Correlation between preoperative endoscopic and intraoperative findings in localizing colorectal lesions

Computer-aided classification of colorectal segments during colonoscopy: a deep learning approach based on images of a magnetic endoscopic positioning device

OBJECTIVE

Assessment of the anatomical colorectal segment of polyps during colonoscopy is important for treatment and follow-up strategies, but is largely operator dependent. This feasibility study aimed to assess whether, using images of a magnetic endoscope imaging (MEI) positioning device, a deep learning approach can be useful to objectively divide the colorectum into anatomical segments.

METHODS

Models based on the VGG-16 based convolutional neural network architecture were developed to classify the colorectum into anatomical segments. These models were pre-trained on ImageNet data and further trained using prospectively collected data of the POLAR study in which endoscopists were using MEI (3930 still images and 90,151 video frames). Five-fold cross validation with multiple runs was used to evaluate the overall diagnostic accuracies of the models for colorectal segment classification (divided into a 5-class and 2-class colorectal segment division). The colorectal segment assignment by endoscopists was used as the reference standard.

RESULTS

For the 5-class colorectal segment division, the best performing model correctly classified the colorectal segment in 753 of the 1196 polyps, corresponding to an overall accuracy of 63%, sensitivity of 63%, specificity of 89% and kappa of 0.47. For the 2-class colorectal segment division, 1112 of the 1196 polyps were correctly classified, corresponding to an accuracy of 93%, sensitivity of 93%, specificity of 90% and kappa of 0.82.

CONCLUSION

The diagnostic performance of a deep learning approach for colorectal segment classification based on images of a MEI device is yet suboptimal (clinicaltrials.gov: NCT03822390).

A single centre audit: repeat pre-operative colonoscopy

BACKGROUND

Repeat colonoscopy may be required for tumour localisation. The aim of the study is to explore the clinical settings it was used and benchmark the quality of initial colonoscopy against standardized guidelines for tumour localisation, tattooing and colonoscopy reporting amongst clinicians.

METHODS

A retrospective study from 2016 to 2021 has been performed on patients who underwent elective colorectal cancer resections at the Northern Hospital. Patient demographics, colonoscopic and operative details were retrieved from the Bi-National Colorectal Cancer Audit (BCCA) Registry database and hospital medical records.

PRIMARY OUTCOMES

changes in operative approach and delays to operation.

SECONDARY OUTCOMES

reasons for a repeat colonoscopy and complications from repeat colonoscopy.

RESULTS

A total of 339 patients were included in this study. 94 (28.6%) underwent a repeat colonoscopy. Re-scoping rate was 29.6% for surgeons, and 26.2% for non-operating endoscopists. Surgeons had a 5.9% localisation error rate, and non-operating endoscopist 6.95% (p = 0.673). Surgeons did not have a lower rate of repeat colonoscopy (p = 0.462). Repeat endoscopy was associated with a longer time to definitive operation (p < 0.001). No complications were associated with a repeat colonoscopy.

CONCLUSION

There was no difference in localisation error rates or repeat colonoscopy amongst surgeons (29.6%) and non-operating endoscopists (26.2%) (p = 0.462). This could be explained by the standardized endoscopy training in Australia governed by a common training board. Lack of tattooing at index colonoscopy and inadequate documentation often led to a repeat endoscopy, which was associated with a longer time to definitive operation. Standardized guidelines in tattooing of lesions and colonoscopy reporting should be implemented.

Clip or Tattooing: A Comparative Study for Preoperative Colon Cancer Endoscopic Localization

Background and Aim

Preoperative endoscopic markers have been extensively used for the localization of colonic neoplastic lesions in laparoscopic surgery. We conducted this respective cohort study to compare the localization accuracy of two commonly used endoscopic marker strategies (endoscopic clip plus abdominal plain film and endoscopic tattooing).

Methods

Patients who received preoperative colonoscopy localization for colonic neoplasia and underwent an elective laparoscopic operation afterward between 2013 and 2020 were included in this retrospective study. The localization accuracy of the two endoscopic strategies was compared, and the predictors of successful endoscopic localization were identified by multivariate regression.

Results

In total, 195 patients [average age 62.4 ± 9.2 years, 123 male (63.1%)] undergoing preoperative colonoscopy localization and subsequent laparoscopic colectomy for colonic neoplasms were included. Endoscopic localization was finally proven to be successful in 150 (76.9%) patients in the surgery. Compared to the tattooing group, patients who had successful localization for colonic lesions were fewer in the clip group (64 of 101 cases, 63.4% vs. 86 of 94 cases, 91.5%, p < 0.001). The multivariate regression analysis showed that the endoscopic tattooing strategy, endoscopic clip strategy, and lesion location were all predictors for successful localization (all with p < 0.001).

Conclusion

Compared with endoscopic clip plus abdominal plain film, endoscopic tattooing had higher localization accuracy and less intraoperative colonoscopy counseling; the endoscopic clip strategy, tattooing strategy, and colonic lesion location were all predictors of successful endoscopic localization.

Intraoperative localization of gastrointestinal tumors by magnetic tracer technique during laparoscopic-assisted surgery (with video)

BACKGROUND

Laparoscopic localization of gastrointestinal tumors has long been an important objective. This study aimed to evaluate the clinical application of a magnetic tracer technique during laparoscopic-assisted surgery.

METHODS

Fifty-seven patients with gastrointestinal tumors, who voluntarily underwent endoscopic marking between May 2019 and May 2020, were enrolled. A magnetic ring was clamped onto tissues adjacent to the lesion and released during preoperative endoscopy. Then, another magnet ring or laparoscopic instrument was delivered to the wall of the digestive tract contralateral to the lesion and attracted, thus achieving accurate intraoperative localization. Observational evaluation included data regarding preoperative marking, intraoperative localization, operation, and safety.

RESULTS

Fifty-six of the 57 (98.2%) patients with gastric tumors (n = 35), duodenal tumors (n = 1), and colorectal tumors (n = 20), successfully underwent marking, localization, and resection. The mean margins of proximal and distal resection of colorectal tumors were 106 and 78 mm, respectively. The mean (± SD) duration of endoscopic marking and laparoscopic localization for gastric/duodenal and colorectal tumors were 5.3 ± 0.3, 1.0 ± 0.1, 5.5 ± 0.4, and 1.0 ± 0.1 min, respectively. No complications occurred in 56 of the 57 patients.

CONCLUSIONS

The magnetic tracer technique demonstrated promising potential as a localization method for gastrointestinal tumors, with superior safety, effectiveness, rapidity, and convenience.

Usefulness of Endoscopic Tattooing Before Neoadjuvant Therapy in Patients with Clinical Complete Response in Locally Advanced Rectal Cancer for Providing a Safe Distal Surgical Margin

Background: Endoscopic tattooing of colorectal tumors enables tumor localization and determination of appropriate surgical margins. It becomes very difficult to detect the distal surgical margins (DSMs) of rectal tumors in patients who obtain clinical complete response (cCR) after neoadjuvant therapy. In this study, our aim is to examine the benefits of endoscopic tattooing of the tumor before neoadjuvant therapy in patients with locally advanced rectal cancer in accurate localization of the previous tumor and in providing appropriate DSMs in cases with cCR. Patients and Methods: The patients who were diagnosed with locally advanced rectal cancer, received neoadjuvant therapy and subsequently achieved cCR, and underwent surgery between January 2015 and October 2020 were included in the study. The patients were divided into two groups according to whether they were endoscopically tattooed before neoadjuvant chemoradiotherapy. Results: A total of 49 cases were included in the study. Significantly better DSMs were observed especially in female gender in the tattooed group. DSMs were found to be closer to the resection margins in the nontattooed group. It was found that endoscopic tattooing had a significant effect on the DSM in the regression analysis (P = .06, R² = 0.47). It was determined that laparoscopy or open surgery alone did not differ in terms of DSMs but open surgery together with tattooing was found to be strongly effective in providing larger DSMs. Conclusion: In locally advanced rectal cancer, endoscopic tattooing of the distal margin of the tumor before neoadjuvant therapy is a reliable and effective method for obtaining a safe DSM and not leaving the residual tumor at the lower end of anastomosis, especially in cases of cCR.

Intraoperative Colonoscopy During Colorectal Surgery Does Not Increase Postoperative Complications: An Assessment From the ACS-NSQIP Procedure-targeted Cohort

Intraoperative colonoscopy (IOC) is an adjunct in colorectal surgery to detect the location of the lesions and assessing anastomotic integrity. The authors aimed to evaluate the safety and feasibility and postoperative morbidity of IOC in left-sided colectomy patients for colorectal cancer. Patients undergoing elective left-sided colectomy without any proximal diversion for colorectal cancer between 2013 and 2016 were reviewed from the American College of Surgeons National Surgical Quality Improvement Program procedure-targeted database. Demographics, comorbidities, short-term outcomes, and postoperative morbidity of patients were evaluated. A total of 8811 patients were identified and IOC was performed for 1143 (12.97%) patients. There was no significant difference in postoperative complications between the IOC and non-IOC groups. Patients with IOC had shorter total hospital length of stay. The use of IOC does not adversely affect short-term outcomes after colorectal resections. Surgeons may utilize IOC liberally for left-sided colorectal resections.

"Is CT Scan more Accurate than Endoscopy in Identifying Distance from the Anal Verge for Left Sided Colon Cancer? A Comparative Cohort Analysis"

Purposes: Accurately localizing colorectal cancer during surgery may be challenging due to intraoperative limitations. In the present study, localization of left-sided colon cancer (LCC) by CT scan is compared to colonoscopy. Material and methods: Consecutive patients with LCC located by colonoscopy and CT scan and undergoing left-hemicolectomy were included. Tumor distance from the anal verge (TDAV) was calculated by both CT-scan and colonoscopy, and then compared, using as reference TDAV measured intraoperatively. Statistical analysis was performed including (1) comparison of means between all three TDAVs, (2) comparison of mean differences between all three TDAVs, (3) comparison of number of patients with a difference between endoscopic TDAV and intraoperative TDAV ≤5 cm and the number of patients with a difference between CT scan TDAV and intraoperative TDAV ≤5 cm (4) statistical relationship between either CT scan and endoscopic and intraoperative TDAVs. Results: Both CT scan and endoscopy overestimate TDAV (25.8 ± 12.5 cm and 24.6 ± 10.6 cm vs. 21.5 ± 7.4 cm, p = 0.005), but CT scan TDAV resulted as being different from intraoperative TDAV (p < 0.01). Regression analysis reported an increasing divergence of measurements with increasing values of intraoperative TDAV, which resulted greater for CT. Tumors within 5 cm of intraoperative TDAV were 22/28 (78.6%) for endoscopy, and 17/28 (60.7%) for CT (p = 0.2448). Conclusions: Accuracy of both examinations seems poor, with a mean overestimation >3 cm and a significant number of tumors found at >5 cm from preoperative evaluation. Preoperative examinations' bias increase proportionally with TDAV length, decreasing their interest especially for tumors located at a greater distance from anal verge.

Diagnostic utility of staging abdominal computerized tomography and repeat endoscopy in detecting localization errors at initial endoscopy in colorectal cancer

BACKGROUND

Colonoscopy has a reported localization error rate as high as 21% in detecting colorectal neoplasms. Preoperative repeat endoscopy has been shown to be protective against localization errors. There is a paucity of literature assessing the utility of staging computerized tomography (CT) and repeat endoscopy as diagnostic tools for detecting localization errors following initial endoscopy. The objective of this study is to determine the diagnostic characteristics of staging CT and repeat endoscopy in correcting localization errors at initial endoscopy.

METHODS

A retrospective cohort study was conducted at a large tertiary academic center between January 2006 and August 2014. All patients undergoing surgical resection for CRC were identified. Group comparisons were conducted between (1) patients that underwent only staging CT (staging CT group), and (2) patients that underwent staging CT and repeat endoscopy (repeat endoscopy group). The primary outcome was localization error correction rate for errors at initial endoscopy.

RESULTS

594 patients were identified, 196 (33.0%) in the repeat endoscopy group, and 398 (77.0%) patients in the staging CT group. Error rates for each modality were as follows: initial endoscopy 8.8% (95% CI 6.5-11.0), staging CT 9.3% (95% CI 6.5-11.0), and repeat endoscopy 2.6% (95% CI 0.3-4.7); p < 0.01. Repeat endoscopy was superior to staging CT in correcting localization errors for left-sided / rectal lesions (81.2% vs. 33.3%; p < 0.01), right-sided lesions (80.0% vs. 54.5%; p = 0.21), and overall lesions (80.8% vs. 42.3%; p < 0.01). Repeat endoscopy compared to staging CT demonstrated relative risk reduction of 66.7% (95% CI 22-86%), absolute risk reduction of 38.5% (95% CI 14.2-62.8%), and odds ratio of 0.18 (95% CI 0.05-0.61) for correcting errors at initial endoscopy.

CONCLUSIONS

Repeat endoscopy in colorectal cancer is superior to staging CT as a diagnostic tool for correcting localization-based errors at initial endoscopy.

Contribution of intraoperative colonoscopy in a colorectal surgery unit. Scand J Gastroenterol 2017;52:1292-1297. [PMID: 28768440 DOI: 10.1080/00365521.2017.1362465]

OBJECTIVES

Intraoperative colonoscopy (IC) is routinely used in colorectal surgery procedures, both oncologic and benign ones. Despite its extensive use there is a lack of literature addressing this important issue. The aims of this paper are to determine the contributions of this tool, especially considering changes in attitude from preoperative designed intervention.

MATERIALS AND METHODS

This study is a retrospective analysis of a prospective maintained database. Patients who underwent colorectal resection and IC during a four-year period (2009-2012). The indications for performing IC in our unit are: Incomplete preoperative colonoscopy, confirm the exact location of the tumor and polypectomy of any lesion distant from the planned resection segment.

RESULTS

The success rate in performing IC is 100%, including 42% of them made trans-anastomotic. No postoperative complications that were attributable to the endoscopy were detected. Routine practice led to a change in attitude in 5% of the patients analyzed; 2% of the global sample corresponded to synchronous tumors finding. Of those patients in whom polypectomies where achieved during the procedure a 14.3% of potentially malignant lesions were resected.

CONCLUSIONS

Intraoperative colonoscopy is a useful and safe tool that in view of these results should be taken into account at any colorectal surgery unit. Trans-anastomotic techniques do not raise morbidity.

[Endoscopic tattooing of colorectal neoplasms and laparoscopic surgery: technical aspects and recommendations]

Accurate mapping of colorectal neoplasms is needed in many clinical situations. Intraoperative mapping of small lesions previously detected by endoscopy is often challenging, especially during laparoscopic surgery. Tumor location assessed during colonoscopy may be inaccurate because of limitations of the procedure. Small flat neoplasms with signs of invasiveness, which are hard to detect by palpation, hold a special place. The same situation is observed for nonradical endoscopic resection of malignant polyps or early cancer, when visual examination shows that the tumor masses have been completely resected but histological examination reveals the positive lateral or horizontal resection margin. Endoscopic tattooing is an effective, safe, and economically sound method to mark intraluminal colorectal neoplasms, which allows one to perform minimally invasive surgeries without using additional operating room resources.

Endoscopic Localization of Colon Cancer Is Frequently Inaccurate

BACKGROUND

Colonoscopic location of a tumor can influence both the surgical procedure choice and overall treatment strategy.

AIMS

To determine the accuracy of colonoscopy in determining the location of colon cancer compared to surgical localization and to elucidate factors that predict discordant colon cancer localization.

METHODS

We conducted a retrospective cross-sectional study of colon cancers diagnosed on colonoscopy at two academic tertiary-care hospitals and two affiliated community hospitals from 2012 to 2014. Colon cancer location was obtained from the endoscopic and surgical pathology reports and characterized by colon segment. We collected data on patient demographics, tumor characteristics, endoscopic procedure characteristics, surgery planned, and surgery performed. Univariate analyses using Chi-squared test and multivariate analysis using forward stepwise logistic regression were performed to determine factors that predict discordant colon cancer localization.

RESULTS

There were 110 colon cancer cases identified during the study period. Inaccurate endoscopic colon cancer localization was found in 29% (32/110) of cases. These included 14 cases (12.7%) that were discordant by more than one colonic segment and three cases where the presurgical planned procedure was significantly changed at the time of surgery. On univariate analyses, right-sided colon lesions were associated with increased inaccuracy (43.8 vs 24.4%, p = 0.04). On multivariate analysis, right-sided colon lesions remained independently associated with inaccuracy (OR 1.74, 95% CI 1.03-2.93, p = 0.04).

CONCLUSIONS

Colon cancer location as determined by colonoscopy is often inaccurate, which can result in intraoperative changes to surgical management, particularly in the right colon.

Analysis of lesion localisation at colonoscopy: outcomes from a multi-centre U.K. study

Background

Colonoscopy is currently the gold standard for detection of colorectal lesions, but may be limited in anatomically localising lesions. This audit aimed to determine the accuracy of colonoscopy lesion localisation, any subsequent changes in surgical management and any potentially influencing factors.

Methods

Patients undergoing colonoscopy prior to elective curative surgery for colorectal lesion/s were included from 8 registered U.K. sites (2012–2014). Three sets of data were recorded: patient factors (age, sex, BMI, screener vs. symptomatic, previous abdominal surgery); colonoscopy factors (caecal intubation, scope guide used, colonoscopist accreditation) and imaging modality. Lesion localisation was standardised with intra-operative location taken as the gold standard. Changes to surgical management were recorded.

Results

364 cases were included; majority of lesions were colonic, solitary, malignant and in symptomatic referrals. 82% patients had their lesion/s correctly located at colonoscopy. Pre-operative CT visualised lesion/s in only 73% of cases with a reduction in screening patients (64 vs. 77%; p = 0.008). 5.2% incorrectly located cases at colonoscopy underwent altered surgical management, including conversion to open. Univariate analysis found colonoscopy accreditation, scope guide use, incomplete colonoscopy and previous abdominal surgery significantly influenced lesion localisation. On multi-variate analysis, caecal intubation and scope guide use remained significant (HR 0.35, 0.20–0.60 95% CI and 0.47; 0.25–0.88, respectively).

Conclusion

Lesion localisation at colonoscopy is incorrect in 18% of cases leading to potentially significant surgical management alterations. As part of accreditation, colonoscopists need lesion localisation training and awareness of when inaccuracies can occur.

Preoperative localization of colorectal cancer: a systematic review and meta-analysis

BACKGROUND

Preoperative colorectal tumor localization is crucial for appropriate resection and treatment planning. As the localization accuracy of conventional colonoscopy is considered to be low, several localization techniques have been developed. We systematically reviewed the tumor localization error rates of several preoperative endoscopic techniques and synthesized information on risk factors for localization errors and procedure-related adverse events.

METHODS

MEDLINE, EMBASE, the Cochrane Library, and the grey literature were searched. Studies were included if they reported tumor localization errors in patients with colorectal cancer undergoing resection with curative intent. Using random-effects models, pooled incidence of tumor localization errors were derived for conventional colonoscopy and colonoscopic tattooing. Due to the lack of comparative studies, a direct comparison of the pooled estimates was performed. Procedure-related adverse events, risk factors for localization errors, and the localization outcomes of other techniques such as colonoscopic clip placement, radioguided occult colonic lesion identification, and the use of magnetic endoscope imaging were also synthesized.

RESULTS

A total of 38 non-randomized controlled and observational studies were included in this review (2578 patients underwent conventional colonoscopy and 643 colonoscopic tattooing). The pooled incidence of localization errors with conventional colonoscopy was 15.4 % (95 % CI 12.0-18.7), whereas that of colonoscopic tattooing was 9.5 % (95 % CI 5.7-13.3), mean difference 5.9 % (95 % CI 0.65-11.14, p = 0.03). Adverse events secondary to tattooing were infrequent, and most were cases of ink spillage. Limited information was available for other localization techniques.

CONCLUSION

Conventional colonoscopy has a higher incidence of localization error compared to colonoscopic tattooing for localization of colorectal cancer. Colonoscopic tattooing is safe and leads to fewer tumor localization errors. Given the widespread adoption of laparoscopic resections for colorectal cancer, routine colonoscopic tattooing should be adopted. However, studies directly comparing different localization techniques are needed.

Intraoperative colonoscopy in patients with colorectal cancer: Review of recent developments

The use of intraoperative colonoscopy has increased alongside progress in the development of colonoscopy-associated devices and techniques, including the colonoscope itself. In the present review, we focus on four circumstances in which intraoperative colonoscopy is beneficial to colorectal surgery: (i) intraoperative determination of a tumor's location; (ii) observation of the proximal colon in cases of obstructive colorectal cancer; (iii) confirmation of the integrity of anastomosis; and (iv) novel surgical techniques that combine laparoscopic and endoscopic surgery. In light of the findings of our review, a combination of colonoscopy and surgery-especially laparoscopic surgery-is expected to facilitate the optimal handling of a variety of colorectal tumors, ranging from benign cases to advanced and obstructive cases.

Discrepancy between gastroenterologists' and general surgeons' perspectives on repeat endoscopy in colorectal cancer

BACKGROUND

A myriad of localization options are available to endoscopists for colorectal cancer (CRC); however, little is known about the use of such techniques and their relation to repeat endoscopy before CRC surgery. We examined the localization practices of gastroenterologists and compared their perceptions toward repeat endoscopy to those of general surgeons.

METHODS

We distributed a survey to practising gastroenterologists through a provincial repository. Univariate analysis was performed using the χ² test.

RESULTS

Gastroenterologists (n = 69) reported using anatomical landmarks (91.3%), tattooing (82.6%) and image capture (73.9%) for tumour localization. The majority said they would tattoo lesions that could not be removed by colonoscopy (91.3%), high-risk polyps (95.7%) and large lesions (84.1%). They were equally likely to tattoo lesions planned for laparoscopic (91.3%) or open (88.4%) resection. Rectal lesions were less likely to be tattooed (20.3%) than left-sided (89.9%) or right-sided (85.5%) lesions. Only 1.4% agreed that repeat endoscopy is the standard of care, whereas 38.9% (n = 68) of general surgeons agreed (p < 0.001). General surgeons were more likely to agree that an incomplete initial colonoscopy was an indication for repeat endoscopy (p = 0.040). Further, 56% of general surgeons indicated that the findings of repeat endoscopy often lead to changes in the operative plan.

CONCLUSION

Discrepancies exist between gastroenterologists and general surgeons with regards to perceptions toward repeat endoscopy and its indications. This is especially significant given that repeat endoscopy often leads to change in surgical management. Further research is needed to formulate practice recommendations that guide the use of repeat endoscopy, tattoo localization and quality reporting.

The anthropometric definition of the rectum is highly variable

PURPOSE

The precise definition of the rectum is essential for localizing colorectal pathology, yet current definitions are nebulous. The objective of this study is to determine the anthropometric definition of common pelvic landmarks in relation to patient characteristics.

METHODS

Seventy-one patients underwent open proctectomy with intra-operative measurements from the anal verge to various pelvic landmarks, and patient characteristics were evaluated. Analyses were performed using Spearman correlation and Wilcoxon rank sum.

RESULTS

The mean landmark distance was dentate line = 1.7 cm (range 0.8-4.0 cm), puborectalis muscle = 4.2 cm (range 2.0-8.0 cm), anterior peritoneal reflection = 13.2 cm (range 8.5-21.0 cm), sacral promontory = 17.9 cm (range 13.0-26.0 cm), and confluence of the taenia = 25.5 cm (range 16.0-44.0 cm). Men had longer mean distances to the dentate line (p = 0.0003), puborectalis muscle (p = 0.03), and anterior peritoneal reflection (p = 0.02). Patient weight significantly correlated with distance to all landmarks except for the confluence of the taenia, which did not correlate with any patient factor.

CONCLUSIONS

The location of common pelvic landmarks is highly variable. The use of predefined absolute measurements from the anal verge to localize rectal pathology is inaccurate and fails to account for patient variability.

Improving lesion localisation at colonoscopy: an analysis of influencing factors

PURPOSE

Colonoscopy detects colorectal cancer and determines lesion localisation that influences surgical planning. However, published work suggests that the accuracy of lesion localisation can be low as 60%, with implications for both the surgeon and the patient. This work aims to identify potential influencing factors at colonoscopy that could lead to improved lesion localisation accuracy.

METHODS

A multi-centred, prospective, observational study was performed that identified patients who were undergoing planned curative resection for a colorectal lesion. Localisation of a lesion at colonoscopy was compared to the intra-operative lesion localisation to determine accuracy of colonoscopic localisation. Patient factors and colonoscopic factors were recorded to determine any influencing factors on lesion localisation at colonoscopy.

RESULTS

One hundred and eleven patients were analysed: mean age 67.4 years (range 27-89); male:female ratio 1.3:1; symptomatic referrals (n = 78, 70.3%); and previous abdominal surgery in 27 patients (24.3%). Complete colonoscopy was recorded in 78 patients (70.3%). In 88 patients (79.3%), colonoscopic lesion localisation matched the intra-operative location. Pre-operative CT imaging was unable to identify the tumour in 24 cases (21.8%). Potential influencing patient and colonoscopic factors on accurate lesion localisation at colonoscopy found complete colonoscopy to be the only significant factor (p = 0.008).

CONCLUSION

Colonoscopic lesion localisation was found to be inaccurate in 79.3% cases, and with pre-operative CT unable to detect all lesions, this study confirms that accurate lesion localisation in the modern era is increasingly reliant on colonoscopy. Incomplete colonoscopy was the only significant factor that influenced inaccurate lesion localisation at colonoscopy.

The accuracy of colonoscopic localisation of colorectal tumours: a prospective, multi-centred observational study

Background and aims

Colonoscopy is essential for accurate pre-operative colorectal tumour localisation, but its accuracy for localisation remains undetermined due to limitations of previous work. This study aimed to establish the accuracy of colonoscopic localisation and to determine how frequently inaccuracy results in altered surgical management.

Method

A prospective, multi-centred, powered observational study recruited 79 patients with colorectal tumours that underwent curative surgical resection. Patient and colonoscopic factors were recorded. Pre-operative colonoscopic and radiological lesion localisations were compared to intra-operative localisation using pre-defined anatomical bowel segments to determine accuracy, with changes in planned surgical management documented.

Results

Colonoscopy accurately located the colorectal tumour in 64/79 patients (81%). Five out of 15 inaccurately located patients required on-table alteration in planned surgical management. Pre-operative imaging was unable to visualise the primary tumour in 23.1% of cases, a finding that was more prevalent amongst bowel screener patients compared to symptomatic patients (45.8% vs. 13%; p = 0.003).

Conclusion

Colonoscopic lesion localisation is inaccurate in 19.0% of cases and occurred throughout the colon with a change in on-table surgical management in 6.3%. With CT unable to visualise lesions in just under a quarter of cases, particularly in the screening population, preoperative localisation is heavily reliant on colonoscopy.

Endoscopic Tattooing to Mark Distal Margin for Low Anterior Rectal and Select Sigmoid Resections

Obtaining a reliable distal margin during anterior colorectal resection can be difficult. In this study, endoscopic transmural tattoos were placed to mark the distal transection point in patients with distal colorectal neoplasms who undergo bowel resection. In the operating room, before surgery, sigmoidoscopy is performed with a 2-channel scope using CO2 insufflation. Through channel 1, a biopsy forceps, marked 5 cm from its end, is inserted to the tumor’s distal edge; in channel 2, a sclerotherapy catheter is placed. The scope is then withdrawn and forceps inserted at the same rate until the mark is seen, next, via the needle catheter, 4 tattoos are placed at that level circumferentially. After rectal mobilization, visible external tattoos guide stapler placement. If no tattoo is seen, sigmoidoscopy is done and the tattoos used to guide stapler placement. In all 27 patients, the tattoos guided stapler placement; tattoos were seen via the abdomen in 26 and the stapler placed as per tattoos in 25. In 2 patients, repeat endoscopy was done and tattoos used to guide or confirm stapler placement. The margin was ≤1 cm from target in 74% while in 22% the margin was 2 to 3.5 cm off target (mean deviation from target margin = 0.33 cm). In conclusion, this method facilitates stapler placement and provides more reliable margins.