EXAMINATION TECHNIQUES FOR ENDOSONOGRAPHY OF THE ANAL-CANAL

Background: To determine whether patient position or sphincter contrac tion influences sphincter thickness or defect assessment. Methods: Ana l endosonography was performed on 35 consecutive patients (30 women, f ive men). Twenty-five were scanned in the left lateral and prone posit ions, and the internal sphincter thickness was measured. In 10 patient s, the internal sphincter, longitudinal muscle, external sphincter, an d length of any defect were measured at rest and during anal squeeze. Results: There was no significant difference in internal sphincter thi ckness measured in the prone and left lateral positions (95% limits of agreement, -0.12 to 0.06). The thickness of the internal sphincter, l ongitudinal muscle, and external sphincter at rest did not change sign ificantly during straining (95% limits of agreement, -0.44 to 0.3, -0. 28 to 0.24, and 0.33 to 0.71, respectively). The squeeze maneuver did not influence defect appearance or length (95% limits of agreement, -2 .845 to 2.379). Greater symmetry of the anterior part of the external sphincter and improved visualization of perineum was achieved in the p rone position. Conclusion: Examination in the prone position is prefer red. Squeeze maneuvers are of no diagnostic benefit.