Natural orifice specimen extraction (NOSE) in colorectal surgery prevents the need for an enlarged port site or minilaparotomy to extract the surgical specimen. The downside of this technique may be an increased risk of bacterial contamination of the peritoneal cavity from the external milieu. The aim of this study was to prospectively analyze the peritoneal bacterial contamination in NOSE and non-NOSE laparoscopic colorectal procedures.

Consecutive patients operated for sigmoid diverticulitis with laparoscopic approach and transanal extraction of the specimen from January to December 2010 at our university hospital were enrolled. Patients who underwent a laparoscopic sigmoidectomy in the same study period with conventional specimen extraction were used as reference. Peritoneal fluid samples were collected under sterile conditions at the end of the procedure and sent for gram stain as well as anaerobic, aerobic, and fungal cultures.

Twenty-nine patients underwent laparoscopic sigmoidectomy for diverticulitis with transanal NOSE, while 9 patients underwent laparoscopic sigmoidectomy with conventional specimen extraction during the same period. The two groups were successfully matched 1:2 (17 NOSE and 9 non-NOSE) according age, sex, ASA, and Charlson comorbidity score. The contamination rate of peritoneal fluid was 100% vs. 88.9% in NOSE and non-NOSE procedures, respectively (P = 0.23). Overall and major complications rates were 27.6% vs. 11.10% (P = 0.41) and 5.08% vs. 11.1% (P = 1) in NOSE vs. non-NOSE procedures, respectively. In the NOSE group there was a statistically significant lower consumption of oral paracetamol (P = 0.007) and of oral tramadol (P = 0.02).

Although a higher peritoneal contamination was found in the NOSE procedures, there were no significant differences in clinical outcomes relative to standard approach. Avoiding a minilaparotomy to extract the specimen resulted in a significantly lower postoperative analgesic requirement in the NOSE group.