328 SPO Abstracts

300 UMBILICAL ARTERY DOPPLER STUDIES BEFORE AND AFTER CORDOCENTESIS IN FETUSES WITH INTRAUTERINE GROWTH RETARDATION (IUGR). ~ RodrjguezX, John BartonX, Michael MorettjX, Brian Mercerx, and Baha Sibai. University of Tennessee, Memphis.

Cordocentesis has become an important procedure in the evaluation of fetuses with severe IUGB. It is hypothesized that the umbilical cord in IUGA fetuses is vulnerable to umbilical flow changes following this procedure. METHODS: Pulsed Doppler (ATl Ultramark 9) studies of the umbilical artery (mid-portion) were performed before and after cordocentesis in 19 fetuses with birth weight confirmed IUGR «5th percentile), undergoing the procedure for karyotype and blood gas analysis. All fetuses were structurally normal. Waveforms were quanmied using the resistance index of Pourcelo!. RESULTS: The karyotype was normal in all fetuses studied and the mean fetal pH was 7.31 ± 0.06.(range 7.17-7.43). The mean ±. SO umbilical artery resistance index prior to cordocentesis was 0.63 ± 0.08. This was significantly higher than the umbilical artery resistance index after cordocentesis 0.57 ±. 0.09 (p<0.02, Wilcoxon signed rank test). This difference in umbilical artery resistance index was mainly due to changes in peak diastolic velocity since the systolic component was unchanged. Three fetuses had transient bradycardia secondary to the procedure (mean duration 8 ±. 4 minutes). There was no dif1erence in the umbilical artery resistance index before and after the procedure in these fetuses. CONCLUSION: Cordocentesis in fetuses with IUGA does not adversely affect umbilical blood flow as measured by the Doppler technique.

301 CONTINUOUS MONITORING OF DOPPLER UMBILICAL ARTERY WAVEFDRMS IN lABOR. M. Maurice Abitbol, M.D.x, B. Rochelson, M.D., I. Castillo, M.D. x , ~Taylor, M.D.x, M. Dionzon, R.N.X , Jamaica Hospital, Jamaica, N.Y.

Doppler velocirnetry has been used in the study of chronic uteroplacental problems such as IUGR. Technical problems have prevented the continuous study of waveforms in labor. We have devised an instrument capable of continuously monitoring umbilical artery waveforms in labor, and have studied 52 laboring women. Results: 1. Continuous umbilical artery velocity waveform analysis is possible and does not require constant presence of personnel. 2. SiD ratios: a) do not change as labor progresses normally b) do not change with protracted labor c) increased with contractions during the active phase in 38% of fetuses, and during the second stage in 80% of fetuses. The change was significant in both the active phase (p < 0.05) and the second stage (p < .001) d) became pathological (> 3.0) during contractions in 7 fetuses (13.5%); there was a strong correlation (p < .001 ) between this change and umbilical artery pH. The determination of the SID ratio during labor could be of benefit in identifying fetal acidosis.

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302 UMBILICAL WAVEFORM VARIATI ONS IN THE DISTRESS­ED FETUS - AN EXPERIMENTAL MODEL IN THE FETAL SHEEP. Alan G. Honheit and M. Maurice Abitbol

x, Dept. OB/GYN, Jamaica Hospital and

SUNY @ Stony Brook, Jamaica & Stony Brook, NY In order to enhance understanding of um­

bilical vascular Doppler waveforms during sudden changes in uterine and umbilical Der­fusion, a chr onic sheeD model in which such changes can be reversibly induced has been developed . Previous study centered upon the i nitially normal fetus (NF) , and accordingly responses of the acidotic fetus (AF) were examined using pregnant ewes of 110-112 days who underwent hysterotomy for place~ent of 4 and 8 mHz flat doppler transducers affixed to the proximal umbilical cord. Inflatable vascular occluders were also placed around the distal maternal aorta and umbilical cord . In contrast to the NF , the AF (pH~7.2) demon­strated more protracted reductions in systolic, diastolic and venous vel ociti es and l acked ve locity reappearance during severe cord occ l usion as well as a r eact ive overfl ow waveform following hypoxic stress. CONCLUSIONS: 1. Umbilical waveform responses of the NF and AF to acute hypoxia app ear different . 2. Eval­uation of these waveforms may be valuable in assessing acute changes in fetal status such as may occur during labor.

303 SUPERIMPOSED AND UNUSUAL VASCULAR I'IAVEFORMS IN THE UMBILICAL CORD OF THE PREGNANT SHEEP. M. Maurice Abitbol

x and Alan G. Monheit, Dept.

OB/GYN , Jamaica Hospital and SUNY @ Stony Brook, Jamaica and Stony Brook, NY

The majority of Doppler velocimetry study has centered around the single arterial or venous waveform (AW or VW) . In order to in­vestigate variations of this " standard" wave­form, pregnant ewes of 110-112 days underwent hysterotomy f or placement of 4 and 8 mHz flat dopp l er transducers affixed t o the prox imal umbilical cord . Inflatable vascular occluders were also placed around the dista l maternal aorta and umbilical cord . With experimentally induced reversible fetal hypoxia, observed waveform variations included: a) single AW and/or single VI-) b) double AW and/or double VI'I c) t riyle AW and/or trip l e V\'T d) combinations of these . CONCLUSIONS: 1 . The observation and g rouping of this multip licity of observed waveforms may serve as a useful reference when unusual ve locity waveforms are encountered . 2 . We speculate that the ~ajority are second­a r y to insonations by the Doppl e r probe of multip le l oops of the umbilical cord and/or anatomic variations of the vessels contained within the cord. 3 . Altering the angle of in­sonation can be valuable in clarifying unusual waveforms.