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PubMed1988

Sonographic estimation of fetal weight and Doppler analysis of umbilical artery velocimetry in the prediction of intrauterine growth retardation: a prospective study.

A prospective study was undertaken to examine whether Doppler velocimetry studies of the umbilical artery give a better or an earlier prediction of intrauterine growth retardation (IUGR) than do sonographic estimation of fetal weight. A total of 385 examinations were performed between 30 and 42 weeks of gestation on 168 patients who were at risk for IUGR. Forty-two (25%) of the patients delivered an infant with a birth weight below the tenth percentile. Although sensitivity was lower for the systolic to diastolic ratio (55%) of the umbilical artery than for the sonographic estimation of fetal weight (76%), the umbilical artery studies had a higher specificity (92% versus 80%) and predictive value of a positive test (73% versus 58%) when the last study to delivery interval was within 2 weeks. Furthermore, among 21 IUGR pregnancies with serial studies, the umbilical systolic to diastolic ratio was abnormal at a significantly earlier gestational age than when the sonographic estimate of fetal weight identified growth retardation. These findings indicate that sonographic biometry is a more sensitive technique for identifying IUGR but that the umbilical artery waveforms are a valuable adjunct for improving the diagnostic accuracy for the prenatal detection of IUGR. These data also provide suggestive evidence that umbilical artery velocimetry may be predictive of IUGR at an earlier gestational age than sonographic estimation of fetal weight.

Adult↗

PubMed1991

The effect of trisomy 18 on transverse cerebellar diameter.

The transverse cerebellar diameter was measured in 19 fetuses with trisomy 18. Eleven of the cerebellar measurements (57.9%) were greater than 2 SD below the mean for the patient's gestational age. If fetal biometry rather than last menstrual period were used to determine gestational age, four of the 19 (21.0%) cerebellar measurements were greater than 2 SD below the mean. Both intrauterine growth retardation and intrinsic central nervous system abnormalities associated with trisomy 18 appeared to affect cerebellar size.

Cerebellum↗

PubMed1992

Fetal humeral length to detect Down syndrome.

OBJECTIVE: Our aim was to evaluate the utility of ultrasonographic humeral length measurements for detection of fetuses with Down syndrome in the midtrimester of gestation. STUDY DESIGN: Ultrasonographic biometry data obtained before genetic amniocenteses on 43 fetuses with Down syndrome and 204 randomly chosen normal fetuses were analyzed. Regression equations relating biparietal diameter to humeral length and femoral length were used to calculate ratios of observed-to-expected length and sensitivity and specificity at various cutoff points. RESULTS: Humeral length in Down syndrome fetuses was significantly shorter than in normal controls (p less than 0.001). A ratio of 0.90 for observed/expected humeral length yielded a sensitivity of 28%, a specificity of 91%, and positive predictive values of 1.23% and 0.41% in populations at risk for Down syndrome of 1 in 250 and 1 in 750, respectively. The equivalent ratio for femoral length yielded a sensitivity of 19%, a specificity of 91%, and positive predictive values of 0.87% and 0.28% for baseline risks of 1 in 250 and 1 in 750, respectively. CONCLUSIONS: The sensitivity of fetal humeral length measurements for Down syndrome detection in our hands was remarkably lower than previously reported. Independence of this parameter from currently used serum screening markers has not been established; therefore implementation in screening programs is not advisable at this point.

Down Syndrome↗

PubMed1995

A new method for on-screen ultrasonographic determination of fetal cardiac axis.

OBJECTIVE: Our purpose was to develop an ultrasonographic method of using multiple electronic calipers for on-screen measurement of fetal cardiac axis. STUDY DESIGN: Two hundred low-risk patients who were seen for antenatal ultrasonography were studied. Standard biometry, anatomic survey, and echocardiography were performed on all fetuses. By use of a four-chamber view fetal cardiac axis was measured with electronic calipers. A table, derived from a trigonometric formula, was created to convert the caliper measurements to cardiac axis in degrees. The results were compared with a protractor-determined fetal cardiac axis. RESULTS: All echocardiograms had normal results. Fetal cardiac axis (+/- 2 SD) by the ultrasonographic method was 43 degrees (+/- 16 degrees) versus 43 degrees (+/- 14 degrees) by the protractor method. This difference was not significant. CONCLUSION: An on-screen method to determine fetal cardiac axis by use of multiple calipers is described. It is comparable to a protractor-measured fetal cardiac axis.

Echocardiography↗

PubMed1989

Custom orbital implant in the repair of late posttraumatic enophthalmos.

We repaired late, posttraumatic enophthalmos in 21 patients by inserting a large, soft, Silastic block through a lower eyelid flap and transconjunctival approach to the orbit. These blocks were hand carved at the time of surgery to match bony defects as characterized by hypocycloidal tomographic biometry. Enophthalmos and hypo-ophthalmos were ameliorated with acceptable appearance in all cases. No implant rejections, migrations, or infections were found. Complications included upper eyelid blepharoptosis, lower eyelid retraction, and conjunctival prolapse. The improvements were stable over a median follow-up of 13 months.

Adult↗

PubMed1976

Interactive editing of biomedical data.

Editing options of an interactive graphical-biometry statistical system are described. A method for screening using a highly reduced data file is illustrated. By utilizing properties of sample Fourier coefficients, the problem of component overlap can be resolved. This, in turn, tends to free edited statistical information from the contamination or truncation inherent in the usual screening process.

Data Display↗

PubMed1989

Functional morphology of accommodation in the raccoon.

The raccoon (Procyon lotor) is a small carnivore which eats in the upright position, using hand- and finger-like front paws and digits to wash, hold and examine its food at close range. These anatomic and behavioral characteristics prompted structural and functional studies of the accommodative capability of this species. By light and electron microscopy, we observed a prominent ciliary smooth muscle and zonular apparatus. When stimulated by carbachol or pilocarpine, the muscle and zonular apparatus exhibited a shift from longitudinal to reticular or circular orientation of some ciliary muscle bundles, anterior movement of the muscle as a whole, and more oblique crossing of the zonular fiber bundles in the zonular plexus. Maximum carbachol-induced accommodative amplitude measured by coincidence refractometry ranged from 3 to 19 diopters in these 1 to 9 yr old animals, with no definite age-accommodation relationship. A-scan ultrasonographic biometry showed that during accommodation the lens thickened very little, if at all, but moved anteriorly, while the apparent cornea to retina distance increased slightly. The raccoon thus exhibits the greatest accommodative capability of any non-primate terrestrial mammal so far studied.

Accommodation, Ocular↗

PubMed1990

Vaginosonographic detection of endometrial cancer in postmenopausal women.

In a prospective study 155 postmenopausal women not on hormone treatment underwent a vaginal ultrasound investigation. All women were routine patients of the regular ambulance. In addition to uterus biometry, the endometrial thickness was also measured. An endometrium of greater than or equal to 4 mm thickness was clarified histologically by means of a curettage. In total we found 7 endometrial cancers and 1 cervical cancer. Vaginal sonography proved to be a very sensitive (81%) and specific (89%) method for the detection of endometrial neoplasia.

Aged↗

PubMed1995

Growth pattern of the Indian fetus.

OBJECTIVES: To determine the pattern of intrauterine growth and the gestation at birth of Indian fetuses. METHOD: One hundred twenty consecutive women who had reliable menstrual histories, low-risk pregnancies and who were booked for delivery at the Christian Medical College Hospital, Vellore, before 20 weeks' gestation were recruited to the study. Ultrasound fetal biometry was carried out at 4-weekly intervals from 20 weeks and at weekly intervals after 36 weeks until delivery. RESULTS: Growth patterns of fetal biparietal diameter and femur length were comparable to those reported in Western populations. However there was a lag in growth of abdominal circumference (AC) after 28 weeks in comparison with that reported in Western populations. The median gestation at delivery following spontaneous labor was 39 weeks. No association was observed between rate of growth of AC and gestation at birth. CONCLUSION: Slowing of growth of the fetal AC after 28 weeks and a shorter length of gestation result in the birth of smaller babies in this ethnic group. The implications of these findings are discussed.

Adult↗

PubMed1992

Correlation of subjective assessment of amniotic fluid with amniotic fluid index.

We assessed the correlation between abnormal amniotic fluid volumes as defined by the two techniques of (1) subjective evaluation and (2) the amniotic fluid index. Ultrasound evaluation of amniotic fluid volume was conducted on 420 pregnant women with known gestational age greater than twenty weeks but less than 42 weeks. Amniotic fluid was evaluated subjectively and placed into one of three categories: normal, oligohydramnios or polyhydramnios. After fetal biometry was performed, the amniotic fluid volume was assessed semi-quantitatively by the amniotic fluid index technique and assigned to similar categories. We analyzed the data with 2 x 2 contingency tables, using amniotic fluid index as the 'gold standard test'. Our study demonstrates that there was moderate agreement (kappa.5) between both amniotic fluid techniques in the identification of oligohydramnios. However, agreement between the techniques was poor for the identification of polyhydramnios (kappa.16).

Amniotic Fluid↗

PubMed1996

The use of second-trimester genetic sonogram in guiding clinical management of patients at increased risk for fetal trisomy 21.

OBJECTIVE: To test the efficacy of ultrasound in detecting fetuses with trisomy 21. METHODS: From November 1, 1992, to December 31, 1995, a second-trimester genetic sonogram was offered to all women with singleton fetuses at increased risk (at least 1:274) for trisomy 21, who had either declined genetic amniocentesis or chose to have a sonogram before deciding whether to undergo an amniocentesis. In addition to standard fetal biometry, the following ultrasound markers for aneuploidy were evaluated: structural anomalies (including face, hands, and cardiac [four-chamber view and outflow tracts]), short femur, short humerus, pyelectasis, nuchal fold thickening, echogenic bowel, choroid plexus cysts, hypoplastic middle phalanx of the fifth digit, wide space between the first and second toes, and two-vessel umbilical cord. Outcome information included the results of genetic amniocentesis, if performed, or the results of postnatal pediatric assessment and follow-up. RESULTS: Five hundred seventy-three patients had a genetic sonogram between 15 and 23 weeks' gestation: 378 patients had advanced maternal age (at least 35 years), 141 had abnormal serum biochemistry, and 54 had both. The majority (495, or 86.3%) had a normal genetic sonogram (absence of abnormal ultrasound markers); 51 (9%) had one marker present, and 27 (4.7%) had two or more markers present. Outcome was obtained on 422 patients (the remaining were ongoing pregnancies or were lost to follow-up). Twelve of 14 fetuses with trisomy 21, one fetus with trisomy 13, and one fetus with triploidy had two or more abnormal ultrasound markers present; one fetus with trisomy 21 had one abnormal marker and one had a completely normal ultrasound. When one or more abnormal ultrasound markers were present, the sensitivity, specificity, and positive and negative predictive values for trisomy 21 were 92.8%, 86.7%, 19.4%, and 99.7%, respectively. When two or more abnormal ultrasound markers were present, the corresponding values were 85.7%, 96.8%, 48%, and 99.5%. In the study population, the amniocentesis rate was 12.7% overall and 17.3% in cases with known outcome. CONCLUSION: Second-trimester genetic sonogram may be a reasonable alternative for patients at increased risk for fetal trisomy 21 who wish to avoid amniocentesis. In experienced hands, this approach may result in a high detection rate of trisomy 21 (93%), with an amniocentesis rate of less than 20%.

Adult↗

PubMed1994

In vivo determination of the biomechanical properties of the component elements of the accommodation mechanism.

A method of obtaining in vivo information about the component elements of the accommodation mechanism is described. Changes in axial lens thickness during accommodation are measured continuously by ultrasonographic biometry. The measurements are fitted with a dynamic biomechanical model of the mechanism of accommodation. This gives a time constant that depends both on the direction of accommodation and on the properties of the lens, zonules and choroid. Two ratios can be calculated that give information about the visco-elastic properties of the lens, zonules and choroid. This information is especially useful to evaluate the changes that lead to presbyopia.

Accommodation, Ocular↗

PubMed2005

Non protein bound iron concentrations in amniotic fluid.

OBJECTIVES: To investigate whether amniotic fluid concentrations of non protein bound iron (NPBI) vary with growth in healthy fetuses and also offer a reference curve in the second trimester of pregnancy. DESIGN AND METHODS: Amniotic fluid concentrations of NPBI were measured by HPLC in 118 women with physiological singleton pregnancies, who underwent amniocentesis for fetal karyotype between weeks 15 and 18 of gestation. RESULTS: NPBI increased progressively from weeks 14--15 to weeks 15--16, peaking at 17--18 weeks of gestation. NPBI values regressed positively with gestational age (GA). Multiple linear regression analysis between NPBI, as dependent variable, and various fetal parameters, as independent variables, showed a statistically significant regression coefficient with GA, bi-parietal diameter and transverse cerebellar diameter. CONCLUSIONS: The present data constitutes the first quantification of NPBI concentrations in amniotic fluid under physiological conditions. Correlations with GA and ultrasound fetal biometry suggest that NPBI may play a role in fetal growth.

Adult↗

PubMed2006

Predictive value of a single early fetal weight estimate in normal pregnancies.

OBJECTIVES: To evaluate the accuracy of ultrasound-based fetal weight estimates made at 28-34 weeks of gestation in predicting small- and large-for-gestational-age infants (SGA, LGA) at term. METHODS: Two-hundred and fifty-nine patients with a healthy, singleton pregnancy in whom fetal biometry measurements were routinely performed between 28 and 34 weeks' gestation, were recruited at term delivery. The sonographic estimated fetal weight (EFW) and the birth weight were converted to percentiles on the basis of locally developed growth charts and compared. Multivariate linear stepwise regression analysis was used to predict the birth weight and birth weight percentile. The resulting equation (projectile formula) was used to determine the calculated birth weight, and that value was compared with the actual birth weight. The Bland and Altman plot and Passing and Bablok regression were used to compare between the calculated birth weight and the actual birth weight. RESULTS: Mean gestational age at ultrasound examination was 32+/-1.6 weeks (28-34), and mean age at delivery was 39+/-1.7 weeks (37-42). The multivariate correlation between the calculated birth weight and the birth weight (R2 = 0.524) was higher than the correlation between the sonographic EFW and the birth weight (R2 = 0.083). Both the sonographic EFW and the calculated birth weight are characterized by low positive predictive values in predicting SGA or LGA infants. The calculated birth weight was more accurate in excluding SGA and LGA infants (negative predictive values of 99.5% and 100%, respectively). On method comparison tests, the calculated birth weight was not significantly different than the actual birth weight. CONCLUSIONS: Fetal weight estimation at the early third trimester poorly predicts the birth weight centile at term. It remains uncertain, however, if it would be useful to use the calculated birth weight in pregnancies with clinically suspected SGA or LGA fetuses.

Adolescent↗

PubMed2004

Surgery for 4 refractive errors in 1 patient.

We report a case of cataract extraction with implantation of a multifocal intraocular lens (IOL) after photorefractive keratectomy for myopia and astigmatism and subsequent laser thermal keratoplasty for surgically induced hyperopia. Good refractive results were obtained using standard biometry techniques for calculation of the IOL power.

Cornea↗

PubMed2004

Using the lens haptic plane concept and thick-lens ray tracing to calculate intraocular lens power.

PURPOSE: To develop a methodology for intraocular lens (IOL) power calculation in which the task of predicting the postoperative position of the IOL is separated from the calculation itself. SETTING: Pharmacia, Groningen, The Netherlands. METHODS: The minimum biometry input needed for IOL power calculation is the mean anterior corneal radius and axial length of the eye. The lens haptic plane (LHP) is the plane where the IOL haptics make contact with eye tissue. It is an anatomical site (eg, the equator of the capsular bag) and is independent of the IOL model. The position of the IOL optic in relation to the LHP is determined from the exact design of the IOL. Gullstrand's eye model is adopted to obtain the posterior corneal radius, thickness of the cornea, and refractive indices of the eye media. Thick-lens ray tracing in the paraxial limit is used for the optical calculation. RESULTS: A spreadsheet is given for the calculation. CONCLUSIONS: The methodology developed allows for IOL power calculation from first principles (ie, using true physical distances, radii, and refractive indices as input for the optical calculation).

Algorithms↗

PubMed2004

Monocular versus binocular pupillometry.

PURPOSE: To quantify differences between monocular and binocular pupil size measurement under scotopic and mesopic conditions. SETTING: Department of Ophthalmology, Johannes Gutenberg-University, and Department of Medical Biometry, Epidemiology and Informatics, University of Mainz, Mainz, Germany. METHODS: Computerized dynamic pupillometry (P2000 SA, Procyon Instruments Ltd.) was used at 3 illumination levels: scotopic at 0.03 lux, mesopic low at 0.82 lux, and mesopic high at 6.4 lux. One hundred forty eyes of 70 healthy volunteers without ocular pathology were examined. The subjects were divided into 2 groups. In the first group, the pupil diameter was measured binocularly first. In the second group, monocular measurement was performed first. For statistical analysis, data description was based on medians and quartiles of the respective pupil diameter measurements. Intraindividual significance was based on sign tests, and interindividual comparison were based on 2-sample Wilcoxon tests. RESULTS: In all eyes, statistically significant differences were found in pupil size, with higher values for the monocular measurement under low and high mesopic conditions (P=.000). For scotopic conditions, a trend toward higher values in monocular measurement was observed that approached statistical significance. CONCLUSIONS: Results indicate that binocular measurement may imitate the patient's life conditions more realistically. Therefore, in eyes with a large pupil diameter with the risk for postoperative scotopic phenomena, binocular measurement should be considered before refractive surgery.

Adolescent↗

PubMed2006

Ultrasound energy and endothelial cell loss with stop-and-chop and nuclear preslice phacoemulsification.

PURPOSE: To evaluate ultrasound (US) energy and endothelial cell loss in cataract surgery using the stop-and-chop and nuclear preslice techniques. SETTING: Vision Institute, Federal University of São Paulo, São Paulo, Brazil. METHODS: This prospective clinical trial comprised 43 patients (50 eyes) with senile nuclear cataract who were randomly assigned to 1 of 2 groups: stop-and-chop (n=26) or nuclear preslice (n=24). The groups were divided according to nuclear density (NO(3) NC(3) and NO(4) NC(4)) using the Lens Opacity Classification System III. A full ophthalmic examination including biometry, specular microscopy, and pachymetry was performed preoperatively and postoperatively. The following parameters were evaluated: age, anterior chamber depth, lens thickness, axial length, phaco time and power, effective phaco time (EPT), infusion volume, ocular inflammation, endothelial cell loss, and best corrected visual acuity (BCVA). RESULTS: Phacoemulsification time, power, and EPT were significantly higher in the stop-and-chop group. Infusion volumes did not vary significantly between the groups. A significant decrease in endothelial cell density occurred postoperatively and was similar with both techniques (stop-and-chop, 8.70%; nuclear preslice, 8.72%). The BCVA improved significantly in both groups. No significant correlations were found between endothelial cell loss and either technique. CONCLUSIONS: Ultrasound energy consumption was lower with the nuclear preslice technique. Both techniques had similar results including endothelial cell loss.

Aged↗