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PubMed2002

Prognostic role of umbilical artery Doppler velocimetry in growth-restricted fetuses.

OBJECTIVE: To correlate umbilical artery Doppler velocimetry with perinatal outcome in a group of growth-restricted fetuses. DESIGN: The study was a retrospective analysis of 578 singleton pregnancies with diagnosis of intrauterine growth restriction (IUGR), delivered in a single obstetric unit, at the Spedali Civili, Brescia, Italy, a university and teaching hospital with 3500 deliveries a year and neonatal intensive care unit (NICU). METHODS: During 1991-99 we studied 578 pregnancies with a diagnosis of IUGR referred for Doppler velocimetry. From this population, four subsets were formed: normal umbilical artery pulsatility index (NUAPI; 334 fetuses); increased pulsatility index but with telediastolic flow (abnormal umbilical artery pulsatility index AUAPI; 137 fetuses); absent end-diastolic flow (AEDF; 70 fetuses); reverse telediastolic flow (RF; 37 fetuses). Fetal biometry, amniotic fluid and fetal-maternal Doppler velocimetry were evaluated in all patients, with biophysical profile and routine non-stress test, when indicated. The following outcomes were examined: mean gestational age at delivery, number of preterm deliveries (< 34 weeks), mean neonatal weight, Apgar score at 5 min < 7, prenatal and neonatal deaths (within the first 28 days of life), admission to the NICU and number of days spent after birth in hospital. Neonatal morbidity was analyzed, including respiratory distress syndrome (RDS), intraventricular hemorrhage (IVH, grade 2-3), necrotizing enterocolitis (NEC) and retinopathy of prematurity. Long-term neurological follow-up is still ongoing and will not be presented in this paper. RESULTS: Out of 578 fetuses with IUGR, 547 were born alive. There were 26 neonatal deaths. The mean gestational age at delivery was 35.6 +/- 4 weeks and mean birth weight 1844 +/- 612 g. There were 28 intrauterine deaths and three elective terminations of pregnancy. A total of 60 cases (11%) were complicated by RDS, 13 cases (2.4%) by retinopathy of prematurity, IVH was present in nine cases (1.6%) and NEC in seven cases (1.3%). Total perinatal mortality was 9.8%; in the 26 cases of neonatal death, the mean week at delivery was 29.6 +/- 4 with a mean weight of 840 +/- 425 g. Patients with NUAPI had a mean week at delivery of 37 +/- 3, those with AUAPI delivered at 34 +/- 3.2, those with AEDF delivered at 31 +/- 3 and those with RF delivered at 29 +/- 2 weeks. In progressively worsening umbilical velocimetry, we observed an increase of incidence of low Apgar score. Days of admission to the NICU and incidence of perinatal mortality increased with the worsening of Doppler velocimetry. CONCLUSIONS: Our study underlines the existence of a strict correlation between umbilical Doppler velocimetry and an increased incidence of perinatal complications in IUGR fetuses.

Blood Flow Velocity↗

PubMed2002

Age-related effects on leaf area/sapwood area relationships, canopy transpiration and carbon gain of Norway spruce stands (Picea abies) in the Fichtelgebirge, Germany.

Stand age is an important structural determinant of canopy transpiration (E(c)) and carbon gain. Another more functional parameter of forest structure is the leaf area/sapwood area relationship, A(L)/A(S), which changes with site conditions and has been used to estimate leaf area index of forest canopies. The interpretation of age-related changes in A(L)/A(S) and the question of how A(L)/A(S) is related to forest functions are of current interest because they may help to explain forest canopy fluxes and growth. We conducted studies in mature stands of Picea abies (L.) Karst. varying in age from 40 to 140 years, in tree density from 1680 to 320 trees ha(-1), and in tree height from 15 to 30 m. Structural parameters were measured by biomass harvests of individual trees and stand biometry. We estimated E(c) from scaled-up xylem sap flux of trees, and canopy-level fluxes were predicted by a three-dimensional microclimate and gas exchange model (STANDFLUX). In contrast to pine species, A(L)/A(S) of P. abies increased with stand age from 0.26 to 0.48 m(2) cm(-2). Agreement between E(c) derived from scaled-up sap flux and modeled canopy transpiration was obtained with the same parameterization of needle physiology independent of stand age. Reduced light interception per leaf area and, as a consequence, reductions in net canopy photosynthesis (A(c)), canopy conductance (g(c)) and E(c) were predicted by the model in the older stands. Seasonal water-use efficiency (WUE = A(c)/E(c)), derived from scaled-up sap flux and stem growth as well as from model simulation, declined with increasing A(L)/A(S) and stand age. Based on the different behavior of age-related A(L)/A(S) in Norway spruce stands compared with other tree species, we conclude that WUE rather than A(L)/A(S) could represent a common age-related property of all species. We also conclude that, in addition to hydraulic limitations reducing carbon gain in old stands, a functional change in A(L)/A(S) that is related to reduced light interception per leaf area provides another potential explanation for reduced carbon gain in old stands of P. abies, even when hydraulic constraints increase in response to changes in canopy architecture and aging.

Germany↗

PubMed2001

Antenatal assessment of the growth restricted fetus.

Babies who are small due to intrauterine growth restriction are at higher risk for poor perinatal and long-term outcome than those who are appropriately grown. Through multiple antenatal testing modalities a sequence of deteriorating fetal status can be documented in such cases. The nature of this compromise is best reflected by the combination of fetal biometry, biophysical profile scoring and arterial and venous Doppler. This combination accurately defines fetal states and therefore risk of stillbirth or poor transition to extrauterine life. In the preterm neonate, fetal factors, gestational age and neonatal course interact significantly to impact on short- and long-term outcomes. The potential for iatrogenic prematurity is great and ongoing appraisal of peripartum management is critical. An integrated management protocol accounting for these factors is examined in this review.

Amniotic Fluid↗

PubMed1984

Ultrasound estimation of gestational age.

Many ultrasonologists feel that if they are unable to obtain a BPD measurement at the time of an ultrasound examination that they have somehow failed to do an adequate job. However, from the information outlined in this chapter, it can be seen that the biparietal diameter is only one measurement that can be taken of the fetus in order to estimate gestational age. Furthermore, since the recognition of variability in fetal head shape, absolute reliance on measurement of the fetal biparietal diameter for estimation of gestational age has become much less common, especially after 20 weeks of gestation. The move toward measurement of several parts of the fetal anatomy has been called fetal biometry. The purpose of this approach is to evaluate body proportion and symmetry of growth of different organ systems, in the hope of elucidating subtle patterns which might be recognized as abnormal in very early stages when some form of prenatal management might improve reproductive outcome. Simultaneously, with the implementation of this approach to estimating age, a desire to inject an element of "quality control" into the obstetric ultrasound examination has come about. It has been found that measurement of more than one fetal parameter, in a sense, prevents overreliance on any single measurement, which, by itself, might mislead the clinician. While an error of clinically significant magnitude can be made in any measurement, it is unlikely that an error of the same magnitude, in "the same direction" of over or underestimation of the actual, would occur. Thus, there is an element of protection of the patient built into this approach which makes it appealing intuitively. However, it is uncertain that measurement of BPD, head circumference, abdominal circumference, and femur length will, in all cases, give a better estimate of gestational age than will measurement of the BPD alone. Recent data from Hadlock et al. showed that in 177 normal pregnancies, there was significant improvement in the ultrasound estimation of estimated date of delivery when two or more parameters were used to make that estimate rather than just BPD alone. Prior to 36 weeks, the optimal combination of parameters included the biparietal diameter, the abdominal circumference, and the femur length. However, after 36 weeks, the head circumference, abdominal circumference, and femur length gave the best estimate, with significant reduction in the mean errors, standard deviations, and size of maximum errors. Thus, it appears that the estimate using MFGP is both more accurate and precise than a single measurement.(ABSTRACT TRUNCATED AT 400 WORDS)

Abdomen↗

PubMed2000

Perspectives of those impacted: airline pilot's perspective.

The airline pilot operates within an environment that consists of circadian dysrhythmia, reduced atmospheric pressure, mild hypoxia, low humidity, and exposure to sound, vibration, cosmic-radiation, and magnetic-field exposure. These occupational exposures present physiological challenges to the long term health of the airline pilot. In particular, exposure to cosmic radiation and its carcinogenic potential have recently received considerable attention. Given the complexity of the environment and possible synergistic exposures, there is an immediate requirement for comprehensive research into both cosmic-radiation and magnetic-field exposures in airline pilots. In response, the Airline Pilots Association International in conjunction with the Medical University of South Carolina (Department of Biometry and Epidemiology) has initiated an extensive research program into these occupational exposures. These investigations include ground based calculations, flight-dose estimates, epidemiological survey and exposure assessment, and biological marker analysis.

Aircraft↗

PubMed1989

Dating through pregnancy: a measure of growing up.

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.

Age Determination by Skeleton↗

PubMed1994

Presbyopia and velocity of sound in the lens.

The elastic properties of lens matter change with age and this contributes to presbyopia. The changes in elasticity of lens matter could be the result of a change in water and soluble proteins (1) or a change in lens fiber cytoskeleton and membranes (2). If it is caused by (1) then the velocity of sound in the lens should change with age. If it is caused by (2) the velocity of sound in the lens will not change. Using the technique of continuous ultrasonographic biometry, the velocity of sound in clear lenses was measured in vivo in a group of 24 healthy subjects aged 15 to 45 years with a visual acuity of 6/6 or better. In this group maximum accommodative amplitude decreased with age. It was found that, despite the occurrence of presbyopia, the velocity of sound did not change with age. Our results support the hypothesis that age-related changes in lens fiber cytoskeleton and membranes are responsible for the change in elastic properties of lens matter and thus contribute to presbyopia.

Accommodation, Ocular↗

PubMed1999

Cycloplegia in African-American children.

PURPOSE: The selection of a cycloplegic agent depends on the desired outcome, the characteristics of the patient receiving the drug, and the associated risks. The Orinda Longitudinal Study of Myopia (OLSM) has used 1% tropicamide to assess the ocular components and cycloplegic refractions in a large cohort of predominantly Caucasian children. Although tropicamide has provided adequate cycloplegia and mydriasis for the OLSM cohort, conventional clinical wisdom and scientific investigations have suggested that tropicamide might not produce adequate cycloplegia and mydriasis for subjects with darker iris pigmentation. In this study one drop of 1% tropicamide followed by one drop of 1% cyclopentolate was used to determine their effectiveness in producing adequate cycloplegia and mydriasis for cycloplegic refraction and ocular component measurements in a group of African-American children. METHODS: Nineteen children [age range 5.5 to 15.6 years, mean 8.4 years +/- (SD) 2.5 years] were tested at Family HealthCare of Alabama, Eutaw, AL. Their accommodative responses were measured using a Canon R-1 autorefractor prior to and at 30, 45, and 60 min after instillation of one drop of 0.5% proparacaine, 1% tropicamide (Mydriacyl), and 1% cyclopentolate (Cyclogyl) in both eyes. A target of 20/155 letters in a 4x4 grid positioned behind a +6.50 diopter (D) Badal lens provided accommodative stimuli of 1.00 D, 2.00 D, and 4.00 D. RESULTS: All results are presented as mean +/-1 SD. Pupils, measured from video frames, dilated rapidly and maximally at 30 min after instillation of eye drops (7.3+/-0.5 mm) Predilation, the mean accommodative responses were 0.17+/-0.29 D for the 1.00 D stimulus, 1.01+/-0.40 D for the 2.00 D stimulus, and 2.77+/-0.74 for the 4.00 D stimulus. At 30 min after drop instillation, the responses were 0.07+/-0.14 D for the 1.00 D stimulus, 0.36+/-0.35 D for the 2.00 D stimulus, and 0.77+/-0.61 for the 4.00 D stimulus. Results were very similar at 45 and 60 min after drop instillation. CONCLUSIONS: Combining 1% tropicamide and 1% cyclopentolate was very effective in providing both cycloplegia and mydriasis adequate for ocular biometry and cycloplegic refractions 30 min after drop instillation in African-American children.

Accommodation, Ocular↗

PubMed2000

Refractive errors in Singapore and Xiamen, China--a comparative study in school children aged 6 to 7 years.

PURPOSE: To compare and contrast the prevalence of myopia and other refractive errors in Xiamen city, Xiamen countryside (Southern China), and Singapore. METHODS: One hundred thirty-two schoolchildren aged 6 to 7 years from Xiamen city, 104 from Xiamen countryside, and 146 from Singapore city were recruited to join the study. Cycloplegic autorefraction, keratometry, and biometry measurements were performed on all children. RESULTS: The prevalence of myopia was 12.3% in Singapore city, 9.1% in Xiamen city, and 3.9% in Xiamen countryside. The prevalence of astigmatism was higher in Singapore compared with Xiamen. The rates of hyperopia and anisometropia were similar in all three locations. CONCLUSIONS: The myopia rate in Singapore city was higher than in Xiamen city; the lowest rates were found in Xiamen countryside. As the Chinese population from all three sites is of similar genetic stock (predominantly from Southern China), it is postulated that the differences in myopia rates in these three localities may be related to environmental factors.

Anisometropia↗

PubMed2000

Ocular components before and after acquired, nonaccommodative esotropia.

BACKGROUND: Acquired nonaccommodative esotropia describes the sudden onset of a constant, comitant strabismus of idiopathic origin in children >6 months of age. CASE REPORT: We present a case of acquired nonaccommodative esotropia at 20 months of age in a subject participating in the Berkeley Infant Biometry Study, a longitudinal study of emmetropization and ocular component development in infants between 3 months and 3 years of age. Ocular components for this child were normal before the onset of strabismus (within 2 SD's of the mean for orthotropic study participants) for refractive error, corneal power, lens radii, lens power, and ocular axial dimensions. Refractive error postsurgically was significantly more hyperopic and crystalline lens power lower than average at +2.38 D and 37.2 D, respectively. CONCLUSIONS: The lack of abnormal ocular parameters is consistent with the idiopathic etiology of acute onset esotropia. This case suggests that ocular component values may not be useful for assessing the risk of acquired nonaccommodative esotropia.

Accommodation, Ocular↗

PubMed1996

Complete ring melanoma of the choroid.

BACKGROUND: Ring melanoma of the uvea is a term generally applied to elongated, circumferentially oriented malignant melanomas of the iris and ciliary body; a complete ring melanoma involving almost exclusively the choroid is extremely uncommon. METHODS: The authors present a case report and clinicopathologic correlation of complete ring melanoma of choroid managed by enucleation. RESULTS: A 74-year-old woman was found to have a diffuse, melanotic thickening of the midzonal to peripheral choroid circumferentially for 360 degrees and an associated subtotal serous retinal detachment with shifting subretinal fluid in her left eye. The thickest portion of the mass measured only 2.3 mm by ultrasound biometry. The eye was enucleated, and histopathologic analysis confirmed a diffuse malignant melanoma composed predominantly of spindle B cells. CONCLUSIONS: A complete ring melanoma of the choroid is a rare and unusual variant of diffuse uveal malignant melanoma. The pertinent differential diagnosis of choroidal ring melanoma includes diffuse choroidal melanocytoma, choroidal melanocytosis associated with ocular melanocytosis, bilateral diffuse uveal melanocytic proliferation associated with systemic carcinoma, and diffuse uveal lymphocytic infiltration.

Aged↗

PubMed1997

Clinical and ultrasound study of peripheral vitreoretinal adhesions.

PURPOSE: To evaluate the frequency of peripheral vitreoretinal adhesions in the region of the vitreous base by ultrasound examination in relation to axial length of the eye and the age of the patient. Patient gender and the presence of visual symptoms also were considered. METHODS: A total of 228 consecutive patients (445 eyes) underwent biometry, ultrasound examination, and biomicroscopic fundus examination. Their medical history also was taken. The patients were divided into three groups according to axial length of the eye (< 24 mm, 24-26.5 mm, and > 26.5 mm) and into three age groups (20-40 years, 41-60 years, and > 60 years). RESULTS: No correlations was found between peripheral vitreoretinal adhesions and gender or between peripheral vitreoretinal adhesions and axial length of the eye. A significant correlation was found between peripheral vitreoretinal adhesions and age (P < 0.001). The proportion of adhesions increased with age (P < 0.001). The association between adhesions and presence of symptoms also was significant (P < 0.001). Multivariate analysis showed that only the presence of symptoms independently correlated with adhesions (relative risk, 1.71, 95%; confidence interval, 1.19, 2.46). CONCLUSION: Our study shows that peripheral vitreoretinal adhesions, detected by ultrasound, were always associated with the presence of symptoms.

Adolescent↗

PubMed1999

Axial length in patients with diabetes.

PURPOSE: To investigate the relationship between axial length and retinal involvement in patients with diabetes. METHODS: A total of 157 consecutive patients with diabetes underwent biometry. The patients were divided into three groups, according to retinopathy: 44 without retinopathy, 37 with background retinopathy, and 76 with proliferative retinopathy. To compare axial length in diabetic versus nondiabetic subjects, a control group of 157 healthy subjects with age and sex distribution similar to the diabetic group was selected from an orthopedic clinic. We investigated in the diabetic group whether the axial length was related to specific type of diabetes (non-insulin-dependent or insulin-dependent), duration of disease, presence of retinopathy, or laser treatment. To eliminate the confounding effect of myopia, we excluded all patients with axial length greater than 24 mm from the two groups. Comparison of diabetic patients without retinopathy versus nondiabetic subjects was also performed. RESULTS: Diabetic patients presented shorter axial lengths compared with the controls (mean +/- standard deviation, 22.4+/-1.3 mm versus 23.4+/-1.3 mm; P<0.001). Significantly shorter axial lengths were found in the background and proliferative retinopathy groups compared with the group without retinopathy (22.0+/-1.2 mm and 22.1+/-1.1 mm versus 23.2+/-1.4 mm, respectively; P<0.05). No difference in axial length was found between the diabetic patients without retinopathy and the nondiabetic subjects (P = 0.3). Multivariate analyses showed that retinopathy was negatively correlated with axial length (P<0.01). Including only the patients with axial length under 24 mm, we obtained similar results. CONCLUSION: Axial length is shorter in diabetic patients than in nondiabetic subjects. Within the diabetic group, patients with retinopathy had shorter axial lengths than did patients without retinopathy.

Anthropometry↗

PubMed2003

Treating astigmatism at the time of cataract surgery.

An increasingly important goal of modern cataract and implant surgery is to obtain the most desirable refractive outcome for our patients, and in so doing, decrease their dependence upon spectacle correction. Refined spherical outcomes are now achieved by directing close attention to biometry technique, through the use of third generation intraocular lens (IOL) power formulae, and refinements in technology such as partial coherence interferometry. Similarly, improvements in astigmatic outcomes are now possible by focusing upon and obtaining more accurate preoperative cylinder measurements, careful surgical planning particularly in regard to incision(s) design, use of toric IOLs, and employing advanced postoperative enhancement techniques. Because of these refinements in technique and technology, the field of cataract and implant surgery has emerged as a true and recognized form of refractive surgery.

Astigmatism↗

PubMed2001

Primary congenital glaucoma: three case reports on novel mutations and combinations of mutations in the GLC3A (CYP1B1) gene.

PURPOSE: To describe three patients with congenital glaucoma homozygous and compound heterozygous for different mutations and benign sequence variants in the cytochrome P 450 1B1 (CYP1B1) gene. METHODS: All patients were examined by slit-lamp biomicroscopy, gonioscopy, measurement of the cornea and optic disc, ultrasound biometry, and automated static threshold perimetry when possible. Direct sequence analysis was performed on DNA extracted from peripheral blood from the patients and their parents. RESULTS: For patient 1, a newborn boy with buphthalmos and an opaque cornea, a novel homozygous C/T transition in codon 355 (CGA>TGA) led to a predicted nonsense codon Arg355X truncating the protein by 188 amino acids. For patient 2, a 24-year-old man, a compound heterozygous mutation 1410-1422del/1546-1555dup was found. For patient 3, a 34-year-old man, two novel heterozygous missense mutations resulting in an Ala443Gly and a Glu229Lys amino acid exchange and five benign sequence variants were found. CONCLUSION: Our results confirm the crucial role of CYP1B1 mutations for congenital glaucoma.

Adult↗

PubMed2003

Primary congenital glaucoma: a novel single-nucleotide deletion and varying phenotypic expression for the 1,546-1,555dup mutation in the GLC3A (CYP1B1) gene in 2 families of different ethnic origin.

PURPOSE: To present new molecular genetic data on primary congenital glaucoma from 2 families, 1 isolated case and 3 familial cases due to mutations in the cytochrome P-450 1B1 (CYP1B1) gene. METHODS: All diagnoses were made by slit-lamp biomicroscopy, gonioscopy, cornea and optic disk measurements, ultrasound-biometry, and automated static threshold perimetry where possible. Mutation screening was performed by direct sequence analysis of DNA extracted from peripheral blood of the patients and their relatives. RESULTS: For the isolated case, a child of 4 years, a homozygous nucleotide deletion within a tetrad of cytosines (nt622-625, 622delC) was found leading to a predicted nonsense codon 93 truncating the protein by 450 amino acids. For the familial cases, the 3 affected members showed a homozygous mutation 1,546-1,555dupTCATGCCACC for which 9 healthy relatives proved to be heterozygous. The phenotypic expression of these 3 patients varied widely. CONCLUSION: Our results confirm the crucial role of CYP1B1 mutations for congenital glaucoma.

Aryl Hydrocarbon Hydroxylases↗

PubMed2003

Angle-closure glaucoma in teenagers.

OBJECTIVE: To report the occurrence of angle-closure glaucoma in 2 teenagers. DESIGN: Observational case reports, review of literature. METHODS: Review of case histories, examinations, biometries, visual fields, and ultrasound biomicroscopy findings in 2 teenagers with angle-closure glaucoma. MAIN OUTCOME MEASURES: Intraocular pressure, gonioscopy, Humphrey 24-2 visual field (SITA Standard), and ultrasound biomicroscopy. RESULTS: The first case involved a 15-year-old white male who presented with an intraocular pressure of 60 mm Hg in the right eye and 24 mm Hg in the left eye and 360-degree appositional closure in both eyes. Ultrasound biomicroscopy revealed prominent bilateral ciliary pigment epithelial cysts pushing the iris anteriorly towards the angle. The second case involved a 14-year-old white male with a strong family history of primary angle-closure glaucoma. The patient had pupillary block and an intraocular pressure of 24 mm Hg in the right eye and 40 mm Hg in the left eye on routine eye examination. Gonioscopy and ultrasound biomicroscopy revealed appositional closure of the angle in all 4 quadrants bilaterally. CONCLUSION: Primary angle-closure glaucoma is uncommon in younger individuals. Therefore, the finding of angle-closure glaucoma in a young individual should alert the physician to the possibility of a secondary cause of angle closure, such as iris pigment epithelial cysts. In addition, special attention to family history is important as the configuration of an occludable anterior chamber angle may, in some instances, be inherited.

Adolescent↗

PubMed2005

Magnetic resonance imaging pelvimetry and the prediction of labor dystocia.

OBJECTIVE: To study whether magnetic resonance imaging (MRI) pelvimetry has the ability to identify those women who require cesarean delivery for labor dystocia. METHODS: From July 2003 to April 2004, nulliparous women scheduled for a labor induction for prolonged pregnancy (42 weeks) were asked to participate in a pelvimetry study. Those who consented underwent fast-acquisition MRI that included two 90-second acquisitions to evaluate fetal biometry and volumetry and maternal pelvimetry, including novel measurements of pelvic bony and soft tissue volumes as determined by MRI. Information about each patient's pregnancy, labor course, and neonatal outcome was prospectively collected. Pelvimetry results for those women undergoing operative delivery for labor dystocia were compared with those who did not. Single fetal and maternal pelvic measurements, as well as ratios of both, were analyzed. In addition, previously described radiographic pelvimetry techniques and formulas to predict dystocia were used. RESULTS: One hundred one women underwent MRI, and 22 of these underwent cesarean delivery for dystocia. No single fetal measurement was statistically associated with dystocia. Several maternal pelvic measures, fetal-to-maternal ratios, and previously reported pelvimetric techniques were significantly associated with dystocia. The ratio of magnetic resonance (MR) fetal head volume to pelvic soft tissue volume had statistical significance (P = .04). Receiver operator characteristic curves were developed for the different measurements, ratios, and formulas studied to assess whether any of the techniques could accurately predict labor dystocia requiring operative delivery. The area under the curve values ranged from 0.6 to 0.8, with the ratio of MR head volume to pelvic soft tissue being 0.7. These values suggest that MRI can identify those women at greatest risk for dystocia, but it cannot with accuracy predict which ones will require a cesarean. CONCLUSION: We found significant associations with MRI pelvimetry and labor dystocia, but MRI was not a significant improvement over previously described pelvimetric techniques. LEVEL OF EVIDENCE: II-3.

Adult↗