NERVE REGENERATION ACROSS COLORECTAL ANASTOMOSES AFTER LOW ANTERIOR RESECTION IN A CANINE MODEL

The disappearance and subsequent return of the recto-anal inhibitory r eflex following low anterior resection was investigated using manometr ic and histological studies. Ten female greyhound dogs were randomised into 2 groups. All underwent low anterior resection. Five had stapled EEA anastomosis of the rectum and 5 were handsewn. The recto-anal inh ibitory reflex was measured before and after surgery using a microtran sducer tipped catheter. Six months postoperatively the recto-anal inhi bitory response was again measured and the animals sacrificed. The col orectal anastomoses were examined histologically using light microscop y to determine the pattern of innervation at the anastomotic site. Man ometric studies showed the recto-anal inhibitory reflex present in all cases pre-operatively, in only 1 case on the tenth postoperative day and was present in eight cases after 6 months. Histological examinatio n of longitudinal sections across the anastomoses showed clear evidenc e of regenerating nerve trunks at the anastomotic site in both stapled and handsewn groups. We conclude that the return of the recto-anal in hibitory reflex is associated with regeneration of intramural autonomi c nerves across the anastomotic scar.