External anal sphincter defects: correlation between pre-operative anal endosonography and intraoperative findings

In order to correlate operative findings with external anal sphincter (EAS) defects identified on anal endosonography (AES), 30 faecally incontinent patients undergoing overlapping sphincteroplasty or total pelvic floor repair were investigated by AES before and after surgery. Endosonic findings were correlated with the appearance of EAS at operation. 21 out of 22 defects seen at surgery had been pre-operatively detected by AES (one false negative). Post-operatively the sphincteroplasty was clearly evident on AES. In three cases of failure it showed an extensive hypoechoic area and these patients underwent dynamic graciloplasty. Endosonography is the method of choice for pre-operative imaging of EAS, having an established role in identifying sphincter defects and correlating well with intraoperative findings. Post-operatively, it has the potential to identify breakdown of the previous repair, allowing prompt surgical intervention. Endosonography is helpful in planning the best type of operation following sphincter injury and is useful in auditing the results of surgery.