Biomedical subjects
Publications and source records attributed to I Morrison.
Cord presentation was diagnosed antenatally in nine patients at term referred for fetal ultrasound assessment (incidence of 0.61%). Seven patients were delivered by cesarean section; cord position was confirmed in four and suspected in three patients. There were two vaginal deliveries, one following spontaneous version and the other a stillbirth associated with cord prolapse.
Fetal biophysical profile scoring was used as a method for antepartum fetal risk assessment in 12,620 high-risk patients referred in a 55-month interval. A total of 26,257 tests were performed on these patients (range, one to 18 tests per patient). Ninety-three perinatal deaths occurred (gross perinatal mortality rate, 7.37 per 1000) of which 62 (66.6%) were due to a major anomaly, seven were due to Rh disease (7.5%), and the remaining 24 deaths (25.8%) occurred in structurally normal fetuses. The corrected perinatal mortality rate was 1.90 per 1000. Eight structurally normal fetuses died within 1 week of a normal test result (corrected false negative rate, 0.634 per 1000). These data suggest fetal biophysical profile scoring is an accurate method for identification of the fetus at risk for perinatal death.
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The rotational diffusion of bacteriophage epsilon 15 was measured before and after virus adsorption to outer membrane vesicles of the host Salmonella anatum. The virus capsid was labeled with eosin isothiocyanate, and the decay of transient dichroism following dye excitation by pulses of plane-polarized light was measured. From the data, the rotational diffusion constant of the unadsorbed virion and its hydrodynamic diameter were estimated and found to be consistent with electron microscopic measurements of the capsid dimensions. Addition of outer membrane vesicles of S. anatum to the virus suspension revealed the immobilization of the virus particles on the membrane surface.
Qualitative amniotic fluid volume determination is a routine part of fetal biophysical profile score testing. The relationship between oligohydramnios and poor perinatal outcome has been previously documented. We have undertaken a retrospective chart review relating qualitative amniotic fluid volume as determined at the time of last biophysical profile score assessment to perinatal outcome in 7582 referred high-risk obstetric patients. Gross and corrected perinatal mortality in association with normal qualitative amniotic fluid volume ranged from 4.65/1000 and 1.97/1000, respectively, to 187.5/1000 and 109.4/1000 in association with decreased qualitative amniotic fluid volume, respectively. The incidences of major congenital anomaly and intrauterine growth retardation were significantly related to qualitative amniotic fluid volume.
Qualitative amniotic fluid volume determination is a routine part of fetal biophysical profile score testing. The relationship between polyhydramnios and poor perinatal outcome has been previously documented. We have undertaken a retrospective chart review which relates qualitative amniotic fluid volume as determined at the time of last biophysical profile score assessment to perinatal outcome in 7562 referred high-risk obstetric patients. Gross and corrected perinatal mortality in association with normal qualitative amniotic fluid volume ranged from 4.65/1000 and 1.97/1000, respectively, to 32.9/1000 and 4.12/1000 in association with increased qualitative amniotic fluid volume, respectively. The incidences of major congenital anomaly and fetal macrosomia were significantly related to qualitative amniotic fluid volume.
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The rapidly evolving ability to detect the presence of major anomalies in the developing fetus and the emerging prospect of intrauterine treatment of some of these disorders are coupled to create an exciting new frontier in care of the high-risk pregnancy. Preliminary reports suggest that in some highly selected instances perinatal death and morbidity may be prevented by intrauterine surgical procedures. The technical ability to treat the disorder as described is at hand and is unlikely to be the limiting factor in the advance of this area of fetal treatment. However, the very fact that treatment is possible cannot be considered as proof of efficacy. The physician faced with the knowledge that a potentially treatable condition is present in a given fetus may feel the necessity of instituting treatment, but the validity of such an approach is far from established. It is our opinion that efforts should be made to set at the earliest point proper controlled scientific studies from which the benefit, if any, of this surgical approach to fetal disease may be established. Such clinical studies should be conducted in concert with studies in appropriate animal models. It should be noted that fetal surgical treatment is not without potentially lethal fetal and maternal complications. Before such risks, however small, are taken, it seems reasonable to determine the long-term benefits of the surgical procedure. To this end, participation in the International Fetal Surgery Registry is encouraged.
The purpose of this study was to obtain a numerically accurate discrete model of the effect of front aspheric soft lenses of various asphericities on the retinal illuminance profiles within the blur circles of a model eye. A computer program was developed for a model eye based on geometrical optics. The ray density was assumed to be proportional to the flux density or illumination. Retinal illuminance profiles are calculated for several values of defocus and asphericity. These results are validated by calculations based on modulation transfer functions (MTFs), observational data from contrast sensitivity and clinical results with Cals aspheric soft lenses. The results suggest that aspheric soft lenses maximize the central illuminance of blur circles and extend the range of desensitivity to retinal defocus in the eye to 4.00 D at the largest asphericity constant investigated.
In this prospective blind study, 735 patients with high-risk pregnancies referred for antepartum testing of fetal well-being were randomly assigned to either a fetal biophysical profile scoring (375 patients) or a nonstress testing scheme (360 patients). Management was based on the results of antepartum tests, but the method of testing used was not disclosed. Fetal biophysical profile scoring resulted in a significantly higher positive predictive value in regards to low Apgar scores. Sensitivity, specificity, and accuracy, although higher with fetal biophysical profile scoring, did not demonstrate significant differences when compared with the nonstress test. The negative predictive value between the two methods was similar. All major anomalies were detected during ultrasound scanning, whereas none of these anomalies were detected by heart rate testing alone.
Circadian rhythms have been identified in a variety of maternal and fetal biophysical and endocrinologic parameters. The authors have undertaken a 24-hour study to identify the normal variation in fetal bladder volumes in the healthy, term human fetus. A significant decrease in fetal bladder volumes occurred between 2400 hours and 0600 hours when compared with other times of the day. It is suggested that this fall in fetal bladder volumes may be related to fetal cardiovascular or adrenal gland function.
In a previous study, it was suggested that the presence of a grade III placenta correlates 100% with a mature lecithin/sphingomyelin (L/S) ratio and may replace amniocentesis in confirming fetal lung maturity. In this study that hypothesis was tested in 563 pregnancies. All patients underwent amniocentesis and simultaneously had placental grading. The correlations of placental grade with an L/S ration greater than or equal to 2 were: grade 0, 17%; grade I, 68%; grade II, 91%. The correlations of placental grade with the presence of phosphatidylglycerol (PG) were: grade 0, 17; grade 1, 41%; grade II, 79%; grade II, 75%. The false positive rates associated with grade III placenta were, therefore, 7% for mature L/S ratio and 25% for PG present: when combined with a biparietal diameter greater than or equal to 9.0 cm, a grade III placenta incorrectly predicted lung maturity in 8.5%. We conclude that placental grading is not accurate enough to replace amniocentesis as the standard test of fetal pulmonary maturity.
Antepartum detection, classification, determination of severity, and ultimately treatment of the fetus at risk for death and damage in utero form the very basis of modern perinatal medicine. The availability of accurate methods for assessing the fetus in utero are now becoming available. In extrauterine medicine, assessment of risk is based in part on the patient's activities and response to intrinsic and extrinsic stimuli. In extrauterine medicine, differentiation of normal sleep from coma is made by assessment of multiple biophysical variables and responses. It is most likely that the same principles hold true for differentiating the normal sleeping fetus from the asphyxiated fetus. Biophysical profile scoring offers one method for differentiation. It is likely that incorporation of this principle will improve the quality of perinatal care.
The results of a prospective clinical management based on fetal biophysical profile scoring method was evaluated in 1,184 referred high-risk patients. Six perinatal deaths occurred in the study group (perinatal mortality of 5.06 per 1,000); only one fetus suffered unpredictable and unpreventable death (true false negative rate 0.8 per 1,000). In addition, 13 fetuses with major congenital anomalies were detected as a result of ultrasound scanning for fetal biophysical activities. These data suggest that this method can be used effectively to screen and manage a high-risk population.
An analysis of 1,994 consecutive parturient women showed that 472 (23%) could be assigned to a high-risk category on the basis of an intrapartum score of greater than or equal to 3. Perinatal mortality, neonatal morbidity, and the rate for operative intervention were all significantly greater for the high-risk group (p < 0.0001). Of the total population, 11% were designated to be at high risk by combining intrapartum and antepartum scores, and 71% of this group had an abnormal intrapartum outcome (p < 0.0001). For this study, 63% of the patients with an abnormal outcome for labor were admitted to the labor floor for 6 hours or longer, and this is an indirect measurement of the potential that exists for optional management. The limitations of intrapartum scoring systems are discussed, particularly with respect to their design, the prediction of preventable deaths, and the category of hospital for which they might prove most useful.
To determine the role of hPL radioimmunoassays in screening for fetal assessment in normal and hypertensive pregnancies the results of 148 pregnancies were examined by measuring the specificity and sensitivity of the test for prospectively defined fetal conditions. Values of hPL were considered abnormal if they were below the tenth percentile for the range of values derived from pregnancies with a normal fetal outcome ( less than 3.8 microgram/ml). The specificity of the test was 95% but it would have correctly predicted a normal fetal outcome in only 85% of pregnancies. The test varied in its ability to accurately predict abnormal fetal outcome; the sensitivity for the single stillbirth and for cases of fetal jeopardy was 87%, whereas for IUGR the result was 41%. There was a significant difference between hPL values associated with fetal jeopardy and uncomplicated IUGR (p less than 0.01). The frequency of sampling and the application of these results to the prospective screening of normal and hypertensive pregnancies is discussed and it is concluded that hPL assays have a limited but specific role in antepartum evaluation. Screening should be reserved for pregnancies associated with hypertension to exclude the risk of stillbirth and fetal jeopardy occurring specifically in the IUGR fetus.
A simplified, numerical form for antepartum risk scoring was introduced as a component of the prenatal record for use in all pregancies in a large geographic area under a variety of collection practices. In a population of approximately 1,000,000 with 16,733 deliveries, 19% of the pregnant population scored greater than or equal to 3 and were designated as high risk on the basis of previous pilot studies. This group with high-risk scores had a perinatal mortality rate of 69/1000 compared to the low-risk group with a perinatal mortality of 7/1000 (P = less than 0.0001). The high-risk group accounted for almost 70% of the total perinatal deaths. The implications of being able to predict the statistical likelihood of perinatal deaths are discussed. It is suggested that the risk scoring system has its greatest potential as a screening process and as a method of recording regional statistical trends rather than in dictating the final management of the pregnancy.
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