Biomedical subjects
Publications and source records attributed to W J Ott.
A detailed description of the development of a computer-based ultrasound data system is presented to provide the background for those physicians interested in developing or using such a system. The system was found to be highly useful for acquisition and organization of ultrasound data, and proved to be an aid both teaching and patient care.
The accuracy of eight ultrasonic fetal weight formulas were analyzed in 1099 fetuses who underwent real-time ultrasound examination within 72 hours prior to delivery. Shepard's formula was most consistently found to give the lowest systematic and random errors throughout all weight categories, though Deter's formula had an almost identical accuracy. The Shepard formula was further analyzed in respect to the effects of fetal sex and birthweight centile grouping on the accuracy of fetal weight estimation. The results indicated that fetal sex had no effect on the accuracy of fetal weight estimation, but that birthweight centile grouping did. The weights of small-for-gestational age infants were systematically overestimated, while the weights of large-for-gestational age infants were systematically underestimated.
Early ultrasonic diagnosis of intrauterine growth retardation (IUGR) can be very beneficial. However, most methods of ultrasonic diagnosis require an accurate knowledge of gestational age. The current study was designed to prospectively evaluate the relationship between fetal femur length and neonatal crown-heel length, and to study the femur length/abdominal circumference ratio as a method of screening for IUGR. Three hundred twenty-six infants who had undergone real-time ultrasound examination within 72 hours before birth were used for the study. Fetal femur length was compared with neonatal crown-heel length, although the most accurate relationship was geometric (r2 = .7474), and a strong linear relationship was also observed: y(crown-heel length) = 11.887 + 5.158 X (femur length), (r2 = .7067; SD = 3.34 cm). Mean femur length/abdominal circumference ratios were significantly different for average-for-gestational-age (22.33 +/- 1.86%), small-for-gestational-age (23.34 +/- 1.89%), and large-for-gestational-age (20.99 +/- 1.32%) infants, but did not reveal a discriminatory value for the diagnosis of IUGR as positive as that reported by Hadlock et al. The femur length/abdominal circumference ratio should be evaluated further as a screening tool in the diagnosis of IUGR.
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Gestational age by four ultrasonic parameters (biparietal diameter, head circumference, abdominal circumference, and femur length) was calculated for 210 normal obstetric patients divided into four gestational age groups based on time of first ultrasound examination. Accuracy of the calculations was determined by comparison of each technique and a simple arithmetic average of the four techniques to the gestational age calculated from the Dubowitz examination of the neonate after delivery. The analysis indicated that each ultrasonic technique has certain advantages and disadvantages, but that the simple arithmetic average of the four techniques had the lowest systematic and random error.
An ultrasonic fetal head circumference curve was developed from a group of 1278 ultrasound examinations in 710 normal obstetrical patients. These data were then used to compare the accuracy of head circumference (HC) to last menstrual period (LMP) and biparietal diameter (BPD) for the prediction of an accurate expected date of confinement (EDC) and, thereby calculate gestational age. The mean error of the signed differences (+/- standard deviation) for HC was -0.8 +/- 11.1 days, which was statistically different from the mean error of -6.1 +/- 10.6 days for BPD and -2.8 +/- 17.8 days for LMP. HC may have an advantage over BPD in situations where head shape (cephalic index) is significantly altered.
One hundred fifty-three of 1,289 patients (11.9%) monitored during labor were identified as having exaggerated fetal heart rate accelerations (EFHRAs), defined as accelerations of the fetal heart rate above the baseline of 30 beats/min or greater and lasting at least 30 seconds. Comparisons of patients with and without EFHRAs showed that the only difference between the two groups was a higher percentage of nulliparous patients in the EFHRA group. Comparisons of intrapartum complications showed a decreased incidence of meconium staining and an increased percentage of abnormal labor patterns in the EFHRA group. Comparisons of neonatal outcome statistics showed lower perinatal morbidity and higher mean birth weight in the EFHRA group.
A previously developed normal ultrasonic fetal weight curve was used for antenatal diagnosis of altered fetal growth in 595 patients who had undergone real-time ultrasound examination within 72 hours before birth. Fetal weight was estimated using biparietal diameter and abdominal circumference and plotted on the normal curve. The diagnosis of small for gestational age (SGA) or large for gestational age (LGA) was based on whether the ultrasonic weight fell below or above the normal limits. After delivery, infants were classified as SGA, LGA, or average for gestational age (AGA) by birth weight, and the postnatal diagnosis was compared to the antenatal ultrasound diagnosis. The sensitivity of the technique for the diagnosis of SGA infants was 89.9%; for LGA it was 73.5%. The overall specificity of the technique was 79.8%.
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Results of 686 nonstress tests with fetal monitoring were analyzed and compared to neonatal outcome. The use of an antepartum cardiotachometry screening (ACS) protocol seems to have reduced the perinatal mortality and morbidity in a high-risk group of patients to that of a low-risk group who did not undergo ACS.
The weights of 101 neonates delivered within 72 hours of real-time ultrasound examination were compared with the weight calculated from the ultrasonically measured biparietal diameter and abdominal circumference. A high degree of correlation (4 = .9624) was found between actual and calculated weights. This method of weight estimation has been clinically useful, especially in infants weighing less than 1500 g.
A detailed analysis of 465 primary cesarean sections (10.4% of total deliveries) performed at St. Mary's Health Center during 1977 and 1978 was undertaken. Cephalopelvic disproportion, malpresentation, and fetal distress were the 3 most common primary indications for cesarean section. An analysis of the effects of fetal monitoring seemed to indicate that the procedure was not a significant factor in increased use of cesarean section.
Four hundred sixty-five primary cesarean sections (10.4% of total deliveries) performed during 1977 and 1978 were reviewed and compared with 465 vaginal deliveries to ascertain factors that may be related to postpartum infection. The overall morbidity (19.7%) related to postpartum infection in the primary cesarean section group was statistically different from the 2.4% morbidity in the vaginal group. Cross comparisons of the effect of membrane status, use of internal electronic monitoring, development of postpartum anemia, duration of active labor, and difference in patient populations showed that internal monitoring had little or no effect on the development of postpartum endometritis. However, the development of postpartum anemia, increased time between membrane rupture and delivery, and, most important, a significant difference in patient populations were believed to be related to the development of postpartum endometritis in both groups.
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