Volume 166 :-.Jumber 1, Part 2

496 ANTENATAL TESTING USING THE AMNIOTIC FLUID INDEX (AFI) BEYOND 280 DAYS GESTATION William MacMillan, M.D., Susan Shmoys, M.D. Corinne Dermont, R.N.' and Daniel Saltzman, M.D. Department of Obstetrics and Gynecology SUNY-Stony Brook, Stony Brook, New York

500 patients were referred for antenatal testing beyond 280 days EGA. AFI and Biophysical Profiles (BPP) were evaluated twice weekly. Adverse labor events and neonatal outcomes were analyzed according to the AFI using Receiver Operating Characteristic (ROC) analyses. Spontaneous and induced labors were included. Clinicians were not blinded to the AFI or BPP scores. The ROC curve for all EGAs shows only a modest effect for AFls< 12.5, above this true positives and false positives are equal. Below this level the ROC curve is quite shallow indicating minimal effectiveness. From 281-287 days the ROC curve indicates better predictive ability; an AFI cur-off of 9.0 yields sensitivity of 100% and specificity of 57%. At more advanced gestational ages the utility reverts to that seen overall; for example and AFI cutoff of 9.0 yields 44% sensitivity and 65% specificity. This lack of prediction of pathology mirrors the known downward trend of AFI in normal pregnancies beyond 40 weeks and makes it imperative to interpret 'oligohydramnios' cautiously at advanced gestational age. AFI norms at greater EGAs are needed, but we have shown that between 281-287 days an AFi<9.0 is a predictor of adverse events or outcomes.

497 OUGOHYDRAMNIOS FOLLOWING PROM; IS THE AMNIOTIC FLUID INDEX (AFI) PREDICTIVE OF OUTCOME? William MacMillan, M.D. Stephanie Mann, M.D.', Susan Shmoys, M.D. and Daniel Saltzman, M.D. Department of Obstetrics and Gynecology SUNY-Stony Brook, Stony Brook, New York

To test whether oligohydramnios following PROM is predictive of adverse labor or neonatal outcomes the records of 193 patients serially tested in the Fetal Diagnostic Unit were reviewed. The last AFI before delivery was subjected to Receiver Operating Characteristic (ROC) analyses. Patients either labored spontaneously or were delivered for indications other than oligohydramnios. Patients had been managed expectantly without tocolytics. AFI was virtually non-predictive at dellvery~36 weeks; the ROC curve was flat with true positives and false positives essentially equal. For patients with EGA at delivery < 36 weeks the ROC curve shows modest prediction of adverse outcomes (other than those related simply to prematurity). Two operating points are suggested by the shape of the ROC curve; a strict cut-off of AFI <4.0 gives sensitivity of 64% and specificity of 72%, a liberal cut-off of AFI <6.0 gives sensitivity of 84% but only a specificity of 43%. Thus AFI is not useful in near-term PROM but should Influence the decision of whether to Intervene or manage pre-term PROM expectantly. Oligohydramnios <36 weeks may reflect placental insufficiency along with mechanical leakage.

spa Abstracts 411

498 FETAL HEART RATE MONITORING FOLLOWING ANTENATAL BLEEDING. A. Samueloff,' B. Rubinoff! D. Weinstein' Dept OBI GYN, Hadassah Medical Center, Jerusalem, Israel.

Antepartum bleeding is associated with fetal stress and increased perinatal morbidity and mortality. It is proposed that as a result of the stress, centra'i nervous system maturation will be accelerated in the fetus. It is assumed that bleeding will result in specific fetal heart rate (FHR) changes reflecting this process (sympathetic). Our hypothesis was tnat early antenatal bleeding Will result in accelerated sympathetic maturation expressed by matured FHR patterns in the J'reterm infant. 91 patients with severe antenatal bleeding an 91 controls with uncomplicated normal pregnancies participated in the study. All women were not in labor and were hospitalized in the High Risk Pregnancy Unit at 2437 gestational weeks. Excluded were patients with premature rupture of membranes, intrauterine growth retardation, diabetes, hypertension and twins. FHR tracings were analyzed during the first week from the initial episode of bleeijing and compared to the control group, FHR tracings were analyzea for basa heart rate, long-term variability, num6er and amplitude of accelerations in the best 20 min segment.

Gest. Age 24-29 wks 30-33 wks 34-37 wks Group Bleeding Control Bleeding Control Bleeding Control Mean GA 27.6 27.2 314 31.3 35.9 354 Baseline HR 1425 142.7 1394 140.7 136.7 1374 # Accelerations

in20min 4.4** 1.0** 55** 3.9** 7.7** 53** Amplitude of acceleration 20.7'* 18.5" 21 7** 18.7" 22 7* 21.6*

% of reactive monitors 89** 37** 95** 71** 100** 87** *p<O,05 **p<O.OOI

The study also reveaiecfl)ootnpTacentiiprevia and ilbruplioplil centa had significantly larger numbers of accelerations with a higher acceleration amplitUde when compared to the control group; 2) no significant differences were found in the FHR charac feristics between these two causes of antenatal bleeding. Our data suggest that accelerated sympathetic maturation expressed by reactive FHR tracing is prominent in pregnancies complicated by antenatal bleeding due to abruptio placenta and placenta previa.

499 LONGITUDINAL AMNIOTIC FLUID INDEX IN POSTDATES PREGNANCIES AND ITS ASSOCIATION WITH FETAL OUTCOME. Michael Y. Divon. M.D., Ariel D. Marksx, M.S., Cassandra E. Henderson M.D. Albert Einstein College of Medicine, Bronx, New York.

Due to the known association between oligohydramnios and adverse fetal outcome, so no graphic evaluation of amniotic fluid index (AFI) is extensively used for fetal testing in postdates pregnancies. However, the relationship between dynamic changes in AFI and fetal outcome is unknown. Purpose: To study the dynamic changes in AFI measurements and their association with adverse fetal outcome in postdates pregnancies. Serial AFls were obtained semi-weekly in 139 reliably dated (certain LMP consistent with early sonographic exam) pregnancies> 41 weeks' gestation. Each patient was evaluated on 2-6 separate occasions and a total of 331 tests were performed. Indications for delivery included poor fetal testing, oligohydramnios (Le. AFI~6.0cm) or a favorable cervix. Adverse fetal outcome was defined by the presence of moderate or thick meconium, FHR decelerations, CIS for fetal distress or NICU admission. The AFI increased in 43 patients (a mean increase of 2.6 cm ± 2.7. ±SD), did not change in 2 patients and decreased in 96 patients (a mean decrease of 3.7 cm ± 2.7). Fourteen of these patients had a final AFt .s: 5.0cm. Prominent changes in AFI (i.e. ± 66%) had no association with adverse fetal outcome. A significant association with the outcome variables was only detected in patients whose final AFI was <5.0 cm (p=0.000011. Mean birth weight was significantly lower in those patients who had a final AFI ~ 6.0cm. The mean gestational age for patients with a

normal AFI was 42 weeks + 3 days and for those with oligohydramnios was 42 weeks + I day (p = NSI. Neither birth weight nor gestational age were predictive of fetal outcome. There was no significant association between oligohydramnios and gestational age. Thus, there was a significant increase in adverse fetal outcome when the final AFI .s: 6.0cm, irrespective of the rate of change in AFI. Fetal outcome was not predictably associated with either gestational age or birth weight ill these patients.