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.

Multiple myeloma (MM) is associated with an increased risk of venous thromboembolic (VTE) complications. Aim of this study was to measure microparticle-associated tissue factor (MP-TF) activity in patients with newly diagnosed MM before and after chemotherapy and to investigate whether MP-TF activity is associated with VTE. MP-TF activity was assessed in 122 newly diagnosed MM patients who were eligible for combination chemotherapy. MP-TF activity levels (17.6 fM Xa/min [8.6-33.2] (median [IQR]) were higher in untreated MM patients compared to normal healthy volunteers (4.1 fM Xa/min [2.3-6.6], p <0.001). MP-TF activity prior to the start of treatment was not different between patients who developed a VTE during follow-up (n=15) and those who did not (n=107). In 75 patients in whom plasma was obtained before and after chemotherapy, MP-TF activity decreased significantly (from 17.4 [10.2-32.8] to 12.0 [7.0-18.5] fM Xa/min, P=0.006). MP-TF activity remained, however, elevated in patients who developed VTE (15.1 [10.3-25.2]), in contrast to patients not developing VTE (11.4 [7.0-25.2], P<0.001). In conclusion, MP-TF activity is increased in patients with MM. Whether MP-TF activity has a pathogenetic role in VTE in MM patients remains to be established in future studies.

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