predict IUGR and/or preeclampsia between 11-18 weeks of gestation. Notsurprisingly, abnormal placental volumes precedes abnormal fetal volume incase of preeclampsia and IUGR.

519 BIRTH WEIGHT DIFFERENCES BETWEEN HISPANICS AND AFRICAN-AMERICANS INA LARGE URBAN HOSPITAL WILLIAM DOBAK (F)1, B.D. RAYNOR2, 1Emory Uni-versity, Gynecology & Obstetrics, atlanta, Georgia, 2Emory University atGrady Health Systems, Atlanta, Georgia

OBJECTIVE: Previously developed institutional birthweight curveswere basedprimarily on African-Americans. As the population shifts to more Hispanicpatients, differences in birthweight distribution were evaluated. To comparedifferences in birthweights between African-Americans and Hispanics.

STUDY DESIGN: Data collected from the perinatal computerized databaseincluded ethnic group, gestational age, and birth weight. Normal distributionfor each gestational age was calculated; 10th, 50th, and 90th percentiles werederived.

RESULTS: Total of 25145 patients were included, 9601 African-Americanand 15544 Hispanic women. Hispanic neonates were heavier than theirAfrican-American counterparts between 25 and 43 weeks. The differencewas as high as 100 grams at 40 weeks. Differences in the 10th percentile weregreater than 100 grams from 36 weeks to 42 weeks.

CONCLUSION: There are differences in birth weight distribution betweenAfrican-Americans and Hispanic neonates which may affect diagnosis of large-and small-for gestational age in each group.

Birth weights

African-American Hispanic

Gestational age 10% 50% 10% 50%

36 2113 2580 2224 277037 2350 2820 2431 299038 2490 3020 2720 318039 2719 3210 2820 331040 2860 3330 2970 3430

520 SHORT CERVIX: DOES THE FOLLOW-UP MEASUREMENT PREDICT PRETERM DELIV-ERY? NATHAN S. FOX (F)1, CLAUDEL JEAN-PIERRE1, MLADEN PREDANIC1, STEPHENT. CHASEN1, 1Weill Medical College of Cornell University, Obstetrics and Gy-necology, New York, New York

OBJECTIVE: Shortened cervical length has been associated with pretermdelivery. Many patients diagnosed with a short cervix undergo serial ultra-sound cervical length measurements. Our objective was to assess if there wasfurther predictive value using the second measurement, and the change fromthe first to second measurement, of cervical length.

STUDY DESIGN: We searched our OB ultrasound database for all cervicallengths !26 mm at gestational ages 16 weeks to 28 weeks from July 2002through July 2005. All patients managed expectantly (no cerclage placement orelective termination of pregnancy) who had a follow-up measurement within 3weeks were included. Hospitalization and delivery data were obtained from thepatients’ computerized medical record.

RESULTS: 109 patients met criteria for inclusion. As of July 2005, deliverydata was available for 88 patients. The median initial cervical length was17.7mm and the median gestational age at first measurement was 22.57 weeks.The median time to the second measurement was 7 days. 38% of the patientshad a shorter cervical length on the second measurement. In these patients,there was a trend towards delivery before 37 weeks (60% vs. 38%, p=.07) andan earlier gestational age at delivery (median GA 36.43 vs. 37.85 weeks,p=.07). The initial cervical length correlated with gestational age at delivery(p=.002) and delivery less than 37 weeks (p=.04). The second cervical lengthmore strongly correlated with gestational age at delivery (p!.001), deliveryless than 37 weeks (p=.002) and with delivery less than 34 weeks (p=.03). Theinterval change in cervical length measured in absolute mm, mm/day, and %change all significantly correlated with gestational age at delivery.

CONCLUSION: In patients diagnosed with a short cervix, the secondmeasurement of cervical length correlated more significantly with pretermdelivery than did the initial length. The change in the cervical length alsocorrelated with earlier gestational age at delivery.

S150 SMFM Abstracts

521 TWO-DIMENSIONAL (2D) ULTRASOUND (US) VERSUS THREE- AND FOUR-DIMENSIONAL (3D/4D) US IN OBSTETRICAL PRACTICE: DOES THE NEW TECHNOL-OGY ADD ANYTHING? LUIS GONCALVES1, JYH KAE NIEN2, JIMMY ESPINOZA1, JUANPEDRO KUSANOVIC1, WESLEY LEE3, BETSY SWOPE1, ELEAZAR SOTO1, MARJORIETREADWELL1, ROBERTO ROMERO2, 1Wayne State University School of Medicine,Department of Obstetrics and Gynecology, Detroit, Michigan, 2PerinatologyResearch Branch, NICHD, NIH, DHHS, Bethesda, Maryland, 3William Beau-mont Hospital, Department of Obstetrics and Gynecology, Royal Oak,Michigan

OBJECTIVE: Examination with 3D US may reduce by half the time requiredto perform a fetal anatomical survey (JUM 2005). It remains to be determinedif examiners can rely solely on 3D/4D US to diagnose congenital anomalies.Many operators acquire volumes and still conduct a 2D US examination. Thisstudy was conducted to determine if the latter examination (2D US) addsdiagnostic information to what is already acquired by 3D/4D US alone.

STUDY DESIGN: 99 fetuses (91 singleton and 8 twins) were examined by 2sonographers who acquired representative 3D/4D volume datasets (includinghead, face, chest, abdomen, limbs and spine). Datasets were evaluated by ablinded independent examiner. After establishing an initial diagnosis by 3D/4D US, the examiner performed a 2D US examination and established a finaldiagnosis. Agreement between the two modalities was calculated using theinter-class correlation coefficient.

RESULTS: 54 normal and 36 fetuses with 80 anomalies were examined.Complete agreement between 2D and 3D/4D US occurred for 88.8% of thediagnoses (119/134; intra-class correlation coefficient 0.809, 95% CI: 0.742 –0.861). The anomalies missed by 3D/4D US were: ventricular septal defect(n=3), horseshoe kidney (n=1), tetralogy of Fallot (n=1), interrupted IVC(n=1), and cystic adenomatoid malformation (n=1). Occult spinal dysraphismwas suspected by 3D/4D US in one fetus but not confirmed by 2D US.Discordant diagnoses (n=2) were: transposition of the great arteries consideredto represent as a double outlet right ventricle and a case of pulmonary atresiainterpreted as tricuspid atresia (diagnosis listed as 3D/4D first and 2D second).

CONCLUSION: There is substantial agreement between the results of 3D/4DUS and 2D US in the majority of cases. An additional 2D US examinationcontributes to a 10% improvement in diagnostic accuracy. However, thisimprovement must be balanced by the potential increased throughput ofroutine 3D/4D US in clinical practice.

522 THE CLINICAL UTILITY OF ULTRASOUND EXAMINATION TO PREDICT DIGITALPELVIC EXAM CHAD GROTEGUT1, MORDECHAI DULITZKI2, JOHN P. GAUGHAN3,REUVEN ACHIRON2, EYAL SCHIFF2, OSSIE GEIFMAN-HOLTZMAN1, 1Temple Univer-sity School of Medicine, Obstetrics, Gynecology and Reproductive Sciences,Philadelphia, Pennsylvania, 2Sheba Medical Center, Tel Aviv University, Ob-stetrics and Gynecology, Ramat-Gan, Israel, 3Temple University School ofMedicine, Biostatistics, Philadelphia, Pennsylvania

OBJECTIVE: To determine the accuracy of ultrasound examination ofcervical length related to digital pelvic examination in term pregnancies.

STUDY DESIGN: We conducted a prospective study of 726 consecutive non-laboring, term pregnant women presenting to the antenatal unit for routinefetal testing. Subjects underwent a trans-vaginal ultrasound for cervical lengthfollowed by a digital cervical examination by a physician blinded to the resultsof the ultrasound. Multiple linear regression analysis was used to correlate thefindings of cervical length by ultrasound with cervical dilation and effacementby digital examination.

RESULTS: The relationship between cervical length measured by ultrasoundand cervical dilation and effacement measured digitally were found to besignificantly related. The linear relationship between cervical length byultrasound and cervical dilation and effacement is significant (p!0.001) butweak with a 15% and 23% fit respectively to the linear model.

CONCLUSION: Using ultrasound to determine cervical conditions at termhas a linear, statistically significant, but weak correlation to manual exam.These findings suggest that ultrasound is a poor predictor of cervical digitalexam and may not replace pelvic exam. Similar to the role of ultrasound inprediction of preterm delivery, further studies of ultrasound exam in compar-ison to pelvic exam at term are needed to determine its usefulness in predictingoutcomes of term pregnancies.