title: The interaction of laser energy with ureter tissues in a long-term investigation.
abstract: This study investigates tissue responses after laser irradiation of the rabbit ureter, which serves as an experimental model for rectourogenital fistulae of children. Twenty-five rabbit ureters were irradiated intraluminally by a Nd:YAG laser 1320 nm (2 Watt, 20 seconds and 3 Watt, 8 seconds) via an applicator with radialsymmetrical light distribution. Immediately, 2 weeks, 4 weeks, 8 weeks, and 16 weeks after irradiation, the ureters were X-rayed with contrast solution and prepared for light and transmission electron microscopy. For the parameters employed, no apparent morphological differences could be observed. Immediately, the central laser zone showed a transmural thermonecrosis prevailed by cellular destruction, condensed ground substance and occlusion of most vascular lumina. Peripheral laser zones displayed urothelial vacuolations. Between 2 and 16 weeks, urothelial regeneration and ingrowth of granulation tissue caused a luminal stenosis or occlusion followed by transformation into scar tissue. In some peripheral laser zones, a hydroureter with marked luminal dilatation developed. We conclude that the ureter is occluded if the expanding force of the growing scar tissue exceeds the hydrostatic pressure of the obstructed urine. A laser occlusion of rectourogenital fistulae will be easier to achieve since fistula occlusion does not entail an obstruction of the urine flow.
authors.affiliation: Institute of Anatomy, University of Münster, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Stratmann
authors.forename: K
authors.initials: K
authors.lastname: Schaarschmidt
authors.forename: R R
authors.initials: RR
authors.lastname: Lehmann
authors.forename: A
authors.initials: A
authors.lastname: Heinze
authors.forename: G H
authors.initials: GH
authors.lastname: Willital
authors.forename: E
authors.initials: E
authors.lastname: Unsöld
mesh_terms: D000818:Animals; D007834:Lasers; D008854:Microscopy, Electron; D011817:Rabbits; D014513:Ureter / Q000473:pathology / Q000528:radiation effects* / Q000648:ultrastructure