Prediction of preterm delivery by transvaginal ultrasound of the cervix in patients with prior cone...

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657 ANTENATAL SONOGRAPHIC PREDICTORS OF NEONATAL SURVIVALIN EXTREME PREMATURITY JOYCE D. RUBIN1, REINALDO FIGUEROA1,ANDREW ELIMIAN1, PAUL OGBURN JR1, J. GERALD QUIRK1, DAVIDGARRY1, 1State University of New York at Stony Brook, Obstetrics,Gynecology and Reproductive Medicine, Stony Brook, NY

OBJECTIVE: The purpose of this study was to determine whether antenatalsonographic biometric measurement(s) could predict survival in extremelypremature neonates.

STUDY DESIGN: The study population included all live-born babies witha GA 22-25 wk, delivered at our hospital from 1995-2002, and who had prenatalultrasound < 10 days prior to delivery. GA was based on LMP or sonographicestimates obtained < 14 wk. The maternal charts were reviewed for basicdemographic characteristics, which included age, parity, and ethnicity.Sonographic biometric measurements included the BPD, HC, FL, AC, andEFW. The EFW was calculated with the formula of Hadlock et al. Excluded fromthe study were cases missing any of the biometric data, stillborns, and those caseswith a chromosomal or structural anomaly. Neonatal information obtained fromthe chart included BW, Apgar score, and survival. Survival was defined asdischarge of a live infant from the hospital. The study was IRB-approved andstatistical analysis considered a P value of < .05 as significant.

RESULTS: There were 120 newborns meeting entry criteria with an overallsurvival of 50%. Neonatal survival rates at 22, 23, 24, and 25 wk were 8%, 23%,56%, and 69%, respectively. The threshold values for each biometricmeasurement below which there was no survival were BPD < 4.8 cm, HC< 18.0 cm, AC <16.4 cm, FL < 3.8 cm, and EFW <450 g. The most significantindependent sonographic predictors of neonatal survival were the HC (P = .04)and FL (P = .01). The EFW, BPD, and AC were not predictors of survival. Themean difference of EFW from actual BW was -33.7 ± 146 g or a �2.4%.

CONCLUSION: Sonographic measurement of the HC or FL can predict

Volume 189, Number 6Am J Obstet Gynecol

SMFM Abstracts S237

PREDICTION OF PRETERM DELIVERY BY TRANSVAGINALULTRASOUND OF THE CERVIX IN PATIENTS WITH PRIOR CONEBIOPSY LEONARDO PEREIRA1, AILEEN GARIEPY1, VINCENZO BER-GHELLA1, 1Thomas Jefferson University, Department of Obstetrics andGynecology, Philadelphia, PA

OBJECTIVE: To determine the predictive value of transvaginal ultrasoundof the cervix (TVU) for spontaneous preterm delivery (SPTD) in patients witha prior cone biopsy.

STUDY DESIGN: Patients with singleton gestations and a history of cervicalcone biopsy by either cold knife (CKC), LEEP, or laser were followedprospectively from 1998-2003 with TVU between 16 and 23 6/7 weeks. Thepredictive value of TVU cervical length (CL) < 25 mm was calculated. Theprimary outcome was SPTD<35 weeks (w).

RESULTS: Of 122 patients with prior cone biopsy identified, 30 wereexcluded for lack of TVU, 10 for prophylactic cerclage, 11 formultiple gestation,1 for medically indicated PTD < 35 w; and 2 were lost to follow-up, leaving 68patients for analysis. Twenty-nine had a prior CKC, 29 a prior LEEP, and 10a prior laser cone. Mean gestational ages at delivery were 36.9 w, 38.4 w, and 38.6w, respectively (v(df)2 = 3.57(2); P = .168), and the overall rate of SPTD < 35 wwas 11.8%. Twenty-two percent (4/18) with CL < 25 mm had SPTD < 35 wcompared to 8% (4/50) of those with CL$25mm (RR 2.78, 95%CI 0.62-12.27).The sensitivity, specificity, and positive and negative predictive values for SPTD< 35 w were 50%, 77%, 22%, and 92%, respectively. Three of the 18 with CL < 25mm received therapeutic cerclage. Two of 3 cerclage patients had SPTDcompared with 2 of 15 expectantly managed patients (67% vs 13%, RR 5.00, 95%CI 0.57-13.95).

CONCLUSION: TVU may predict SPTD < 35 w in patients with prior conebiopsy. Future trials are needed to determine the efficacy of therapeutic cerclagein this population.

A RELATIONSHIP BETWEEN CERVICAL LENGTH AND AMNIOTICFLUID INTERLEUKIN-6 SONIA HASSAN1, ISRAEL HENDLER1,LORRAINE LAJEUNESSE1, EVIE RUSSELL1, MARJORIE TREADWELL1,YORAM SOROKIN1, ROBERTO ROMERO2, 1Wayne State University, Obs-tetrics/Gynecology, MFM, Detroit, MI 2Wayne State University, Detroit, MI

OBJECTIVE: A short cervix is a strong predictor of spontaneous pretermdelivery. However, the etiology of a short cervix in most cases is unknown.Cervical ripening, which eventually leads to a short cervix, has been likened toan inflammatory reaction (Liggins). Alternatively, patients with sub-clinicalintraamniotic infectionmay shorten the uterine cervix prior to the clinical onsetof preterm PROM or may have a clinically incompetent cervix. The objective ofthis study was to determine if there is a relationship between a short cervix andamniotic fluid concentrations of IL-6, a well-established marker of intrauterineinflammation.

STUDY DESIGN: A prospective study of patients at risk for preterm deliverywas conducted in our cervix clinic. Patients underwent transvaginal sonographicexamination every 2 weeks until delivery. Fluid was retrieved for standard clinicalindications. All patients were asymptomatic. Amniotic fluid concentration of IL-6 was determined with a sensitive and specific immunoassay. The relationshipbetween cervical length and amniotic fluid IL-6 was tested with non-parametricSpearman’s Rho.

RESULTS: Forty-two patients met inclusion criteria. The median GA atamniocentesis was 20.4 weeks (range 15.2-23.3), while the median cervicallength at amniocentesis was 11.5 mm (range 0-39). Median amniotic fluid IL-6levels were 557.18 pg/mL (range 29.90-60000). There was a significantcorrelation between cervical length and amniotic fluid IL-6 concentrations(P = 0.01,-0.4).

CONCLUSION: Our study indicates that the shorter the cervix, the higherthe amniotic fluid IL-6 concentration, suggesting that some asymptomaticpatients with an extremely short cervix have intraamniotic inflammation, whichis sub-clinical in nature.

neonatal survival in extremely premature neonates. This information should beof value for obstetric decision making and counseling of patients.

658 SECOND-TRIMESTER BIPARIETAL DIAMETER/NASAL BONE LENGTHRATIO IS NOT A STRONG POSTIVE PREDICTOR OF TRISOMY 21 LANTRAN1, LEE MITSUMORI2, DARCY B. CARR1, LAURENCE SHIELDS1,1University of Washington, Obstetrics and Gynecology, Seattle, WA 2Univer-sity of Washington, Radiology, Seattle, WA

OBJECTIVE: We evaluated the utility of the fetal biparietal diameter(BPD)/nasal bone length (NBL) ratio in the second trimester as a screeningtool for trisomy 21 (T21).

STUDY DESIGN: A case-control study was performed of women who hadultrasound and genetic amniocentesis between 14-24 weeks’ gestation foradvanced maternal age, abnormal serum screening, or prior aneuploid fetus.Thirty-two cases of T21 werematched to 137 euploid fetuses. Data were analyzedwith logistic regression. A receiver-operator characteristic (ROC) curve wasplotted for sensitivity and 1-specificity.

RESULTS: The BPD/NBL was independent of gestational age in theeuploid fetuses. NBL was significantly shorter (2.4 ± 0.3 vs 3.9 ± 0.1), andBPD/NBL was significantly greater (16.5 [6.2-114] vs 9.5 [5.8-80]) in the T21group (P < 0.001). The odds of T21 increased 2.4-fold (95%CI 1.7-3.4) with every1-mm decrease in NBL and increased 1.08-fold (95% CI 1.03-1.12) with each 1-unit increase in BPD/NBL (P < 0.001). At a BPD/NBL cutoff of$16.7, sensitivitywas 50% with a false-positive rate of 5%. Assuming a 1.2% prevalence of T21 inthe high-risk population, the positive predictive value was 10.8% and negativepredictive value was 99.4%.

CONCLUSION:Although second-trimester BPD/NBLwas a significant pre-dictor of T21 in this high-risk population, the sensitivity and positive predictivevalue did not support its use as an isolated screening tool. However, combiningBPD/NBL with other sonographic markers may improve T21 detection.

ROC for BPD/NBL to Predict T21