OC35.02: Individual and group learning curves for ultrasound fetal biometry measurements: cumulative sum analysis

Abstract

Oral communication abstractsdescent of pelvic organs on ultrasound on the one hand and hiatal dimensions on the other hand (all P < 0.001). Conclusions: Hiatal dimensions vary markedly in women symptomatic of pelvic floor disorders. Vaginal childbirth seems to be the main environmental influence, with a clear relationship between the number of deliveries and hiatal area. The most marked changes seem to occur with the first baby delivered vaginally. Hiatal dimensions seem to correlate strongly with the degree of prolapse. OC34.07Measurement of muscles of anal canal using 3D ultrasound D. Pretorius, N. M. Guaderrama, J. Liu, C. W. Nager, G. Sheean, R. K. Mittal University of California, San Diego, USAObjective: To identify how to acquire and display the anatomy of the pelvic floor using 3D ultrasound (3DUS) to measure the lengths of the muscles. Methods: 24 asymptomatic nulliparous women (age 36.7 ± 13.9 years) were evaluated with 3DUS imaging and anal manometry simultaneously during rest and squeeze maneuvers. Volume data were acquired from 1) transabdominal curved array 2-5 MHz transducer placed on the perineum (n = 2), 2) transvaginal (TV) 5-9 MHz transducer placed at the vaginal introitis (n = 17) and 3) TV transducer placed on the perineum (n = 11). Both multiplanar and rendered displays were used after rotating the volume into a standard, reproducible orientation to optimize visualization of the internal anal sphincter (IAS), the external anal sphincter (EAS) and the puborectalis muscle (PRM). Results:The best resolution to evaluated measurements of the IAS, EAS and PRM were obtained using the TV probe placed in the introitis. Volumes obtained using the TV probe on the perineum were best suited to evaluate changes in the pelvic floor hiatus, to measure the anorectal angle, to identify a reproducible measurement from the anorectal angle to the symphysis pubis and to identify the PRM. Movement of the cursor dot, which identifies the exact same location in all 3 perpendicular planes of the volume, was critical to understanding the anatomy of the pelvic floor. Measurements of the length of the IAS, EAS and PRM were 28 ± 2 mm, 19 ± 1 mm, and 18.0 ± 1.0 mm in the resting state and 28 ± 2, 22 ± 1 and 18.0 ± 1.0 mm during squeeze, respectively. Measurement of the pelvic hiatus chanced from 51.7 ± 5.0 mm at rest to 47.4 ± 4.1 mm during squeeze. Conclusion: 3DUS techniques are useful to assess the anatomy of the pelvic floor, and more specifically, the anal canal. Measurements of muscles and relationships between structures are useful in understanding the physiology of the pelvic floor. OC35.01Chorionicity determination is the key factor in the antenatal care of twins Objective: to evaluate the outcome of screening for structural malformations in twins and to evaluate the outcome of screening for twin to twin transfusion syndrome (TTTS) among monochorionic (MC) twins through a number of scans from 12 weeks of gestation. Methods: In a prospective multicenter observational study twin pregnant women were included before ...