Regeneration of the Normal and Pseudopregnant Rabbit Endometrium After Neodymium:YAG Laser Photocoagulation

The regeneration of the normal and pseudopregnant rabbit endometrium subjected to Nd:YAG laser photocoagulation was studied in three experimental groups: Group I (n = 11) was subjected to laser photocoagulation after surgical exposure of the endometrium and evaluated at 1,2, and 4 weeks after primary surgery and photocoagulation. Group II (n = 12) was subjected to laser photocoagulation 7 days after hCG administration and evaluated as group I. In group III (n = 8), hCG was administered 4.5 weeks after laser photocoagulation and evaluated 1, 2, and 3 weeks after hCG administration (up to 7.5 weeks post laser photocoagulation). Within 4 weeks, complete regeneration occurred only in 3 of 23 experimental horns (groups I and II) as compared to 15 of 22 in the control horns. In all other specimens, tissue necrosis, edema, hemorrhage, fibrosis, and granulation were still evident. In 4 of the photocoagulated endometrial specimens and in 2 of the controls (contralateral uterine horns), minimal focal atypical changes were observed. These changes probably represent atypia of repair or regenerative atypia rather than premalignant lesions. In the third group, complete regeneration was observed with morphologic evidence of normal pseudopregnant endometrial transformation and no persistent atypia. Delayed regeneration of the rabbit endometrium after Nd:YAG laser photocoagulation is completed after 4–5 weeks. Focal atypical changes may be related to repair after Nd:YAG laser photocoagulation, and the progestational endometrium may be more susceptible to these changes.