Natural orifice translumenal endoscopic surgery (NOTES) potential applications

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Editor-In-Chief: Mohammed A. Sbeih, M.D. [mailto:msbeih@perfuse.org] Phone:617-849-2629

Synonyms and keywords: Natural orifice translumenal endoscopic surgery, Single incision laparoscopic surgery, Minimally invasive surgery, Transanal endoscopic microsurgery, Natural orifice surgery consortium for assessment and research, Society of american gastrointestinal and endoscopic surgeons.

Natural Orifice Translumenal Endoscopic Surgery (NOTES) Potential Applications
NOTES procedures have been performed through different natural orifices. So far, transvaginal approach is the most commonly used and has the highest success rate for certain procedures.

Transvaginal NOTES
Transvaginal route is the most common approach for NOTES procedures. This approach has been used for cholecystectomy, appendectomy, colon resections, abdominal wall hernia repair, and sleeve gastrectomy. Transvaginal fertility procedures and oocytes procurement transvaginally have been performed for years. Transvaginal cholecystectomy and transvaginal appendectomy have been performed in humans. Around 85% of the Notes procedures that have been reported in Germany are transvaginal cholecystectomy (the most common). There are many advantages for this approach which include:
 * The organs, such as gallbladder, appendix or others, can be extracted easily through the flexible walls of the vagina. This is considered an advantage for the large size organs.
 * It is relatively easier and safer to perform some procedures via this approach. Vaginal wall closure is less complex than gastric wall closure and has less complications rate . A single stitch can be easily used to close the incision.
 * In general, transvaginal NOTES has lower complications rate than other approaches.
 * Transvaginal rout is considered the best rout for performing minor uterine procedures for benign uterine diseases.
 * Sexual function is not affected by transvaginal extraction of the uterus or other organs.

The long-term effects of transvaginal procedures have not been investigated yet. Some of the drawbacks of this approach include:
 * It can be used only in females.
 * The NOTES surgeon should have the basics of gynecological surgery before performing a transvaginal procedure.
 * Women may present with dyspareunia and infertility after the transvaginal NOTES procedure
 * There is a potential risk for urinary tract infection after urinary bladder cannulation (required in transvaginal NOTES procedures).
 * There is a risk for injury to nearby organs. The rectum and the sigmoid colon are at higher risk than other structures. Visualizing the pelvis directly by a laparoscope (through the trocar site) may be a safe method to ensure there are no injuries for pelvic organs.
 * Transvaginal approach may have higher incidence rates for certain complications (bladder injury and vaginal hematoma) than other surgical approaches.

Transvaginal cholecystectomy procedure is usually performed with a single 5mm umbilical port. An additional 3mm transabdominal port can be used as a safety precaution in few cases. The average operating time to perform the procedure is 2 hours. Blood loss is less than 50 ml in most cases. Using the laparoscopic hook which is inserted via the umbilical port to dissect the gallbladder from the liver is considered easier, quicker and safer than the dissection by using the smaller size endoscopic hook. Currently, laparoscopic clipping of the cystic duct is the safest and most secured method for securing the duct. More occlusive endoscopic clips and instrumentation should be developed.

In transvaginal NOTES (and most NOTES procedures), insufflation through a laparoscopic port, which can be used also for single laparoscopic instrument insertion, is more easily controlled than endoscopic insufflation.

Transanal/Transrectal NOTES
Transanal rectosegmoid resection using transanal endoscopic microsurgery (TEM) and laparoscopic assistance has been demonstrated to be feasible and safe in a swine survival model and in human cadavers. Currently, there are clinical trials that aim to assess the oncological safety of this approach in treating benign and malignant colorectal tumors.

Transanal colorectal resection procedures require a stable platform for endolumenal and direct translumenal access to the peritoneal cavity. Gergard Buess (from Germany) introduced in the 1980s the Transanal Endoscopic Microsurgery (TEM), a natural orifice procedure used for full-thickness resection of rectal tumors followed by suture closure of the resultant defect. TEM fulfils most requirements for the ideal NOTES operating platform based on what was published in NOSCAR white paper. TEM provides stable base, suction, irrigation, multiple working ports, pneumoperitoneum maintainance, and the capacity to close the viscotomy. This is considered a less invasive option to perform colorectal procedures, such as resection of colonic ulcers, adenomas, and early colorectal cancers. Fecal incontinence may result from the pressure on the anal sphincter by the platform during performing the procedure.

In transrectal approach, spatial orientation permits visualizing abdominal organs easily with the endoscopes (no need for retroflextion). Another advantage over other approaches is the ease of closure of the colotomy after the procedure. Studies have demonstrated that there is no higher risk of infection or peritonitis by entering into the peritoneal cavity via a transcolonic/transanal puncture in the presence of adequate closure for the colotomy.

Transrectal surgery is considered a unique NOTES approach to perform transrectal rectosegmoid resection due to these facts:
 * The punctured organ in this approach is the diseased organ itself, which should be excised, rather than puncturing an organ to operate in another organ as in other NOTES approaches.
 * Closure of the puncture is achieved via colorectal anastomosis which is required in all cases regardless the surgical method of performing the procedure.
 * A larger instruments can be introduced through the compliant anorectum . Also, a larger specimens could be removed by this approach.

A pilot study at Harvard Medical School and Massachusetts General Hospital has demonstrated that although it is more time consuming, a longer segment of the sigmoid colon can be resected and extracted transanally by combining transgastric and transanal dissection rather than transanal dissection alone. In an attempt for performing a completely incisionless procedure, a transgastric flexible endoscope has been used by Sylla et al to facilitate transrectal colon mobilization and resection in a swine survival model.

The first clinical case of NOTES transanal resection for rectal cancer using TEM and laparoscopic assistance has been performed successfully by a team of surgeons from Barcelona and Boston in 2009. The procedure has been performed successfully on a 76-year-old woman with a T2N2 rectal cancer. The women recovered well and was discharged on the fourth postoperative day.

The progression and substantial improvement in NOTES instrumentation may optimize this approach to be widespread applied in humans, and may ultimately permit completely NOTES transanal colorectal resection.

Steps for performing a NOTES transanal/transrectal rectosigmoid resection procedure using transanal endoscopic microsurgery with laparoscopic assistance include the following :
 * The distal rectum is closed using a Purse String method at the beginning of the procedure. This may minimize fecal contamination and outflow.
 * At the anorectal ring, the presacral space is entered posteriorly and the rectum and mesorectum are dissected circumferentially. Patients who need low anterior resection procedure are good candidates for transanal colorectal resection (NOTES).
 * The peritoneal cavity is entered after dividing the peritoneal reflection and separating the anterior rectal wall from the surrounding structures.
 * Endoscopic resection of the rectum, sigmoid, and their mesentery is performed.
 * The specimen is resected and extracted through the anus.
 * Colorectal anastomosis and endoscopic stapler closure of the defect is completed.

A transabdominal needle is still required to monitor and control the intraperitoneal pressure during transrectal procedures. It may also help in positioning during performing the procedure and establishing the anastomosis.

Transgastric NOTES
Initially, there were some difficulties in achieving orientation and navigation based on retroflection of the endoscopes to visualize the upper abdomen and perform upper abdominal procedures. Better results had been achieved for lower abdominal surgeries, such as pelvic surgery, tubal ligation, and appendectomy.

This NOTES approach is more sophisticated than the transvaginal route, especially in terms of gastric wall closure after extracting the organ (requires laparoscopic assistance). Also, the complication rate is higher in this approach compared with the transvaginal route. Trials in the field (on animal and cadaver models) are trying to create a new devices and techniques to simplify the closure of the stomach incision.

Appendectomy, cholecystectomy and cancer staging have been performed by this approach. Retrieval of dislodged endoscopic gastrostomy tube via this approach has been reported as well. however, all cases require some degree of hybridization (laparoscopic assistance) which is required for most transgastric NOTES procedures. This approach can be used in all patients regardless their gender but the extracted specimen (through the oral cavity) needs to be relatively smaller than those extracted by other routs.

In general, the following steps should be considered for most NOTES transgastric procedures:
 * The patient should be in an overnight fasting state. General anesthesia is inducted and single dose intravenous antibiotics are administered (amoxicillin and metronidazole). The position of the patient is usually Lloyd-Davies position.
 * Gastric lavage should be done before the procedure using chlorhexidine solution.
 * The puncture site is chosen for adequate visibility to perform the procedure. The best areas of entry are the proximal body and the distal antrum of the stomach (both are relatively avascular).
 * A flexible endoscope is inserted via the oral cavity to the stomach. The puncture is made by a needle knife and the puncture site is dilated by an endoscopic balloon. The scope is inserted into the peritoneal cavity.
 * Intraperitoneal pressure is controlled using laparoscopic carbon dioxide insufflator while the procedure is being performed. Usually 2 to 3mm trocars are used in the procedure.
 * The puncture site is closed by a suturing device after extracting the specimen/organ via the oral cavity.

Peritonitis and esophageal rupture may occur after transgastric procedures. In general, complications are more common in transgastric procedures than in transvaginal procedures.

Transesophageal NOTES
This approach can be used for the management of achalasia (failure of relaxation of the lower esophageal sphincter that causes dysphagia). Many cases of per oral endoscopic myotomy (POEM) have been performed successfully to treat achalasia. Esophageal injuries could be prevented during performing the procedure by using gastroesophageal overtubes. The instruments and ports for transesophageal NOTES have more restrictions in their size and shape compared with other approaches. Large organ (specimen) extraction is not suitable for this approach (a maximal diameter of 2 cm) according to the relatively smaller size of esophageal lumen compared with other hollow organs.

In most transesophageal NOTES procedures, a submucosal tunnel is performed as an access to the mediastinum, pleural cavity, lungs, and heart. Interventions include mediastinoscopies, thoracic organs biopsy, and epicardial operations. Usually, conventional flexible endoscopes and other instruments are used to perform the procedure. Incisional closure is achieved by clips, T-bars, or both. According to some studies, spontaneous closure of the incision is possible without any intervention. Differences in the esophagus and mediastinum between humans and pigs should be considered upon transferring the experimental results to human settings. Sterility and hygiene of the mediastinum in this approach should be investigated.

Peroral esophageal segmentectomy and anastomosis with single transthoracic trocar has been reported in 2011 by Rolanda et al. Transesophageal mediastinoscopy and thoracoscopy have been performed and studied in a nonsurvival animal models. A transesophageal mediastinal lymph node resection and pleural biopsy also has been reported.

Transurethral/Transcystic NOTES
Some procedures can be performed through the urethra or the urinary bladder. Transurethral resection of the prostate (TURP)is a urological operation to treat benign prostatic hyperplasia (BPH). As the name indicates, it is performed by visualising the prostate through the urethra and removing tissue by electrocautery or sharp dissection. This is considered the most effective treatment for benign prostatic hyperplasia (BPH). Outcome is considered excellent for 80-90% of BPH patients.

This approach has been used to perform percutaneous needle biopsy of tumors of intraabdominal organs and retroperitoneal structures. Particularly, the anterior transcystic approach is usually used for biopsy and can be done easily with sonography. However, it is more difficult to take a biopsy from a posterior pelvic lesions (located posterior to the bladder) using the same method.

Ovarian follicles aspiration has been performed using the transcystic approach.