Differences in anal function in patients with incontinence to solids and in patients with incontinence to liquids.

Manometric radiological and neurophysiological measurements of the anal sphincter were carried out in 19 female patients who were incontinent to liquid faeces only, 15 female patients who exhibited incontinence to solid and liquid faeces and 18 normal female controls. Both groups of patients had abnormally obtuse anorectal angulation and perineal descent, a weak and easily inhibited sphincter tone and similar degrees of neuropathy during electromyography. However, patients who were incontinent to solids and liquids exhibited lower squeeze pressures during standard manometry and lower peak pressures during saline infusion than patients who were only incontinent to liquids. These findings suggest that it is the additional weakness of the external sphincter that renders patients incontinent to solids as well as liquids.