Biomedical subjects
Publications and source records attributed to E A Reece.
Embryoscopy is a new technique for direct visualization of the first-trimester conceptus. A rigid fiberoptic endoscope is passed transcervically under ultrasonographic guidance into the chorionic cavity. Anatomic scrutiny and direct access to the developing embryo are made possible by this technique.
Antiphospholipid antibodies, which include lupus-like anticoagulant and anticardiolipin antibody, have been linked to a number of adverse pregnancy outcomes, although their exact pathogenic mechanisms remain poorly defined. The relative risk of complications such as intrauterine growth retardation, spontaneous abortions, and stillbirth in patients with antiphospholipid antibodies also remains undetermined. Heightened attention has been focused on the association, leading to investigations into the pathogenesis. Uncontrolled studies have also explored therapeutic regimens such as aspirin, steroids, and heparin, and clinical trials have used various treatment protocols. Although knowledge into the association of antiphospholipid antibodies and recurrent adverse pregnancy outcome is limited and continues to evolve, this association provides new insights into the disease and offers promise for pharmacologic prophylaxis. In this article, current concepts on pathogenesis, diagnosis, and therapy are reviewed and recommendations are made for clinical care of these patients.
A longitudinal ultrasound study was conducted in 45 insulin-dependent diabetic patients who maintained good glycemic control (mean plasma glucose less than 120 mg/dl) throughout most of their pregnancy in order to assess growth of the fetal head in the presence of euglycemia. Patients with and without vasculopathy were found to be comparable with regard to their glycemic control, medical and obstetric complications, as well as incremental growth and the velocity of growth of the fetal biparietal diameter (BPD). When compared with the control group, the velocity of growth of the BPD was not significantly different throughout pregnancy. However, the actual increment in BPD growth remained less than that of the control fetuses, especially during the second trimester when a significant statistical difference was found. Possible explanations may include delayed ovulation, reduced growth velocity in the first trimester, or constitutionally smaller embryos among the diabetic group. The pattern of BPD growth among diabetics was best described by a third degree polynomial regression equation. These results demonstrate that in well-controlled diabetics, although the increment in BPD was less than controls, the growth pattern of the fetal BPD was similar among the White classes B to FR, and the velocity of growth of the BPD was similar among diabetics and nondiabetics.
A prospective ultrasound study was conducted in 160 normal pregnant women with gestational ages ranging from 14 to 40 weeks. Several fetal biometric measurements were obtained, including the posterior horn width (PHW) and the cerebroposterior horn distance (CPHD) of the lateral ventricles. Curvilinear relationships were found between the gestational age and the ratio of the PHW/CPHD (r = 0.665, p less than 0.0001); and the PHW/hemispheric width (HW), (r = 0.716, p less than 0.0001) and also between the biparietal diameter and the PHW/CPHD ratio (r = 0.649, p less than 0.0001), and the PHW/HW ratio (r = 0.732, p less than 0.0001). A correlation in growth was also observed between the femur length and the PHW/CPHD (r = 0.660, p less than 0.0001), and the PHW/HW (r = 0.734, p less than 0.0001). Nomograms of the PHW, CPHD, and the ratio of PHW/CPHD against gestational age were generated. The establishment of normal indices of the posterior horn provides new, precise, and comprehensive data that will serve as a standard against which the evaluation of early abnormal ventricular growth and anomalous development of the central nervous system may be compared.
The effect of gestation on the rate of decline in renal function was studied in 11 pregnancies complicated by diabetic nephropathy. For each pregnancy, serum creatinine levels were available within 4 years before pregnancy, during pregnancy, and within 4 years after delivery. Although all of these patients were hypertensive and had increased proteinuria during pregnancy, the mean serum creatinine just prior to conception (1.3 +/- 0.5 mg/dl) and the last follow-up value (1.2 +/- 0.3 mg/dl) were not significantly different. When the inverse of serum creatinine (1/Scr) was used to estimate creatinine clearance, the renal function was either improved or remained stable in the majority of the pregnancies (7 of 11). The observed decline in renal function through the end of follow-up appeared to be consistent with the expected natural course of diabetic nephropathy in the absence of pregnancy. Furthermore, the slope for inverse serum creatinine before and after pregnancy was not significantly different. In conclusion, pregnancy in patients with mild to moderate diabetic nephropathy does not seem to accelerate the rate of decline in renal function.
Diabetes mellitus is associated with fetal growth acceleration and retardation. These aberrations in fetal growth seem to be influenced by a variety of factors including vascular disease, glycemic control, hypertension and smoking. In order to characterize fetal growth under the above conditions, longitudinal sonographic evaluations were performed in 52 pregnant, insulin-dependent diabetic women with the usual monitoring of the patients' metabolic control. Regression analyses revealed that vascular disease and glycemic conditions were the most important influences for growth, with manifestation beyond the second trimester. With stringent glucose control (mean whole blood less than or equal to 100 mg/dl) in the absence of vasculopathy (white classes A, B, C), fetal growth was similar to that in normal pregnancies. In the presence of vasculopathy (white classes D and FR), growth was reduced, especially when near-normal glycemic levels were achieved. Conversely, in poorly controlled diabetic women, enhanced fetal growth were observed in patients with and without vasculopathy. No aberrations in fetal growth were observed, however, before the third trimester. The findings of our study demonstrate that vasculopathy and glycemia are dominant and independent regulators of fetal growth. However, their influences are not manifested in growth changes before the third trimester.
It has been estimated that more than half of all pregnant women in the United States undergo diagnostic ultrasound during their pregnancies. In light of this, the question of safety is of fundamental importance. Nondiagnostic ultrasound has been shown to produce biologic effects by thermal and cavitational activities. However, diagnostic ultrasound uses much lower intensities, and no evidence exists to suggest that it is associated with adverse effects. Numerous studies have examined the biologic effects of diagnostic ultrasound in insects, plants, cell suspensions, and even small mammals. The data from these experiments are confusing when attempting to relate these findings to the human. Epidemiologic data in humans, used to evaluate the potential adverse effects of exposure to diagnostic ultrasound, have revealed no ill effects from such exposure. Current data indicate that there are no confirmed biologic effects on patients and their fetuses from the use of diagnostic ultrasound and that the benefits to patients exposed to prudent use of diagnostic ultrasound outweigh the risks, if any. This review discusses the available information on the safety of obstetric ultrasonography.
The choroid plexus cyst is one of many malformations of the central nervous system that can be detected in utero by ultrasonography. Choroid plexus cysts occur in 2.3% of fetuses. Because previous reports have shown an association between choroid plexus cysts and chromosomal anomalies, we analyzed 82 prenatally diagnosed cases, 65 of whom had chromosome analysis performed. Of the group, 6.2% had chromosomal anomalies of the trisomy 18 type. The remaining 17 cases were clinically normal at birth. These cases of trisomy 18 were also associated with multiple structural anomalies. Therefore, we suggest that after the diagnosis of choroid plexus cysts is made, a complete ultrasonographic survey of the fetal anatomy be performed. Fetal karyotype determination may be offered to patients, especially in the presence of structural anomalies.
The oral glucose tolerance test is the recommended method for the assessment of carbohydrate metabolism in pregnancy. However, available glucose drinks are often associated with varying degrees of gastrointestinal symptoms that might preclude meaningful studies. Polycose (Ross Labs, Columbus, Ohio) is a glucose saccharide polymer mixture containing 3% glucose, 7% maltose, 5% maltotriose, and 85% polysaccharide of 4 to 15 glucose units, with an osmotic load one fifth that of glucose. We assessed the efficacy of this glucose polymer in the performance of a 3-hour carbohydrate tolerance test with glucose and glucose polymer used 3 to 5 days apart in each patient tested. After 2 days of 300 gm carbohydrate-enriched diets, 48 patients underwent 3-hour carbohydrate tolerance tests at a mean gestational age of 30 +/- 3 weeks. Statistical analysis revealed a moderate level of agreement (kappa = 0.45, p less than 0.001) between the results of both carbohydrate tolerance test preparations. Patients experienced fewer gastrointestinal symptoms with the glucose polymer than with glucose. These preliminary data suggest that glucose polymer may be effectively used in the performance of a 3-hour carbohydrate tolerance test.
A prospective ultrasonographic study was conducted in 100 normal pregnant women with gestational ages that ranged from 36 to 42 weeks in which multiple biometric measurements were obtained. Dimensions of the distal femoral, proximal tibial, and proximal humeral epiphyseal ossification centers, as well as the placental and colonic grades, were also evaluated. A high statistical correlation was found between gestational age and each of the five variables (p less than 0.001). With a stepwise linear logistic regression analysis, we determined that gestational ages (36 to 39 weeks and 40 to 42 weeks) could be ascertained with a high probability with the use of a combination of the proximal humeral epiphysis and colonic grades. Probability estimates were not significantly affected by the addition of the distal femoral, proximal tibial epiphyses, placental grade, or amniotic fluid volume. From these data, probability prediction tables were generated. The results of this study provide an alternate method by which gestational age may be estimated in late pregnancy.
Thirty-two patients with uncomplicated twin pregnancies had ultrasonographic examinations for genetic amniocentesis, confirmation of twinning, or assessment of fetal growth. The dividing membranes between the fetuses were visualized, and the thickness of the membranes was measured. With a thickness of 2 mm used as a cutoff point, the accuracy in predicting monochorionic or dichorionic twinning was 82% and 95%, respectively. Prenatal assessment of these dividing membranes may be helpful in the management of twin gestations.
The accurate estimation of gestational age is an essential part of pregnancy management, since the consequences of erroneous dating carry increased risks of perinatal morbidity and mortality. Ultrasonography offers a unique opportunity to objectively measure quantitative changes in growth increments of various fetal structures, as well as qualitative changes occurring near term which are indicative of fetal maturity. Therefore, dating through pregnancy is possible by the use of various parameters such as the crown-rump length, the trunk circumference, and the biparietal diameter in the first trimester; the biparietal diameter, the cerebellum, orbital distance, clavicular length, lengths of the long bones of the upper and lower extremities, and the foot length in the second and third trimesters; and the indices of maturity in the late third trimester such as colonic grading and epiphyseal ossification centers of the long bones of the upper and lower extremities. Using a combination of fetal biometry and maturity indices permit dating through pregnancy as a measure of growing up.
The metabolic changes during pregnancy are characterized as "accelerated starvation" and "facilitated anabolism" which are, in turn, worsened by the presence of diabetes mellitus. The current roles of dietary fiber and exercise as adjunctive therapeutic modalities in the management of diabetic pregnancies are discussed herein.
Ultrasound visualization of the first trimester embryo was compared using abdominal and transvaginal sonography. The parameters evaluated included the ability to obtain biometry, the ability to visualize detailed internal anatomy, and a subjective assessment of the overall image clarity. In 120 patients studied, transvaginal sonography was superior to abdominal sonography in obtaining biometric measurements in 51 cases (43%) and for visualizing internal anatomy in 45 cases (38%); also the image clarity of transvaginal sonography was subjectively better in 75 cases (63%). Vaginal sonography was superior to abdominal sonography in gestations less than or equal to 10 weeks, in obese patients, and in patients with retroverted uteri. The major difficulty encountered with transvaginal sonography was the limited maneuverability of the probe to generate specific views. Vaginal sonography can be a valuable tool in imaging the first trimester fetus, complementing, not replacing, abdominal sonography.
The modern management of pregnancy complicated by erythroblastosis fetalis is based on serial amniocenteses followed by either intrauterine transfusions or early delivery of affected infants, depending on the gestational age. A retrospective study was undertaken involving 92 isoimmunized pregnancies in which ultrasonography and amniotic fluid analyses were used to assess the relative predictive values for neonatal complications. Our data demonstrated that ultrasonography and optical density analyses were comparable in the evaluation of the isoimmunized pregnancy. The combined information from both these modalities did not increase the predictive value over that observed with either one alone. Both instruments were found to have high negative predictive values. However, neither method, used singly or in combination, was highly predictive of neonatal complications. In light of the low positive predictive values, caution should be exercised in using the results of amniotic fluid spectral analyses and/or ultrasound examinations for predicting perinatal complications.
A prospective ultrasound study was conducted on 171 normal pregnancies ranging in gestational age from 15 weeks to term to evaluate the developmental anatomy of the atria of the lateral ventricles. The atrial width showed no significant modifications throughout gestation, remaining fairly constant. Significant linear relationships were found between the cerebroatrial distance and gestational age (R2 = 0.88; P less than .0001) and between the cerebroatrial distance and the biparietal diameter (R2 = 0.936; P less than .0001), with a first- and second-order regression equation being the best fit, respectively. From these data, growth of the atria was characterized both biologically and mathematically, providing a comprehensive evaluation of the atrioventricular system throughout pregnancy. Such data offer the potential for early prenatal diagnosis of various types of developmental abnormalities of the fetal ventricular system.
We described previously the morphologic alterations of the visceral endodermal yolk sac cells of rat conceptuses cultured under hyperglycemic conditions which occurred concomitantly with major embryonic malformations. To determine whether the transport function of the yolk sac was impaired simultaneously as a result of these hyperglycemic conditions, horseradish peroxidase was used as a tracer protein to assess the transport function of the visceral endodermal yolk sac cells of conceptuses cultured in both control and hyperglycemic media. Cellular uptake of peroxidase, which was added to the culture medium for 3 or 24 hours, was observed in controls. This differed from the marked diminution in peroxidase uptake seen in conceptuses cultured in hyperglycemic medium. These results demonstrate that during hyperglycemia-induced embryopathy, there is concomitant yolk sac failure evidenced by morphologic alterations and impaired endocytosis. These findings therefore strengthen our hypothesis that diabetes-related malformations, as demonstrated experimentally in rat conceptuses, are associated with impairment in the structure and functions of the visceral yolk sac cells during a critical period of organogenesis.
The results of a prospective ultrasound study of the posterior fossa structures in 19 fetuses with spina bifida are reported. The transverse cerebellar diameter is below the normal limits and the cisterna magna is obliterated in all cases. Decreased cerebellar size and failure to visualize the cerebellum appear to be specific findings for spina bifida since they are not present in a group of 17 fetuses with isolated hydrocephalus. The results of this study indicate that ultrasound investigation of the posterior fossa may prove useful in the prenatal diagnosis of spina bifida.