Residency · Residency · General Surgery
Natural Orifice and Single-Incision Surgery
Introduction
The evolution of minimally invasive surgery has progressed from multi-port laparoscopy toward approaches that further reduce abdominal wall trauma and improve cosmetic outcomes. Single-incision laparoscopic surgery (SILS) and natural orifice transluminal endoscopic surgery (NOTES) represent the frontier of this continuum. While NOTES remains largely experimental for most applications, single-incision surgery has gained broader clinical adoption for select procedures. Understanding the rationale, techniques, instrumentation, and evidence base for these approaches is important for the contemporary general surgery trainee.
Historical Context and Rationale
The evolution of minimally invasive surgery has progressed from open surgery to multi-port laparoscopy to reduced-port surgery to single-incision surgery to NOTES, with each step aiming to reduce tissue trauma and improve recovery. Patient demand for improved cosmesis drives innovation, and the umbilicus serves as a natural scar that can conceal single-incision access. Potential benefits include reduced port-site complications (hernia, infection, pain), improved cosmesis, decreased analgesic requirements, and faster recovery. The driving forces behind these innovations include patient preferences, industry innovation, and competitive differentiation among surgeons and institutions.
Natural Orifice Transluminal Endoscopic Surgery (NOTES)
Concept
NOTES involves surgical procedures performed entirely through natural orifices (mouth, anus, vagina, urethra) using flexible endoscopes, with the peritoneal cavity accessed through an intentional viscerotomy such as a gastrotomy, colotomy, or vaginotomy. Theoretical advantages include the absence of abdominal incisions, elimination of port-site hernias, reduced wound infections, potentially less pain, faster recovery, and improved cosmesis. The Natural Orifice Surgery Consortium for Assessment and Research (NOSCAR), established in 2006 by SAGES and ASGE, was created to guide the safe development of NOTES and identified key barriers to clinical translation.
Access Routes
The transgastric route involves passing a flexible endoscope through the mouth into the stomach and creating a gastrotomy to access the peritoneal cavity. It is the most studied approach in animal models, though challenges include reliable gastrotomy closure, spatial orientation, and infection risk. The transvaginal route uses a posterior colpotomy to access the peritoneal cavity and is the most clinically adopted NOTES access route, used for specimen extraction in hybrid procedures and for transvaginal cholecystectomy. The transrectal route accesses through the rectum and is used for transanal minimally invasive surgery (TAMIS) and transanal total mesorectal excision (taTME). The transvesical route accesses through the bladder and is limited to animal studies and select clinical applications.
Key Challenges (NOSCAR Identified Barriers)
Reliable and secure viscerotomy closure remains the most significant technical barrier, as incomplete closure risks peritonitis and sepsis. Spatial orientation is compromised by flexible endoscope platforms that create disorientation due to retroflexion, non-fixed camera positions, and loss of anatomic triangulation. Infection prevention is challenging because entering the peritoneal cavity through a non-sterile orifice introduces bacterial contamination, requiring antibiotic prophylaxis and meticulous technique. Current flexible endoscopes lack the rigidity, triangulation, and dexterity for complex surgical tasks, though dedicated NOTES platforms are in development. Suturing and hemostasis capabilities are limited with flexible endoscopic tools. There is no standardized training pathway for NOTES, and the steep learning curve involves novel skill requirements.
<image>Conceptual illustration comparing the four NOTES access routes (transgastric, transvaginal, transrectal, and transvesical) with anatomical cross-sections showing the endoscope path through the natural orifice and the viscerotomy site for peritoneal access</image>
Clinical Applications
Transvaginal specimen extraction is widely adopted as a hybrid approach, with specimens from laparoscopic colectomy, cholecystectomy, or appendectomy extracted through a posterior colpotomy to avoid enlargement of abdominal port sites. Transvaginal cholecystectomy has been performed as a hybrid (combined with transumbilical port) or pure NOTES procedure, though clinical adoption is limited due to technical complexity and the availability of single-incision alternatives. Transanal total mesorectal excision provides a "bottom-up" approach to rectal cancer surgery through the anus, facilitating distal rectal dissection in the narrow pelvis and requiring simultaneous transabdominal and transanal surgical teams. Transanal minimally invasive surgery enables transanal excision of rectal lesions using a single-port platform and is superior to traditional transanal excision for visualization and reach. Peroral endoscopic myotomy (POEM) uses a submucosal tunneling technique for treatment of achalasia, performed through the mouth with a flexible endoscope, and has shown equivalent results to laparoscopic Heller myotomy in short-to-medium-term follow-up.
Single-Incision Laparoscopic Surgery (SILS)
Concept and Terminology
SILS is laparoscopic surgery performed through a single small incision, typically at the umbilicus, using a specialized multi-channel port or multiple fascial punctures through one skin incision. Alternative terms include single-port access (SPA), laparoendoscopic single-site surgery (LESS), single-access laparoscopic surgery, and one-port umbilical surgery. The philosophy is to achieve the benefits of minimally invasive surgery with a single scar hidden in the umbilicus, approaching the cosmetic ideal of "scarless" surgery.
Access Platforms
Multi-channel ports such as the SILS Port (Covidien), GelPOINT (Applied Medical), and TriPort (Olympus) provide multiple working channels (2-4 instrument channels plus camera) through a single fascial incision of 2-3 cm. The glove port is a low-cost alternative using a surgical glove attached to a wound retractor with trocar ports placed through the fingers and is widely used in resource-limited settings. Multiple fascial punctures through a single skin incision avoid the cost of specialized ports. The single-port robotic da Vinci SP platform is designed for single-incision surgery, delivering four articulating instruments and camera through a single 25 mm cannula and addressing many ergonomic limitations of conventional SILS.
Technical Challenges
Loss of triangulation is a fundamental challenge, as instruments enter the abdomen through the same axis (coaxially), eliminating the triangulation that is fundamental to laparoscopic technique and causing instruments to frequently clash (sword fighting). To achieve any degree of triangulation, the surgeon's hands must cross, creating counterintuitive control in which the right-hand instrument operates on the left side and vice versa. The camera occupies the same axis as the instruments, reducing the working angle and operative view. Multiple instruments through a small incision limit range of motion and create external collisions. Solutions include articulating instruments, curved instruments, flexible-tip laparoscopes, low-profile camera heads, and robotic single-port systems.
<image>Comparison illustration showing the setup and instrument arrangement for standard multi-port laparoscopy with triangulated instruments versus single-incision laparoscopic surgery with coaxial instrument alignment, demonstrating the loss of triangulation, crossed instruments, and external instrument crowding challenges in SILS, alongside the single-port robotic platform solution</image>
Clinical Applications of SILS
Cholecystectomy is the most commonly performed SILS procedure, with feasibility and safety demonstrated in multiple series and conversion to multi-port laparoscopy in 2-10% of cases. However, no significant advantage over standard laparoscopic cholecystectomy has been demonstrated in randomized controlled trials for pain, recovery, or cosmesis, as the LEOPARD trial showed no difference in quality of life. SILS appendectomy is safe and feasible with a cosmetic advantage in young patients and comparable outcomes to multi-port approaches. SILS right hemicolectomy and sigmoid colectomy are performed by experienced surgeons but are technically demanding, with oncologic equivalence demonstrated in case-matched studies. SILS-TEP (totally extraperitoneal) hernia repair is feasible but technically challenging with limited adoption. SILS sleeve gastrectomy has been reported but is technically demanding with limited evidence of benefit over the standard multi-port approach.
Transanal Approaches
Transanal Minimally Invasive Surgery (TAMIS)
TAMIS uses a single-port access device (GelPOINT Path) placed in the anal canal with standard laparoscopic instruments for dissection. Indications include excision of benign rectal polyps, T1 rectal cancers (well-differentiated, no lymphovascular invasion, sm1 invasion), and selected T2 rectal cancers after neoadjuvant therapy in organ preservation protocols. Its advantages over traditional transanal excision include improved visualization, ability to reach higher lesions (up to 15 cm from the anal verge), and more precise excision with better margin quality. Compared to transanal endoscopic microsurgery (TEM), TAMIS offers lower cost, more widely available equipment, and a shorter learning curve.
Transanal Total Mesorectal Excision (taTME)
The taTME technique provides a "bottom-up" approach to total mesorectal excision, with a transanal platform providing direct visualization of the distal rectum and circumferential dissection performed in the TME plane from below, meeting the transabdominal dissection from above. Potential advantages include improved visualization in the narrow male pelvis, more precise distal margin, and lower conversion rates. Concerns include a steep learning curve, risk of urethral injury (2-3%), CO2 embolism risk, and the COLOR III trial results showing higher positive circumferential resection margin rates in the taTME group, leading to caution about adoption. Structured training programs (LOREC) are required, and outcomes are highly volume-dependent.
Evidence Summary and Current Status
NOTES remains largely experimental for intra-abdominal procedures, though hybrid approaches such as transvaginal extraction, POEM, and TAMIS have achieved clinical acceptance; pure NOTES is limited by instrumentation and safety concerns. SILS is technically feasible for many procedures but has not demonstrated clinically meaningful advantages over standard multi-port laparoscopy for most operations, and adoption has plateaued for conventional SILS, though robotic single-port systems may revitalize interest. TAMIS is established for rectal lesion excision, while taTME remains investigational pending further safety and efficacy data. Careful patient selection is essential, as obese patients, those with prior surgery, and complex cases are generally not ideal candidates for SILS or NOTES.
Key Clinical Pearls
NOTES remains largely experimental, and the most successful clinical translations are hybrid approaches like transvaginal specimen extraction, POEM, and TAMIS. Single-incision surgery offers a cosmetic advantage but has not demonstrated clinically significant benefits in pain, recovery, or complications compared to standard laparoscopy for most procedures. The robotic single-port platform (da Vinci SP) addresses many ergonomic limitations of conventional SILS and may broaden the applicability of single-incision surgery. Transanal minimally invasive surgery has become the standard for excision of rectal lesions, replacing TEM in many centers. Conversion from SILS to multi-port laparoscopy is safe and appropriate, and patient safety should never be compromised for cosmesis.
References
- Rattner D, Kalloo A. ASGE/SAGES Working Group on Natural Orifice Transluminal Endoscopic Surgery. Surg Endosc. 2006;20(2):329-333.
- Antoniou SA, Koch OO, Antoniou GA, et al. Meta-analysis of randomized trials on single-incision laparoscopic versus conventional laparoscopic appendectomy. Am J Surg. 2014;207(4):613-622.
- Veltcamp Helbach M, Deijen CL, Velthuis S, et al. Transanal total mesorectal excision for rectal carcinoma: short-term outcomes and experience after 80 cases. Surg Endosc. 2016;30(2):464-470.
- Marks JM, Phillips MS, Tacchino R, et al. Single-incision laparoscopic cholecystectomy is associated with improved cosmesis scoring at the cost of significantly higher hernia rates (LEOPARD trial). Ann Surg. 2017;265(5):895-900.
