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TECHNICAL DETAILS
Patients may be positioned according to surgeon preference. Some prefer to always position patients in
high dorsal lithotomy regardless of tumor location ensuring abdominal access, should there be inadvertent
peritoneal entry [1,11,15,21] . Others prefer patients to be positioned to allow the target lesion to be centered
at the 6 o’clock position. Thus, patients with anterior tumors are placed in prone jackknife, and patients
with posterior tumors are placed in dorsal lithotomy [17,22,23] . Lateral decubitus position is utilized for lateral
[17]
[23]
tumors . Split-leg position is necessary to facilitate exposure in lateral decubitus or prone jackknife .
Multiple ports have been described and utilized. Currently, there are two FDA-approved devices. Atallah et al.
[1]
TM
initially described TAMIS with a single-incision laparoscopic surgery port (SILS Port, Covidien,
Mansfield, MA), which is lubricated and introduced into the anal canal by steady manual pressure
anchoring just above the anorectal ring. Once in place, endoscopic access is gained and pneumorectum is
established. The SILS port is made of a soft, flexible thermoplastic elastomer allowing for conformity and
provides for three cannulas enabling instrumentation with commonly used laparoscopic instruments. It is
35 mm in diameter and 37 mm in length. The second FDA-approved port is the GelPOINT Path Transanal
Access Platform (Applied Medical, Rancho Santa Margarita, CA) and is the only disposable multichannel
port specifically designed for TAMIS [7,13,24] . It comes in three access channel sizes: 4 cm × 4 cm, 4 cm ×
5.5 cm, and 4 cm × 9 cm. The GelPOINT Path Long Channel is also available and allows reach of lesions
up to 15 cm from the anal verge, and for visually obstructed lesions at rectal folds . Similar to SILS, the
[17]
GelPOINT Path port is lubricated and seated into the anal canal with steady manual pressure. The SILS
port is advantageous for use in patients with narrow or fibrotic anal canals that prohibit the placement of
[17]
the GelPOINT Path . In addition to the SILS and GelPOINT Path ports, multiple other transanal ports
have been described [Table 1] [11,13,14,17,18,21,25-29] .

CONVENTIONAL TAMIS [TABLE 1]
[1]
In the 6 patients included in their initial publication, Atallah et al. described tumor locations ranging
from 6 to 11.5 cm from the anal verge, with operative times of 4 patients that were less than 60 min, one
patient of 121 min (difficulty maintaining insufflation) and another patient of 192 min (difficult anterior
intraperitoneal lesion). Set up times averaged less than 2 min per patient. One patient had positive margins
and underwent fulguration. There were no complications through six postoperative weeks, and all patients
were discharged by postoperative day two (average 0.83 days).

[13]
A systematic review was published in 2014 by Martin-Perez et al. analyzing 33 retrospective studies and
case reports and 3 abstracts, amounting to 390 TAMIS procedures for local excision of rectal neoplasia
from 16 countries. Of these, 152 (39%) resections were performed for benign disease (adenomas and high-
grade dysplasia), 209 (53.5%) for malignancy (carcinoma in situ and invasive disease), and 29 (7.5%) for
other pathology. Average size of lesions was 3.1 cm (range 0.8-4.75 cm), mean distance was 7.6 cm (range
3-15 cm) from the anal verge. Twenty-five studies reported on margin positivity, present in 12 of 275 cases
(4.36%), and tumor fragmentation occurring in 4.1% of cases. Mean operative time was 76 min (range 25-
162 min). Nine of 390 cases required conversion to TAE, TEM or abdominal laparoscopy. Average length
of stay was 2 days. Complications occurred in 29 cases (7.4%), with 10 cases of self-limited bleeding and 4
cases of peritoneal entry. Recurrence was described in 16 publications, totaling 259 cases, and occurred in 7
[13]
(2.7%) cases at a 7.1-month mean follow-up .

Since these early studies, larger series have been published shedding more light on intermediate outco
mes [11,17,18,21,23,25-27,30] . The largest series to date was published by Lee et al. in 2018, who reported their
[11]
intermediate outcomes in 200 consecutive resections in 196 patients. Notably, 185 (92%) of cases were
performed with laparoscopic instrumentation while 15 (8%) were performed with the da Vinci Si robotic