With an ADR 4000/L scanner, a Hewlett-Packard 8040 A monitor, and a specially programmed IBM microcomputer, we studied 100 normal term fetuses during 60-minute epochs. Each gestation had normal amniotic fluid volume and fetal tone. Normative values for the dynamic variables, expressed as means +/- SD were: fetal heart rate, 137 +/- 6.3 bpm; incidence of fetal breathing movements, 25.0% +/- 17.3%; rate of fetal breathing movements, 46.0 +/- 9.4 breaths/min; total fetal breathing movements, 823 +/- 61; incidence of fetal body movements, 8.5% +/- 3.9%; accelerations (greater than 15 bpm, 15 seconds), 14.1 +/- 6.3. We conclude that this approach is practicable, respects the biologic cycles of fetal behavior, and provides a basis for population standards and sequential study of the same fetus.

Sequential nonstress testing with use of each fetus as its own control

The sequential nonstress tests of 126 high-risk fetuses were assessed for baseline fetal heart rate, acceleration frequency, amplitude, and duration and the observance of fetal heart rate decelerations. In 108 fetuses (563 tests) with normal perinatal outcomes, no significant trends in these parameters were found. In 18 fetuses (104 tests) with perinatal compromise, 16 had significantly declining acceleration frequencies, 15 had decreasing acceleration duration, four had rising mean baseline rates, and seven, in their last test before delivery, had repetitive late or severe variable decelerations. The last tests of 11 of these 18 fetuses met institutional criteria for reactivity. When the nonstress tests of compromised fetuses were viewed sequentially, acceleration frequency declined by an average of 59% and acceleration duration by an average of 40%. Sequential assessment of the nonstress test, when compared with the use of standard reactivity criteria, improved test sensitivity from 39% to 89% and negative predictive value from 91% to 98%. We conclude that sequential nonstress test assessment in individual fetuses may improve the diagnostic value of this modality and lead to earlier recognition of fetal compromise.

The effects of vibroacoustic stimulation on baseline heart rate, breathing activity, and body movements of normal term fetuses

To determine the fetal biophysical effects of vibroacoustic stimulation produced by an electronic artificial larynx we studied 20 normal term pregnancies assigned either to control (no stimulus) or experimental (stimulus) groups. Each fetus was observed for 3 hours; either no stimulus or a 3-second stimulus was delivered after the first hour. Fetal heart rate baseline and variation, breathing movement incidence, rate, and variation, and body movement incidence data were acquired concurrently and analyzed at 15-minute intervals. Intergroup comparisons showed that, after stimulation, fetal heart rate baseline and variation increased significantly, whereas breathing incidence fell during the first 15 minutes. Within-group analyses showed that poststimulus elevation of fetal heart rate baseline was the only significant time interaction over the 3 hours. Vibroacoustic stimulation appears to be primarily associated with transient alterations in fetal heart rate baseline; concomitant changes in breathing activity probably reflect normal biologic cycles.

FOETOS in clinical practice: A retrospective analysis of its performance

Abstract The results of the first validation of the prototype expert system FOETOS are presented. FOETOS is designed to assist the obstetrician in the diagnosis of antepartum and intrapartum foetal well-being. To evaluate the performance of this system, 20 delivered patients were selected for retrospective analysis. All patients underwent three antenatal tests (hon-stress test, foetal biophysical profile, and contraction stress test), and their labor data were available. The validation tool utilized was the man-machine performance method. While our results are encouraging, certain aspects of the system require modification to accommodate it to a real clinical environment. With such modifications FOETOS could be developed into a useful tool for the assessment of high risk pregnancies.