Natural orifice specimen extraction in colorectal surgery: patient selection and perspectives

Over the past 30 years, colorectal surgery has evolved to include minimally invasive surgical techniques. Minimally invasive surgery is associated with reduced postoperative pain, reduced wound complications, earlier return of bowel function, and possibly shorter length of hospital stay. These benefits have been attributed to a reduction in operative trauma compared to open surgery. The need to extract the specimen in colorectal operations through a "mini-laparotomy" can negate many of the advantages of minimally invasive surgery. Natural orifice specimen extraction (NOSE) is the opening of a hollow viscus that already communicates with the outside world, such as the vagina or distal gastrointestinal tract, in order to remove a specimen. The premise of this technique is to reduce the trauma required to remove the specimen with the expectation that this may improve outcomes. Reduction in postoperative analgesic use, quicker return of bowel function, and shorter length of hospital stay have been observed in colorectal operations with NOSE compared to conventional specimen extraction. While the feasibility of NOSE has been demonstrated in colorectal surgery, failures of this technique have also been described. Selection of patients who can successfully undergo NOSE needs further investigation. This review aims to guide surgeons in appropriately selecting patients for NOSE in colorectal surgery. Patient and specimen characteristics are reviewed in order to define patient populations in which NOSE is likely to be successful. Randomized trials comparing NOSE to conventional specimen extraction in colorectal surgery tend to enroll patients with favorable characteristics (body mass index <30, American Society of Anesthesiologists class ≤3, specimen diameter <6.5 cm) and demonstrate improved outcomes. Adopters of NOSE should restrict using this technique to the populations in which feasibility has been defined in the literature. Wider application to other populations, particularly patients with body mass index >30 and those with significant comorbidities, requires further study.