Lund J N, Binch C, McGrath J, Sparrow R A, Scholefield J H
Department of Surgery, University Hospital, Nottingham NG7 2UH, UK.
Br J Surg. 1999 Apr;86(4):496-8. doi: 10.1046/j.1365-2168.1999.01026.x.
It has been suggested that anal fissure is an ischaemic ulcer caused by a combination of poor blood supply to the posterior midline of the anal canal and spasm of the internal anal sphincter. This study investigated the topographical distribution of blood supply to quadrants of the anal canal above and below the dentate line.
Cadaveric anal canals were removed and 1-cm blocks were cut above and below the dentate line. Blocks were sectioned at 10 microm and every 25th section was mounted. Using the technique of systematic random sampling, fields in the subanodermal space and the internal anal sphincter in posterior, lateral and anterior quadrants of the anal canal were chosen. The numbers of small arterioles in each field were counted. Mean counts were compared for both subanodermal space and internal anal sphincter between quadrants and levels above and below the dentate line using Page's L test for trends.
Anal canals from eight cadavers were examined. There was a significant trend to an increasing number of arterioles from posterior to anterior in the subanodermal space at all levels and at two of three levels in the internal anal sphincter.
The arteriolar density is less in the posterior quadrant throughout the anal canal. It may be that this poor blood supply predisposes to the development of anal fissures at their most common site in the posterior midline.
有人提出肛裂是一种缺血性溃疡，由肛管后中线血液供应不足和肛门内括约肌痉挛共同引起。本研究调查了齿状线上下肛管各象限血液供应的地形分布。
切除尸体肛管，在齿状线上下切取1厘米的组织块。将组织块切成10微米厚的切片，每25张切片进行装片。采用系统随机抽样技术，选取肛管后、侧、前象限皮下间隙和肛门内括约肌的视野。计算每个视野中小动脉的数量。使用Page趋势L检验比较齿状线上下各象限以及皮下间隙和肛门内括约肌之间的平均计数。
检查了8具尸体的肛管。在所有水平的皮下间隙以及肛门内括约肌三个水平中的两个水平，从后向前小动脉数量有显著增加的趋势。
整个肛管后象限的小动脉密度较低。可能正是这种血液供应不足导致肛裂在其后中线最常见部位的发生。
