Endosonography of the anal sphincters in solitary rectal ulcer syndrome.

Twenty-one patients with histologically proven solitary rectal ulcer syndrome (SRUS) were examined by anal endosonography (AES) in order to determine the frequency of any ultrasound abnormality. Comparison was made with a group of 17 age and sex matched asymptomatic subjects. Four patients with SRUS had anal sphincter defects on AES. All were of the internal anal sphincter (IAS), which appeared fragmented in two patients with complete rectal prolapse. Measurements of internal and external anal sphincter (EAS) diameter and cross-sectional area were taken, excluding the 4 patients with defects. The submucosa was inhomogeneous (P = 0.0016) and thickness increased in patients with SRUS (median 4.0 mm vs 2.0 mm; P < 0.0001). IAS diameter was increased (median 3.8 mm vs 2.0 mm; P < 0.0001), as was cross-sectional area (median 241 sq mm vs 112 sq mm; P < 0.0001). EAS diameter was also increased (median 8.5 mm vs 7.0 mm; P = 0.0173), as was cross-sectional area (median 905 sq mm vs 594 sq mm; P = 0.0052). The ratio of EAS to IAS thickness was reduced in patients with SRUS (median 2.6 vs 4.0; P = 0.0029). The mechanism of these changes is unclear but apparent muscle hypertrophy on ultrasound may diagnose those patients with SRUS in whom defecatory difficulty is a predominant symptom.