348 SPO Abstracts

174 ULTRASOUND DETECTED FREE-FLOATING PARTICLES IN AMNIOTIC FLUID: CORRELATION WITH MATERNAL SERUM a-FETOPROTEIN. Mordechai Hallak, Ivan E Zador", Peter G PrydeX,

Mark P Johnsonx, Nelson B Isada, David B Cotton, Mark I Evans. Dept. of OblGyn, Wayne State UniversitylHutzel Hospital, Detroit, Michigan OBJECTIVE: To determine the rate of ultrasound detected free-floating

particles in amniotic fluid during the early second trimester and their relationship with maternal serum a-fetoprotein (MSAFP).

STUDY DESIGN: Ninety-eight consecutive patients undergoing second trimester amniocentesis for various indications were prospectively studied. Before undergoing amniocentesis, each patient had a level II ultrasound examination and evaluation of the presence of the free-floating particles. Subjective estimate of particles amount and measurement of the size of the

largest particle seen were made. Patients were stratified into three groups

according to their MSAFP level (low, nonnal, high). RESULTS: " P < .05 high versus normal andlor low MSAFP

Maternal serum a-Fetoprotein

Low Normal High (N = 28) (N = 54) (N =16)

FFP present 12 (43%) 23 (43%) 15 (94%)'

Size of largest 1.6 ±. 0 .5 1.7 ± 0 .5 2 .27 ± 0.6" Amount: Low 4 (33%) 7 (30%) 3 (20%)

Medium 7 (58%) II (48%) 4 (27%) High I (9%) 5 (22%) 8 (53%)*

CONCLUSIONS: The presence of free-floating particles in amniotic fluid of normal patients during the early second trimester precludes its use as a

reliable indicator for fetal lung maturity. High MSAFP is significantly correlated with the ultrasonographic appearance of free-floating particles, as well as with larger size and higher amount.

175 THE EFFECTS OF INDOMETHACIN AND TERBUTALINE ON HUMAN FETAL UMBILICAL ARTERY VELOCIMETRY: A RANDOMIZED, DOUBLE-BLIND STUDY. Mordechai Hallak, Kenneth J. Moise, Jr., E. O'Brian Srnithx, David B. Cotton. Depts. Ob/Gyn, Baylor College of Medicine, Houston, TX, and Wayne State Univ., Detroit, MI. OBJECTIVE: To study the effects of indomethacin and terbutaline on umbilical artery impedance as measured by the SID ratio. STUDY DESIGN: Normal, low risk patients at 26-32 weeks' gestation were enrolled. A baseline evaluation of the umbilical artery SID ratio was performed. The patients were then randomized to one of three groups and received a coded capsule that contained either terbutaline (5mg), indomethacin (50mg), or placebo. Repeat evaluation of the umbilical artery SID ratio was performed 4 hours later. The SID ratios before and aI1er administration of the medication were compared in the control and study groups. Analysis of variance and paired Student's I test were applied.

RESULTS: None of the baseline demographic variables were statistically

different among the three groups. Comparison of groups with respect to pre

and post-treatment pH, P02' and PCOz detected no statistically significant treatment effects. The changes in SID ratio in the indomethacin and

terbutaline grOUpS as compared to the placebo grOUp were not significant.

Indomethacin Placebo Terbutaline (0=15) (0=14) (0=12)

Pre-treatment 3.2 ± 0 .4 3.2 ± 0.8 3.0 ± 0.3

SID ratio Post-treatment 3.1 ±0.5 3.3 ± 0.9 2.8 ± 0.2

SID ratio CONCLUSIONS: Terbutaline and indomethacin do not have significant effect on the human umbilical artery impedance as measured by the SID

ratio.

January 1993 Am J Obstet Cynecol

176 THE GESTATIONAL SAC AND 3-D SONOGRAPHY ~', H Steine?' , G Bogne?', A Staudach" , and CP Weiner'. DeplJl. Ob/Gyn, Univ. of Iowa', Iowa City,lA. and General Hospital Salzburg', Salzburg, Austria. OBJECTIVE: Continuation of pregnancy bcyond the early first trimester can be correlated to hormone levels, gestational sac (GS) quality or largelt dimension. and confirmation of fetal cardiac activity. Fint trimester amniotic

Iluid is an ultrafiltrate of maternal plasma, and accounlJl for a large component of gestational sac volume (GSV) . We hypothesized GSV determined using 3-0 sonography would rellect uteroplacental function in the mid 10 lau first trimester and provide a basis for predicting ultimate pregnancy outcome.

STUDY DESIGN: Naturally conceived pregnancies (n =24) underwent first trimester GSV measurements using a 3-D transabdominal 3 .5 MHz annular

array volume transducer (Kretz Technik, AUSlJ'ia). Serum for SHCG, estradiol

(E2) , and progesterone (P) was obtained. Gestational age (GA) wu determined by a careful history and ultrasound. "Normal" outcome wu defined by confir­mation of GA and viability after the mid-second trimester. "Blighted ovum-,

twin sacs , and embryonic demise were considered "abnormal" outcomes. Independent-t-tests, and Regression analysis were used.

RESULTS: There were 18 "normal" and 6 "abnormal" pregnancies studied be­

tween 5 and t I wcc:lcs gestation (mean 8.3 wcc:lcs). The log [GSY) correlated well with GA (r- .83, p < .(01) while neither SHCG, log [SHCG], E2, or P correlated with GA in this range. The mean and standard deviation (SO) of the

log [GSV] for each completed week of gestation was determined. 2/2 preg­nancies with a twin sac had a GSV within 1 SO of the mean . 2/3 cases of "blighted ovum" were> 2 SO from the mean. I viable embryo which later aborted spontaneously had a GSV 4 SO. below the mean for GA.

CONCLUSION: This i. the first study investigating the clinical utility of 3-0 volumetry in pregnancy. The reoulto suggest that measurement of GSV hal

potential to predict ultimate pregnancy outcome in the mid 10 lare first trimester.

177 ACCURACY OF 3-0 SONOGRAPHIC VOLUME MEASUREMENTS_ AR Gregg' , H Steiner"', A Staudach'" and CP Weiner' . Dept •. Ob/Gyn,

Univ. of Iowa', Iowa City, IA and General Hospital Salzburg', Salzburg, Austria. OBJECTIVE: Three dimensional (3-D) ultrasound provides a theoretic buil

for volume measurement in obstetrics. We prospectively tested the accuracy and reproducibility of 3-D volume measurement in a controlled environment. STUDY DESIGN: Two examiners independently studied a .phere with a known volume (26.95 ml) using a 3-D annular array 5 mHz tranaducer (Kretz

Technik, Austria) . The area imaged in the "B" plane was traced and the volume computed by multiplying the distance between images in the '0" plane. The effect of magnification (IX, 1.98X), "volume box" size (60°, 90°), and distance between sphere and transducer (S and lOcm) was determined . Analysis included ANOVA and Independent-t-te"""

RESULTS: 128 volumes were calculated. The average was 27.3 ml (+1.3% error) and did not differ between examiners . The error in measurement was

greatest when the transducer was ncar the sphere (29.3 ml, +8 .0% error)

versus farther away (25.3 ml, -6 . 1% error, p<.OI). When the transducer distance was kept constant (far or near), small but significant differences

(p<.05) were observed at high and low magnifications (far:25 .0 VI 25.5 ml, ncar: 29 .7 vs 29.1 ml) and 60° and 90° volume box size. (far :25.5 vs 25 .1 ml). McasurcmcnlJl were independent of the number of "8' plane images used

to compute volume when transducer distance was constant, however the

number of planes available for tracing was significantly different (p < .01)

when the tranaducer was far (14) v. ncar (19).

CONCLUSION: The distance between the tranaducer and objcct of interest influences volume measurements. Divergence of the "B" plane image which i£

greatest for objecIJIlocated far from the tranaducer likely """"unU for many of our findings_ These statistical variations are alone insufflCient to exclude the

application of volumetry to obstetrics.