Anal endosonography: relationship with anal manometry and neurophysiologic tests

Thirty-seven patients were referred for evaluation of anal function; their clinical diagnoses were traumatic fecal incontinence (13), idiopathic (pudendal neuropathy) fecal incontinence (7), fecal soiling (9), and other (8). In all patients, anal endosonography (sphincter defects and internal sphincter thickness [IST]) and anal manometry (maximal basal pressure [MBP] and maximal squeeze pressure [MSP]) were performed. In 18 patients, neurophysiologic tests (EMG-maximal contraction pattern [MCP], single-fiber EMG [fiber density; FD], and pudendal nerve terminal motor latency [PNTML]) were also performed. Endosonography demonstrated in seven patients both an internal and external sphincter defect (Group 1), in seven patients an internal sphincter defect and in one patient an external sphincter defect (Group 2), and in 22 patients no sphincter defect (Group 3). There was a significant difference among these three groups for MBP and MCP, the lowest being in Group 1. Between the patients with traumatic fecal incontinence and idiopathic fecal incontinence, no differences in IST, MBP, MSP, MCP, FD, and PNTML were found. In two patients with a suspected obstetric trauma, there was an unexpected additional severe pudendal neuropathy. In one patient with a suspected obstetric trauma, no damage of the anal sphincters could be demonstrated. In one patient with suspected idiopathic fecal incontinence, there was an additional, unsuspected defect of the internal sphincter. There was concordance between endosonography and EMG in the mapping of the external sphincter. Clinical diagnoses can be misleading in differentiating between traumatic and idiopathic fecal incontinence; anal endosonography provides unsuspected and additional information about the sphincters; PNTML can reveal unsuspected neuropathy in traumatic fecal incontinence. Therefore, the combination of endosonography and PNTML is promising in selecting patients for surgery.