VAGINAL ENDOSONOGRAPHY - NEW APPROACH TO IMAGE THE UNDISTURBED ANAL-SPHINCTER

PURPOSE: Although anal endosonography provides clear images of anal sp hincters, the probe in the anal canal may distort epithelial structure s and sphincter muscles may be compressed, producing inaccurate muscle thickness measurements. The aim of this study is to describe a new ap proach using vaginal endosonography to image the anal canal undistorte d. METHODS: Twenty females (10 healthy volunteers and 10 with fecal in continence) had both anal and vaginal endosonography performed. RESULT S: The undisturbed anorectum, submucosa, anal cushions, and anal sphin cter muscles were clearly visualized by vaginal endosonography, and an atomy was described. Although anal and vaginal endosonographic measure ments of internal sphincter muscle thickness correlated (r = 0.83; P = 0.01), anal endosonography consistently underestimated the thickness (2.3 +/- 0.5 vs. 3.2 +/- 1.2 mm; mean +/- standard deviation). Anterio r internal and external anal sphincter defects were identified accurat ely with both techniques. CONCLUSIONS: Vaginal endosonography is a new technique that enables accurate imaging of anal sphincters and epithe lial structures at rest. In addition to making the diagnosis of anal s phincter defects, it has potential applications in the imaging of anov aginal sepsis and malignancy and possibly in understanding the pathoge nesis of anal fissure and hemorrhoids.