Lawrence Chik

Clinical application of high-risk scoring on an obstetric service

Obstetric risk scoring is a formalized way of recognizing, documenting, and cumulating antepartum and intrapartum factors to predict later complications for mother, fetus, and infant. If simple, practical, and reliable, risk scoring can be clinically useful in determining appropriate levels of care. In this prospective study, antepartum and intrapartum risk scales were integrated into the clinical record, and the relationship of risk scores to outcome was evaluated for 1,275 consecutively delivered gravid women. The forms could be simply and quickly filled out by the staff. Increased risk on both scales was significantly related to lowered one- and five-minute Apgar scores. The perinatal mortality rate increased from 0 to 93.4 per thousand from the lowest to the highest risk group. More than 80% of all perinatal deaths occurred in the one quarter of patients in the highest risk group. These results suggest that this risk scoring system can be used effectively in a clinical setting to identify patients at increased risk for neonatal depression and perinatal death.

Clinical estimation of gestational age: rules for avoiding preterm delivery.

Reliable knowledge of the duration of pregnancy prior to birth is often of crucial importance in making obstetric care decisions. Laboratory methods for estimating fetal maturity have received considerable attention, but the usefulness of historical information has only rarely been addressed. In order to examine the value of clinical estimators of fetal gestational age (GA) in 690 pregnancies, the correlations of menstrual history (LMP), first unamplified audible fetal heart tones (FFH), and quickening (Q), with GA, based on the modified Dubowitz examination at birth, were examined. Evaluation of each of the data sets used alone reveals that in order to be 90% certain that an infant will be mature at delivery (greater than or equal to 38 weeks), a reliable LMP must have been noted for 42 weeks prior to birth, the FFH heard for 21 weeks, and Q felt for 25 weeks. These findings suggest that carefully obtained historical and physical examination information remains a cornerstone of appropriate obstetric care.

Regular and irregular human fetal respiratory movement

Fetal respiratory movements (FRM) were studied using abdominal strain gauges (tocodynamometers). The patterns of the FRM were evaluated during both active and quiet fetal time periods, which were determined by the fetal heart rate (FHR) and fetal body movement (FM). The FRM were classified into Regular and Irregular patterns based on neonatal respiratory criteria for sleep-state studies in the term infant. Evaluation of the breath-to-breath intervals (BBI) showed statistically significant respiratory differences during active and quiet fetal time periods. Irregular fetal respiratory movement patterns were noted during fetal active periods. It would appear that the correlation of regular fetal respiratory movement with fetal quiet periods in the term fetus adds additional evidence that a quiet sleep state may exist in the term fetus.

The effect of delivery route on outcome in breech presentation.

This study was undertaken to determine the effect of choice of birth route on infant outcome in fetal breech presentation. The study group excluded infants who were footling breeches and infants with major congenital anomalies. The mothers were in labor with the fetal heartbeat present at entry into the labor room. Outcome variables were intrapartum and neonatal deaths and neonatal neurological morbidity. Delivery route was not significantly associated with neonatal death in the 500 to 999 gm (p = 0.43) and 1,000 to 2,499 gm (p = 0.43) categories. Over 2,500 gm, there were no neonatal deaths. In similar manner, delivery route was not significantly associated with neonatal neurological morbidity. In both neonatal death and morbidity, birth weight and modified Dubowitz score explained the largest proportion of the variance for outcome in breech presentation.

An approach to the study of brain damage: The principles of fetal electroencephalography☆

Abstract Fetal electroencephalography (EEG) is technically feasible and has been accomplished in more than 300 monitored fetuses. The electrical alterations found are identifiable both in individual fetuses and between different fetuses. These patterns and changes can be differentiated from pre-existing patterns and associated with certain fetal cardiovascular heart rate changes. The preliminary follow-up findings on a small group of infants followed until one year of life are presented. The information presented here should be used as guidelines for the introduction of this technique rather than answers to the problems of clinical monitoring during birth and the relationship of that monitoring to brain damage.

Human fetal brain response to sound during labor.

Abstract The human fetal auditory evoked response (AER) to a sound stimulus is obtained early in labor and serially studied throughout childbirth. Considerable intersubject variation exists. The fetal AER latency interval is similar to that obtained in the neonate and is in the range of 200 to 500 msec. with an average amplitude of 10 μV. The response is confirmed in the neonate and has a similar latency interval but an increased amplitude of response when compared to the same fetus in utero.

What affects fetal pulmonary maturation during diabetic pregnancy

Previous studies differ as to whether the fetus of the woman with diabetes mellitus has altered formation of lung surfactant. The factors responsible for these differences remain unclear. In this study, measures of blood glucose control, including birth weight percentile and the presence of factors potentially influencing fetal pulmonary maturation, such as diabetic class, maternal chronic hypertension, and preeclampsia, were compared with the amniotic fluid lecithin/sphingomyelin ratio, phosphatidylglycerol, and phosphatidylinositol within a group of 90 diabetic pregnancies. The factors were evaluated in combination with the techniques of canonical correlation and multiple regression analysis. Gestational age had the strongest effect in determining levels of amniotic fluid phospholipids, and hypertension was found to significantly accelerate the appearance of phosphatidylgycerol (p less than 0.05). The effect of hypertension was one third as important as that of gestational age. Neither diabetic blood glucose control, White classification, nor the remaining explanatory variables were found to play a significant role in determining the amniotic fluid phospholipid levels. This study suggests that, in the clinical management of diabetes, gestational duration remains the single most important determinant of amniotic fluid phospholipid levels.

Programmed identification of fetal heart rate deceleration patterns

Abstract Fetal heart rate (FHR) deceleration patterns had been characterized with histograms of the lag times, cross-correlation coefficients (with respect to intrauterine pressure [IUP]), and the spectral moments between onset time and recovery time. These parameters were used for computer-assisted interpretation of 505 FHR deceleration patterns from 20 patient files which had previously been interpreted visually. Within this sample of 505 patterns, up to 91 per cent were identified consistently, depending on the lag time criterion used in the decision logic. On a patient-to-patient basis, for the 20 patients studied, the outcomes approximated 85 per cent in consistency.

The association between cesarean birth and outcome in vertex presentation: Relative importance of birth weight, Dubowitz scores, and delivery route

The effect of the obstetricians choice for delivery route on infant outcomes was studied in 17,260 mothers in labor, with the fetus alive at the onset of labor, in vertex presentation, and without major congenital anomalies. At birth weight categories, stratified by 500 gm increments, there was no improvement in intrapartum and neonatal mortality or in neonatal morbidity associated with the cesarean birth route. The major dependent variables important in neonatal outcome were birth weight and neonatal maturity. The association between cesarean section delivery and outcome in vertex presentations is limited. This information documents the need for prospective randomized and controlled studies with respect to proposed changes in birth route for the very low-birth weight fetus.

Temporal characterization of intrauterine pressure data

Abstract The development of an algorithm for the identification and characterization of uterine contractions (UC), which yields results consistent with clinical visual interpretation of intrauterine pressure (IUP) curves, has been complicated by the presence of artifacts and variations in the base line and shapes of intrauterine pressure. In order to meet these problems, real time programmed analysis of intrauterine pressure data is accomplished by an algorithm which first smooths the data and then determines temporal characteristics of uterine contractions, including onset time, peak time, and end time, ulitizing elementary methods of calculus. The interval between contractions is also defined. Results from 94 intrauterine pressure data files, each 512 seconds in length, are presented. Atypical intrauterine pressure records which complicate algorithmic characterization are illustrated.