Volume 166 N umber I, Part 2

256 ASSESSMENT OF THE INFLUENCE OF CHERNOBYL ON BIRTH DEFECTS AND ABORTION RATES IN AUSTRIA. xM C H Haeusler xA. 8erghold, xM. Schaffer, xw. Schoell.

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Dept. of OBfGYN, Karl-Franzens University & Joanneum Research, Graz, Austria

The teratogenic potential of low dose radiation is difficult to determine. The purpose of this study was to assess whether measured radioactive fallout (predominantly 1131 or Cs 137) following the Chernobyl disaster in April 1986 altered the rate, pattern or regional distribution of birth defects (BO) or abortion rates in southern Austria. The Styrian malformation register (SMR) was set up as a population-based regional multi-source system whereas the existing government register still relies on one source and therefore provides poor ascertainment especially in cases of internal defects (overall BO rates: 2.3% vs 1 %). Over a period of 5 years (1985-89) the SMR monitored 66,740 total births. 64 sources provided data on 1695 cases of BO, of which 1617 were suitable for analysis. All cases were analysed in terms of their calculated conception date and coded (IC09) and divided into 3 main groups, based on their vulnerable phase of embryogenesis: QrQ.wLJ. (n=157): cyclopy, NTO, esophageal atresia, etc. ~ (n=630): CHO, facial clelting, diaphragmatic hernia, syndactyly, etc. ~ (n=133): de novo chromosomal anomalies. In group III the vulnerable time of spermato­and oogenesis was considered. To study possible regional clustering, the pre- and post-Chernobyl rates were plotted in 17 subdistricts. No significant changes in incidence or regional distribution of BO were observed, but a baseline BO rate has been established for future surveillance. To study other possible effects of the disaster, the overall abortion rate and the counselling frequency at termination clinics for periods of 1.5 years before and after the event were compared. All Styrian pathology departments provided data on 7775 abortions (16% of 48,017 total births). The abortion rate and the counselling frequency was not been altered significantly following the disaster.

UNEXPLAINEDELEVATEDSECONDTRIMESTERMATERNAL SERUM ALPHA FETOPROTEIN: A MARKER FOR LOW BIRTH WEIGHT. M. Maberry. x, R. Stettler", K. Moorex, B. Dowdy", R. Putnam", K. Leveno, L GUstrap, Dept Ob/Gyn, University of Texas Southwestern Medical Center, Dallas, Texas.

The association between elevated maternal serum alpha fetoprotein (MSAFP) values and fetal anomalies, multiple gestations and intrauterine demises has been well described. However, the significance of unexplained elevated MSAFP values remains unclear as does the appropriate subsequent pregnancy management for these women. The purpose of our study was to prospectively follow those women with unexplained elevated MSAFP values throughout their pregnancies. From the beginning of our MSAFP screening program in March 1988 until February 1991, 12,530 women in our single center, indigent population underwent MSAFP sampling between 15 and 19 weeks of gestation. Of these women, 259 had elevated MSAFP values (greater than or equal to 2.5 MoM). 51 women (19%) had unexplained elevated MSAFP values after repeat blood sampling and high resolution ultrasound, with or without amniocentesis for amniotic fluid AFP, acetylcholinesterase, and fetal karyotype. These women were subsequently followed with frequent clinic visits and serial ultrasound examinations for fetal growth. There were two spontaneous abortions and 49 live born infants, 13 (27%) of which were low birth weight Qess than 2500 grams). This differs Significantly from the rate in our general obstetric population (10%, P <0.001) during this time. We conclude that in our population, unexplained elevated MSAFP values are associated with an increased incidence of low birth weight infants, the cause of which remains unclear.

SPO Abstracts 349

258 ABNORMAL SECOND TRIMESTER Ul TRASOUNDS ARE ASSOCIATED WITH KARYOTYPIC ABNORMALITIES. MP Dombrowski, SM Berry, NB Isada, MI Evans, Dept of Ob/Gyn, Hutzel Hosp./Wayne State Univ., Detroit MI

Anecdotally, it is evident that fetal aneuploidy is associated with abnormalities of amniotic fluid volume (AFV) and fetal structural anomalies, however, the risks have not been determined. We reviewed prospectively collected data from 2822 second trimester ultrasounds and karyotypes in a high­risk, referral population. Abnormal AFVs were diagnosed by subjective and objective criteria. The index-risk sample included gravidas < 35y with structurally normal fetuses and normal AFV. Odds ratios and 95% confidence limits (Cl) for abnormal karyotypes among structurally normal fetuses with abnormal AFV are listed below:

Decreased AFV 4 of 63 5.0 ICl 1.7 to 15.2) Oligohydramnios 0 of 28 Decreased + Oligo 4 of 91 3.4 (Cl 1.1 to 10.2) Increased AFV 3 of 26 9.7 (Cl 2.7 to 35.0) PolyhydramniOS 1 of 17 4.6 ICl 0.6 to 36.8) Increased + Poly 4 of 43 7.6 (Cl 2.5 to 23.4)

The risk of abnormal karyotype was greater among all cases of abnormal AFV (8 of 134) than age >35y (16 of 1027); 4.0 (Cl 1.7 to 9.6). Structurally abnormal fetuses with normal AFV were at markedly increased risk for abnormal karyotypes (16 of 116); 11.9 ICl 5.9 to 23.7). We conclude: 1) 2nd trimester abnormalities of AFV, whether increased or decreased, have a significantly increased risk of abnormal karyotypes, 2) such patients should be offered karyotypes, 3) structural anomalies, even with NAFV, are associated with a markedly increased risk of abnormal karyotype.

259 AMNIOTIC FLUID ACETYlCHOLNESTERASE (ACHE) IS FOUND WITH GASTROSCHISIS BUT NOT OMPHALOCELE. AA Saleh, NB Isada, MP JohnsonX, RJ Sokol, MP Dombrowski, MI Evans, Center for Fetal Diagnosis & Therapy, Dept ObIGyn, Wayne State University/Hutzel Hospital, Detroit, tJI

Amniotic fluid ACHE has been used to assist in the evaluation of neural tube defects. It has also been detected in ventral wall defects. We examined amniotic fluid ACHE in 24 pregnancies, 16 complicated by gastroschisiS and 8 by omphalocele. One omphalocele was ruptured ante natally and was excluded. In 22 out 01 23 cases, a normal karyotype was found; one omphalocele had trisomy 13. ACHE was measured by polyacrylamide gel electrophoresis as previously reported and results reported as positive, suspiciOUS, or negative.

I db h' ResuHs shown be ow were analvze c I-gluare. ACHE Omphalocele Gastroschisis

Positive 0 12 Neaative 7 0 Susoicious 0 4

X2=.0001 All omphaloceles were negative for ACHE, while all gastroschises were positive or suspicious. We conclude that a positive or suspicious ACHE is highly associated with gastroschisis or a ruptured omphalocele, but not with an intact omphalocele. Such findings are consistent with the differing origins of the defects and may be used in the differential diagnosis.