Volume 166 Number 1, Part 2

520 ANGIOTENSIN TESTING PREDICTS FETUSES BENEFITTING FROM LOW DOSE ASPIRIN. BJ Trudinger,

C-M Cookx , Dept. OblGyn, Univ. Sydney, Westmead Hospital, Westmead, Australia.

Low dose aspirin improves fetal growth when used to treat placental insufficiency identified by an abnormal umbilical Doppler study, and a positive angiotensin infusion sensitivity test (AIST) identifies fetuses with an abnormal study at greatest risk of subsequent morbidity, even in the absence of maternal hypertension. We therefore investigated the effect of aspirin therapy in a group of mothers without hypertension identified by a high umbilical SID and a positive AIST response (a group with a poor fetal prognosis). From 604 high fetal risk pregnancies 40 were found to have a high umbilical SID of whom 23 exhibited a positive response to AIST. Gestational age at enrolment ranged from 26 to 35 weeks. This group was treated with aspirin IOOmg/day. The AIST was repeated after at least 7 (range 7-23) days. In all 7 fetuses with absent diastolic flow the test remained positive. In the remaining 16 a negative repeat study (n=6) was associated with a decrease towards normal in umbilical SID. The mean centile birth weight was less (6 to 26, p<O.OO5) and mean gestation at delivery earlier (35.1 to 38.6 wks, p<O.OOI) in the positive compared to negative second AIST result groups. The group with an intial negative AIST were not treated with aspirin and their outcome was comparable to the negative restudy group. We conclude that a positive AIST predicts the true positive high umbilical SID fetuses with vascular disease in the fetal placenta and this response remains positive if aspirin fails to arrest the placental obliterative vascular pathology.

521 VIBRATORY ACOUSTIC STIMULATION STIMULATES HUMAN

FETAL VOIDING. E. Z. Zimmerx, C. R. Chaox, G. P. GuyX, F.

Marks, W. P. Fiferx, Dept. of Ob/Gyn, Columbia University, New York, NY

Although vibroacoustic stimulation (VAST) is a popular adjunct to fetal heart rate testing, its effects on many fetal organ systems are unknown. We hypothesized that VAST might stimulate fetal micturition. Fetal bladder volume was determined by ultrasound in 20 healthy fetuses at 38-41 weeks gestation. Measurements were taken 5 minutes prior to and immediately preceding a 3-second VAST and at 1 and 5 minutes following the VAST. All stimuli were performed during the filling phase of the bladder cycle; i.e., the volume immediately prior to VAST was greater than at 5 minutes prior to VAST.

Bladder Volume (mil Mean SEM GrouD* 5 minutes Drior 17.7 2.1 a Immediately Drior 22.7 2.4 b 1 minute after 14.2 2.2 a 5 minutes after 13.3 1.9 a

'p =0.001, repeated measures ANOVA. Groups With same letter are not different by Neuman-Keuls post-hoc analysis at p < 0.05; groups with different letters are significantly different at that level

Mean bladder volume was significantly decreased 1 minute and 5 minutes following the VAST compared to the volume immediately prior to the stimulus. The volume decrease was observed in 19 of the 20 cases at 1 minute following VAST. We speculate that fetal micturition following VAST may be part of a fearful reaction to the stimulus.

SPO Abstracts 417

522 ELEVATED MSAFP AND RISK ASSESSMENT FOR PREGNANCY OUTCOME. W Moroder', RR Viscarello, S Yarkoni, D Brioschi*, and JC Hobbins, Dept. of OB/GYN, Yale University Sch. of Medicine, New Haven, CT.

Although elevated levels of MSAFP in pregnancy are associated with congenital anomalies, pre-eclampsia, low birth weigbt, and fetal death, it is difficult to assign accurate risks for these outcomes. The purpose of this study was to examine the relationship between elevated MSAFP levels and the risk of adverse pregnancy outcome. During a 2 year period, 439 patients with MSAFP levels >2.0 MOM were referred for targeted ultrasound examination. Sonographic rmdings and pregnancy outcome data were retrospectively reviewed in 355 patients (81 %). Fetal or placental anomalies were noted in 141 pregnancies (39.7%), including 33 structural defects and 7 chromosomal aberrations. Mean MSAFP levels were significantly higher in patients with fetal anomalies (4.9 MOM vs. 2.6 MOM; p< 0.01). Placental abnormalities were detected in 14% of patients and were associated with a mean MSAFP value of 2.97 (range: 2.0 to 11.4). While 3.4% of pregnancies had oligohydramnios and 1.4% had polyhydramnios (mean MSAFP = 6.6 MOM), only the former was associated with a lower mean birthweight (2431g vs. 3181g; p< 0.01). Pregnancy complications included 6 cases of intrauterine fetal demise, 38 premature deliveries, and 34 patients with PIH (10%). Patients with pre-eclampsia had a mean MSAFP value of 2.6 MOM, which correlated with a significantly lower birthweight (p< 0.005). Of note, hemangiomas were reported in 23 neonates (7%) who were born to mothers with otherwise uncomplicated pregnancies, which suggests that these birthmarks have been a previously unrecognized cause of elevated MSAFP values. Our data confirm previous observations that an unexplained. elevated MSAFP level is a marker for high risk pregnancies. In addition, the increased risk for fetal and/or placental anomalies suggests that a targeted ultrasound examination is warranted in all patients with elevated levels of MSAFP.

523 RELATION OF MILD IDIOPATHIC POLYHYDRAMNIOS TO PERINATAL OUTCOME. C.Smith, R.Plambeck', W, Rayburn, K. Albaugh" Dept of OB/GYN, Univof Nebraska College of MediCine, Omaha, NE.

The relation between clinically obvious polyhydramnios and poor perinatal outcome is well established. Much less is known about mild unexplained polyhydramnios, which usually is initially suggested by sonographic examination late in gestation. The purpose of the present investigation was to relate mild idiopathic polyhydramnios to perinatal outcome. Mild polyhydramnios was defined sonographically as an amniotic fluid index of 25-39 during fetal biophysical testing. All cases involved single gestations not complicated by conditions known to predispose to polyhydramnios. Mild polyhydramnios was diagnosed in 97 (8.2%) of 1177 patients undergoing fetal testing between 26 and 42 gestational weeks. Findings of premature delivery, intrapartum complications, and neonatal depreSSion were no more frequent in pregnancies complicated by mild, unexplained polyhydramnios than in a comparable control group of patients but with a normal fluid volume. The incidence of birth weights greater than 4,000 grams was significantly higher in the mild polyhydramnios group than in the control group (18.6% vs 8.6%; p<O.05). We conclude that mild idiopathic polyhydramnios based on sonographic examination in late gestation is not associated with an increased risk of adverse perinatal outcomes, except for a higher incidence of large-for-gestationa/-age fetuses.