Analysis of the therapeutic effect of transanal endoscopic microsurgery on large rectal adenoma : Journal of Minimal Access Surgery

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Original Article

Analysis of the therapeutic effect of transanal endoscopic microsurgery on large rectal adenoma

Zhang, Yongbo1,*; Yu, Peng2,*; Wang, Peng3,*; Jiao, Mingwen1; Liu, Yulin1; Xu, Kang1; Liu, Xiang1; Yang, Hui1; Xia, Lijian1,,**; Chen, Jingbo1,,**

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Journal of Minimal Access Surgery 18(4):p 571-577, Oct–Dec 2022. | DOI: 10.4103/jmas.jmas_273_21
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Rectal adenoma is one of the most common tumours of the rectum,[1] and it is recognised as a pre-cancerous lesion of rectal cancer.[2] In recent years, with rapid development of digestive endoscopic technology, patients with rectal polypoid lesions and early cancer are diagnosed and treated early. However, for large rectal adenoma (LRA), endoscopic resection has higher requirements because this may need the support of other surgical techniques.[3] The advantages of radical rectal surgery are economical and low operational requirements, whereas its disadvantages are high risks of urogenital and anorectal dysfunction.[456] Local anal resection is an alternative way for low rectal adenoma, but some patients who underwent local anal resection have a higher recurrence rate.[7] Through its ingenious and fine design, as well as magnifying, clear, three-dimensional visual effect or display picture of endoscopic imaging system and using fine instruments, a surgeon can achieve various operations in the expanded intestinal cavity. Rectal adenoma is one of the absolute indications for transanal endoscopic microsurgery (TEM), especially for sessile or non-pedicled rectal adenoma. This technology has the advantages of large operating space, clear field of vision and more thorough and accurate tumour resection. As an effective and safe resection of local microsurgery for benign rectal tumours and early rectal cancer, its application in local resection of rectal tumours is gradually increasing.[8]

The clinical data of 85 patients with LRA were analysed to study the application value of TEM technology in the treatment of LRA and to evaluate the efficacy and safety of the technology, in order to guide the choice of treatment for such patients.


Inclusion criteria

(1) Pre-operative colonoscopy, histopathology of biopsy, endorectal ultrasound, computed tomography (CT) or magnetic resonance imaging and other relevant examinations confirmed that the patient had single tumour, without signs of intestinal tissue invasion or distant metastasis. (2) TEM was performed in all patients. (3) Patients with rectal adenoma ≥3 cm in diameter.

Exclusion criteria

Patients with adenocarcinoma initially considered adenoma but later confirmed by TEM pathology were excluded from the study.

From 2007 to 2017, the patients who received TEM operation in the Department of Gastrointestinal Surgery, Qianfoshan Hospital, Shandong Province, were included in the study. All patients were required to sign informed consent before surgery, and the patients were informed about the advantages and risks of the operation.

Pre-operative preparation

Pre-operative bowel preparation and the use of prophylactic antibiotics were same as traditional transrectal surgery. Before surgery, a catheter was placed to relieve the bladder pressure.

Operation method

All patients were given combined spinal–epidural anaesthesia. According to the tumour position of the patient, the appropriate surgical position was selected. The surgical principle is to expose the tumour to the lower half of the surgical field, and lithotomy was performed in patients with a tumour circling the rectum. The surgeon first marked the normal mucosa around the tumour (the resection line), 0.5–1 cm away from the tumour, and then removed the tumour with an ultrasonic scalpel along the marked points. For benign adenomas, a submucosal resection is usually selected to remove the lesion from the margin more than 0.5 cm. For patients whose tumours were limited to the submucosa (Tis or T1 stage) on pre-operative endorectal ultrasonography, but whose tumours were indicated as malignant by pre-operative biopsy or rapid pathology during the surgery, full-thickness resection of the intestinal wall was performed, with a cutting margin more than 1.0 cm away from the lesion. The integrity of the specimen should be ensured as much as possible during the resection. A 1-0 absorbable suture was selected for the wound of the intestinal wall, and the suture was completed with the aid of introducer under direct vision. The suture direction is the longitudinal axis of the intestinal canal. Finally, the surgeon examined the margin and the tumour of the resected specimen and then fixed the specimen on the soft plate with a pin for histopathological examination. According to the time of operation and the size of the tumour, the patients were given appropriate fasting (generally, liquid diet is recommended on the 2nd day after surgery) and antibiotics. After the formed normal stool was discharged, the patients can be discharged from the hospital. The patients can leave the hospital after normal excrement.

Post-operative follow-up

The patients were followed up by telephone and outpatient visits, and the patients were asked to return to the hospital regularly for colonoscopy and review the relevant examinations. Follow-up was performed at 1 month, 3 months, 6 months and 12 months after the operation, and after that, the patients were followed up annually. Follow-up included colonoscopy, digital rectal examination and serum tumour markers. When necessary, the patients were examined by intrarectal ultrasound, pelvic CT and abdominal ultrasound.

Local recurrence was defined as a histology-proven tumour at the site of the previous TEM excision scar. One month after the operation, the patient was re-examined by electronic colonoscopy. Wound healing was characterised by scar formation under colonoscopy, no peripheral congestion or oedema. Positive margin was defined as the presence of adenoma tissue along the cauterised edge of the specimen or within 1 mm of the excised lateral edge.

Statistical analysis

Prospective data collection allowed analysis without losing any value. Quantitative and categorical variables were described in accordance with standard statistical rules. The measurement data were expressed as X ± S, and the comparison between the two groups was performed by independent sample t-test. The χ2 test or Fisher's exact probability test was used for enumeration data comparison, and the risk factors were analysed using logistic regression. P < 0.05 was considered statistically significant.


In this study, a total of 85 patients were enrolled, including 47 (55.29%) males and 38 (44.71%) females; the age range was 15–95 years, and the average age was 63 years. Twenty-five (29.41%) patients had tumours in the anterior wall of the rectum, 20 (23.53%) patients had tumours in the posterior wall of the rectum, 18 (21.18%) patients had tumours on the left lateral wall of the rectum, 16 (18.82%) patients had tumours on the right wall of the rectum and 6 (7.06%) patients had tumours circling the rectum. The median distance of the adenoma from the anal margin was 5 cm. Six (7.06%) patients had adenomas with local cancer, and 79 (92.94%) had adenomas without cancer. Seventy-seven (90.59%) patients were negative margins and 8 (9.41%) were positive margins. No patient had complications such as rectal perforation, urinary retention, rectovaginal fistula, perirectal abscess, faecal incontinence and delayed haemorrhage. During the follow-up period, eight patients were lost to follow-up, and 3 (3.90%) patients developed rectal stenosis. One month after the surgery, only 50 of them went to the centre for electronic colonoscopy, 26 of them (52%) had wound healing and 24 of them (48%) did not have wound healing. On univariate analysis, gender, age, hypertension, diabetes, pathological type of adenoma, adenoma location, adenoma size, resection method and resection margin were not high-risk factors affecting wound healing of rectal adenoma [Table 1]. The adenoma recurred in 20 (25.97%) patients and 57 (74.03%) patients did not have recur after 2 consecutive years of follow-up. Table 2 shows a univariate analysis of the group based on the presence or absence of recurrence of adenoma patients. The positive resection margins and adenoma size were variables that were significantly associated with recurrence. The recurrence rate was higher when the adenoma was larger or the incisional margin was positive. There were no statistically significant differences in the effects of gender, age, hypertension, diabetes, pathological type of adenoma, resection method and presence of local cancerisation on the recurrence of adenoma. We also found that the size of the adenoma was correlated with the cutting edge [Table 3]. The larger the adenoma size, the higher the positive rate of the adenoma resection margin. In [Table 4], the dependent variable is recurrence (recurrence = 1, no recurrence = 0), and the variable with P < 0.05 in Table 5 is used as the independent variable for binary logistic regression analysis. Results showed that positive margin was an independent risk factor for recurrence of adenoma, odds ratio = 0.074, P < 0.05, 95% confidence interval (0.008–0.714).

Table 1:
Analysis of related factors in wound healing
Table 2:
Analysis of related factors of adenoma recurrence
Table 3:
Adenoma size and margin
Table 4:
Logistic regression of relapse-related factors
Table 5:
Complication statistics


Rectal adenoma is one of the most common rectal tumours.[9] Rectal adenoma is a pre-cancerous lesion with an increased risk of malignancy as the volume of the adenoma increases. Early diagnosis and treatment of rectal adenoma can significantly reduce the incidence of rectal cancer. At present, surgical resection should be the first choice for the treatment of rectal adenoma. The current common surgical methods include traditional radical surgery and endoscopic mucosal resection (EMR), endoscopic mucosal resection with a ligation device (EMR-L), endoscopic submucosal dissection (ESD), TEM and transanal minimally invasive surgery. TEM as a minimally invasive surgical approach for rectal tumours has unique advantages over other surgeries, including better field of vision, higher complete resection rate and lower recurrence rate.[101112] The full-thickness resection of LRAs by TEM surgery is conducive to sufficient histopathological evaluation of the margin of resection. The rectal wound is usually sutured with absorbable suture to close the wound accurately. TEM surgery has the advantages of less trauma and faster recovery.[13] This provides more options for the treatment of LRAs.

Many literature have shown that the recurrence rate of rectal adenoma is about 5%–25.6%.[3121415] Most of the recurrent adenomas can be treated by TEM again, and the early recurrence can be treated by EMR or ESD resection. Scala et al. defined that adenomas with a diameter of 3–5 cm are large adenomas and a diameter >5 cm are giant adenomas.[16] TEM is safe and feasible in the treatment of large benign rectal tumours (diameter >5 cm).[17] The recurrence rate of the adenoma with a diameter >5 cm is higher.[16] Some researchers have suggested that adenoma diameter was not related to recurrence.[18] However, our results showed that adenoma diameter is an important factor affecting the recurrence of adenoma after TEM, and the recurrence rate is higher in patients with giant adenoma. However, adenoma size was not an independent risk factor for recurrence. In terms of TEM technology, there is a long learning curve. In this study, most of the recurrent adenomas occurred at the early stage of TEM technology, and the number of recurrent adenomas decreased significantly with the maturity of the technology. Previous studies have shown that the learning curve of TEM is long and the skill level of the operator is a factor affecting local recurrence.[19]

Studies have shown that the size of adenomas is related to the rate of positive margins.[20] Our conclusion was consistent with the above study, that is, the larger the adenoma size, the higher the positive rate of the adenoma resection margin. Moreover, multivariate analysis showed that positive margin was an independent risk factor for recurrence of adenoma.[21] In any case, patients should be fully informed of the risk of recurrence when they are to be treated with TEM. It is recommended that patients with giant rectal adenoma go to a larger medical centre for TEM surgery. For these patients who belong to the positive marginal group, it is recommended to strengthen follow-up and regular electronic colonoscopy to find new lesions and treat them in time.

The common complications after TEM include wound dehiscence, bleeding, rectal stenosis and urinary retention; serious complications include rectal perforation, rectal–vaginal fistula, perirectal abscess and urethral injury.[722] In the study of our centre, there were 3 patients with post-operative rectal stenosis and 24 patients without wound healing 1 month after surgery, and no other complications were found. TEM is superior to other surgical procedures in the incidence of post-operative complications and post-operative quality of life in related literature.[72324] However, it has also been reported that ESD is as effective and safety as TEM in the treatment of large rectal tumours.[25] In this study, the average size of adenomas in the ESD group and TEM group was 64.6 mm and 43.9 mm, and the recurrence rate was 9.1% and 15.5%, respectively. No statistically significant difference was found.[26] Studies have shown that adenoma size is a risk factor for adenoma malignancy, and TEM has a higher complete resection rate compared to ESD.[27] Undeniably, ESD resection of rectal giant adenoma has high medical costs, poor acceptance of patients and their families, long operation time and other problems. Some studies hold the view, believing that long-term faecal incontinence after TEM surgery should not be ignored, and advanced age is an independent risk factor. In those studies, 28.8% of patients developed varying degrees of faecal incontinence after surgery.[28] Current studies suggest that TEM has little effect on anorectal function and is short-term reversible without permanent faecal incontinence. After surgery, the function of the sphincter can be restored in a short time through reasonable diet and pelvic floor muscle training.[2930] In our study, none of the patients had faecal incontinence after surgery. Rectal stenosis is one of the rare complications after TEM. Serra-Aracil et al. mentioned that post-TEM stenosis was associated with large rectal defects.[21] It is beneficial to reduce the risk of post-operative stenosis by closing the wound vertically. In this study, there were three patients with rectal stenosis symptoms after operation: one patient underwent TEM operation again to relieve the stenosis and recovered well after operation; no abnormal defecation was found in regular follow-up, and two patients did not undergo operation and defecation improved after diet improvement. The incidence of rectal stenosis is low, which can be improved by changing diet or reoperation after the occurrence, with a better prognosis.

In our study, because some patients did not come to our centre for colonoscopy review, the sample size was relatively small, so no risk factors affecting wound healing were found. Previous studies have found that the wound-healing speed after resection of rectal adenoma is related to the size of the wound. If the surgical wound is too large, there is still a high risk of wound dehiscence even if the wound is sutured during the operation.[9] Some studies have suggested while it is safe to leave rectal defects open when there is a robust mesorectal fat layer.[1231] We should extend follow-up for such patients. The unhealed wound is often manifested as erosion and ulcer at the wound site and hyperaemia and oedema around it. After prolonged follow-up, most patients could heal by themselves without special intervention. Adenoma classification methods are more, in addition to the pathological classification.[3233] Due to the small number of patients included in this study, classification statistics were not performed based on Yamada's classification.


Our data are sufficient to show that TEM can be used as a treatment option for patients with giant rectal adenomas for surgeons with TEM experience. A larger sample size is needed to find the risk factors for recurrence and complications.

Financial support and sponsorship

The study was financially supported by:

  1. The clinical application and popularisation of TEM in rectal diseases (201602177) - Ji'nan Science and Technology Development Plan
  2. Research and development of colorectal cancer screening software platform based on BP artificial neural network (2017WS368) - Medical Science and Technology Development Plan of Shandong Province.

Conflicts of interest

There are no conflicts of interest.


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Complications; efficacy; large rectal adenoma; recurrence; transanal endoscopic microsurgery

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