Biomedical subjects
R K Tamura
Publications and source records attributed to R K Tamura.
Urinary estriols in diabetic pregnancy: a reappraisal.
The clinical usefulness of serial urinary estriols was tested in 138 insulin-dependent diabetic pregnant women. No action was taken on an estriol drop if fetal well-being was demonstrated by a reactive nonstress test and/or negative contraction stress test within 24 hours. Of 3085 estriol values, a greater than or equal to 40% estriol drop, confirmed by a greater than or equal to 40% decrease in the estriol-creatine ratio, was observed in 21 tests. In only two of these tests, was fetal distress indicated by a nonstress test or contraction stress test. A significant linear correlation was demonstrated between the mean level of estriol excretion and birth weight, placental weight, and fetal abdominal circumference measured by ultrasound. Chronically low estriol excretion (less than 12 mg per 24 hours at greater than 36 weeks' gestation) related to smaller placentas but not to fetal jeopardy.
Diminished biparietal diameter and abdominal circumference growth in twins.
Forty-three women with uncomplicated twin pregnancies and reliable menstrual dates had serial ultrasonic measurements of the fetal biparietal diameter (BPD) and abdominal circumference. The 25th, 50th, and 75th fetal BPD and abdominal circumference growth percentiles were generated from this normal twin population and compared with those for singletons. A slowing of both BPD and abdominal circumference growth in twins was noted in the third trimester. However, newborn anthropometric data were collected that suggest that the head circumference of twins is comparable to that of singletons. This discrepancy between ultrasonic BPD and neonatal head circumference in predicting head size may possibly be explained by dolichocephaly attributed to uterine crowding. For the antenatal assessment of growth in twins the authors recommend the use of BPD and abdominal circumference charts derived specifically from such uncomplicated twin pregnancies. When the BPD growth is abnormal, the head circumference and abdominal circumference should be measured to assess whether or not fetal growth is normal.
A simple estimated fetal weight equation based on real-time ultrasound measurements of fetuses less than thirty-four weeks' gestation.
Based on ultrasonographic mensuration, a number of equations have previously been devised for the purpose of estimating fetal weights. The objective of this study was to develop a mathematical equation that is simple, accurate, and easy to use when applied to preterm or low-birth weight fetuses (less than 2,500 gm). Real-time ultrasound measurements of fetal biparietal diameters (BPDs) and abdominal circumferences (ACs) were obtained in 62 pregnant women within one week of premature delivery. Mean gestational age and mean birth weight +/- SD for this study group of neonates were 28.5 +/- 3.5 weeks and 1,135 +/- 343 gm, respectively. With the aid of computer analysis, a simple regression equation was derived: EFW = (BPD x AC x 9.337) - 229. When predicted estimated fetal weight (EFW) was compared with actual birth weight (ABW), multiple regression analysis demonstrated a correlation coefficient (R) of 0.957. Preliminary results on 19 patients of a prospective study showed an absolute mean difference between the computed EFWs and the ABWs to be within 7.0% of ABW (70 gm/kg of ABW). The standard deviation of the difference was 9.3% of ABW (93 gm/kg of ABW). Based on these data, this simple equation appears to be clinically reliable and easy to use when estimating weights of preterm or low-birth weight fetuses of less than 2,500 gm.
Fetal surgery for hydrocephalus: successful in utero ventriculoamniotic shunt for Dandy-Walker syndrome.
The diagnosis of fetal hydrocephalus based on dilation of the ventricular system presents a broad range of management decisions. The options are presented and a case of Dandy-Walker syndrome managed by fetal ventriculoamniotic shunt placement is presented as an example. Under ultrasonic guidance, a shunt was placed at 30 weeks' gestation by later newborn Dubowitz examination. Delivery was delayed for five weeks, one to two weeks following probable shunt malfunction, after achieving fetal lung maturation. Follow-up six months after definitive neonatal ventricular shunting and three weeks after shunt revision revealed a socially active male infant with a motor development index of 87 and a psychomotor development index of 95. Potential advantages of fetal surgery including achievement of term gestation are presented. Proposed guidelines for determining the benefit of such procedures are also presented.
Failure to detect polycystic kidneys in utero by second trimester ultrasonography.
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The use of ultrasound in obstetrics.
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Sonographic abdominal circumference: dynamic versus static imaging.
The ultrasonic abdominal circumference (AC) measurement is one of the essential parameters used for assessment of fetal status. Whereas the AC was traditionally derived by static equipment, dynamic scanners are presently used for that purpose. In this study, the AC values obtained by two gray-scale ultrasonic imaging modalities (static and dynamic) were compared; the differences between the mean AC measurements were not statistically significant. Additionally, when the outline of the AC in a fetus near term was larger than the sonic field displayed by dynamic equipment, the partially incomplete boundary could be "filled in" without affecting the accuracy of the result.
Antenatal ultrasonic diagnosis of genetic defects: present status.
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Percentile ranks of sonar fetal abdominal circumference measurements.
We present the percentile ranks of sonar fetal abdominal circumference (AC) measurements from 18 to 41 weeks' gestation. The ACs are derived from both longitudinal and cross-sectional ultrasonic studies of 200 low-risk pregnant women. The reproducibility of sonar AC falls within 2% of the mean value; this variation permits antenatal distinction of the fetus with a small AC (less than twenty-fifth percentile) or large (greater than eightieth percentile) reading. The fetal AC measurements add another dimension to the interpretation of cephalic growth, particularly in identifying macrosomic fetuses as well as those who are either asymmetrically or symmetrically undergrown. Additionally fetal AC measurements are useful as adjuncts to the diagnosis of hydrocephalus by quantitating the difference between cephalic and body size. In the presence of fetal ascites the AC also can be used to assess the severity and progression of the abnormality.
Fetal cranial and craniocervical masses: ultrasound characteristics and differential diagnosis.
Ultrasound is assuming an essential role in the detection of fetal cranial and spinal anomalies. Illustrated in this article is the sonographic appearance of cranial abnormalities wherein the diagnosis of encephalocele is clear cut because the anatomic defect of the neural tube is visualized. Additionally presented is a variety of cranial and craniocervical cystic masses, including meningocele, wherein the anatomic defect of the neural tube is not apparent and the diagnosis is reached by careful attention to the specific ultrasonic characteristics of each mass.
Diagnosis of intrauterine growth retardation.
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Fetal movements and chromosome anomalies.
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