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229

SPO Abstracts

SONOGRAPHIC ESTIMATION OF FETAL TRUNCAL ASYMMETRY CORRELATES WITH THE BODY MASS INDEX MEASURED IN NEO- NATES BORN TO DIABETIC MOTHERS. ~2haniePennin~ ~, Bruce Cohen, Scott Naylor ~, Debbie Anslef , Susan Zwerling ~ and Manuel Porto University of California, Irvine Medical Center, Orange, Californim

OBJECTIVE: We have recently demonstrated a strong association be- tween fetal truncal asymmetry and the risk of severe shoukler dystocia in diabetic patients. Truncal asymmetry was determined sonographically dul~ ing the antenatal period by measuring the difference between the fetal abdominal and biparietal diameters (AD - BPD difference). In the current investigation, we assessed the validity of the sonographic estimation of fetal asymmetry by attempting to correlate the AD - BPD difference with the neonatal body mass index.

STUDY DESIGN: Diabetic women who delivered at UC h'vine from 1993-5 and who underwent ultrasound examination within one week of delivery were eligible for the study. The AD - BPD difference, expressed in centimeters, was measured sonographically and calculated using the follow- ing equation: AD - BPD - (Abdominal Circumference/3.14) - BPD. The neonatal body mass index, expressed in units of kg/m 2, was obtained directly by nursery personnel using a measuring tape to determine neonatal length and a scale to determine weight within one day of delivery. A linear regression analysis was performed using the AD - BPD difference and neonatal body mass index as the independent and dependent variables, respectively.

RESULTS: There were 198 diabetic women who underwent an ultra- sound examination within one week of delivery. A strong positive correla- tion was found between the AD - BPD difference and the neonatal body mass index at birth (r = .6, P < .00001).

CONCLUSION: The AD - BPD difference is a valid method of estimating fetal truncal asymlaaetry and correlates well with actual measure- ments of neonatal asymmetry if performed within one week of delivery.

231

January 1997 Am J Obstet Gynecol

SONOGRAPHIC MEASUREMENT OF FETAL ASYMMETRY CORRE- LATES WITH THE INCIDENCE AND SEVERITY OF SHOULDER DYS- TOCIA IN DIABETIC PREGNANCIES. Bruce Cohen, Stephanie Penning ~, Deborah Ansley x, Scott Naylor Susan Zwerling\ and Thomas Carite. University of California, lrvine Medical Center, Orange, California.

OBJECTIVE: To demonstrate a dose dependent relationship between the degree of ultrasound-measured fetal asymmetlw and the incidence and severity of shoulder dystocia in diabetic women.

STUDS* DESIGN: We conducted a review of the ultrasound data obtained for diabetic women delivering at UC hwine from 1993-5. Fetal asymmetry was quantified as the difference in centimeters between tile abdominal diameter and the biparietal diameter (AD - BPD). The residual AD - BPD value was defined as the difference between an individual's AD - BPD value and the 50th percentile AD - BPD value for that individual's gestafional age as determined in our cohort. Once the diagnosis of shoulder dystocia was determined by the delivering obstetrician, we defined mild shoulder dystocia as the need for McRofiert's maneuver and suprapubic pressure to affect delivery and severe dystocia as the delivery requiring extraction of the posterior arm and the Wood's corkscrew manem,er.

RESULTS: 602 ulu-asound examinations were performed on 343 dia- betic women during weeks 25-42 of gestation. The overall incidence of shoulder dystocia was 9.6%. As the residual AD - BPD value, determined by ultrasound, increased from - 2 to +2 era, the incidences of shoulder dystocia were as follows: - 2 cm/0%, 1 cm/6%, 0 cm/18%, 1 cm/37%, 2 cm/80% The mean residual AD - BPD values for those having no shoulder dystocia, a mild shoulder dystocia, and a severe shoulder dystocia were .2 cm, +.1 cm and +.4 cm, respectively. These differences were significant eve~ when controlling for maternal age, weight, parity and, most impor- tantIy, the birthweight of the iuf~ant (p = .009, ordinal logistic regression analysis)

CONCLUSION: There is a dose dependent relationship between sono- graphically measured fetal truncal asymmetry and the incidence and severity of shoulder dystocia in the diabetic pregnancy.

230 PROSPECTIVE ASSESSMENT OF PLACENTAL CORD INSERTION IN TWIN GESTATION. 7~ Westover, R. Pe~y, 72 Dinh, R. Fiseho; Dept. OB/ GYN, Cooper Hosp, UMDNJ/RVcJ Med School, Camden, N~J.

OBJECTIVE: Twin gestations have a higher incidence of abnormal placental cord insertion (defined as marginal or velamentous insertion) than singletons. The ability of grey scale and color Doppler sonography to detect these abnormal insertion types has not been adequately tested. The purpose of this study is to prospectively determine the accuracy of color Doppler and grey scale imaging in the detection of abnormal placental cord insertion in twin gestation.

STUDY DESIGN: During a 16-month period, 80 twin pregnancies were prospectively evaluated with Gray scale and color Doppler imaging to determine the site of placental cord insertion for each twin. Cord insertion was defined as eccentric, marginal, or velamentous. Each pregnancy was only evaluated once. All placentas were evaluated pathologically after delivery and the true type of cord insertion documented. The percentage of successiMIy visualized cord insertions and the accuracy of tfie prenatal characterization was compared across three gestational age cohorts. Chi square was used to assess significance.

RESULTS: Thirty-one pregnancies have delivered to date with patho- logic data.

Successful visualization of both cords

Correct prediction of insertion type (if insertion seen)

<24 weeks 24-30 weeks >30 weeks P value

14/14 6/8 2/9 .001

28/28 11/13 9/10 NS

CONCLUSION: Our ability to visualize two placental cord insertions in twin pregnancy dropped significantly as gestational age advanced. If the cord insertion was seen sonographicatly, we demonstrated a high predictive value for insertion type regardless of gestational age.

232 ULTRASOUND AND NONSTRESS TESTS IN TWIN GESTATION. 72 Tharakan, A. Williams ~, f KilkennyL Dept Ob/Gyn, College of Physicians & Surgeons, Columbia University and Colmnbia Presbyterian Medical Center, New York, NY.

OBJECTIVE: To assess whether ultrasound (USG) correlates with abnor- mal nonstress tests (NST) and perinatal compromise in twin gestation.

STUDY DESIGN: Retrospective cohort study of 190 twin pregnancies from 1/94-7/96. USG performed every month, abnormal if discordancy >25%, inU'auterine growth retardation, (IUGR <10th percentile), struc- tural anomaly, monoanmionicity, oligo- or polyhydramnios. NSTs within 1 week of deliver), reviewed. Perinata] outcome reviewed, abnormal if fetal or neonatal demise, 5 rain Apgar <7, acidosis, mecnnimn aspiration, seizures. Analysis-chi squared, Yates correction where applicable.

RESULTS: The mean gestafional age at delivery was 35.3 _+ 3.9 wks, and 180 patients (95%) had USG within 4 weeks of delivery--54/180 (30%) abnormal. NSTs within 1 week of delivery in 138/190 (72.6%). No NST in 26 normal and 16 abnormal USG cases.

USG abnm'mal NST nc, vnal NST

abnormal (abn) 24 14 normal (nl) 6 94

Sensitivity 80~, Specificity 87%, PPV 63%, NPV 94~. N1 vs abr~ USG, 8/126 (6.5%) vs 14/54 (26%) abn outcome; p < 0.001. N1 vs abn NST, 3/108 (2.8%) vs 8/30 (26.7%) abn outcome, p < 0.001. Abn outcome due to extreme prematurity 4 /8 with nl USG; 5/14 with

abn USG (p - NS), mainly in 'no NST' group.

CONCLUSION: Abnormal USG in twin gestation correlates with abnor- mal NST and with abnormal perinatal outcome. Normal USG has 94% NPV for NST, and may be used to restrict testing to a smaller population with a greater potential benefit.