Perianal appearances associated with constipation. The perianal appearances were studied prospectively of 136 constipated children (mean age 3.9 years, 67 boys, 69 girls). Anal dilatation, fissures, tags, warts, perianal oedema, redness, blueness, and veins were recorded. It was noted whether dilatation occurred immediately or at 30 and 60 seconds with the buttocks minimally separated, and on subsequent firm lateral traction of the buttocks. The degree of faecal loading was assessed in all children. Anal dilatation was found in 24 (18%) and first appeared on lateral traction in eight (6%). In three quarters of the children with dilatation faecal loading or perianal signs were present. Fissures were found in 35 (26%) children and tags in seven (5%). Perianal redness was more likely to be associated with fissures, and blueness with dilatation. We conclude that there are no pathognomonic perianal signs in childhood constipation and that the technique of anal examination should be standardised. 