Laparoscopic rectosigmoid resection has become the preferred treatment for rectosigmoid cancer and diverticulitis. The key steps of the procedure—complete left colon and splenic flexure mobilization, mesenteric vascular ligation, and intracorporeal anastomosis—can be safely completed exclusively through 5 and 10 mm trocars. Removal of the intact specimen, however, requires creation of a 5–10 cm abdominal wall incision. Several surgeons, in an effort to realize the greatest benefits of minimally invasive surgery, omitted this large abdominal extraction incision by using the open rectum through which to remove the colonic specimen (Video 23.1). This technique has come to be termed natural orifice specimen extraction (NOSE). Both transanal and transvaginal specimen (Videos 23.2 and 23.3) extraction have been described [5], but this section will focus on transanal specimen extraction following laparoscopic rectosigmoid resection. Interest in NOSE has significantly increased over the past 10 years.

Franklin was the first to report a large case series of NOSE during laparoscopic rectal and sigmoid resections dating back to 1991. He described delivering “the resected specimen out of the peritoneal cavity through an anatomic passage rather than through an abdominal incision” [6, 7]. This technique has subsequently been utilized and modified by others [8, 9]. The key steps of the technique are listed in Table 23.2. A standardized laparoscopic low anterior resection and mobilization is completed utilizing a total mesorectal excision technique. Intraoperative colonoscopy or proctoscopy is performed to confirm location of the pathology. Prior to rectal division, the rectum is copiously cleansed with 5 % Betadine solution irrigation. The bowel is divided intracorporeally either sharply or with endoscopic linear stapling devices, ensuring adequate oncologic margins. The specimen is then placed in a retrieval bag and passed to a ring forceps placed through the gently dilated anus. The specimen is extracted through the open rectum. The anvil of the circular stapler is then passed into the abdomen transrectally and secured in the proximal bowel. The upper rectum is then closed with a laparoscopic linear stapling device. End-to-end or side-to-end colorectal anastomosis is fashioned using a transanally delivered circular stapler. Finally, confirmatory air leak test is then performed.

Franklin has reported remarkably good results in 277 patients undergoing transanal specimen removal [7]. The anastomotic leak rate was 1.1 %, with a major complication rate of 3.6 %. Hospital length of stay, however, remained comparable to standard specimen extraction at 6.9 days. Some complaints of minor fecal soiling were reported, but significant fecal incontinence has only occurred in three patients (1 %) [6]. They also do not report on what their specimen size cutoff was, as attempting to remove a large specimen transanally might damage the rectum or sphincter. Other groups have limited transanal specimen size to 4–5 cm, and larger specimens would then be delivered via an abdominal extraction incision.

Yet, in order to successfully utilize this approach, morbidity (including infectious complications and anastomotic leak) must be kept to a minimum. A prospective study of peritoneal fluid contamination following laparoscopic left-sided resections with and without NOSE demonstrated positive peritoneal cultures in 100 % and 89 % of patients, respectively. Only one of 17 patients in the NOSE group developed an anastomotic leak, and there was no difference in infectious complications between the two groups [10].

Despite the success in using natural orifice specimen extraction at these selected institutions, this technique has not yet caught on in most centers due to the additional time and technical skills required to perform these increasingly complex operations. In addition, there are ongoing concerns regarding potential damage to the rectum and sphincter complex, as well as fecal contamination of the peritoneum. As with the other complex laparoscopic procedures, more surgeons will likely adopt this technique over time as clinical experience and confidence increase.

Early NOTES procedures that made headlines involved operations performed transorally or transvaginally. Further development of transoral procedures, however, has been markedly hindered because of their exclusive reliance on flexible instrumentation. To date, flexible endoscopic platforms fail to provide consistent and reliable traction and countertraction, visibility, hemostasis, and viscotomy closure capabilities compared to the laparoscopic corollary. In addition, the small diameter of the esophagus and pharynx limits specimen extraction size. Transvaginal access therefore became the most common NOTES access site as it overcomes much of these limitations. Using this platform, flexible instruments are replaced by the more familiar long laparoscopic instruments. Entry and closure of the viscotomy (i.e., colpotomy) is relatively simple and safe, and the vagina permits large specimen extraction with a low risk of complications.

Transanal NOTES was initially eschewed by many because of the obvious concerns over fecal contamination of the peritoneal cavity and the risk of a leak at the viscotomy site. These real concerns aside, the key components of NOTES are conceptually grounded in the training and practice of colorectal surgery. Colorectal surgeons regularly operate through the natural orifice (i.e., the anus) and are trained in the recognition and management of associated complications. Most colorectal surgeons are also adept at both advanced therapeutic endoscopy and advanced laparoscopic surgery. Lastly, intraperitoneal entry and closure via the anus occurs not infrequently during already established colorectal procedures such as an Altemeier perineal rectosigmoidectomy for rectal prolapse [11] and transanal endoscopic surgery [12]. Anatomically, the rectum and anus share the potential benefits of vaginal access, including a viscotomy site located close to the natural orifice (15 cm or less) and a compliant organ that allows for insertion of larger surgical instruments and permit extraction of large specimens. This collection of key skills and clinical experience provide the foundation from which the development of transanal NOTES surgery has occurred.

It is well known that total mesorectal excision (TME) remains the gold standard for rectal cancer surgery. The principle behind a proper TME is sharp dissection, under direct vision, in the embryonic fusion planes between the mesorectum and the surrounding parietal tissues continued down to the pelvic floor [13]. The TME plane of dissection also affords identification and avoidance of the parasympathetic and sympathetic nerves innervating the urogenital regions. Despite its wide acceptance, TME does have its technical challenges related to exposure and dissection of the proper planes in the confines of the deep bony pelvis. The pelvic curvature makes visualization of the anterior structures difficult, particularly in the obese or in males with an enlarged prostate. Long lighted retractors and/or headlights are required to gain visualization in the deep pelvis. Identification of the distal oncologic margin is estimated by techniques of external palpation, digital rectal examination, or visualization of a diffused tattoo—and this critical step is relegated to the end of the procedure. Even following successful pelvic dissection, current laparoscopic stapling devices utilized for rectal division have limited angulations, making a perpendicular rectal division and seal with a single cartridge application the exception rather than the rule. Hence, distal rectal division often necessitates several overlapping staple lines to complete the distal rectal transection, which may lead to increased risk of anastomotic leak [14, 15].

While NOTES surgery is being performed in very select cases in specialized centers, in reality, it is proceeding through three overlapping phases of clinical development. The first (and still ongoing) phase involves preclinical work identifying safety and efficacy, appropriate procedures, technical factors, and instrument development. A second phase will be early adoption of hybridized procedures that are a combination of established laparoscopic and transanal procedures. This phase is also starting to gain traction, though still remains somewhat of a niche. With increasing experience and new instrument development, the laparoscopic components can be phased out, and the third phase of fully transanal NOTES procedures will transcend.