Can the sonographer predict the accuracy of ... - Wiley Online Library

14th World Congress on Ultrasound in Obstetrics and Gynecology

P14.66 Can the sonographer predict the accuracy of sonographic estimation of birth weight?

Poster abstracts

P14.67 Ultrasound estimation of fetal weight in prolonged pregnancy F. Sethna, V. Padma, B. T. Hollis, B. Thilaganathan, A. Bhide

M. Luria1 , R. Rabinowitz2 , O. Shen2

St George’s Hospital Medical School, London, UK

Haddassah Mt Scopus, Israel, 2 Shaare Zedek Medical Center, Israel

1

Introduction: When performing fetal biometry measurements, the examiner occasionally has the impression that the sonographic estimation is less accurate due to technical limitations. Our objective was to evaluate the possible association between the examiners assessment of the measurement accuracy and the actual error between fetal weight estimation and actual birth weight. Methods: 186 women, within 10 days of delivery, were examined prospectively using fetal biometric measurements. Fetal weight estimates were calculated using Hadlock’s formula employing FL, AC and BPD. The sonographers were asked to give a subjective score to each measurement; one point if the quality of the measurement was technically good, two points if the measurement was of medium quality and three points if the measurement was of poor quality. The difference between the corrected sonographic fetal weight estimation and the actual birth weight was analyzed with respect to the scoring given by the examiner. Results: As shown in tables 1–3 for none of the three measured parameters did the perceived measurement accuracy predict the actual error in predicting birth weight. Table 1 Differences between actual and predicted birth weights by biparietal diameter (BPD) measurement quality scoring BPD measurement quality

Good Medium Poor

N

Mean difference (%)

SD

122 49 15

6.19 6.23 9.11

4.57 4.53 4.32

P = 0.062.

Table 2 Differences between actual and predicted birth weights by abdominal circumference (AC) measuremnt quality scoring AC measurement quality

Good Medium Poor

N

Mean difference (%)

SD

109 68 9

6.27 6.55 7.62

4.43 4.89 4.40

P = 0.678.

Table 3 Differences between actual and predicted birth weights by femoral length (FL) measurement quality scoring FL measurement quality

Good Medium Poor

N

Mean difference (%)

SD

151 32 3

6.76 5.30 2.09

4.76 3.41 2.84

P = 0.065.

Comment: The subjective impression of the quality of biometric measurements does not have a significant correlation with the actual accuracy of the fetal weight estimation. Remarks pertaining to the quality of measurements should not be included in the report of fetal weight estimates.

364

Objective: To estimate the limits of agreement between the predicted and actual fetal weight in prolonged pregnancy beyond 41 + 3 weeks’ gestation. Methods: Analysis of data prospectively collected in a dedicated post-dates clinic over a period of one year. Women undelivered at 41 + 3 weeks of pregnancy were offered an ultrasound fetal assessment. Estimated birth weight was calculated at this scan based on the Hadlock formula. Results: 342 women at 41 + 3 weeks were included in the analysis. Delivery occurred a median of 3 days (range 0 to 15) after ultrasound fetal assessment. There was a close association between estimated and actual birthweight (r = 0.72, p < 0.001). The mean difference between the estimated and actual birthweight was 54.22 g (95% CI -585.5 g to 693.9 g). Conclusion: Although there is a very good correlation between ultrasound estimates of fetal weight and actual birthweight, the limits of agreement are fairly wide. Ultrasound estimates of birthweight overestimates the neonatal weight by an average of 52 g.

P14.68 Three consecutive pregnancies with Dekaban-Arima syndrome with variable expression M. van der Laan1 , A. J. van Essen2 , A. Timmer2 , W. B. Dobyns3 , B. Arabin4 1 St Antonius Hospital, Netherlands, 2 University Hospital Groningen, Netherlands, 3 University of Chicago, USA, 4 Isala Clinics Zwolle, Netherlands

Introduction: A hypoplastic cerebellar vermis is a common feature in Joubert syndrome, as well as related conditions, such as Dekaban-Arima syndrome, Senior-Loken malformation, Meckel syndrome, COACH syndrome, hepatic fibrosis syndrome and juvenile nephronophtisis. Case: We report on a case in which three consecutive pregnancies were complicated by malformations due to Dekaban-Arima’s cerebello-oculo-hepato-renal syndrome. This syndrome is regarded as a subgroup of Joubert’s syndrome. It is thought to be an autosomal recessive disease and at present the exact gene locus is unknown. Thus imaging procedures are the only way to prenatally diagnose the syndrome which is characterised by hypoplastic or aplastic cerebellar vermis, cystic renal dysplasia, congenital liver cirrhosis or ductal plate malformation and retinal colobomas. Establishing the exact diagnosis especially at early gestation can be difficult due to the variability in expression. In the reported case the first and second pregnancy were followed by neonatal death and final diagnosis of the syndrome was only conclusive after detailed post mortem analysis of the first two babies and MRI imaging of the second child. On MRI-imaging a molar tooth sign could be detected. This sign can be visualized in an axial plane and consists of: (1) enlarged superior cerebellar peduncles, non decussating in the pontomesencephalic junction (2) deepening of the interpeduncular fossa and (3) a hypoplastic vermis of the cerebellum In the third pregnancy diagnosis was suspected by ultrasound as early as by 12 weeks and further evaluated by prenatal MRI imaging. The third pregnancy was terminated by 18 weeks. Discussion: As this syndrome can only be diagnosed prenatally by imaging procedures, we hereby illustrate that detailed ultrasonography can detect the various anomalies present and that in doubt MRI imaging of the fetus can provide excellent information with respect to the differential diagnosis of the syndrome.

Ultrasound in Obstetrics & Gynecology 2004; 24: 269–372