Effect of Morphine and incision length on bowel function after colectomy

Return of bowel function remains the rate-limiting factor in shortening postoperative hospitalization of patients with colectomies. Narcotics are most commonly used in the management of postoperative pain, even though they are known to affect gut motility. Narcotic use has been felt to be proportional to the length of the abdominal incision. The aim of this study was to determine whether return of bowel function after colectomy is directly related to narcotic use and to evaluate the effect of incision length on postoperative ileus.

A prospective evaluation of 40 patients who underwent uncomplicated, predominantly left colon and rectal resections was performed. Morphine administered by patient controlled analgesia was the sole postoperative analgesic. The amount of morphine used before the first audible bowel sounds, first passage of flatus and bowel movement, and incision length were recorded. Spearman correlation coefficients were calculated between all variables.

The strongest correlation was between time to return of bowel sounds and amount of morphine administered (r = 0.74; P = 0.001). There were also significant correlations between morphine use and time to report of first flatus (r = 0.47; P = 0.003) and time to bowel movement (r = 0.48; P = 0.002). There was no relationship between incision length and morphine use or incision length and return of bowel function in the total group.

Return of bowel sounds, reflecting small-intestine motility after colectomy, correlated strongly with the amount of morphine used. Similarly, total morphine use adversely affects colonic motility. Because no relationship with incision length was found, efforts to optimize the care of patients with colectomies should be directed less toward minimizing abdominal incisions and more toward diminishing use of postoperative narcotics.