Total mesorectal excision - does the choice of dissection technique have an impact on pelvic autonomic nerve preservation?

Background: The aim of this experimental study was to assess the quality of pelvic autonomic nerve preservation of different dissection techniques. Material and Methods: Twelve pigs underwent low anterior rectal resection (LARR) with scissors, ultracision, monopolar diathermy, and waterjet, each in three animals. Assessment of pelvic autonomic nerve preservation was carried out by stimulation of the pelvic splanchnic nerves under electromyography of the internal anal sphincter (IAS). Neurostimulation was performed bilaterally after posterior dissection, after complete mesorectal dissection, and after rectal resection. Results: Stimulation resulted in significantly increased amplitudes of the time-based electromyographic signal of the IAS, confirming nerve preservation. The stimulation results after complete mesorectal dissection showed comparable median amplitude increases for dissection with scissors (10. 34 V (interquartile range [IQR], 5. 58; 14. 74)) and ultracision (9. 79 V (IQR, 7. 63; 11. 6)). Lower amplitude increases were observed for monopolar diathermy (4. 47 V (IQR, 2. 52; 10. 46)) and waterjet (0. 61 V (IQR, 0. 07; 2. 11)) (p = 0. 038). All animals undergoing dissection with scissors, ultracision, and monopolar diathermy had bilateral positive results. Of three animals undergoing LARR with waterjet, one had bilateral positive results. Two had unilateral negative results, indicating incomplete nerve preservation. Conclusion: Scissors, ultracision, and monopolar diathermy might have comparable nerve-sparing potentials and differed from waterjet.