[X-ray measurement of the level of rectal carcinomas and its dependence on the functional status of the pelvic floor].

The influence of the various functional states of the pelvic floor on the radiological assessment of the tumour levels and the distant tumour-free distance in rectum neoplasms was investigated. The parameters "anal canal length", "anorectal angle" and "impression of the puborectalis muscle" were measured in lateral distant views of the rectum in a series of healthy controls (n = 160). In addition, these parameters and the "distant tumour-free distance" were measured in patients with rectal cancer (n = 40). For each patient the lateral distant view at rest, during contraction and during maximal relaxation (straining) of the pelvic floor, were available for retrospective analysis. Depending on the various functional states of the pelvic floor, the differences between the same parameters were statistically significant (p less than 0.001). The average difference between the distal tumour-free distances during contraction and straining was 1.5 cm. Therefore, measurements of this distance in one lateral distant view exclusively may result in an inaccurate assessment of the tumour level. For the individual planning of extreme sphincter-saving surgery in low rectal cancer based on lateral distant view, the view at rest appears to be the most suitable. However, additional x-rays during contraction and maximal relaxation of the pelvic floor, respectively, should be available to identify the view at rest for an accurate assessment of the tumour level and to avoid misinterpretations which would have falsely influenced the planning of rectum surgery in 20% of our cases.