Volume 166 Number 1, Part 2

165 SONOGRAPHICALLY THICK PLACENTAS: INCREASED PERINATAL MORBIDITY AND MORTALITY. MP Dombrowski, HM Wolfe, AA Saleh, MI Evans, Dept of Ob/Gyn, Hutzel Hosp./Wayne State Univ., Detroit MI

In order to determine the incidence and significance of sonographically thick placentas, we reviewed the computerized records of 18,827 viable, singleton pregnancies. Of these, 116 (0.6%) had placentas which appeared subjectively thick and measured at least 4 cm by ultrasound. Thick placentas, initially diagnosed at a mean of 28.6 ± 5.5 weeks (range ~ 15 to 38), were associated with shorter gestations (36.6 ± 4.5 v 38.5 ± 3.1 wks, p < .0001), decreased birth weights (2832 ± 967 v 3070±718 g, p < .05), 31 (26.7%) had decreased amniotic fluid (AFV), 8(6.9%) had oligo, 13(11.2%) had increased AFV, and 6 (5.2 %) had polyhydramnios. Odds ratios and 95% confidence limits (CL) for adverse pregnancy outcomes associated with thick placentas are listed below:

5·min Apgar < 7 6.7 (CL 4.0 to 11.3) Abruptio placentae 2.9 (CL 1.1 to 8.1) NICU admission 4.1 (CL 2.8 to 6.1) Anomalies 8.4 (CL 4.9 to 14.4) Perinatal mortality 12.0 (CL 7.5 to 19.4) Total morbidity/ 4.5 (CL 3.1 to 6.6)

mortality Possible causes of the 116 thick placentas included: Rh isoimmunization ~ 6, diabetes ~ 11, abruptio ~ 4, but none with syphilis. Congenital anomalies, and not the above, were the leading cause of perinatal mortality. On the basis of these data, pregnancies with thick placentas are at risk for compromised perinatal outcome; sonographic evaluation should be peformed to rule out coexistent anomalies.

166 PERINATAL OUTCOME WITH SONOGRAPHICALLY THIN PLACENT AS. MP Dombrowski, AA Saleh, SM Berry, DB Cotton, Dept Ob/Gyn, Hutzel Hosp./Wayne State Univ., Detroit, MI

In order to determine the incidence and significance of sonographically thin placentas, we reviewed the computerized records of 18,937 viable, singleton pregnancies. Of these, 122 (0.6%) had subjectively thin placentas by ultrasound. The diagnosis of a thin placenta was initially made at a mean gestational age of 29.4±7.4 weeks (range ~ 8.6 to 40.1 weeks). Thin placentas were not associated with shorter gestations (38.6±3.0 v 38.5±3.1 wks), but 20.5% had polyhydramnios, 19.7% had increased amniotic fluid volume (AFV), 12.3% had decreased AFV, and 1.6% had oligohydramnios. Odds ratios and 95 % confidence limits (CL) for thin placenta adverse pregnancy outcomes are listed below.

Weight < 10th %tile 2.4 (CL 1.5 to 3.8) Abruptio placentae 2.0 (CL 0.6 to 6.5) NICU admission 2.2 (CL 1.4 to 3.5) Anomalies 3.6 (CL 1.7 to 7.4) Perinatal mortality 3.4 (CL 1.7 to 7.1) Total morbidity/ 2.1 (CL 1.4 to 3.1)

mortality Possible causes of the 8 perinatal mortalities with thin placentas included: esophageal atresia, sacrococcygeal teratoma with abruptio, anencephaly, placental hemorrhagic endovasculitis, thoracic dysplasia, abruptio, diaphragmatic hernia, and ventricular septal defect. In conclusion, pregnancies with thin placentas are at increased risk for perinatal morbidity and mortality; a careful sonographic evaluation should be performed to rule out coexistent fetal anomalies.

SPO Abstracts 325

167 SIMPLE GEOMETRIC RELATIONSHIPS BETWEEN AMNIOTIC FLUID INDEX AND AMNIOTIC FLUID VOLUME. Robert A Bracex. Division of Perinatal Med, Dept of Reproductive Med, University of California, San Diego, CA 92093

The 4 quadrant amniotic fluid index (AFI) is used increasingly as an indicator of amniotic fluid volume (AFV) even though no established relationship exists between these two variables. The purpose of this study was to establish idealized relationships among AFI, AFV, and fetal size by treating the uterus and the fetus as either spheres or circular ellipsoids (len/dia=2). Using a com puter, the weight of the fetus was varied from 0 to 3000 gm and the AFI from 20 to 300 mm. AFV (ml) was determined as the difference between uterine and fetal volumes. We found that the size of the fetus had dramatic effects on the relationship between the AFI and AFV. That is, as fetal weight increased, there were large shifts upward and to the left in the curve relating AFI (x) to AFV (y). For example, for AFI = 100 mm, AFV for a 3000 gm fetus (876 ml) was 26.1, 7.9, and 2.0 times that of a 10, 100, and 1000 gm fetus, resp. In addition, when the size of the fetus was near zero, there was a cubic relationship between AFI and AFV. As fetal weight increased, the relationship between AFI and AFV became progressively less curvilinear. For a fetal weight of 3000 gm, the relationship was nearly linear (AFV = 10.7 x AFI . 162, r=0.998, p<O.OOOOl for spheres and AFV = 14.6 x AFI ·271, r=0.996, p<O.OOOOl for ellipsoids). These relationships help explain the ncar linear relationships between the AFI and AFV previously observed in animal and human studies. Thus, the relationship between the AFI and AFV is unique for each gestational age because of the strong dependence on fetal weight.

168 FETAL ILIAC BONE AND FEET MEASUREMENTS: NOMOGRAMS AND APPLICATION IN SKELETAL DYSPLASIAS. R. Jaffe, W. Meyer,X S. Warsof University of Illinois, Chicago, IL.

Skeletal dysplasias is a heterogenous group of disorders affecting the skeleton. With detection of disorders of bone growth a general diagnosis is often made in-utero because many anomalies have similar features. This study was performed to create nomograms for growth of iliac bone(IB) , length and width of fetal feet as well as their growth relative to the femur. The study included 250 women. Correlation between gestational age (GA), femur length (FL), iliac length and feet measurements were established. The growth of IE and feet were found to correlate lineJrly with GA with a R2 of 0.933 for IB, 0.828 for length and 0.820 for width of fetal foot. There was a linear relation between feet measurements and FL with a R2 of 0.875 for length and 0.805 [or width of foot. The IB is affected in many skeletal dyspla­sias and other anomalies whereas in some it is un­affected. The fetal feet measurements were shown to correlate well with both GA and FL. Both IB and feet measurements improved the diagnosis of skeletal dysplasias found in-utero. CONCLUSION: The addition of nomograms for IB and fetal feet measurements will enable improved recognition of specific anomalies and patient counseling.