Irradiation of true pelvis for bladder and prostatic carcinoma in supine, prone or Trendelenburg position.

Small bowel transit was performed in 50 patients with bladder or prostatic carcinoma. The patients were all examined in supine and prone positions; some were also studied in 25 degrees Trendelenburg position and 25 degrees inclined procubitus to investigate the effect of the various positions on the displacement of the small bowel loops out of the true pelvis. The prone position proved to be superior to the supine position in 78% of patients. A mean displacement of 0.9 cm was obtained. Greatest shifts generally were found in the Trendelenburg position and inclined procubitus, with a mean displacement of 1.9 and 2.0 cm, respectively. The patients' height, weight, maximal abdominal circumference and Quetelet's index were analyzed with regard to the shifts of bowel loops under the various conditions. Only weight and Quetelet's index were correlated with the shifts in the Trendelenburg and inclined procubitus positions. The shifts were generally larger in case of heavier patients. We conclude that pelvic irradiation should preferably be done in the Trendelenburg or inclined procubitus position, especially in case of obesity.