Anodermal blood flow at the posterior midline is less than in the other segments of the anal canal. The perfusion of the anoderm at the posterior commissure is strongly related to anal pressure. The higher the pressure, the lower the flow. Our findings support the hypothesis that anal fissures are ischemic ulcers.

Microvascular perfusion of the anoderm was assessed by laser Doppler flowmetry in 27 patients with anal fissure. Anal pressure was recorded simultaneously. Both measurements were repeated 6 weeks after lateral internal sphincterotomy and compared with those obtained from 27 controls. Means(s.d.) maximum anal resting pressure was significantly higher in those with a fissure than in controls (121.07(24.48) versus 68.78(16.97) mmHg, P < 0.001). Anodermal blood flow at the fissure site was significantly lower than at the posterior commissure of the controls (0.46(0.20) versus 0.76(0.28) V, P < 0.001). The fissure healed in 24 patients within 6 weeks of sphincterotomy. In these patients a significant pressure decrease was noted (35 per cent) which was accompanied by a consistent rise in blood flow (65 per cent) at the original fissure site. The increased internal sphincter tone in patients with a fissure reduces anodermal blood flow at the posterior midline. Reduction of anal pressure by sphincterotomy improves anodermal blood flow at the posterior midline, resulting in fissure healing. These findings provide evidence for the ischaemic nature of anal fissure.

External anal sphincter atrophy can only be visualized on endoanal MRI and affects continence after sphincteroplasty. Endoanal MRI is valuable in the preoperative assessment of patients with faecal incontinence. Presented to the American Society of Colon and Rectal Surgeons in Philadelphia, Pennsylvania, USA, June 1997

No abstract

Three-dimensional EUS and endoanal MRI are comparable for detecting EAS defects. However, correlation between the two methods for EAS thickness, length and area is poor. This is also the case for EAS volume determined on 3D EUS and EAS thickness and area measured on endoanal MRI. Three-dimensional EUS can be used for detecting EAS defects, but no 3D EUS measurements are suitable parameters for assessing EAS atrophy.