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Biomedical subjects

F P Hadlock

Publications and source records attributed to F P Hadlock.

At least 37 records · Page 2Linked to original sources
PubMed1985

Use of ultrasound in the detection of macrosomia: a review.

The early detection of the macrosomic fetus is important to the obstetric management of pregnancies in which this growth abnormality occurs. Ultrasound has been used for this purpose but for this approach to be effective, a clear definition of macrosomia, selection of the appropriate parameters for measurement, and specification of the optimal time for carrying out the ultrasound studies are required. In this review we examine the definition of macrosomia and introduce two new terms, mechanical macrosomia and metabolic macrosomia. We also evaluate the effectiveness of the limited number of parameters studied to date and conclude that they are marginally effective, primarily because of their low sensitivity and the limitations of current ultrasound methods for estimating fetal weight. The use of the growth profile, a multiparameter approach to the evaluation of fetal growth, is suggested as a possible means for improving the effectiveness of ultrasound in detecting the macrosomic fetus.

Birth Weight↗
PubMed1985

Use of femur length/abdominal circumference ratio in detecting the macrosomic fetus.

The femur length/abdominal circumference ratio, expressed as FL/AC X 100, was determined in 156 fetuses and evaluated as a predictor of fetal macrosomia within one week prior to delivery. The normal range (mean +/- 2 SD) in the 105 normal-weight fetuses was 22.0 +/- 2, while the normal range in the 51 macrosomic fetuses was 20.5 +/- 2; these differences were highly significant (P = less than .0001). The predictive power of a positive ratio was 68%, with a sensitivity of 63%. This ratio was particularly useful in the subset (n = 9) of macrosomic fetuses whose mothers were diabetic, correctly identifying 89% of this group. Because it is age independent, this ratio should prove most helpful in identifying fetuses at risk for macrosomia in patients whose dates are not known, since it may become abnormal before the fetal weight falls above the 90th percentile at term (3,900 g). In patients whose dates are known, early fetal macrosomia is best predicted by evaluating the abdominal circumference against normal standards for age.

Abdomen↗
PubMed1985

Ultrasound prediction of fetal lung maturity.

Amniocentesis for determination of fetal lung maturity and ultrasonographic (US) evaluation of the biparietal diameter (BPD) and placental grade were performed simultaneously in 261 nondiabetic pregnant women. A BPD of at least 9.3 cm and a grade 3 placenta were evaluated as predictors of fetal lung maturity using amniotic fluid phospholipids as indicators of a mature lung profile. The ability of the sonographic parameters to predict fetal lung maturity was closely related to menstrual age. Before 37 weeks, the false-positive prediction rate using a grade 3 placenta was 100%, and the false-positive prediction using the BPD was 85.6%. After 37 weeks, the false-positive rate using a grade 3 placenta was 5.9%, and the false-positive rate using the BPD was 9.5%. Thus menstrual age, and not these two US parameters, dictated fetal lung maturity. The authors conclude that the best use of US for predicting fetal lung maturity is in establishing menstrual age early in pregnancy.

Adult↗
PubMed1985

Fetal femur length: a critical reevaluation of the relationship to menstrual age.

This investigation has reexamined the measurement of the femur length and the use of this measurement as a growth and dating parameter. Straight-line measurements of shaft length were found to be smaller than measurements made along the bone curvature. However, the maximum difference did not exceed 2 mm. Thus, because of its simplicity, use of straight-line measurements appears justified. The optimal (R2 = 96.1%) growth curve model was a linear-quadratic function, with variability around the regression line increasing with menstrual age. The optimal (R2 = 96.8%) dating curve model was a linear-quadratic function in which loge menstrual age is a function of femur length. The variability associated with age estimates increased with femur length. These data were used to construct new standard curves for growth assessment and dating of fetuses using femur length measurements.

Cephalometry↗
PubMed1984

Sonographic estimation of fetal weight. The value of femur length in addition to head and abdomen measurements.

Sonographic estimation of fetal weight in utero was performed in 167 live-born fetuses examined within one week of delivery. Regression models were based on measurements of abdominal circumference, head circumference, biparietal diameter, and femur length, both alone and in combination. The best results (1 S.D. = 7.5% of actual weight) were obtained by combining measurements of the fetal head, abdomen, and femur, most likely due to the strong linear relationship between femur length and crown-heel length.

Abdomen↗
PubMed1984

Estimating fetal age: computer-assisted analysis of multiple fetal growth parameters.

Regression models for predicting menstrual age based on real-time sonographic measurements of four fetal parameters (biparietal diameter, head circumference, abdominal circumference, and femur length), used alone and in combination, were developed in a cross-sectional study of 361 fetuses between 14 and 42 menstrual weeks. The head circumference and femur length were the strongest individual predictors of age. A number of combinations of fetal parameters, including the combination of head circumference and femur length, provided age estimates that were significantly better (p = 0.05) than those using any single parameter alone. It was also demonstrated that simply averaging individual age estimates in a given case could provide results that were not significantly different from those obtained by using the same parameters in a complex regression equation. The advantages and potential pitfalls of this system of fetal dating are discussed.

Abdomen↗
PubMed1984

Relation of fetal femur length to neonatal crown-heel length.

Sonographically measured femur lengths in 102 fetuses were compared with neonatal crown-heel lengths within 72 hours of delivery. The optimal model for describing crown-heel length as a function of femur length was a linear model, with a coefficient of determination (r2) of 66 per cent; the standard deviation in predicting crown-heel length from femur length was 2.4 cm. These data were compared with autopsy data from the literature, which showed an even stronger correlation between femur length and crown-heel length. Because of the strong correlation between these two dimensions, the femur length should prove useful in the detection of intrauterine growth retardation when crown-heel length is compromised. It should also be useful as a variable in the prediction of fetal weight in utero, since crown-heel lengths at the extremes of normal can significantly affect in utero weight estimates using ultrasound.

Body Height↗
PubMed1984

The femur length/head circumference relation in obstetric sonography.

The relationship of sonographic femur length to biparietal diameter (BPD) in utero may be useful in detecting short-limb dwarfism, hydrocephaly, microcephaly, and measurement errors. Because BPD can be adversely affected by head shape changes (e.g., dolichocephaly), falsely high or low values of femur length/BPD could result. Because head circumference is less affected by head shape changes than is BPD, it should be a better standard of head size against which to judge limb length. The authors report normal values for the relationship between femur length and head circumference, based on a cross-sectional analysis of 361 normal fetuses (15-42 weeks) using real-time ultrasound.

Cephalometry↗
PubMed1983

Computer assisted analysis of fetal age in the third trimester using multiple fetal growth parameters.

A new technique is described for predicting menstrual age in the third trimester of pregnancy (28-42 weeks) using multiple fetal growth parameters (biparietal diameter, head circumference, abdominal circumference, femur length). Evaluation of this technique in 177 normal third trimester pregnancies demonstrated that significant improvement in the variability in predicting menstrual age can be achieved when two or more parameters are used collectively instead of a single parameter used individually. The optimal combination prior to 36 weeks was biparietal diameter, abdominal circumference, and femur length, while after 36 weeks the optimal combination was head circumference, abdominal circumference, and femur length. The use of these combinations resulted in smaller mean errors, standard deviations, and maximum errors. Regression equations and tables of normal values are provided to facilitate the use of this dating method.

Diagnosis, Computer-Assisted↗
PubMed1983

A date-independent predictor of intrauterine growth retardation: femur length/abdominal circumference ratio.

The relation between sonographically measured fetal femur length and abdominal circumference (expressed as femur length/abdominal circumference X 100) was studied in 361 normal pregnancies between 15 and 42 weeks. This ratio was found to be independent of menstrual age, with a normal range after 21 weeks (mean +/- 2 SD) of 22 +/- 2. This ratio also was evaluated as a predictor of intrauterine growth retardation in 30 cases using the 90th percentile (23.5) as the upper limit of normal, which resulted in identification of 63% of the growth-retarded fetuses. Because it is independent of menstrual age, this ratio should prove most useful in evaluating high-risk patients who present in the third trimester of pregnancy with no dates. It is also of value in detecting growth retardation in patients with good menstrual history, since it was shown to become abnormal in asymmetrically growth-retarded fetuses before the estimated weight fell below the 10th percentile.

Abdomen↗
PubMed1983

A prospective evaluation of fetal femur length as a predictor of gestational age.

Variability (+/- 2 SD) in prediction of fetal gestational age from ultrasonographic measurements of fetal femur length was evaluated prospectively in 287 fetuses between 18 and 42 weeks' gestation. Variability increased throughout pregnancy, ranging from +/- 11.6 days between 18 and 24 weeks to +/- 22.7 days in the last six weeks of pregnancy. These findings are comparable with variability in prediction of gestational age from biparietal diameter measurement between 18 and 42 weeks, which indicates that the femur length may serve as an adequate alternative for prediction of gestational age in cases in which the biparietal diameter cannot, for technical reasons, be obtained.

Female↗
PubMed1983

Ultrasonic demonstration of ectopic ureterocele.

The gray scale ultrasound findings in two children with ectopic ureterocele are presented and correlated with traditional radiographic findings. In one case, the diagnosis was made in utero, utilizing ultrasound. The examination is noninvasive and performed quickly, and it may be able to replace the intravenous pyelogram in the initial evaluation of patients suspected of having such congenital anomalies. Retrograde cystography will still be necessary to detect vesicoureteral reflux.

Adult↗
PubMed1982

Longitudinal studies of fetal growth with the use of dynamic image ultrasonography.

To characterize the growth of individual fetuses, serial measurements of the crown-rump length (CRL), biparietal diameter (BPD), head circumference (HC), and abdominal circumference (AC) were made at specified intervals of 2 to 3 weeks (between 6 to 8 weeks [conceptual age] and delivery) in 20 normal fetuses with known dates of conception. Values for the HC-AC ratio and the estimated fetal weight were also obtained from these data. Measurements of CRL were similar to those reported previously, except in those cases in which the follicular phase was prolonged or the fetal growth potential was reduced. Mathematical modeling demonstrated that the linear-cubic model was optimal for the BPD and HC growth curves, the linear model for the AC, and the linear-quadratic model for fetal weight. The HC-AC ratio could not be modeled adequately because of significant individual variability. Optimal models for average longitudinal growth curves were determined for the BPD, HC, AC, and fetal weight from individual growth curves. These average longitudinal curves were similar in shape, mean values, and variability to those obtained in previous cross-sectional studies. Statistical analysis indicated that the coefficients of the average longitudinal curves are not likely to change by more than 5% to 15% if the size of the sample is increased very significantly. These results indicate that the average longitudinal growth curves are good estimators of the true population growth curves.

Adult↗
PubMed1982

Ultrasonically determined menstrual age as an indicator of fetal lung maturity.

The usefulness of ultrasonically determined menstrual age as a predictor of fetal lung maturity has been evaluated in patients without fetal or maternal disease undergoing repeat cesarean section. The menstrual age of each fetus was determined at 18-32 wk using biparietal diameter (BPD) measurements and previously established BPD growth curves. Lung maturity prior to delivery was assessed by measuring the lecithin/sphingomyelin (L/S) in amniotic fluid. The menstrual age at the time of the amniocentesis was derived by extrapolation from the results of the first scan. When the Sabbagha Composite BPD growth curve was used for menstrual age determinations, the L/S was less than 2.0 in all cases before 34 wk, both less than 2.0 and greater than or equal to 2.0 between 34 and 38 wk, and greater than or equal to 2.0 in all but one case after 38 wk. This one case represents 1.2% of fetuses studied. These results suggest that in the absence of fetal and maternal disease, a menstrual age of 38 wk or older, based on an early BPD measurement and use of the Sabbagha Composite BPD growth curve, is indicative of lung maturity in most cases.

Female↗