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

Updated: Oct 04, 2018
  • Author: David E Stein, MD; Chief Editor: Vikram Kate, MBBS, MS, PhD, FRCS, FACS, FACG, FRCS(Edin), FRCS(Glasg), FIMSA, MAMS, MASCRS, FFST(Ed)  more...
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Transanal endoscopic microsurgery (TEM) offers several advantages over conventional transanal excision. It provides better exposure, visualization, and access to reach lesions higher in the rectum than standard transanal excision. It is associated with less morbidity and quicker recovery time than a radical transabdominal approach. The major limitations of TEM are 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 these issues. 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. 



TEM can be used as a curative operation for rectal polyps that are not amenable to colonoscopic resection. [2] In addition, it may be used in selected patients with rectal cancer. [3, 4] 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 [5]
  • 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 [6]
  • Well-differentiated or moderately differentiated lesions [7]
  • Lesions not associated with lymphovascular invasion

Management of rectovaginal fistulas and anastomotic dehiscence management by means of TEM has also been reported. [8]

TEM has become an accepted procedure for benign adenomas [9, 10, 11, 12, 13, 14, 15] and potentially for early carcinomas of the rectum. [16, 17]

Low recurrence rates have been reported for adenomas treated with TEM. [10, 12, 13, 18, 19]

Definitive treatment of T2 or T3 rectal lesions with TEM is not recommended.

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. [20, 21]



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) [10, 22]
  • 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. [23] The use of preoperative endoluminal ultrasonography (US), [24]  pelvic magnetic resonance imaging (MRI), [25, 26]  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. [27]

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 [28] 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. The recurrence rates of tumors following TEM have been reported to range from 2.4% to 16%, [10, 12, 13, 14, 22, 29, 30]  whereas the recurrences rates associated with conventional anal excision range from 4% to 36%. [31, 32, 33]

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. [34] 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. 

TAMIS 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 is generally comparable, though it may be shorter for laparoscopic surgeons already proficient with single-port approaches. [35] In the hands of experienced laparoscopic surgeons, this technique also provides magnified visualization of tumors by the rectosigmoid junction. [36] Thus, it is a cost-effective, [37] innovative, safe, and feasible approach in carefully selected patients. [38]

Although TAMIS is a promising approach, [39] more comparative studies and randomized trials are required to establish its efficacy with respect to cancer recurrence rates and overall survival.