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394 SPO Abstracts

UHBXPLAINED ELEVATED MATERNAL SERUM ALPBA­FETOPROTEIN AND PLACENTAL ABNORMALITIES. DE Hickok, M Williamsx, R ZingheimX, J KimelmiLnx, as MahonyX, DA Nybergx. Swedish Medical Center, Seattle WA. OBJECTIVE: We investigated whether women with unexplained elevated second trimester maternal serum alpha-fetoprotein (MSAFP) levels were more likely to have placental abnormalities detected by ultrasound. STUDY DESIGN: Comparison was made between a cohort of 227 women with unexplained MSAFP elevations (n=227) and sequentially selected women with normal MSAFP (n=23l). RESULTS I Risk ratios (RR) and confidence intervals (CI) for the subtypes of placental abnormalities were:

t IlSAFP III IlSAFP 110.-1 placent. 190 225 Abno.-l placent. 37 6 s..x:horianic h..,rmage 3 2 Sanolucenci es/lllkes 5 0

RR (95% CI) 1.0 6.2(2.7·14.5) 1.8(0.3-10.4)

Thickened placent. 17 2 9.3(2.2-39.7) MIll tiple lesions 12 2 6.7(1.5-29.6)

CONCLUSIONS I Placental abnormalities occurred more frequently among women with elevated KSAFP (RR-6.2), compared with those with normal levels. Thickened placentas or multiple abnormalities were significantly related to unexplained elevated MSAFP, yet subchorionic hemorrhage. were not. This suggest. that greater attention be given placental structure during elevated MSAFP evaluation, which may modify the decision to perform more invasive diagnostic tests.

LACK OF ASSOCIATION OF VILLOUS msrOLOGY WITH KARYOTYPE IN CHROMOSOMALLY NORMAL AND ABNORMAL PLACENTAS. C. Meyers, T. Parmley, A. Tharapel', V. Prenger', S. Elias. Depts. OblGyn, Univ. of Tenn., Memphis, TN and Univ. of Arkansas, Little Rock, AR. OBJECTIVE: We sought to identify any characteristic villous histology associated with chromosome abnormalities in ultrasonographically confirmed, viable pregnancies. STUDY DESIGN: We retrospectively identified 44 individuals undergoing pregnancy termination for various indications: controls [elective terminations] (CONT) N = IS, fetal neural tube defects (NTD) N = IS , and fetal chromosome abnormalities (CA) N = 14. Placental histologic sections were reviewed for the presence of edema (present or absent) and trophoblastic islands (TI) (present or absent) by an examiner blinded as to the indication for termination. RESULTS:

Mean VE Gestational andlor Age VE TI TI

N (Range) (%+) (%+) (%+)

CA 14 14.6 wks (11-18) 80 57.1 80 NTD 15 18.1 wks (16-20) 86.7 53.3 93.3 CONT 15 15.9 wks (8-19) 92.9 26.7 92.9

CONCLUSIONS: No significant differences were found in the proportion of subjects with VE andlor TI among the three study groups. Therefore, villous histology in this study was Dot useful in predicting fetal karyotype.

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January 1993 Am J Obslet Gynecol

DETECTtNG FIRST TRtMESTER FETAL ANOMALIES - WILL AFP ANALYSIS BE USEFUL? C Brumfield, R. Davis, M. DuBard, S. Rnley", L. Boots'. Dept. Obstetrics & GyneCOlogy, Laboratory of Medical Genetics, Univ. of Alabama at Birmingham, Birmingham, AL. OBJECTIVE: To evaluate the usefulness of alpha·fetoprotein (AFP) analysis in the detection of fetal anomalies prior to 14 weeks gestation. In current clinical practice, AFP analysis is not thought to be accurate in screening for fetal anomalies at this point in gestation. STUDY DESIGN: During a four year period from 1988·1992, a targeted ultrasound and a maternal serum AFP were performed on each patient prior to undergoing an early amniocentesis at 11 -13 weeks gestation. Amniotic fluid was obtained for AFP analysis in addition to the fetal karyotype. A retrospective chart review was done to identify all patients in whom a fetal structural defect had been diagnosed at the time of early amniocentesis. The MSAFP and AF-AFP values from these patients were then oompared to the type of fetal anomaly and the karyotype results. An AFP value <t 2.0 MOM was considered to be elevated. RESULTS: 268 patients underwent early amniocentesis. 20 of 268 patients (7.4%) had a MSAFP value <t 2.0 MOM. Twelve fetal structural defects were identified as listed in the table.

Karyotype ~ JLBs. Abnormal/# PIs Anencephaly 3 No 0 Anencephaly + Omphalocele 1 No 0 Cystic Hygroma 6 Yes 3 Encephalocele 1 No 0 Nonimmune Hydrops Yes 1

MSAFP and AF-AFP values were eleva1ed in all four cases of anencephaly. Three patients had this diagnosis at 13 weeks and 1 at 12 weeks. No other structural defects had an elevated AFP value. Three of 6 fetuses with cystic hygroma had an abnormal karyotype and 1 fetus with nonimmune hydrops had a trisomy 18. CONCLUSION: MSAFP and AF-AFP analysis may prove to be useful in the detection of open neural tube defects prior to 14 weeks gestation.

OPTIMIZED AMNIOCENTESIS METHODS ENHANCE PERFORMANCE OF FLUORESCENCE IN SITU HYBRIDIZATION (FISH) FOR PRENATAL DIAGNOSIS. J. Moskowitz><. B. Ward'. M. WeINtelN'. The Amniocentesis Center of N.V .. New York. NY; Integrated Genel1cs. Framingham MA. OBJECTIVE: Rapid detecl10n of chromosomal aneuploidies for chromosomes 13. 18.21. X and Y In uncultured amnlocytes Is possible with region-specific DNA probes and FISH technology. ThIs study examined the effect of amniocentesis protocols on the performance characteristics of FISH technology. STUDY DESIGN: Previous studies have shown aneuploidy detect10n In uncultued amniotic fluid cells by FISH Is rapid (2 days) and accurate. However. uninformative results do occur and are typically due to 1, Significant numbers of maternal cells. 2. A paucity of nuclei In the amniotic fluid. or 3. Subopl1mal performance of probes. The quality of the amnlol1c fluid sample dlrectty affects the first two causes. FISH results were compared between a pracl1ce using a strict amniocentesis protocol versus the general referral group. The protocol Includes ultrasound guidance. avoidance of transgression of the placenta. and a speclnc fluid collection protocol. RESULTS: In a clinical series of 2.514 specimens. 7.5% of all specimens submitted for FISH were ·unlnformatlve·. The above protocol (n=412) resulted In a 2.9% unlnfomnatlve rate. a significant reduction In the unlnformal1ve rate. Maternal cells were rarely encountered and the rate of samples with a paucity of cells was reduced by half. Accuracy In both gr~ was equivalent at levels of greater than 99.8%. CONCLUSION: Str1ct amniocentesis protocols can Improve the perfomnance characteristics of FISH protocols. This allows rapid informative. accurate results In greater than 9r4 of the tested samples with a dlagnosl1c accuracy of greater than 99.8% vs traditional cytogenel1cs.