Transanal Endoscopic Microsurgery (TEM) and Transanal Minimally Invasive Surgery (TAMIS)

Updated: Sep 02, 2022
Author: David E Stein, MD, MHCM; Chief Editor: Vikram Kate, MBBS, MS, PhD, FACS, FACG, FRCS, FRCS(Edin), FRCS(Glasg), FFST(Ed), FIMSA, MAMS, MASCRS 



Transanal endoscopic microsurgery (TEM) offers several advantages over conventional transanal excision. It provides better exposure and visualization than standard transanal excision and affords access to lesions higher in the rectum. It is associated with less morbidity and quicker recovery time than a radical transabdominal approach. The major limitations of TEM have been that it requires expensive, highly specialized equipment and has a steep learning curve.[1]  Accordingly, it should be performed only by skilled and experienced surgeons.

Transanal minimally invasive surgery (TAMIS) was developed to address some of the issues encountered with TEM.[2] It offers several benefits over TEM: It requires minimal setup time, and the use of existing laparoscopic cameras and instruments offers a lower-cost alternative to TEM. Nonetheless, the learning curve appears to be generally comparable. 

A comparison of patients who underwent TEM (n = 53) or TAMIS (n = 68) for resection of intraluminal rectal tumors showed that although median operating time was significantly shorter for TAMIS (45 vs 65 min), blood loss was negligible in both groups.[3]  Resection margins, lesion grade, and invasion depth were comparable for the two approaches; however, the postoperative readmission rate was significantly higher in the TEM group (17% vs 4.4%).

Robotic TAMIS (R-TAMIS) has been proposed as a potential alternative to both TEM and standard TAMIS.[4] In a case series by Schwab et al,[5] the three techniques were compared, and R-TAMIS tended to be faster than TEM and TAMIS and to be more likely to result in negative surgical margins.


TEM can be used as a curative operation for rectal polyps that are not amenable to colonoscopic resection.[6] In addition, it may be used in selected patients with rectal cancer.[7, 8] The following indications have been recommended by various surgical societies, including the American Society of Colon and Rectal Surgeons (ASCRS):

  • Lesions smaller than 3 cm; however, a study by Khoury et al reported the use of TEM to treat benign rectal lesions in the range of 5-8 cm [9]
  • Mobile lesions
  • Polypoid lesions
  • Anatomically accessible lesions localized to the bowel wall (T1N0)
  • Lesions confined to the extraperitoneal region of the rectum
  • Lesions occupying less than 40% of the circumference of the bowel lumen; however, the use of TEM for giant circumferential rectal adenomas has been reported [10]
  • Well-differentiated or moderately differentiated lesions [11]
  • Lesions not associated with lymphovascular invasion

Management of rectovaginal fistulas and anastomotic dehiscence management by means of TEM has also been reported.[12]

TEM has become an accepted procedure for benign adenomas[13, 14, 15, 16, 17, 18, 19] and potentially for early carcinomas of the rectum.[20, 21]  Low recurrence rates have been reported for adenomas treated with TEM.[14, 16, 17, 22, 23]  

Definitive treatment of T2 or T3 rectal lesions with TEM has not been recommended. However, a study by González et al, which examined surgical and long-term oncologic outcomes of TEM for treatment of T2-3 rectal cancer after chemoradiotherapy and complete clinical response, found TEM to be oncologically safe and effective in this setting.[24] The use of TEM as palliative surgery for advanced rectal lesions is also acceptable for patients with comorbid conditions and disseminated disease who are otherwise unfit for more radical surgery.[25, 26]

In a meta-analysis comparing TEM with endoscopic submucosal dissection (ESD) for the treatment of rectal tumors, the two procedures were found to be similar with regard to the rates of resection, adverse events, and recurrence; however, both the procedure time and the duration of hospitalization were shorter with ESD.[27]  An international collaborative study by Kim et al found ESD to be safer and more cost-effective than TEM for the treatment of early rectal cancer.[28]

An approach that combines TEM with ESD (TEM-ESD) has been described.[29]

TEM under fluoroscopic-endoscopic guidance was reported to manage anastomotic site stricture in a patient who had undergone a modified Duhamel operation for Hirschsprung disease, which was treated by creation of a neoanastomosis.[30]


Contraindications for TEM include the following:

  • Positive lymph nodes
  • Distant metastasis
  • Ulcerated tumor
  • Large tumor extending into muscularis propria (contraindicated owing to the increased risk of lymph node invasion) [14, 31]
  • Poorly differentiated tumor
  • Lymphovascular invasion

Technical Considerations

Procedural planning

Patient selection is the key consideration, and strict criteria are defined for appropriate candidates.

Preoperative clinical evaluation and histologic grading of rectal lesions often prove inaccurate in assessing the staging and local spread.[32] The use of preoperative endoluminal ultrasonography (US),[33]  pelvic magnetic resonance imaging (MRI),[34, 35]  or both is imperative to ensure the most accurate assessment of tumor depth and nodal status.

In a study comparing transrectal US (TRUS) with MRI for preoperative evaluation of patients with rectal villous adenoma treated with TEM, Raynaud et al suggested that TRUS was preferable for this purpose, noting that MRI overstaged lesions in 54% of patients.[36]

In a study of 12 patients who underwent TEM where endoscopic US (EUS) was used in the preoperative staging of early rectal cancer, EUS was found to be accurate in determining the T stage in 90.8% of cases and the N stage in 76.7%, as confirmed histopathologically.[37]

Despite advances in clinical staging, as many as 15% of tumors may be staged inaccurately.

Complication prevention

Standard preoperative preparation is required to prevent complications. Optimizing medical status for anesthesia, when indicated, is important. In addition, prophylaxis for deep vein thrombosis (DVT), bowel preparation or preoperative rectal irrigation, and preoperative antibiotic prophylaxis are provided. A Foley catheter is placed after induction of anesthesia.

Preoperative nutritional status may be the most significant predictor of outcomes. Every effort should be made to assess the patient's nutritional status and to improve it if needed.


Winde et al conducted a prospective study and found that the operating time, blood loss, length of hospital stay, and analgesic requirement associated with TEM were significantly less than those associated with abdominal resection.[38] The recurrence rates of tumors following TEM have been reported to range from 2.4% to 16%,[14, 16, 17, 18, 31, 39, 40]  whereas the recurrences rates associated with conventional anal excision have been in the range of 4-36%.[41, 42, 43]

In a systematic review and meta-analysis of local resection or TEM versus radical resection in stage I rectal cancer, Veereman et al found that for primary outcomes (overall survival, disease-free survival, local recurrence-free survival, and metastasis-free survival), no evidence could be found for the superiority of local or radical resection.[44] For secondary outcomes (blood loss, hospital stay, operating time, number of permanent stomas, and perioperative deaths), the evidence favored local resection.

There is a need for additional randomized studies comparing TEM with traditional local excision and radical resection. 

In a multicentric trial aimed at assessing long-term oncologic outcome and health-related quality of life (QoL) in patients with cT1-3N0M0 rectal cancer who underwent neoadjuvant chemoradiotherapy (CRT) followed by TEM, Stijns et al reported a 7.7% 5-year recurrence rate, an 81.6% 5-year disease-free rate, and an 82.8% overall survival rate.[45] Two thirds of the patient had good long-term oncologic outcome and health-related QoL, with some amount of bowel dysfunction.

TAMIS offers several benefits over TEM. It requires minimal setup time, and its use of existing laparoscopic cameras and instruments is associated with lower cost. Nonetheless, the learning curve is generally comparable, though it may be shorter for laparoscopic surgeons already proficient with single-port approaches.[46] In the hands of experienced laparoscopic surgeons, TAMIS also provides magnified visualization of tumors by the rectosigmoid junction.[47] Thus, it is cost-effective,[48] innovative, safe, and feasible in carefully selected patients.[49]  More comparative studies and randomized trials are required to establish its efficacy with respect to cancer recurrence rates and overall survival.[50]


Periprocedural Care


Equipment used for transanal endoscopic microsurgery (TEM) (Buess et al/Richard Wolf TEM instrument system) includes the following:

  • Operating sigmoidoscope, 12 or 20 cm in length and 4 cm in outer diameter with binocular optical system
  • Rectoscope tube
  • Grasping forceps, monopolar
  • Scissors
  • Knife, monopolar
  • Needle holders
  • Suture clip forceps
  • Suction tube
  • Retractable needle
  • U-shaped support arm
  • TEM combination system

Equipment used for transanal endoscopic operation with a Storz rectoscope (Karl Storz, Tuettlingen, Germany) includes the following:

  • Operating rectoscope, 40 mm in diameter, with a working length of 15 cm, a handle, and a Luer-Lok connector for smoke evacuation
  • Obturator for use with the operating rectoscope tube during its insertion
  • Working attachment for the operating rectoscope tube, with fixation for the telescope and channels (one 5-12 mm and two 5 mm) for instruments, including a silicone leaflet, the operating rectoscope tube, a handle, valve, sealing caps, and a Luer-Lok connector for insufflation
  • Forward oblique 30° telescope, 5 mm in diameter and 21 cm in length, provided with a 45° angled eyepiece and incorporated fiberoptic light transmission
  • Holding device to fix the operating rectoscope with a mounted video camera to the operating table
  • Laparoscopic energy dissector of the surgeon's choice
  • Laparoscopic grasping forceps
  • Needle holders
  • Suction tube
  • Scissors

Equipment used for transanal minimal invasive surgery (TAMIS; laparoscopic gel point technique) includes the following:

  • Access channel with introducer
  • Gel seal cap with insufflation port
  • Self-retaining ports (5-10 mm)
  • Angulated laparoscope (30°)
  • At least two video monitors
  • Laparoscopic tissue grasper
  • Laparoscopic energy dissector of the surgeon's choice (the authors prefer a Harmonic device from Ethicon Endo-Surgery, Cincinnati, OH)
  • Laparoscopic clip applier (5 mm)
  • Scissors

Patient Preparation


The authors prefer general anesthesia, but no paralysis is required. Local anesthesia with sedation and spinal anesthesia are acceptable alternatives.


Positioning the patient for TEM in either the lithotomy or the prone jackknife position depends on the location of the tumor and the distance from the anal verge. A lesion located on the anterior wall of the rectum requires the patient to be in the prone position, whereas a lesion on the posterior wall can be reached with the patient in the lithotomy position. Some patients need to be placed in the lateral position.

For TAMIS, most surgeons prefer lithotomy regardless of the location of the lesion; accordingly, the patient is placed in the lithotomy position with legs elevated in the Lloyd-Davies position. In contrast to TEM, the laparoscopic instruments are not attached to the operating table; this allows more freedom in movement.

The authors prefer to position the patient in accordance with the location of the tumor.

Studies show that the lithotomy position decreases the risk of position-related nerve injuries[51, 52] and loss of airway control[53]  as compared with the prone position.

Monitoring & Follow-up

Patients are admitted for observation and maintained on antibiotics. Oral nutrition is commenced immediately, and the patient's diet is advanced as tolerated. The patient is discharged on postoperative day 1 if he or she is tolerating a diet.

Patients should undergo routine surveillance endoscopy every 3 months for the first 2 years postoperatively to monitor for any signs of tumor recurrence.



Transanal Endoscopic Microsurgery (Wolf and Storz)

The anal sphincter is dilated after local anesthesia is injected, and the rectoscope is introduced into the rectum. The lumen of the rectum is insufflated and the lesion identified.

With the aid of a high-frequency energy device, clear margins are identified by marking dots. A 5-mm margin is adequate for an adenoma, whereas a 10-mm margin is required for cancer.

Dissection is initiated at the lower edge of the lesion by circumcising the lower circumference. The tumor is folded upward so that the base is well exposed. Vessels are coagulated via diathermy at every step. Any spurting vessels can be grasped with forceps and their walls compressed before coagulation.

The plane of dissection is full thickness. In cases of cancer, the posterior surface and parts of the perirectal fat, including lymph nodes, can be resected with the specimen. Resection of mesorectum is also possible for posterior-wall tumors.

Dissection of the superior margins of the tumor can be difficult because of restricted vision; in such cases, dissection can be commenced from one marking dot to another, reducing the risk of leaving tumor behind.

After excision, it is important to note the healthy margins of macroscopic normal-looking mucosa.

Irrigation of the rectum with cancericidal agents such as povidone is believed to prevent implantation of cancer cells.

The defect is closed with transverse running sutures. Buess originally used polydioxanone sutures in a 5H needle, shortened to a maximum length of 10 cm. After a number of bites of the suture needle, the suture material is placed under tension and fixed with the aid of silver clips; knotting is difficult in this procedure. Semicircumferential defects require about three sutures, whereas complete segmental defects need as many as eight.

Although hospital admission is common, it has been suggested that TEM can also be performed as day surgery in appropriate circumstances.[54]

Laparoscopic Gel Point Technique (Transanal Minimally Invasive Surgery)

The patient is positioned in either a lithotomy or a prone jackknife position, according to the location of the tumor or polyp. Digital rectal examination is performed to localize the lesion.

After local anesthetic is injected, rectal access is achieved with the transanal access channel and introducer, which helps dilate the anal sphincter. After the access channel is inserted, it is sutured firmly to the skin with 2-0 silk sutures.

A gel seal cap, with the insufflation port and three 5-mm trocars already placed, is firmly fixed upon the access channel. The rectal lumen is insufflated with CO2 with a pressure up to 12 mm Hg. A 30° endoscope, a tissue grasper, and an energy dissector are introduced through the trocars.

The lesion is visualized and its extent noted. The margins of resection are then marked 1-1.5 cm circumferentially around the lesion with the help of an energy dissector.

The tumor or polyp is grasped, and full-thickness circumferential excision is commenced, with hemostasis achieved at every step. Perirectal fat should be visible beneath the lesion to confirm full-thickness excision. Larger vessels in the perirectal fat can be identified and coagulated or clipped.

After tumor excision, it is important to evaluate the healthy margins of macroscopic normal-looking mucosa.

Irrigation is performed as described above.

The defect is closed by using laparoscopic needle holders to place transverse running sutures (2-0 polyglactin sutures on a UR-6 needle). Owing to the restricted mobility of the needle holders inside the rectal tumor, some tricks are required to master the suturing technique. After five to eight bites of the needle, the suture material is kept under tension and fixed with clips or laparoscopic ties; knotting is difficult and unnecessary. The number of sutures depends on the size of the defect to be closed.


Complications are rare,[55] but the following adverse results can occur:

  • Pain, if dissection is closer to the dentate line
  • Sense of fullness due to insufflation
  • Gas explosion
  • Trauma to the bowel wall or perforation - These are the most serious complications that can be avoided by surgical abilities and operative skills; if the peritoneum is entered during surgery, adequate closure of the defect is all that is required
  • Infection
  • Bleeding
  • Urinary retention and urinary tract infection
  • Vaginal mucosa injury
  • Fecal incontinence
  • Scars and strictures
  • Failure of equipment

In experienced hands, complication rates are low, in the range of 4-7%.

In a systematic review of 29 studies comprising 1297 patients, Marinello et al assessed for pre- and postoperative fecal continence (23 studies), quality of life (QoL; 10 studies), and manometric scores (15 studies) after TEM and TAMIS.[56] Most of the studies showed some deterioration in manometric scores, but without major impairment of QoL.