ENDOSONOGRAPHY OF THE ANAL SPHINCTERS IN SOLITARY RECTAL ULCER SYNDROME

Twenty-one patients with histologically proven solitary rectal ulcer s yndrome (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. Fou r patients with SRUS had anal sphincter defects on AES. All were of th e internal anal sphincter (IAS), which appeared fragmented in two pati ents with complete rectal prolapse. Measurements of internal and exter nal anal sphincter (EAS) diameter and cross-sectional area were taken, excluding the 4 patients with defects. The submucosa was inhomogeneou s (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 m m vs 7.0 mm; P = 0.0173), as was cross-sectional area (median 905 sq m m vs 594 sq mm; P = 0.0052). The ratio of EAS to IAS thickness was red uced in patients with SRUS (median 2.6 vs 4.0; P = 0.0029). The mechan ism of these changes is unclear but apparent muscle hypertrophy on ult rasound may diagnose those patients with SRUS in whom defecatory diffi culty is a predominant symptom.