Low colorectal anastomoses.  An experimental assessment of two sutured and two stapled techniques. 
Extraperitoneal colorectal anastomoses were constructed in dogs by four methods: one layer of sutures (N = 10), two layers of sutures (N = 10), EEA staples (N = 10), and SPTU staples (N = 10).  Dehiscence occurred in eight sutured and one stapled anastomosis (P less than 0.05).  The four leaks following two layer sutured anastomoses caused three deaths, whereas all four leaks following one-layer sutured anastomoses were only detected radiologically (P less than 0.02).  In the stapled group, the single leak followed EEA anastomosis and was fatal.  Anastomotic narrowing was greater in sutured than stapled groups (P less than 0.05).  Two layers of sutures produced gross narrowing compared with one layer (P less than 0.002).  Two rows of staples (EEA) produced more narrowing than one row (SPTU) (P less than 0.01).  Mean hydroxyproline concentrations and bursting pressures on the seventh postoperative day were higher in stapled than sutured anastomoses (P less than 0.05).  Submucosal alignment, mucosal continuity, tissue viability, and stage of healing were all inferior for two-layer sutured anastomoses, reaching statistical significance for tissue viability (P less than 0.05).  Stapled anastomoses were completed significantly faster (32.6 +/- 7.3 minutes) than sutured (54.1 +/- 8.4 minutes) (P less than 0.01).  This experimental study has demonstrated that stapling is a fast and reliable method of colorectal anastomosis with a low complication rate.  The shortcomings of the standard two-layer sutured anastomosis are discussed.