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Transanal endoscopic microsurgery (TEM)
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摘要
The description of the transanal endoscopic microsurgery (TEM) covers all aspects of the surgical procedure used for the local excision of rectal tumors located between 4 cm and 18 cm above the anal verge.
Operating room set up, position of patient and equipment, instruments used are thoroughly described. The technical key steps of the surgical procedure are presented in a step by step way: resection, repair.
Consequently, this operating technique is well standardized for the management of this condition.
Operating room set up, position of patient and equipment, instruments used are thoroughly described. The technical key steps of the surgical procedure are presented in a step by step way: resection, repair.
Consequently, this operating technique is well standardized for the management of this condition.
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媒體類型
 刊物
2002-03
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普通的
最愛
 音訊
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數位出版
WeBSurg.com, Mar 2002;2(03).
URL: http://www.websurg.com/doi-ot02en204.htm
URL: http://www.websurg.com/doi-ot02en204.htm
Transanal endoscopic microsurgery (TEM)
1. Introduction
Transanal endoscopic microsurgery (TEM) is a minimally invasive technique for the local excision of rectal tumors located between 4 cm and 18 cm above the anal verge. The smaller incisions involved lead to faster recoveries (Demartines et al., 2001).Compared with conventional transanal resection, TEM provides superior exposure of tumors higher up in the rectum, up to 18 cm from the anal verge. The greater precision of the resection along with lower morbidity (5%) and a shorter hospital stay (5.5 days) make this technique a reliable and, in some cases, a more effective surgical approach than laparotomy and low anterior resection (Winde et al., 1996).
However, the technique is not yet established because of the specific instrumentation required, the unusual technical aspects of the approach and the stringent patient selection criteria.
2. Anatomy
• Principles
The rectum is the straight and terminal portion of the digestive tract.Across the superior third of the rectum, its anterior and lateral surfaces are covered by the peritoneum. In addition, the rectum is surrounded by a fascia (fascia propria), which defines the limits of the mesorectum from behind.
1. Peritoneum
2. Fascia propria
3. Mesorectum
• Topography
The rectum, mesorectum and fascia propria are surrounded by the pelvic fascia located anterior to the sacrum and the sacral nerves, medial to the ureters, large pelvic vessels and hypogastric nerve plexus, and posterior to the urinary and genital organs. These various fascial layers comprise circular zones in close proximity. Therefore, a surgical plane exists between the fascia propria of the rectum and the parietal fasciae.1. Sacral nerves
2. Iliac vessels
3. Presacral fascia
4. Ureter
5. Denonvilliers’ fascia
• Morphology
The rectum forms a cylindrical reservoir between 12 cm and 15 cm long, and extends from the sacral promontory posteriorly against the anterior surface of the sacral concavity. Proximally and distally it is 3 cm to 4 cm in diameter, and its middle portion is between 6 cm and 8 cm in diameter, although it may be much wider.• Mesorectum
The rectum, especially its posterior surface, is surrounded by fatty tissue called the mesorectum. The mesorectum extends inferiorly from the mesosigmoid, becoming progressively narrower and ending on the posterior surface of the rectum above the anal sphincters. It contains the terminal and proximal branches of the inferior mesenteric vessels and their lymphatic glands.1. Abdominal aorta
2. Inferior mesenteric artery
3. Superior rectal artery
4. Fascia propria
5. Peritoneum
6. Mesosigmoid
7. Mesorectum
3. Indications
Benign tumorsThe main indication consists of adenomas located within 4 cm to 18 cm of the anal verge that cannot be treated by colonoscopy. The “optimal” tumor size ranges in diameter from 20 mm to three-fourths of the lumen circumference. A full thickness resection is recommended to ensure an appropriate margin of safety. This procedure is technically easier than a mucosectomy. It also decreases the risk of missing small rectal cancers that may be located inside the villous adenoma. In fact, such small encapsulated cancers have been reported in up to 31% of cases (Winburn, 1998).
Low-risk rectal cancer
TEM is also used for the removal of malignant neoplasms in patients presenting with T1 low-risk cancer. However, careful selection of the proper neoplasm is critical for the outcome in this indication. It has been shown that the recurrence rate after TEM in T1 low-risk cancer ranges from 4% to 8% (Mentges et al., 1997) compared with up to 30% in T1 high-risk cancer (Heintz et al., 1998).
Stenosis
TEM may be an alternative for the resection of stenoses within 5 cm to 15 cm of the dentate line (ie inflammatory stenoses after high fistulae or colorectal anastomotic stenoses).
Other indications
Other indications such as transanal rectopexy by TEM or transcutaneous treatment of gastric cancer by TEM have been proposed. However, there is not enough evidence to draw definite conclusions.
4. Preop period
• Patient selection
Preoperative assessment to stage and grade the type and severity of the tumor is crucial to the success of the TEM. This generally consists of a clinical examination with rectoscopy and a biopsy, endorectal sonography using a 360° endoprobe (7 MHz) and a sphincter function test. Only patients with benign tumors and low-risk rectal cancer (G1, G2) T1 tumors should be considered for TEM.1. Benign tumor
2. T1 tumor
• Patient preparation
Bowel preparation is the same as for a formal laparotomy, consisting of a 4-hour lavage with a polyethylene glycol solution. Antibiotic prophylaxis for Gram-negative and anaerobic strains is given at the time of anesthetic induction. 5. Operating room set-up
• Patient
The position of the patient and the surgeon depends on the position of the tumor on the rectal wall. The objective is to always operate on a tumor located in the inferior part of the operative field. The patient may be:1. in a supine position (posterior tumor),
2. in a prone position (anterior tumor)
3. in a right or left lateral decubitus position (tumor situated on the right or left wall of the rectum respectively).
The surgery is usually performed under general anesthesia, but epidural or spinal anesthesia is also possible.
• Team
As the operative equipment offers a direct view, the surgeon is seated so as to directly view the region through the rectoscope. This offers a stereoscopic view of the operative field.• Equipment
Basic TEM equipment consists of rectoscopic instruments: a videocamera connected to the optic of the operative rectoscope allows the assisting surgeons and staff to follow the procedure on a video monitor. The binocular optic allows a stereoscopic view magnified 6-fold.An insufflator provides for regulated insufflation in the rectum space and simultaneous aspiration of fluid and smoke due to the coagulation of the tissue. The insufflator is connected to the operative rectoscopy for several functions: insufflation; irrigation of the operating field; irrigation of the optic; aspiration; pressure control monitor; light cable.
1. Multifunctional instrument
2. Monocular optic bearing the camera
3. Stereoscopic binocular optic
4. Insufflator
5. Cold light cable
6. Instruments
• Principles
An operative rectoscope 40 mm in diameter and 120 or 200 mm in length, with a stereoscopic view magnified six-fold is used. The end of the rectoscope is bevelled downward.The surgical instruments used through the operative rectoscope are similar to those in laparoscopic surgery. However, the surgical ends of these instruments are at an angle of 40° to enhance the view of the tumor. Two instruments (ie a grasper and coagulation scalpel or suction or needle-holder) are introduced simultaneously into the rectoscope.
To optimize access to the entire tumor, the rectoscope orientation must be changed frequently to compensate for the limited operating field and length of the surgical instruments. The use of a U-shaped multi-angular supporting arm makes such frequent shifts in perspective possible.
1. Rectoscope
2. Monocular optic
3. Stereoscopic binocular optic
• Instruments
1. Rectoscope2. Grasper (right or left angulation)
3. Needle-holder
3a. Absorbable monofilament thread 3.0
3b. Silver clip used to block the thread
4. Clip applier
5. Scissors
6. Coagulation scalpel
7. Resection
• Air insufflation
The rectoscope is inserted after gentle dilatation performed with the rectoscope itself and paraffin oil.Carbon dioxide is insufflated with the insufflator with the goal of maintaining a pressure of 10 cm H2O, to enlarge the intrarectal space and facilitate precise resection. To avoid air leakage, the surgical instruments are inserted in the operative rectoscope protected by a plastic cap to ensure airtightness.
The combined suction-insufflation endosurgical unit is used to ensure a constant, high flow of gas and to evacuate the smoke from coagulation. The high flow is regulated by the pressure and is similar to the high flow used during conventional laparoscopy.
The tumor is then well-exposed, and can be dissected.
• Resection
The first step is a gentle grasping of the tissue near the base of the tumor on the right side, with the grasper, to apply tension to the mucosa. 1. Coagulation is used to label the region and identify the boundaries of resection.
2. The mucosa is coagulated again and incised with electrocautery at a right angle into the perirectal fat tissue. During this procedure, it is important to retain at least 5 mm of healthy tissue up to the coagulated surface. This is possible because of the stereoscopic magnified view of the operating field.
3. Coagulation is performed progressively in a right caudal to left cranial direction in the perirectal fat tissue, where the isolated vessels are visualized and selectively coagulated. Usually, the multifunctional probe has to be periodically cleaned to remove coagulated tissue particles. The probe is used to simultaneously or successively perform division, coagulation, lavage and aspiration. It is important to perform coagulation before the sectioning as the bleeding vessels may retract into the fat tissue, making further coagulation more difficult.
• Extraction
After it is separated from its posterior attachments, the specimen is extracted, and the operative region is washed with a betadine solution. Once the tumor is resected, hemostasis is easier; the bleeding vessels may be grasped and coagulated at the base. In our experience with 50 transanal endoscopic micro-resections, we had no postoperative bleeding. The suture of the mucosa defect should take some perirectal fat tissue, which is an additional element allowing good hemostasis. 1. Extraction
2. Betadine lavage
8. Repair
• Rectal wall suturing
1. Inferior resection margin2. Superior resection margin
3. Clip fixation
4. Transverse suture
5. End of suture
The region is closed by an interrupted or a running suture. The rectal wall is sutured with 3.0 absorbable monofilament synthetic polyglycol continuous sutures that are closed with silver clips, since the small operative space precludes the use of an intra-rectal knot. Stitches are passed caudad to cephalad, successively taking the inferior margin and then the superior margin of the resection region. Once the suture has been fastened, it is fixed by a clip. The suture is followed transversely until complete closure of the rectal wall is achieved. The transverse suture aims to avoid a secondary rectal stenosis.
• End of the procedure
Finally, the biopsy specimen is affixed to a preparation plate to allow the pathologists a precise description of the resection margin in 5 mm of healthy tissue.9. Postoperative period
Patients are allowed to sit and walk as soon as the anesthesia wears off. A liquid diet is maintained for 48 hours.
Patients are discharged on postoperative day 3 or 4.
Initial clinical follow-up occurs 6 weeks postoperatively and final clinical examination, including endorectal sonography, 3 months afterwards.
Serial follow-up, every 3 months during the first year, every 6 months during the second and yearly thereafter, is necessary to detect recurrence of cancer.
10. Complications
Rate of complicationsOverall, the rate of local complications associated with transanal resection lies between 4% and 8.3% of cases while systemic complications range between 14% and 21% (Mentges et al., 1997; Winde et al., 1996). Lethal complications are very rare. Among the 3,000 TEM cases reported in the literature, only one fatality occurred. This was due to a retroperitoneal phlegmon after TEM resection leading to septic shock and death.
Effect on sphincter function
It is surprising that prolonged anal dilatation of 4 cm (due to the operative rectoscope) induces few sphincter function problems. We observed transitory, grade II incontinence in 15% of our patients with full postoperative recovery after 3 months. This is comparable to that already reported (Hemingway et al.,1996).
Manometric analyses of the effects of anal dilatation show a decrease in sphincter tonus ranging from 25% to 37% of preoperative sphincter pressure, with complete recovery to clinical continence within 6 to 16 weeks postoperatively (Banerjee et al., 1996).
11. Limitations
Limitations of TEM in cancer treatmentLymph node invasion is the primary factor limiting the effectiveness of local treatment in early rectal cancer. The lymph node metastasis rate of T1 rectal tumors lies between 0% and 15.4% depending on tumor grade (Heintz et al., 1988) and age. Age (>45 years) is recognized as a significant risk factor for lymph node metastasis (Sitzler et al., 1997).
Local excision offers a significant advantage as shown by a recurrence rate of 3.8% after TEM (Mentges et al., 1997) compared with 23% after conventional transanal surgery (Warneke et al., 1989).
TEM and adjuvant therapy
Conservative management of rectal cancer with radiation therapy or endocavitary contact radiation therapy has a 30% failure rate. Consequently, the indications for neo-adjuvant or adjuvant radiation chemotherapy following local resection of rectal cancer by TEM remain controversial. Moreover, most of the literature on this subject is dominated by single-institution retrospective reports that fail to support local excision as equal to radical surgical excision for management of invasive distal rectal adenocarcinoma (Weber and Petrelli, 1998).
12. Conclusion
TEM distinguishes itself from other endoscopic or laparoscopic procedures in various ways:- use of a magnified binocular stereoscopic device: compared with that obtained with monocular instruments or video cameras, the view of the operating field obtained with TEM provides a depth of field of extremely good quality;
- surgical instruments are inserted and moved in parallel planes, unlike laparoscopy. Without specialized training and skill, full tumor exposure can therefore be difficult to obtain;
- costly equipment (~US$50,000): the pathologies treated with TEM are less frequent than those treated by laparoscopy. Because TEM equipment is costly, worldwide promotion of this technique is actually limited to a few teams;
- uneventful postoperative course: the postoperative analgesic requirement is generally limited to a few doses of acetaminophen, the duration of hospital stay is shorter and the rate of complications is lower than those reported for low anterior resection.
With strict patient selection and precise preoperative staging, the use of transanal endoscopic microsurgery for treatment of low-risk T1 carcinomas is possible with a lower complication rate than radical surgical therapy. Preliminary results suggest no difference in the 5-year survival rate for local and radical surgical therapy. For TEM, low-risk cancer is defined as T1 tumors with differentiation G1-G2 without lymphangitis carcinomatosa and a resection margin of at least 5 mm in patients older than 45 years. However, this recommendation must be tempered by the lack of controlled studies to provide support. According to the literature and our own surgical experience to date, all other types of rectal cancer should be treated by total mesorectal excisions. The contribution of adjuvant therapy to local treatment of rectal cancer is still being assessed.
Despite the fact that this technique is still under evaluation because of the rare indications, the specialized technique and the high material costs, there are few publications on the subject. The results of the ongoing prospective randomized studies should clarify the exact indications of transanal endoscopic microsurgery in case of rectal cancer. Currently, the only accepted indications are T1 G1 G2 small rectal cancers without lymphangitis carcinomatosa.
13. Reference
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Hemingway D, Flett M, McKee RF, Finlay IG. Sphincter function after transanal endoscopic microsurgical
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Mentges B, Buess G, Effinger G, Manncke K, Becker HD. Indications and results of local treatment of
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Sitzler PJ, Seow-Choen F, Ho YH, Leong AP. Lymph node involvement and tumor depth in rectal cancers:
an analysis of 805 patients. Dis Colon Rectum 1997;40:1472-6.
Warneke J, Petrelli NJ, Herrera L. Local recurrence after sphincter-saving resection for rectal
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Winburn GB. Surgical resection of villous adenomas of the rectum. Am Surg 1998;64:1170-3.
Winde G, Nottberg H, Keller R, Schmid KW, Bunte H. Surgical cure for early rectal carcinomas (T1).
Transanal endoscopic microsurgery vs. anterior resection. Dis Colon Rectum 1996;39:969-76.