622 DETECTION OF FETAL CARDIAC ANOMALIES IN DIABETIC MOTHERS: THE UTILITY OFFETAL ECHOCARDIOGRAPHY SCOTT PETERSEN1, MICHAEL PITT2, JANICE HENDERSON1,JUDE CRINO1, 1Johns Hopkins University, OBGYN/MFM, Baltimore, Maryland,2Johns Hopkins University, School of Medicine, Baltimore, Maryland

OBJECTIVE: Infants of diabetic mothers are more likely to have congenitalcardiac malformations than the general population. In our institution, we obtaina four-chamber view (4CH) as well as outflow tracts (LVOT, RVOT) on allfetuses and refer pre-gestational diabetics for a fetal echocardiogram. Theobjective of this study was to determine the utility of a fetal echocardiogramafter a normal anomaly scan.

STUDY DESIGN: Pre-gestational diabetic mothers were identified who hadundergone screening ultrasound and fetal echocardiography at our hospitalduring the last four years. A retrospective review of maternal records wasconducted to obtain these study results. Neonatal records were reviewed, whenavailable, for confirmation of antenatal findings.

RESULTS: One hundren and eighty-one patients had both a sonographic 3-view evaluation of the heart (4CH, LVOT, RVOT) and a fetal echocardiogramattempted, of which 146 had both completed. In this subgroup, eleven neonates(n = 67) were identified with abnormal postnatal echocardiograms. Four hadclinically relevant cardiac disease which we defined as the need for surgical ormedical intervention. The sensitivity for detecting clinically relevant disease was75% (NPV 98.4%) for both sonographic methods (a VSD requiring surgicalcorrection was not detected by either method). One fetus with a normal 3-viewevaluation was found to have pulmonary stenosis with mild pulmonary andtricuspid regurgitation by fetal echocardiogram. These findings were confirmedin the neonatal period, but the child has had an uncomplicated clinical course.

CONCLUSION: In our pre-gestational diabetic population, 3-view screening ofthe heart and fetal echocardiography have similar detection rates for cardiacanomalies. Given the high cost and limited availability of fetal echocardiogra-phy, 3-view screening alone may identify the majority of clinically importantcardiac lesions. Fetal echocardiography may be reserved for suspected cardiacanomalies on a screening sonogram or patients with an incomplete study.

624 MAGNETIC RESONANCE IMAGING OF THE CERVIX DURING PREGNANCY: EFFECT OFGESTATIONAL AGE AND PRIOR VAGINAL BIRTH MICHAEL HOUSE1, MARKO’CALLAGHAN2, JONATHAN KINI2, DANNY WU1, SAMUEL PATZ2, STEPHANEBAHRAMI1, RAFEEQUE BHADELIA2, 1Tufts-New England Medical Center,Maternal Fetal Medicine, Boston, Massachusetts, 2Tufts-New EnglandMedical Center, Radiology, Boston, Massachusetts

OBJECTIVE: To investigate how gestational age and prior vaginal birth affectcervical anatomy on MR imaging during pregnancy.

STUDY DESIGN: In 56 consecutive pregnant patients referred to MRI fora suspected fetal or placental abnormality, high-resolution images of the cervixwere obtained. A 1.5 Tesla system was used with a phased array surface coil. Aproton density pulse sequence was chosen (TR 9900 ms, TE 10 ms). MRI imagemeasurement was performed using a standardized image processing protocol.The following outcome variables were measured: (1) signal intensity of thecervical stroma (normalized to the signal intensity of the bladder contents); (2)cross-sectional area of the cervical canal and cervical stroma; and (3) angle of thecervix with respect to the uterus. Gestational age and obstetric history wererecorded. Regression was used to determine whether the outcome variables wereaffected by gestational age or prior vaginal birth.

RESULTS: Adequate images were obtained in 53 of 57 patients, at gestationalages 17–36 weeks.

1. Decreased contrast between the cervical stroma and the bladder wasobserved with increasing gestational age, reflecting increased stroma hydration.For example, the mean relative signal intensity at 20 weeks gestation was 0.84(95% confidence interval [CI] 0.81–0.86). The mean relative signal intensity at 32weeks was 0.92 (95% CI 0.88–0.95), a 10% increase compared to 20 weeks.

2. As gestational age increased 12 weeks, the mean cross-sectional area of thecervical canal and cervical stroma increased 31% (95% CI 0-73) and 31% (95%CI 11-55), respectively.

3. The mean anterior angle of the cervical canal was greater than theposterior angle (127 vs 95 degrees, P ! .001) and did not vary with gestationalage.

None of the outcome variables were affected by prior vaginal birth.CONCLUSION: MR imaging of the cervix demonstrated that increasing

gestational age was associated with increased cross-sectional area and increasedstroma hydration. Prior vaginal birth did not affect cervical anatomy on MRimaging.

625 ULTRASOUND DETECTION OF FETAL ANOMALIES IN THE FIRST TRIMESTER INCONJUNCTION WITH NUCHAL TRANSLUCENCY SCREENING: A FEASIBILITY STUDYFIONNUALA MCAULIFFE1, KATHERINE FONG2, ANTS TOI3, DAVID CHITAYAT4,SARAH KEATING5, JO-ANN JOHNSON6, 1University College Dublin, Dublin,Ireland, 2Mount Sinai Hospital, Radiology, Toronto, Ontario, Canada,3University of Toronto, Medical Imaging, Toronto, Ontario, Canada,4University of Toronto, Paediatrics, Toronto, Ontario, Canada, 5Mount SinaiHospital, Feto-pathology, Toronto, Ontario, Canada, 6Mount Sinai Hospital,Toronto, Obstetrics & Gynecology, Toronto, Ontario, Canada

OBJECTIVE: To determine the effectiveness of a fetal anatomic surveyperformed in conjunction with nuchal translucency (NT) screening ultrasoundin an unselected pregnant population.

STUDY DESIGN: This is a prospective observational study of womenpresenting for NT screening for chromosomal defects. An anatomic surveywas performed following a standardized protocol. All studies were performedtransabdominally. Transvaginal ultrasound was done when indicated. Themaximum scan time was restricted to 30 minutes.

RESULTS: 325 singleton fetuses (11 + 2 to 13 + 6 weeks) were examined.Mean duration of scan was 26 minutes. In 89 (24.6%) cases, transvaginalultrasound was performed. NT was successfully measured in all fetuses. MeanNT was 1.7 mm (range 0.8 to 3.1 mm). Fetal anatomic structures were seen asfollows: cranium 324 (99.7%), intracranial anatomy 319 (98%), nasal bone 308(95%), 4 chamber view 274 (84%), cord insertion 322 (99%), stomach 319(98%), bladder 291 (89.5%), spine 147 (45%), all four limbs 323 (99%).Complete anatomy was seen in 109 (33%). Anomalies detected included 1 openneural tube defect and 1 umbilical cord cyst. The 18-20 week scan was performedat our institution in 274 (84%) fetuses and 2 open neural tube defect , 1hypoplastic left heart syndrome and 1 case of polydactyly were detected. Factorsaccounting for our low visualization of complete anatomy include: 41 (12.6%)fetuses less than 12 weeks gestation, 124 (38%) maternal body mass indexgreater than 25, limited scan time, multiple operators and selective use oftransvaginal ultrasound.

CONCLUSION: A complete fetal anatomic survey was successful in 33% offetuses in a time-limited screening program between 11-14 weeks gestation.Sonographer education and protocol modification would likely improve thesuccess rate. Since some anomalies are not evident in the early scan, it isimportant to perform the 18-20 week scan.

SMFM Abstracts S175

623 NUCHAL TRANSLUCENCY (NT) MEASUREMENTS FOR 1ST TRIMESTER SCREENING:THE ‘‘PRICE’’ OF INACCURACY MARK EVANS1, HILDE VAN DECRUYES2,KYPROS NICOLAIDES3, 1Columbia University, Institute for Genetics & FetalMedicine, New York, New York, 2Fetal Medicine Foundation, London,England, United Kingdom, 3King’s College Hospital, Harris BirthrightResearch Centre, London, England, United Kingdom

OBJECTIVE: 1st trimester aneuploidy screening is in transition from the phaseof ‘‘development’’ to that of ‘‘diffusion.’’ As seen with other technologies, there isgreat risk of diminished performance until newer centers are well experienced.Typically, inexperienced sonographers under measure NT’s. Training andcontinual monitoring are needed to ensure accurate measurements. Here weassess the impact of systematic under measurement on abnormality detection, ie.garbage in/garbage out.

STUDY DESIGN: Actual NT measurements from 13,887 normals, 82 trisomy21s (T21) and 61 others abnormalities (OA) with birth outcome data weremathematically modified to show either a 25% or 0.5 mm decrease inmeasurement. Impacts upon, sensitivity (Sens) and screen positive rates wereassessed.

RESULTS: Reducing the NT measurements of T21 and OA cases lowers thesensitivity from 81.7% and 70.5% respectively to 67.1% and 62.3% (P ! .01) Ifnormals are correspondingly lowered, then the screen positive rate is reducedfrom 6.9% to 2.0% and 2.5%. To maintain the same screen positive rates andsensitivity, the risk threshold would have to be increased from 1/300 to 1/556.

CONCLUSION: Minor inaccuracies in NT measurements as small as 25% or0.5mm will have very significant negative impact upon abnormality detection -reducing detection rates by 18% (81.7% to 67.1%). Just as it is completelyaccepted that laboratory measurements require standardization and qualityassurance, NT measurements, because they are used in an algorithm, need thesame rigor in order for the published data from those centers that havedeveloped such screening to be valid in counseling patients by other operators atother sites.

NT modifications: Impact upon sensitivity

Risk cut-off Nl (Screen +) T 21 (Sens) OA (Sens)

N 13,887 82 61

NT 1/300 6.9% 81.7% 70.5%

«25% 1/300 2.0% 67.1% 62.3%

«0.5 mm 1/300 2.5% 71.9% 65.6%

«25% 1/556 6.9% 81.7% 70.5%

«0.5 mm 1/538 6.9% 81.7% 70.5%