Volume 164 Number 1. Part 2

360 DISCORDANT 1WIN GROWfH AT 20-24 WEEKS:A PREDICTOR FOR BIRTII WEIGHT DISCORDANCE AND ADVERSE OUTCOME?

361

CT SLOAN,M.D.;MH KUHN,M.D.;RP LORENZ,M.D/,CH COMSTOCK M.D.1; Divisions of Maternal-Fetal Medicine and Fetal Imaging, Wilham Beaumont Hospital and Wayne State Universi~, Royal Oak, MI 48073

Discordant fetal growth occurs in 15-30% of twin gestations and is associated with adverse outcome. OBJECTIVE: To investigate if early onset discordant fetal growth(EOD) at 20 - 24 weeks is predictive of discordance or adverse outcome at birth. METIIODS: All twin gestations that underwent ultrasound evaluation between 20-24 weeks in two years were reviewed. Discordant growth was defined as a difference in estimated fetal weight ~ 20%.Estimated fetal weights were calculated by formulas of Shepard(1982) and Hadlock (1984). RESULTS: 13% (9/69) of twins studied at 20·24 weeks had EOD. Twins with EOD differed from the other twins in: rate of anomalies(33% vs 3%;p<.03) weight discordance at birth(37% vs 13%; p<.05)and mean birth weight (1770 vs 2413gm;p<.05). They did not differ in mean gestational age at delivery, incidence of prematurity, stillbirth, or same-sex twinning.

TABLE DISCORDANCE AT 20·24 WEEKS VS AT BIRTII

20-24 WEEKS +

AT BIRTII + 7 6 29

CONCLUSION: In the 43 twin pregnancies with follow up information (see table), the presence of discordance at 20-24 weeks was related to discordance at birth (p<.OOOl;sensitivity 54%,specificity 97%, predictive value - positive 88%, negative 83%),lower birth weights, and more anomalies.

THE AMNIOTIC FLUID INDEX AS A PROGNOSTIC INDICATOR IN POLYHYDRAMNIOS

Lisa M. Peacock, MIf, Lewis H. Hamner III, MD Paul C. Browne, MD Emory University School of Medicine, Grady Memorial Hospital, Atlanta, Georgia

Sonographic assessment of amniotic fluid volume using the amniotic fluid index (AFI) is a reproducible method of amniotic fluid evaluation. We performed AFI evaluation on 500 patients with known LMP's and ul trasound evaluations that agreed with the LMP to establish a nonaal curve for our population. We then prospectively stUdied 2200 patients. Among non-diabetic singleton pregnancies there were 72 (3.2\) with an AFI greater than 25 em which is 2 standard deviations above our population mean. A comparison was made between this group and a control population of 569 patients with normal AFI's. Congenital anomalies were noted in 23.6% (17/72) of pregnancies with polyhydramnios VS. 2.8\ in the control group. The gross perinatal mortality rate was 83.3/1000 vs 12.3/1000. However the corrected perinatal mortality rate was only 13.8/1000 in the study group as 83% of the fetal deaths were secondary to major congenital anomalies. Central nervous system anomalies accounted for the largest percentage. All patients with polyhydramnios were offered genetic amniocentesis. However, only 15 patients consented with one abnormal karyotype found (Trisomy 18). Although karyotypes were not performed on the remaining patients with polyhydramnios, no genetic problems were suspected after newborn evaluation. Therefore, the lowest possible incidence in this study of chromosomal abnormalities for patients with polyhydramnios and no structural malformations is 1.8\ (1/55). This equals the total risk for chromosomal abnormalitl.es of a 41 year old woman. This data suggests that a finding of an AFI > 25 cm should warrant detailed sonoqraphic evaluation for congenital anomalies and amniocentesis for chromosomal analysis. The exclusion of structural defects and chromosomal abnormalities should offer some reassurance when counselling the pregnant patient wi th polyhydramnios.

SPO Abstracts 345

362 ULTRASONIC DIAG~OSIS OF FETAL HYDROPS J Santolaya M.D.,S L Warsof M.D. UIC,Chicago,IL

The aim of the study is to determine the in­cidence and etiological factors associated with the non-specific finding of fetal hydrops in a tertiary center covering a mixed racial popula­tion. Out of 1257 patients referred for ultraso und examination from 1985-April 1990, 446(3.5%) fetuses presented with a detectable anomaly. Of these 76 had Hydrops(0.6% of the total, 17% of the anomalies). The distribution of Immune to non-immune was 10:66. Of the non-immune 30% we­re associated with a chromosomal abnormality. Morphologically: 27.6% had cystic hygromas, 17% heart anomalies, 13% multiple malformations, 2.6% sacrococcigeal-teratomas, 2.6% Twin-Twin Transfusion Syndrome, 1.3% placental anomalies, 1.3% maternal infection and 22% were classified in-utero as idiopathic. CONCLUSION: In tertiary centers the incidence of hydrops can be as high as 1:165 pregnancies. With the advances of prenatal diagnosic techni­ques the etiology of hydrops can be determined in-utero in almost 80% of the cases. At least 30% of non-immune hydrops are associated with a chromosomal abnormality. For this population and in contrast to findings in homogeneous ra­cial groups, the most common morphological ab­normality was cystic hygroma.

363 SPINA BIFIDA: COMPARISON OF PRENATAL FINDINGS WITH POSTNATAL OUTCOMES. N. Callan, S. Sheth X , J. Freemanx , U. Hamper X, R. Sanders X, K. Blakemore, The Johns Hopkins University, Baltimore, Maryland 21205

We followed 30 consecutive patients with the prenatal diagnosis of spina bifida (SB). Despite balanced counselling, all 16 patients with the diagnosis prior to 22 weeks elected termination. Of 14 fetuses diagnosed after 24 weeks, one with severe hydrocephalus and a large open thoracolumbar meningomyelocoele died. Eleven infants had repair of the spinal defect within 24 hours and two with skin covered lesions at 3 days and 8 months. All 13 survivors required shunt procedures for hydrocephalus. The 13 had varying degrees of motor deficits with bladder and/ or bowel dysfunction. Skin covered lesions (3 of 13) resulted in little or no neurologic deficit but this diagnosis was not established prenatally. While prenatal sonography was highly accurate in identifying the anatomic level of defect this was not predictive of the actual motor deficit in the majority of survivors.