Determination of depth-dependent diffraction data: a new approach.

A direct method for determining powder diffraction data at specific depths from angle-dependent diffraction data is described. The method is non-destructive and only traditional data collections, where the angle of incidence is varied, are required. These angle-dependent spectra are transformed to give diffraction data arising from different depths, which may then be exploited using any conventional method. This is a novel approach as traditional methods are forced to tolerate the inherent depth averaging of grazing-angle diffraction, or only examine specific structural characteristics. In order to obtain depth-dependent X-ray diffraction data, a Fredholm integral equation of the first kind is solved using regularization techniques. The method has been validated by the generation of pseudo-experimental data having known depth profiles and solving the Fredholm integral equation to recover the solution. The method has also been applied to experimental data from a number of thin film systems.

Prenatal diagnosis of congenital cytomegalovirus infection with abnormal triple-screen results and hyperechoic fetal bowel.

A 14-year-old primigravid adolescent with abnormal triple-marker screen results at 18 weeks' gestation was found to have hyperechoic fetal bowel. Amniotic fluid culture was positive for cytomegalovirus. Serial ultrasonography demonstrated progressive lateral ventriculomegaly, intrauterine growth retardation, and hydrops fetalis; fetal death occurred at 32 weeks' gestation.

Maternal youth and pregnancy outcomes: middle school versus high school age groups compared with women beyond the teen years.

OBJECTIVE: We sought to measure and compare pregnancy complications in middle school versus high school versus older maternal age groups. STUDY DESIGN: From January 1988 through December 31, 1991, maternal and infant data from 16,512 consecutive nulliparous women were collected and electronically stored. These women were divided into three study groups: middle school (11 to 15 years old), high school (16 to 19 years old), and women 20 to 22 years old at delivery. Statistical analysis included logistic regression to control for potentially confounding demographic variables. RESULTS: Middle school-aged mothers were disproportionately black (50% vs 36% Hispanic vs 14% white), and very low birth weight (4% vs. 2%, p = 0.003) was increased in these youthful mothers. First births to high school-aged mothers were not found to be compromised compared with those of women 20 to 22 years old, and, indeed, cesarean birth was less frequent in these women compared with those > or = 20 years old. CONCLUSIONS: We conclude that the health hazard associated with school-age pregnancy is predominantly prematurity and is increased only in middle school-aged mothers. High school-aged mothers do not experience excess medical complications of pregnancy compared with older women. We suggest that middle school pregnancy, particularly for inner-city teenagers, should be a special focus for pregnancy prevention and intervention.

Class A1 gestational diabetes: a meaningful diagnosis?

OBJECTIVE: To compare pregnancy outcomes in women diagnosed as having class A1 gestational diabetes with those of a group with a normal 3-hour glucose tolerance test (GTT) to assess morbidities attributable to glucose intolerance. METHODS: Selective 50-g GTT identified pregnant women who received a 3-hour GTT. Over a 16-month period, 159 women were diagnosed as having class A1 gestational diabetes according to the National Diabetes Data Group criteria. During the latter 12 months of this time period, 151 women who had a normal GTT result were identified for comparison. RESULTS: There were statistically significant differences in age and the development of peripartum hypertension in women with class A1 gestational diabetes compared with the normal 3-hour GTT group. There were no significant differences in any neonatal outcome variable, including percent delivering large for gestational age (LGA) neonates in women with A1 diabetes compared to controls. Overall, 111 (36%) of the 310 neonates were classified as LGA, a rate more than double that in the singleton population in our hospital. Maternal weight, parity, and a history of a previous macrosomic infant were significantly associated with LGA outcome. Mean maternal weight was the same in the two GTT groups, implying an independent effect on fetal size. Obstetric interventions were not significantly different between the groups, so differences in intervention could not account for the lack of difference in outcome variables. The impact of dietary counseling in the class A1 diabetic women is also an unlikely explanation for the lack of differences in outcome. Within the normal-GTT group, women with one abnormal 3-hour value had a frequency of LGA infants similar to that of women with all normal 3-hour GTT values. These results suggest that there is a selection effect of screening for glucose intolerance that may relate more to other risk factors for LGA outcome than to glucose intolerance. Maternal obesity is an independent and more potent risk factor for large infants than is glucose intolerance. CONCLUSION: The diagnosis of class A1 gestational diabetes is not significantly associated with obstetric and perinatal morbidities. A nondiscriminating diagnostic test undermines the validity of population screening for glucose intolerance.

Liver histopathologic findings in women with sickle cell disease given prophylactic transfusion during pregnancy.

Forty women with a major sickle hemoglobinopathy (hemoglobin SS, SC, or S-beta-thalassemia) were given red blood cell transfusions prophylactically during pregnancy. A mean of 13.6 units of erythrocytes per woman was given and none received more than 28 units. Direct-vision needle biopsy of the liver was performed in conjunction with cesarean section or puerperal sterilization. Although iron deposition in hepatocytes and Kupffer cells was identified commonly, neither cirrhosis nor widespread hepatocellular necrosis was found. We conclude that the risk of irreversible hepatic damage is negligible in women with sickle hemoglobinopathies who are given erythrocytes prophylactically during one pregnancy.

Vasopressin and catecholamine secretion during metabolic acidemia in the ovine fetus.

It has been suggested that the substantial rise in fetal plasma arginine vasopressin (AVP) during intrauterine hypoxia/asphyxia reflects decreases in PaO2 and/or pHa; however, the components of these "stresses," i.e. PO2, PCO2, and pH, have not been controlled. Recently, only modest increases in fetal AVP secretion were seen during hypoxia independent of changes in pH and PCO2. Since the independent effects of metabolic acidosis on fetal AVP secretion are unknown, we induced acute metabolic acidemia in fetal sheep at 137 +/- 4 (mean +/- SD) days gestation with 1 M NH4Cl, while monitoring mean arterial pressure, heart rate, PaO2, PaCO2, pHa, plasma osmolality, and blood concentrations of electrolytes, AVP, dopamine, norepinephrine, and epinephrine. Mean arterial pressure, PaO2, PaCO2, and plasma osmolality and sodium were unchanged; pHa decreased from 7.37 +/- 0.01 to 7.04 +/- 0.05 (p less than 0.05) during NH4Cl and did not return to control levels until 24 h later. AVP increased from 2.85 +/- 0.23 to 5.26 +/- 1.11 microU/ml (p less than 0.05) at the time of maximum acidosis, correlating with the fall in pHa (r = -0.67, (p = 0.001); however, after stopping NH4Cl, AVP returned to baseline levels although pHa remained less than 7.15. In control studies using the same osmolar load, volume, and rate of infusion, AVP levels were unchanged. Only epinephrine was significantly (p less than 0.05) elevated during acidosis, but did not correlate with pHa or plasma AVP. Marked metabolic acidemia appears to have little or no effect on fetal AVP secretion, and fetal catecholamine secretion is variable.

Comparison of ultrasonic measurement of backfat depth on live pigs and carcases with a digital recording instrument.

A hand-held, digital recording ultrasonic backfat tester (Sonalyser) was used on 200 live pigs and their carcases to predict carcase P2 backfat depth measured with the Introscope optical probe. Readings were taken on live pigs at a position which approximated to the P2 site on the carcase. This site was tattooed. Sonalyser and Introscope readings were taken on the carcase at the P2 site and at the tattooed site. Regression equations of Introscope readings as a function of Sonalyser live pig and carcase measurements were developed. Calculation of partial F values showed the Sonalyser was more precise in measuring backfat on the live pig than the carcase. With R(2) = 0·77 and residual standard deviation (rsd) = 1·35 mm was judged to be acceptable for predicting carcase Introscope backfat from live pig measurement. Due to the lower precision, and other practical limitations to its use in abattoirs, the Sonalyser was not suitable for measuring backfat on the carcase. The limiting factors may have contributed to the lower R(2) (0·69) and higher rsd (1·55 mm) of the regression between Sonalyser and Introscope carcase fat depth.

Puerperal pelvic thrombophlebitis: impact on diagnosis and treatment using x-ray computed tomography and magnetic resonance imaging.

The clinical diagnosis of puerperal pelvic thrombophlebitis was confirmed by x-ray computed tomography in 11 women, and further documented in six by magnetic resonance imaging. Venous thrombi were demonstrated in ovarian, iliofemoral, and inferior vena caval vessels. In six women with ovarian vein involvement and no evidence of iliofemoral thrombophlebitis, resolution followed intravenous antimicrobial therapy alone, and in three of these, resolution was confirmed by x-ray tomography. In contrast, three of five women with symptomatic iliofemoral thrombophlebitis had a prolonged febrile course despite antimicrobial and heparin therapy. The clinical courses of these 11 women were consistent with the observation that pelvic thrombophlebitis is associated with pelvic infection. Disease manifested within a few days after parturition was more likely due to ovarian vein involvement, whereas disease with later onset of symptoms was more likely due to iliofemoral thrombosis, with or without vena caval extension. Through the use of x-ray computed tomography and magnetic resonance imaging, the natural course of pelvic thrombophlebitis can be better elucidated and therapeutic regimens more clearly evaluated.

Magnetic resonance imaging and ultrasonography in the antenatal evaluation of conjoined twins.

Magnetic resonance imaging and sonography were used as diagnostic aids in the antepartum evaluation of two sets of conjoined twins. Magnetic resonance imaging was performed at 20 weeks' estimated gestational age on thoracopagus/omphalopagus twins and on omphalopagus twins at 20 and 30 weeks. Magnetic resonance imaging is a complementary adjunct to ultrasonography and provides additional anatomically precise clinical data. The advantages of this noninvasive technique include a large diagnostic window allowing total fetal imaging with excellent resolution of tissue composition. Unlike computerized tomographic imaging, there is no associated radiation exposure. The principal disadvantages of magnetic resonance imaging at this time are the cost of the equipment and the lack of real-time imaging capability.

Pelvic masses in pregnant patients: MR and US imaging.

Sixteen pregnant patients with pelvic masses detected with ultrasound (US) were studied with magnetic resonance (MR) imaging at 0.35 T. Two patients were in their first trimester, eight in the second, and six in the last. On MR images, 34 masses were seen, including 19 uterine leiomyomas. With US, 20 masses were detected. All masses not seen with US were leiomyomas. Only 20 masses (in 11 patients) were removed for histologic study. In nine cases, MR imaging and US provided similar information on the origin, extent, and type of mass. In seven patients, MR imaging contributed additional information. MR imaging depicted more leiomyomas than US in three patients. In another case, MR images showed that a mass depicted with US was actually a loop of bowel. MR images allowed differentiation between a solid soft-tissue mass and a hemorrhagic fluid-containing mass, correctly depicted the presence of an abdominal pregnancy, and allowed evaluation of the parametrium for spread of cervical carcinoma.

Magnetic resonance imaging in human pregnancy.

Magnetic resonance imaging is a new noninvasive diagnostic technique that involves no ionizing radiation, has no known significant adverse biologic effects, and produces high resolution cross-sectional body images. When compared with sonography and x-ray computed axial tomography, magnetic resonance imaging may have several advantages. To investigate its clinical role in obstetrics, magnetic resonance imaging was used to examine 11 women with abnormal pregnancies. Prior ultrasound examination showed abnormal appearing fetuses in five, abnormalities of the amnionic fluid volume in five, and one each with a large adnexal mass and a molar pregnancy. Examples of images obtained from these women are presented and described. Maternal anatomy was well visualized in all women studied. Based on the preliminary experience, the authors believe that magnetic resonance imaging will be a useful adjunct for diagnostic visualization of normal and abnormal maternal anatomy. Detailed fetal imaging was also possible, and it is anticipated that magnetic resonance imaging will prove useful for fetal evaluation, especially fetal intracranial anatomy and fetal anatomy in pregnancies complicated by oligohydramnios. Because fetal subcutaneous fat is prominently depicted with magnetic resonance imaging, this technology may be useful for assessment of fetal nutritional status.

Ultrasound prediction of fetal weight in prolonged pregnancy.

In this study we applied two commonly used birth weight prediction equations to a sample of 121 women with prolonged pregnancies. Subjects had sonographic measurements of biparietal diameter and abdominal perimeter taken within 2 days of delivery at Parkland Memorial Hospital. Although the two prediction equations were obtained from a population of women in New Haven, Connecticut, who delivered over a wide range of gestational ages, when the equations were applied to the sample of prolonged pregnancies in Dallas, Texas, there was a strong correlation (0.71) between predicted and actual birth weight. Moreover, reestimation of the New Haven equations with use of the Dallas data yielded similar regression coefficients. Finally, birth weight prediction equations for black, white, and Hispanic patients in Dallas were not significantly different. These findings suggest a remarkably constant relationship between fetal head and abdominal dimensions and birth weight over different gestational ages and for different population groups.

Magnetic resonance imaging in obstetric diagnosis.

Five patients with abnormal pregnancies were examined with ultrasound (US) and magnetic resonance imaging (MR). Three had a malformed fetus, 1 had a molar pregnancy, and 1 had an ovarian mass. Both maternal and fetal structures were clearly shown, although fetal motion may have resulted in image degradation in some cases. The authors suggest that MR may be useful in obstetric diagnosis.

Sinusoidal fetal heart rate pattern after intrauterine transfusion.

Two pregnancies complicated by severe Rh-isoimmunization and the development of sinusoidal fetal heart rate patterns immediately after intrauterine transfusions are presented. An intermittent sinusoidal pattern resolved, in one fetus, with sonographic evidence of delayed but complete absorption of transfused red blood cells. In contrast, the second fetus exhibited a continuous sinusoidal pattern coincident with cardiac decompensation detected by echocardiography, severe anemia, and failure to absorb transfused red blood cells. Possible pathophysiologic mechanisms for the development of sinusoidal patterns after fetal transfusions are discussed. It is concluded that a sinusoidal fetal heart rate pattern may occur after fetal transfusion and that the subsequent course of this pattern provides meaningful information about fetal condition as well as the success of intrauterine transfusion.