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17 Transanal Robotic Surgery andFuture Directions
167
mastery of single-port laparoscopy. Robotic
TAMIS, or robotic transanal surgery (RTAS) is a
natural evolution of the approach and promises to
address the technical challenges of reach, visualization, retraction, and ergonomics that has limited endoluminal surgery.
Current Applications andOutcomes
Atallah etal. demonstrated the feasibility of robotic
TAMIS using the da Vinci Si robotic platform in a
cadaveric model in 2011 and reported the rst
human case with resection of an early stage rectal
cancer in 2012 [15, 16]. Subsequently several
authors have reported on the feasibility and safety
of robotic TAMIS. The advantage of robotic surgery comes with its magnied 3D view, wristed
movements, tremor elimination, and excellent ergonomics, which allow for greater precision. Initially
used for local excision of rectal neoplasms, robotic
TAMIS was soon adopted for more complex procedures, with the rst report of RTAS-TME (i.e.,
robotic taTME) in 2013 by Atallah etal. [17]
Robotic TAMIS using the da Vinci multi-arm
robotic platforms works through a transanal disposable access channel, for example, the
GelPOINT path transanal access platform [18].
Such access channels are required to create a seal
that maintains the insufation within rectum
needed for adequate visualization. The da Vinci
Si robotic system, while demonstrated to be feasible for local excision of distal rectal tumors, is
limited by its multiple bulky arms and restricted
eld of view which prevent effective treatment of
more proximal lesions. Hompes etal. in a series
of 16 patients, where both malignant and benign
rectal lesions were locally excised, used a transanal glove port which permitted wider movement
of instruments within the rectum and reduced
arm collision externally [19]. The next- generation
Xi system addressed this partially with decreased
arm bulk, in turn, allowing easier transanal docking and more proximal operative reach. The
major disadvantage with this platform is the lack
of 5-mm instrumentation, a signicant issue in
the small working space of the anus and rectum
(currently, only 8mm instrumentation is available with the Xi platform).
Despite the limitations of these multi-arm
robotic platforms, Atallah etal. have successfully
performed taTME and repair of complex stulae
via robotic TAMIS [20]. They reported on four
patients who underwent RTAS-TME for invasive
adenocarcinoma of the distal rectum. All specimens were found to be complete or near complete mesorectal excisions with negative distal
and circumferential margins. Similarly, in a prospective pilot study by Gomez etal. using the da
Vinci Si, RTAS-TME was performed in ve
patients, and all TME specimens showed complete mesorectal excision with negative distal and
circumferential margins [21]. Robotic TAMIS
for these applications has only been reported in
small series, and long-term oncologic outcomes
have yet to be studied.
Transanal surgery is highly demanding due
to the conned anatomic space in the pelvis,
restricted exposure, and limited proximal
reach. The conventional multi-trocar robotic
platforms were originally designed for transabdominal access [22]. The effector arms of these
systems are not exible, limiting dexterity in
the narrow pelvis, and the 8mm instruments
add bulk and subtract from eld view in this
conned space [22]. Furthermore, the sacral
angulation in the pelvis and instrument torque
prevents dissection beyond 7–8 cm from the
anal verge. The current platforms have limitations with control of operative eld, endoluminal suturing, and surgeon ergonomics– making
it challenging even for those with extensive
experience [23]. Most importantly, while
workable, the Si and Xi da Vinci platforms used
transanally represent a potential risk to the
external sphincter complex and present ergonomic obstacles which cannot be overcome.
Due to these factors, it is not likely that robotic
transanal approach will be widely adopted
without platform innovation.
New Platforms inRobotic TAMIS
Despite the demonstrated benets of minimally
invasive surgery (MIS), the eld of colorectal
surgery has been slow to adopt MIS techniques,
especially for transanal procedures. The high
168
K. M. Izquierdo et al.
technical difculty of TEM and TAMIS is the
primary barrier to wide adoption. The effectiveness of an operative technique is determined by
the level of difculty relative to other
approaches. Thus, broadly speaking, a specic
operative approach is highly effective if the
majority of surgeons can perform the operation
with high completion rates and good/excellent
clinical outcome. If an operation is so difcult
that few surgeons can perform it with good outcome, it is effective in the hands of a select few
but has limited effectiveness in the wide world
of surgical practice. Thus any technology which
reduces the technical difculty in the execution
of an operation will automatically increase its
effectiveness and ultimately benet patient care.
This aim motivates ongoing innovation in
robotic transanal surgery.
An ideal platform for robotic TAMIS
addresses four challenges of robotic TAMIS: (1)
optimal visualization, (2) ergonomic instrument
control, (3) improved proximal access, and (4)
ease of tissue extraction and manipulation. To
address these goals, a multitude of systems have
been and are under development. The Flex®
Robotic System, STRAS (Single-Access
Transluminal Robotic Assistant for Surgeons)
robot, and the da Vinci Single-Port (SP) Surgical
System are all emerging robotic platforms
designed to meet the challenges of transanal
surgery.
Flex® Robotic System
The Flex® Robotic System together with the
Flex® Colorectal (CR) Drive (MedRobotics,
Corp. Raynham, MA, USA) is a semi-robotic
apparatus specically indicated for transanal
surgery. This single-port access platform with
exible effector arms allows for instrument triangulation and purposeful steering of the instrument head along nonlinear circuitous pathways
making it more suitable for NOTES, even for
transluminal lesions proximal to the rectosigmoid junction (Fig.17.1a). The robotic console
or Flex® cart, driven by the operating surgeon at
the bedside, has a control knob that can be
manipulated to control the Flex® scope
(Fig. 17.1b). The Flex® Base accommodates a
disposable Flex® Scope CR drive, which is then
docked transanally (Fig. 17.1c). The two main
units of this system are operated by a single surgeon, eliminating the need for a bedside assistant. Flexible, pistol-grip instruments are used to
perform the surgery, through a bedrail-mounted
apparatus, permitting triangulation (Fig.17.1d).
This exible robotic system allows access to
remote anatomic elds with an operative reach
of 17 cm. In addition, smaller 3.5 mm instruments allow for minimal restriction of the eld
of view [24].
Obias, Sylla, and Pigazzi presented their initial experience of this system for transanal access
in a preclinical setting during the proceedings of
the American Society of Colon and Rectal
Surgeons and Tripartite Meeting in Seattle,
Washington, in 2017 [25]. Feasibility of this platform in performing targeted NOTES operations
in a cadaveric model was reported by Atallah in
2018 [22].
Visualization with the Flex® Robotic System
is improved compared to laparoscopic TAMIS
in that it does not require an assistant and the
operative eld of view can be set by the operating surgeon. The primary advantage of the
Flex® Robotic platform is that it allows transmission of the platform along circuitous pathways for better access to more proximal lesions
than would otherwise not be possible by conventional methods. Drawbacks of this platform
are that the robotic camera and platform movements use separate modules and redening the
operative eld of view is time consuming [22].
In addition, the exible arms are not robotically
assisted, and thus this system is considered
semi-robotic. This introduces the problem of
tremor, and this can detract from the precision
of an operation. The exible pistol-grip instruments also require a high level of laparoscopic
technical skill, even more so than the straight
instruments used in laparoscopic TAMIS.While
this platform addresses some of the fundamental
challenges of transanal surgery, it has signicant ergonomic shortcomings that are likely to
limit its adoption.
17 Transanal Robotic Surgery andFuture Directions
169
Fig. 17.1 Flex® Robotic System. (a) Two 3.5-mm diam-
eter exible effector arm interface. (b) Round control
knob that serves as the master control for the Flex®
Robotic Scope. (c). Flex® Robotic base accommodates
STRAS Robot (Single-Access
Transluminal Robotic Assistant
forSurgeons)
The STRAS is an ergonomic master–slave system, with an intuitive control interface allowing
the surgeon to comfortably operate the system.
Andras etal. reported the feasibility of this system in colonic endoscopic submucosal dissection
in animal models in 2017 [26]. The slave unit
consists of a carrier cart and a detachable exible
endoscope, which is a 50cm exible device with
two 4.2 mm working channels for instruments
and one 2.8 mm working channel for conventional exible endoscopic instruments (Fig.17.2)
[27]. The 50cm endoscope should allow access
to lesions within the sigmoid colon. The motorized endoscope is initially inserted under endo-
the Flex® Robotic Colorectal Drive. (d). Simulation of a
transanally docked Flex® Robot System with Colorectal
Drive. (From Atallah [24])
Fig. 17.2 STRAS operating tip. Comprised of a 50cm
exible device with two 4.2mm channels through which
instruments are passed. The black arrow indicates the
2.8 mm working channel for conventional endoscopic
tools, and the red arrow identies the two arms on the
open side, which allow for the triangulation of robotic
instruments. (From Légner etal. [27])
170
scopic visual control, and once it reaches the
target, the endoluminal view is established as it is
re-attached to the slave cart. Like the Flex®
Robotic System, the STRAS robot requires signicant time to redene the operative visual eld.
The endoscope needs to be positioned into place
manually, and the STRAS master console provides limited control of the endoscope.
The robotic instruments consist of a proximal
motor and a exible shaft with a bendable distal
tip. The two opening arms at the tip of the endoscope allow for endoluminal triangulation for
Fig. 17.3 The da Vinci SP system’s single 25-mm cannula through which three 6 mm, multi-joined, wristed
instruments and a 3D 0
the instruments. The master console provides
continuous feedback regarding the actual position of the tools. With only two robotically controlled instruments, a notable limitation of this
system is the lack of effective retraction.
Additionally, this platform lacks suturing capabilities, thus limiting its use beyond partial thickness excisions.
As currently congured, both the Flex®
Robotic System and the STRAS robot are optimized for partial thickness local excisions of the
rectum. However, the current generation’s limitations hinder these platforms’ adoption to more
complex operations such as taTME, stula repair,
Fig. 17.4 At-large view of the da Vinci SP platform’s set
up intraoperatively
and pure NOTES proctocolectomy.
Notwithstanding, these platforms improve ergonomics to a signicant degree compared to standard, laparoscopic-based TAMIS.
(Fig.17.5) allows for manipulation of the operative eld so that all quadrants of the rectum can
be accessed without repositioning the patient. A
holographic monitor of instrument position
Future Directions: da Vinci SP Surgical System
assists the surgeon to better understand intraluminal instrument collisions; effectively, it serves
as a navigational aid to keep track of instrument
The next-generation da Vinci robotic platform,
which is pending FDA clearance for use in
TAMIS procedures, is a single-arm, single-port
system. The da Vinci SP system includes three
6mm, multi-jointed, wristed instruments and the
rst da Vinci jointed 3D 0° HD camera.
position. This feature combines well with three-
arm control that assists in creating optimal instru-
mental retraction easily. The fully robotic wrist
with 6° of movement articulation allows for the
control that previous surgeons have become
accustomed to with the robot.
Collectively, the three instruments and the camera head are transmitted through a single 25-mm
cannula (Fig.17.3). This advanced platform with
its unique “cobra camera” and exible end effector arms allow for more proximal reach transanally (Fig.17.4). Signicant benets of this new
technology are many. A rotating 360° platform
tarium of the transanal surgeon. Current limita-
tions include the absence of an RTAS suction
device, vessel sealer, and stapler. However, these
same challenges have been overcome with every
new generation of robot, so it can be reasonably
predicted the same will take place here. This
K. M. Izquierdo et al.
°
HD camera extend
RTAS approaches will expand the armamen-
17 Transanal Robotic Surgery andFuture Directions
171
Fig. 17.5 da Vinci SP Surgical System. (a) Three-arm control shown working in the rectum. (b) Local excision using
three-dimensional retraction. (c) Transanal knot tying. (d) Full thickness transanal rectal closure
Fig. 17.6 The da Vinci
SP Surgical System with
Applied GelPOINT Path
Transanal Access
Platform
system has been studied in the preclinical setting
by Marks et al. [23] The da Vinci SP Surgical
System with Applied GelPOINT Path Transanal
Access Platform (Fig.17.6) was used to perform
transanal local excision in cadavers. Twelve simulated lesions were excised with negative margins and without fragmentation. In addition,
suture closure of the defect and endoluminal knot
tying were carried out with relative ease [23].
To date, the feasibility and safety of this exible single-arm robot has been studied primarily
for transoral applications. This system is yet to be
validated in a clinical setting for transanal surgery in the United States; in Hong Kong, it is
172
K. M. Izquierdo et al.
being used in early clinical trials for colorectal
applications, including taTME. This exciting
new technology in endoluminal access will likely
expand its applications, stepping into the current
era of NOTES.
Future Directions: Pure NOTES Colorectal Surgery
The concept of NOTES has gained popularity
since the first transgastric appendectomy performed by Rao and Reddy in 2004. In concept, however, Dr. Buess’ TEM in 1983 was
the first NOTES procedure. Now, nearly
40years later, technology has advanced to a
point where this concept can be revisited by
surgeons.
Avoiding altogether an abdominal incision
and its associated risks, such as surgical site
infections and incisional hernias, as well as providing perfect cosmesis, RTAS represents a paradigm shift in MIS.The nal step on the path of
transanal NOTES colorectal surgery would be to
perform a rectal resection via a transanal endoscopic approach without requiring access through
the abdominal wall.
Cumulatively, the published data from case
series on taTME demonstrate technical feasibility
and preliminary oncologic safety in carefully
selected patients. The quoted benets of a transanal
endoscopic approach for very low rectal cancers in
particular include the ability to expand the upper
limit of intersphincteric resection under much
improved visualization and exposure and the facilitation of a complete rectal and mesorectal dissection. This is especially helpful in male patients with
narrow pelvises in whom a laparoscopic approach
poses substantial technical difculty, with a high
risk of conversion, as well as a high rate of poor
quality, incomplete mesorectal excision.
The natural extension of the taTME movement
has been to perform the entirety of the operation
transanally; however, the general applicability
outside of a few centers remains limited.
With the existing robotic platforms, which
were originally designed for transabdominal surgeries, proper working angles (and the inability
to obtain them) represent an important limitation.
Interesting developments in robotic surgery, as
described above, promise to increase the ability
to perform larger portions or even entire colorectal operations transanally. This has been demonstrated in cadavers by Marks, Ng, and Mak with
transanal dissection and transection of the inferior mesenteric artery using the da Vinci SP
Surgical System (Fig.17.7).
However, taTME in its current form using the
available transanal platforms has several limitations. Lesions located in the upper rectum are
more difcult to reach. The anastomosis in
taTME for lesions at this level is more difcult
due to inadequate visual exposure and requires
endoscopic placement of the purse-string suture
rather than by hand. Another major limiting factor of pure NOTES is its extreme technical
demand, including the preference for having two
complete surgical teams to perform the operation
(at most centers).
With the newly FDA-approved Single-Port da
Vinci robot, the performance of transanal NOTES
and its democratization in the surgical community will undoubtedly be facilitated.
Conclusions
An ideal platform for robotic TAMIS would
have single-port access and exible camera
and effector arms capable of triangulation for
optimal visualization and ergonomics.
Additionally, the system would be able to adapt
and navigate itself along the circuitous pathways of the distal gastrointestinal tract, reaching beyond the anal verge with the curve of the
sacrum. The da Vinci SP, Flex® Robotic
System, and STRAS robot realize some of
these specications and will serve as high-utility platforms in the continued evolution of
robotic TAMIS.
17 Transanal Robotic Surgery andFuture Directions
173
Fig. 17.7 RTAS Transection of IMA. (a) After entry into
the peritoneum, the arms of the da Vinci SP Surgical
System retract the small bowel out of the pelvis. (b)
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TAMIS: Current Controversies
andChallenges
HeatherCarmichael andPatriciaSylla
18
Introduction
Transanal minimally invasive surgery (TAMIS)
is increasingly being used as an alternative to
transanal endoscopic microsurgery (TEM) for
transanal excision of both rectal adenomas and
early rectal cancer. There are multiple ongoing
controversies about the benets of and limitations of TEM and TAMIS. Given the relatively
recent and limited experience with TAMIS as
compared to TEM, published data on this platform is more limited, with no prospective series
that compare the two platforms (and their respective techniques) directly. What is known about
the current controversies regarding TAMIS will
be summarized in this chapter.
Local Recurrence andtheUse
ofTAMIS forEarly Rectal Cancer
Arguably the most signicant ongoing controversy about both TEM and TAMIS is the appropriateness of their use inlocal excision of early
H. Carmichael
Department of Surgery, University of Colorado,
Aurora, CO, USA
e-mail: heather.carmichael@ucdenver.edu
P. Sylla (*)
Division of Colon and Rectal Surgery, Icahn School
of Medicine at Mount Sinai, New York, NY, USA
e-mail: patricia.sylla@mountsinai.org
rectal cancer. This debate is not specic to
TAMIS, and much of the available evidence has
been extrapolated from experience with
TEM.Relative to the large body of literature on
TEM, or even to published data on the transanal
endoscopic operation (TEO), few studies have
reported specically on TAMIS. Furthermore,
there have been no prospective clinical trials
comparing TEM and TAMIS and few studies
reporting long-term follow-up for oncologic outcomes after TAMIS.
One review published by Martin-Perez etal.
reviewed 390 TAMIS procedures encompassing 33 published retrospective case series as
well as 3 abstracts [1]. Of these, over half of
TAMIS procedures were performed for rectal
adenocarcinoma, with adenoma representing
the second most common indication. Margins
were positive in 4.4% of cases overall, specimen fragmentation occurred in 4.1%, and overall morbidity was 7.4%. Larger TAMIS series
have generally found similar short-term oncologic results, supporting the conclusion that
TAMIS is likely a safe alternative to TEM for
carefully selected, T1 rectal cancer [1–9]. A
matched analysis comparing 419 patients who
underwent TEM and 228 patients who underwent TAMIS for both benign and malignant
disease found no differences in the rates of positive margins or lesion fragmentation, again
suggesting similar results for the two operative
platforms [10].
© Springer Nature Switzerland AG 2019
S. Atallah (ed.), Transanal Minimally Invasive Surgery (TAMIS) and Transanal Total Mesorectal
Excision (taTME), https://doi.org/10.1007/978-3-030-11572-2_18
175
176
H. Carmichael and P. Sylla
In terms of local recurrence, in a retrospective
series of 50 patients undergoing TAMIS excision
for rectal cancer, Albert etal. reported one case of
local recurrence in a patient with a pT1 tumor
(6.3% of all pT1 lesions reported) with a mean
follow-up of 20 months [8]. Lee et al. and
McLemore etal. reported a series of 25 and 34
patients undergoing TAMIS with no cases of
local recurrence but with only short-term follow up (9.8months or 3–23weeks, respectively) [3,
11]. Schiphorst et al. in a series of 37 patients
found one case of local recurrence for a pT1
lesion (25% of pT1 lesions) with 11months mean
follow-up [12]. In a recent series of 50 patients
by Caycedo-Marulanda et al., there were two
cases of local recurrence (6%) after TAMIS for
early rectal cancer, with a median follow-up of
21months [13]. More recently, Lee etal. reported
outcomes of 200 TAMIS cases for local excision
of rectal neoplasia from the center that established TAMIS as a technique (Orlando, FL,
USA). The authors reported a 7% overall margin
positivity and 5% rate of specimen fragmentation. Of 110 malignant lesions excised using the
TAMIS technique, 6% recurred locally, and 2%
presented with distant organ failure (follow-up
was 14.4months) [14]. Overall, these results suggest that local recurrence after TAMIS for early
rectal cancer is similar to TEM; however, large
series with long-term oncologic outcomes are
lacking.
Technical Limitations
withtheTAMIS Platform: Low
andHigh Rectal Lesions
TAMIS, given the shorter length of the disposable platform, is generally limited to the rst
8–10cm from the anal verge. Beyond this point
it becomes difcult to provide adequate retraction to visualize upper rectal lesions, particularly
those located behind and beyond the rectal
valves [15].
TEM and TEO, on the other hand, have rigid
rectoscopes as long as 15–20 cm in length [16,
17]. While these platforms may be limited by a
narrow rectosigmoid junction or other anatomical
constraints, TEM and TEO generally allow the
surgeon to stent past the rectal valves to access
high rectal tumors [18]. This underscores a fundamental difference between the two platforms;
as with TEM and TEO, the access channel (shaft)
itself is advanced to the target lesion, whereas,
with the TAMIS technique, the access channel
remains in the same position, and, instead, only
the laparoscopic instruments are navigated to the
target lesion.
TAMIS, on the other hand, is limited in access
to very low rectal tumors because the TAMIS
transanal port occupies the rst several centimeters of the anal canal [19]. The TEM platform, by
virtue of being secured to the operative room
table, can be withdrawn to the level of the anal
verge itself, allowing access to very low rectal
tumors [18]. A hybrid approach can be used with
TAMIS for these low lesions, dissecting the distal
margin using a conventional transanal approach
with retractors, followed by insertion of the
TAMIS port for the proximal dissection [20].
Peritoneal Entry inTAMIS
Versus TEM
Peritoneal entry during transanal endoscopic surgery is not uncommon and is not usually considered a complication, so long as the surgeon can
adequately repair the defect without conversion
to a transabdominal procedure. For TEM, the rate
of peritoneal entry in the reported literature varies widely from 0% to 32.3% [21–23]. More
recent series with over 300 patients have demonstrated lower rates of 5–10.7% [24, 25]. However,
expanding indications for TEM and TAMIS
including the increasing use for resection of more
proximal, anterior, and circumferential tumors
have the potential to make peritoneal perforation
a more common occurrence over time [23, 26].
The loss of pneumorectum that occurs following peritoneal entry can impede visualization and
retraction, presenting a signicant technical challenge for the surgeon. Prone positioning of the
patient with a high anterior lesion can help to minimize the impact of CO
nal cavity should peritoneal entry occur [26].
leakage into the abdomi-
2