Chinese translation of benefits and challenges in implementation of artificial intelligence in colonoscopy: World Endoscopy Organization position statement / 中华消化杂志

The number of artificial intelligence (AI) tools for colonoscopy on the market is increasing with supporting clinical evidence. Nevertheless, their implementation is not going smoothly for a variety of reasons, including lack of data on clinical benefits and cost-effectiveness, lack of trustworthy guidelines, uncertain indications, and cost for implementation. To address this issue and better guide practitioners, the World Endoscopy Organization has provided its perspective about the status of AI in colonoscopy as the position statement.

Estudio prospectivo acerca de la precisión diagnóstica del test inmunológico de sangre oculta en materia fecal en una única ronda para la realización de pesquisa del cáncer colorrectal en pacientes de riesgo promedio en la Argentina / Prospective study on the diagnostic accuracy of the immunochemical fecal occult blood test in a single round for colorectal cancer screening in average risk patients in Argentina

Introducción: El cáncer colorrectal (CCR) es la segunda causa de muerte por cáncer en Argentina. Debido a su alta prevalencia es fundamental normatizar un programa de pesquisa para la prevención y detección temprana. La precisión del test de sangre oculta en materia fecal inmunológico (SOMFi) para pesquisa de CCR en población de riesgo promedio ha demostrado ser adecuada según la bibliografía internacional, no habiendo, sin embargo, información a nivel local. El objetivo es evaluar en nuestro medio la precisión diagnóstica del test de SOMFi en una única ronda para la pesquisa de CCR en pacientes de riesgo promedio. Diseño: Prospectivo de precisión diagnóstica. Material y Método: Se incluyeron pacientes con riesgo promedio que consultaron para realizar una videocolonoscopía (VCC) por pesquisa de CCR en el Hospital Alemán de Buenos Aires, entre el 1 de junio del 2015 y 31 diciembre de 2017. Se excluyeron todos los pacientes con riesgo incrementado para CCR. Todos los pacientes realizaron el test de SOMFi y posteriormente la VCC. Los endoscopistas estaban ciegos para el resultado del test al momento de realizar la VCC. Se evaluó la precisión diagnóstica del test SOMFi para detectar lesiones neoplásicas avanzadas (LNA) calculando la sensibilidad (S), especificidad (E), valor predictivo positivo (VVP) y negativo (VVN), coeficiente de probabilidad positivo (CP+) y negativo (CP-). Se evaluó también la precisión para la detección de adenomas de bajo riesgo, pólipos aserrados y CCR. Resultados: Se incluyeron un total de 300 pacientes; 273 (91%) entregaron la muestra de materia fecal para realizar el test de SOMFi y completaron la VCC. La edad media de los pacientes fue de 56.9 (40-85) años y 54% fueron hombres. Del total de pacientes que realizaron ambos estudios (273), 53 pacientes (19%) presentaron al menos un adenoma de bajo riesgo, en 18 pacientes (6,59%) observamos al menos un adenoma aserrado sésil y en 21 pacientes (7,7%) al menos una lesión neoplásica avanzada (LNA). Solo 4 pacientes (1.5%) presentaron CCR. En cuanto a la precisión diagnóstica del test de SOMFi en una única ronda para detectar LNA observamos una S de 30%, E de 84%, VPP de 13% y un VPN de 94%. Para adenomas de bajo riesgo observamos una S de 13%, E de 84%, VPP de 17%, VPN de 79%. Para adenomas aserrados sésiles observamos una S de 16.7%, E de 87%, VPP de 11% y de VPN 91%. La precisión para el CCR fue la siguiente, S de 75%, E de 83%, VPP 6%, VPN 99%. No se observaron complicaciones post procedimientos. Conclusiones: La precisión diagnóstica del test de SOMFi en nuestro medio es comparable a los resultados internacionales. Sin embargo, la baja precisión observada en una única ronda realza la necesidad de realizarlo de forma anual o bianual para poder optimizar su precisión y lograr programas de pesquisa efectivos.(AU)

Background: Colorectal cancer (CRC) is the second leading cause of cancer death in Argentina. Due to its high prevalence, it is essential to standardize a screening program for prevention and early detection. According to international literature, the accuracy of the immunochemical fecal occult blood test (FIT) for CRC screening in an average-risk population has proven to be adequate, but there is no information at the local level. Objective: To evaluate the diagnostic accuracy of the FIT test in a single round for CRC screening in average-risk patients in our setting. Design: Diagnostic accuracy prospective study. Material and Methods: Average-risk patients who consulted for a CRC screening video colonoscopy (VCC) at the Hospital Alemán of Buenos Aires, between June 1, 2015 and December 31, 2017 were included. All patients with increased risk for CRC were excluded. All patients performed FIT and subsequently VCC. The endoscopists were blind to FIT result at the time of VCC. The diagnostic accuracy of FIT to detect advanced neoplastic lesions (ANL) was evaluated by calculating sensitivity (S), specificity (Sp), positive predictive value (PPV), negative (NPV), positive likelihood ratio (LR+) and negative likelihood ratio (LR-). The accuracy for the detection of low-risk adenomas, serrated polyps and CRC was also evaluated. Results: A total of 300 patients were included; 273 (91%) submitted the stool sample to perform FIT and completed VCC. The mean age of patients was 56.9 (40-85) years and 54% were men. Of the total number of patients who carried out both studies (273), 53 (19%) patients had at least one low-risk adenoma, 18 (6.59%) patients had at least one sessile serrated adenoma and 21 (7.7%) patients had at least one ANL. Only 4 (1.5%) patients presented CRC. The diagnostic accuracy of FIT in a single round to detect ANL was: S 30%, Sp 84%, PPV 13%, NPV 94%; for low-risk adenomas: S 13%, Sp 84%, PPV 17%, NPV 79%; for sessile serrated adenomas: S 16.7%, Sp 87%, PPV 11%, NPV 91% and for CRC: S 75%, Sp 83%, PPV 6%, NPV 99%. No post-procedure complications were observed. Conclusions: The diagnostic accuracy of FIT in our setting is comparable to international results. However, the low precision observed in a single round highlights the need to do it annually or biannually in order to optimize its accuracy and achieve effective screening programs. (AU)

A rare case of steroid cell tumor of ovary: case report

Steroid cell tumors of the ovary account for less than 0.1% of all ovarian tumors. These tumors may present at any age with presentations related to the hormonal activity and virilizing properties of tumor. A 61-year-old postmenopausal women presented with complaints of postmenopausal bleeding for 15 days. Parity score of P3L3, not tubectomised. Menopaused 16 years back. History of weight loss noted. She is a known case of diabetes mellitus for 6 years not on any treatment and a known case of depressive disorder for 35 years on treatment on trihexphenidyl lurasidone. Had undergone sigmoid colon polyp removal in June 2018. On examination, P/A- mild gaseous distension (+). P/S- cervix flushed with vagina, pulled up cervix. P/V- uterus size and position couldn’t be made out, anterior fornix fullness (+). Ultrasonography showed bulky uterus with fibroid 4x4cm, endometrial thickness- 9 mm? Krukenberg tumor and posterior mediastinal lymph nodes. Patient underwent Total abdominal hysterectomy with bilateral salpingo-oophorectomy with frozen section on 01/07/19. Frozen section: 1. Ovaries: right ovary - fibrothecoma, left ovary- simple cyst. 2. Uterus- endometrial hyperplasia with atypia. 3. Myometrium- leiomyoma and adenomyosis. Postoperative period was uneventful. On microscopic examination, impression: right ovary- steroid cell tumor, uterus-endometrial hyperplasia with cytological atypia. Ovarian steroid cell tumors are grouped under sex chord stromal tumors and are usually benign, unilateral and characterized by a steroid cell proliferation. Steroid cell tumors are associated with androgenic changes with variable frequency, ranging from 12% to over 50% respectively. The primary treatment is surgical extirpation of the primary lesion and there are no reports of effective radiation or chemotherapy. In a young patient with stage IA disease, a unilateral salpingo oophorectomy is adequate.

Risk Factors for Recurrent High-Risk Polyps after the Removal of High-Risk Polyps at Initial Colonoscopy

PURPOSE: Colonoscopic polypectomy and surveillance are important to prevent colorectal cancer and identify additional relative risk factors for adequate surveillance. In this study, we evaluated risk factors related to recurrent high-risk polyps during the surveillance of patients with high-risk polyps. MATERIALS AND METHODS: We included 434 patients who had high-risk polyps (adenoma > or =10 mm, > or =3 adenomas, villous histology, or high-grade dysplasia) on the baseline colonoscopy and underwent at least one surveillance colonoscopy from 2005 to 2011 at Severance Hospital. Data regarding patient characteristics, bowel preparation and polyp size, location, number, and pathological diagnosis were retrospectively collected from medical records. Patients with recurrent high-risk polyps were compared with patients with low-risk or no polyps during surveillance. RESULTS: Patients were predominantly male (77.4%), with a mean age of 61.0+/-8.6 years and mean follow-up of 1.5+/-0.8 years. High-risk polyps recurred during surveillance colonoscopy in 51 (11.8%) patients. Results of multivariate analysis showed that male gender, poor bowel preparation, and a larger number of adenomas were independent risk factors for recurrent high-risk polyps (p=0.047, 0.01, and <0.001, respectively). Compared with high-risk polyps found during initial colonoscopy, high-risk polyps on surveillance colonoscopy had higher proportions of small adenomas, low-risk pathology, and fewer adenomas overall, but there was no difference in location. CONCLUSION: Male patients and those with poor bowel preparation for colonoscopy or higher numbers of adenomas were more likely to experience recurrent high-risk polyps.

Follicular Dendritic Cell Sarcoma of the Inflammatory Pseudotumor-like Variant Presenting as a Colonic Polyp

Follicular dendritic cell (FDC) sarcoma is rare and is classified either as conventional type or inflammatory pseudotumor (IPT)-like variant. Extranodal presentation is uncommon and nearly all gastrointestinal FDC tumors are of the conventional type. IPT-like variant tumors occur almost exclusively in the liver and spleen and are consistently associated with Epstein-Barr virus (EBV). Here we report the case of a 78-year-old woman with an IPT-like FDC sarcoma presenting as a pedunculated colonic polyp. Histologically, scanty atypical ovoid to spindle cells were mixed with a background of florid lymphoplasmacytic infiltrate, which led to an initial misdiagnosis of pseudolymphoma. These atypical cells expressed CD21, CD23, CD35, and D2-40, and were positive for EBV by in situ hybridization, confirming the diagnosis. The patient was free of disease five months after polypectomy without adjuvant therapy. Although extremely rare, the differential diagnosis for colonic polyp should include FDC sarcoma to avoid an erroneous diagnosis. A review of the 24 cases of IPT-like FDC sarcoma reported in the literature reveal that this tumor occurs predominantly in females with a predilection for liver and spleen, and has a strong association with EBV.

Association Between Colon Diverticulosis and Development of Colorectal Cancer / 대한내과학회지

The prevalence of colorectal cancer (CRC) and diverticular disease has increased in recent years. Both have common risk factors such as age and a lack of dietary fiber. A causal relationship between diverticulosis and CRC has been suggested in different studies. Despite common epidemiological trends and risk factors, there are conflicting data concerning the association between diverticular disease and CRC. Such discrepancy could be referred to the highly heterogeneous study design and setting in the diff erent epidemiologic series. Unravelling the dilemma seems to be clinically relevant, because a different screening and/or surveillance protocol for CRC could be scheduled in patients with diverticula. The present review aimed to perform a comprehensive evaluation of the available data.

The Association Between Colon Polyp and the Metabolic Syndrome in Asymptomatic Korean Adults

BACKGROUND: Recently, the prevalence of colorectal cancer related with metabolic syndrome is increasing in Korea. The aim of this study was to reveal a relationship between components of metabolic syndrome and the development of colon polyp. METHODS: Among the subjects who visited a health promotion center of one university hospital and underwent colonoscopic examination from February 2010 to February 2011, a total of 1,630 (males 1,156, females 474) asymptomatic adults were included for the study. Sex, age, body mass index, waist circumference, blood pressure, fasting blood glucose, total cholesterol, triglyceride, HDL-cholesterol levels and the presence of colorectal polyps were measured. Alcohol consumption, smoking and exercise were assessed by a self-administered questionnaire. Metabolic syndrome was defined by criteria of 2004 American Heart Association/Updated NCEP Adult Treatment Panel III. RESULTS: The prevalence of colon polyps and metabolic syndrome was 21.7% and 16.0% respectively among study subjects. After adjustment for sex and age, metabolic syndrome (odds ratio [OR]=1.72, 95% confidence interval [CI] 1.05-2.82, P=0.031) and waist circumference (OR=1.04, 95% CI 1.01-1.06, P=0.009) were associated with increased risk of colorectal polyps. CONCLUSION: Metabolic syndrome and waist circumference were associated with increased risk of colon polyps in asymptomatic Korean adults.

Histological comparison of colon polyps by endoscopic forceps biopsy compared to polypectomy / 대한내과학회지

BACKGROUND/AIMS: Adenomatous polyps of the colon are believed to be precursor of colon cancer. Total polyp resection is indicated when they are identified. However, resection of the polyp is not always attainable at the initial colonoscopy. The aim of this study was to assess the validity of cold biopsy findings as representative of the whole polypectomy specimen, with regard to the histopathological features. METHODS: We analyzed 221 patients with colon polyps that were biopsied at their initial colonoscopy and had their adenomas subsequently removed by polypectomy within 2 weeks from the initial procedure. We analyzed the histopathological discrepancies between the cold biopsy and the polypectomy specimens. RESULTS: We analyzed 302 cases from 221 patients. There was 71.2% agreement between the forceps biopsy and the polypectomy. When colon polyps were diagnosed as carcinoma and villous adenomas, the diagnosis was the same in the polypectomy. Discrepancy between in forceps biopsy with polypectomy was found in the tubular adenomas obtained by forceps biopsy. Fifty tubular adenoma samples obtained by forceps biopsy had a deferent diagnosis than did the polypectomy. Fourteen of 50 tubular adenomas were underestimated by the forceps biopsy samples and seven of the 50 tubular adenomas were finally diagnosed as carcinoma from the polypectomy specimens. Seven villous adenomas were diagnosed as carcinoma and had severe dysplasia (n=4) or 1>=(n=1) size. CONCLUSIONS: Accurate tissue sampling of colorectal adenomas is crucial for their management. However, forceps biopsy does not accurately reflect the histology of colon polyps. Total resection of colon polyps is needed for an accurate diagnosis.

Utility of CT colonography in detecting colon polyps as a colon cancer screen / 대한내과학회지

BACKGROUND/AIMS: CT colonography is a rapid and safe imaging method for detecting polyps in the colon and rectum. We assessed the efficacy of CT colonography in colorectal polyp detection. METHODS: We prospectively studied 84 subjects (mean age 55.7+/-11.1 years; 52 men, 32 women) undergoing CT colonography followed by colonoscopy. Based on the results of CT colonography, all polyps were classified by size (any size, and those larger than 5, 7, and 10 mm) and were checked for location, morphology, and histological characteristics. We determined the sensitivity and specificity of CT colonography using colonoscopy as a reference standard with a segmental unblinding method. RESULTS: A total of 56 lesions were identified in 26 of 79 subjects undergoing both CT colonography and conventional colonoscopy. The sensitivities of CT colonography for polyps of any size, and larger than 5, 7, and 10 mm were 60.7%, 70.5%, 75.9%, and 81.8%, respectively. The per-subject sensitivities of CT colonography for the polyps of any size, and larger than 5, 7, and 10 mm, were 80.7%, 95.0%, 93.3%, and 90.9%, respectively. The per-subject specificities of CT colonography for polyps were 86.8%, 89.8%, 95.3%, and 100.0%, respectively. The sensitivities of CT colonography for flat, sessile, and pedunculated polyps were 30.8%, 85.0%, and 90.0%, respectively. CONCLUSIONS: CT colonography is a useful diagnostic method for screening colorectal neoplasias larger than 7 mm diameter, showing 75.9% sensitivity and 71.0% positive predictive value.

Clinical Characteristics and Risk Factors of Colon Polyps in Gyeongju and Pohang Area / 대한소화기학회지

BACKGROUND/AIMS: The purposes of this study were to investigate various environmental factors for colon polyps and to analyze locoregional clinical characteristics of colon polyps in Gyeongju and Pohang area. METHODS: From October 2005 to September 2006, patients who underwent colonoscopy were analyzed based on their ages, genders, body mass indices (BMI), dietary habits, smoking behaviors, accompaying diseases, and medications as risk factors for the occurrence of colon polyps. Then clinical manifestations, gross appearances and pathologic findings of polyps were investigated. RESULTS: Among 253 patients enrolled, a total of 296 colon polyps were found in 108 patients. The incidence of colon polyps in more than 50-year old patients was 3.2-fold greater compared to less than 50-year old patients. Smoking habits were also significantly associated with the occurence of colon polyps. Among adenomatous polyps, tubulovillous type and moderate to severe dysplasia were frequently observed as the size increased, yet the location of polyps was not significantly associated. CONCLUSIONS: Older age and smoking habit increase the risk of colon polyps. Rectal polyps have less chance to be adenomatous type. The larger the polyp grows, the more likely it to be tubulovillous and dysplastic.

A Case of Endoscopic Polypectomy Using a Hand-Made Detachable Snare Made of Nylon Fishing Line / 대한소화기내시경학회지

Hemorrhage is the most common complication of polypectomy. Though most bleeding stops spontaneously and can be managed with conservative therapies, some may necessitate intensive therapies. The detachable snare was firstly introduced in 1986. It has been reported that the use of detachable snare can effectively prevent both immediate and delayed bleeding. The detachable snare has been reformed, and now a commercial article is used in practice. But, it is expensive and cannot be used in larger polyps measuring over its fixed size of loop. A hand-made detachable snare made of nylon fishing line was introduced to prevent postpolypectomy bleeding in 2003. We have further improved it and experienced a case of successful removal of a large colonic polyp using our hand-made snare. The hand-made detachable snare is inexpensive and seems to be practical in ligating the polyp regardless of its size.

Synchronous Lesions in Colorectal Cancer

PURPOSE: The detection and removal of synchronous cancer and polyps in colorectal surgery is important to prevent the future development of metachronous cancer. However, it is occasionally impossible to evaluate the entire colon with colonoscopy preoperatively due to luminal obstruction by tumors. The aim of this study is to evaluate the incidence of synchronous colorectal tumors and to emphasize the importance of their peri-operative detection through vigorous application of colonoscopy. METHODS: Three hundreds two patients underwent a potentially curative resection for colorectal cancer in Ilsan Paik Hospital from January 2000 to March 2005. Colonoscopy was performed preoperatively or intraoperatively. All the synchronous polyps detected by colonoscopy and contained in the surgical specimen were included in the analysis. The data on synchronous cancer and polyps were collected through medical records and colonoscopic databases. The incidence, the risk factors, and the effects of synchronous polyps on surgery were analyzed. RESULTS: A total of 268 polyps were detected in 112 patients (37%) when all types of polyp were included whereas true adenomatous polyps were present in 78 patients (26%) among 302 patients. Synchronous cancers were found in 14 patients (4.6%). The detection of polyps on preoperative colonoscopy changed the surgical strategy in 30 out of the 223 patients (13.5%) who had completed preoperative colonoscopy. Neither the age and the gender of the patient, the location and the stage of the tumor, nor the family history were related with increased risk of synchronous polyps. Seventeen among 46 intraoperative colonoscopy cases had synchronous lesions which were not known on preoperative evaluation. Another bowel resection was needed to remove the lesions in nine of them. CONCLUSIONS: Synchronous colorectal polyps or cancer is frequent, and preoperative detection is important. Intraoperative colonoscopy can provide valid information if a preoperative colonoscopic evaluation is not available.

Colonoscopic Polypectomy in Outpatients / 대한소화기내시경학회지

BACKGROUND/AIMS: The incidence of colon cancer has increased since 1990 in Korea. Though the cause of colon cancer is not clear, there are two theories of its development (adenoma-carcinoma sequence and de novo cancer). Recently, frequently performed colonoscopy and videoscopy make it possible to find colon polyps including tiny ones and do polypectomy. So, the authors studied safety of colonoscopic polypectomy on out-patient basis and its clinico-pathologic results. METHODS: From April 1999 to April 2000, the authors performed colonoscopy and polypectomy in patients for various gastrointestinal symptoms, follow-up after colon cancer operation, and colon cancer screening. We studied prospectively in out-patients basis after checking of bleeding tendency. If there was possibility of bleeding or perforation risk, we had done hemoclipping for prevention of complications. RESULTS: One thousand three hundred five colon polyps were found in 586 patients. 1,191 (91.3%) were smaller than 1 cm. Among the total 1,305 polyps, 10 revealed malignant transformation, in which 6 were smaller than 1 cm. Sigmoid colon and ascending colon are most common site of colon polyps, which could be removed with endoscopic mucosal resection snare. Only 1 case of postpolypectomy bleeding was noted after 9 days with mucosectomy without any other complications as perforation. CONCLUSIONS: The colon polyps are popular in the Korean and even the small polyps can be malignant. Any polyps could be removed in spite of small size and the polypectomy in out-patient basis is a safe procedure if postpolypectomy complications are fully comprehended and preventing endoscopic procedures are carried adequately.

Clinical Observation in Endoscopic Treatment of Colonic Polyps / 대한소화기내시경학회지

BACKGROUND AND AIMS: Colonic polyps are premalignant lesion, whose removal is important for the prevention of colon cancer. METHODS: A series of 116 patients (195 polyps) who undergone colonoscopic polypectomy at Chung Nam National University Hospital from March 1994 to Feb.1997 were analyzed. RESULTS: 1) The ratio of males and females was 81:35, with the average age being in the 60's. 2) Colorectal polyps were found at the rectum (39.5%), sigmoid colon (35.9%). The size of the polyps was less than 0.6 cm in diameter (44.6%), between 0.6 and 1.0 cm (27.7%), between 1.1 and 2.0 cm (22.6%). The number of polyp was single polyp (59.5%). According to the Yamada classification, type III was the most common (43.1%). 3) Histopathologic findings were as follows. Tubular adenomas (58.6%), LSPs was in 3 cases, and malignant changed polyps in 14 case. 4) The malignantly changed polyps peaked in those in their 70's, had sizes ranging between 1.1 and 2.0 cm. Histopathologic finding were villous adenomas (50.0%), tubular adenomas (13.2%), LSPs (33.3%) in orders. CONCLUSION: Although the prevalence of cancer of villous adenomas and LSP was higher than other polyps, the size of the adenomas, their numbers do not seem to influence the malignancy rate in this report.

The Prevalence and Characteristics of Colorectal Polyps found by Sigmoidoscopy in Asymptomatic Korean Adults / 대한내과학회지

OBJECTIVES: Colorectal polyps play an integral role in the development of colon cancer. The prevalence of colorectal polyps in Korea was reported to be 5-12%. However, these results were obtained from retrospective studies, in which the subjects were symptomatic patients. Therefore, we performed a prospective study in asymptomatic Korean adults to determine the prevalence, characteristics, and risk factors of colorectal polyps. METHODS: Flexible sigmoidoscopy was done during the period between August 1994 to November 1995 in 2,985 aymptomatic individuals who visited Samsung Medical Center for health check-ups. RESULTS: 1) Polyps were found in 590 subjects (20.4%) out of 2,985 individuals. The prevalence rate increased with age. 2) In histologic findings of colorectal polyps, there were 369 cases (45.8%) of adenomatous polyps, 245 cases (30.4%) of hyperplastic polyps and 5 cases of carcinomas. 3) Moderate to severe dysplasia was found in 15.4% of adenomatous polyps and the grade of dysplasia increased with polyp size. 4) The prevalence rate of polyps increased according to obesity, blood cholesterol and triglyceride level, the frequency of alcohol consumption and the amount of smoking in cases. Conclusions : Screening by sigmoidoscopy is considered to be beneficial for detection of colorectal polyps in asymptomatic Korean adults, especially in individuals with risk factors such as obesity, heavy smoking and alcohol consumption.

Endoscopic India Ink Marking of the Colonic Mucosa / 대한소화기내시경학회지

It is now generally accepted that most, if not all, colon cancers originate within previously benign adenomas. Endoscopic polyp resection and regular follow up endoscopic examination are essential for prevention of carcinoma fro benign adenoma. However, small colorectal polyps are difficult to recognize during follow up endoscopic examinations because of the lack of reliable endoscopic landmarkers. Endoscopic Indiaink marking of the colon was first described by Ponsky and King in l975. The method has subsequently been advocated by expert as the best available means to mark the site of a colonic lesion. We prospectively studied the effectiveness of India ink as a long term colonic mucosal marker. Twelve patients who were diagnosed as colorectal polyp had a India ink marking with standard sclerotherapy needle. All patients who were followed at 6 months interval (mean duration 13 months) continue to display intensely stained mucosa at the original sites. No side effects or complications were encountered. India ink appears to be a safe and effective long term marker for colonic mucosal lesions.