氩气刀结合黏膜下注射治疗结肠息肉的安全性研究

目的探讨氩气刀结合黏膜下注射治疗结肠息肉的安全性。方法取健康肉猪的新鲜乙状结肠30份,每份均设立实验组（黏膜下注射后氩气烧灼）和对照组（直接氩气烧灼）,烧灼后病理组织学观察猪结肠壁各层损伤情况并行组间对比分析。另选择10例结肠广基息肉患者（息肉直径1～2cm,厚度在3mm以内）,均分成观察组（黏膜下注射后氩气烧灼）和对照组（直接氩气烧灼）,烧灼后超声内镜观察人结肠壁各层损伤情况。结果病理组织学观察显示,对照组损伤猪结肠固有肌层5份、黏膜下层25份（上1／34份、中1／312份、下1／39份）,实验组损伤猪结肠黏膜下层26份（上1／322份、中1／34份）、黏膜肌层4份,2组差异有统计学意义（P〈0．01）。超声内镜观察显示：对照组人结肠黏膜层与黏膜下层融合、层次不清,局部黏膜下层与固有肌层边缘毛糙、不规则;观察组人结肠1、2层边缘稍毛糙模糊,其余各层层次界限清晰。结论黏膜下注射对氩气刀烧灼损伤具有保护作用,可减少结肠息肉患者氩气刀治疗发生穿孔的概率。     

Histology assessment of bipolar coagulation and argon plasma coagulation on digestive tract

AIM: To analyze the effect of bipolar electrocoagula-tion and argon plasma coagulation on fresh specimens of gastrointestinal tract. METHODS: An experimental evaluation was performed at Hospital das Clinicas of the University of So Paulo, on 31 fresh surgical specimens using argon plasma coagulation and bipolar electrocoagulation at different time intervals. The depth of tissue damage was his-topathologically analyzed by single senior pathologist unaware of the coagulation method and power setting applied. To analyze the results, the mucosa was divided in superficial mucosa (epithelial layer of the esophagus and superficial portion of the glandular layer of the stomach and colon) intermediate mucosa (until thelamina propria of the esophagus and until the bottom of the glandular layer of the stomach and colon) and muscularis mucosa. Necrosis involvement of the layers was compared in several combinations of power and time interval. RESULTS: Involvement of the intermediate mucosa of the stomach and of the muscularis mucosa of the three organs was more frequent when higher amounts of en-ergy were used with argon plasma. In the esophagus and in the colon, injury of the intermediate mucosa was frequent, even when small amounts of energy were used. The use of bipolar electrocoagulation resulted in more frequent involvement of the intermediate mucosa and of the muscularis mucosa of the esophagus and of the colon when higher amounts of energy were used. In the stomach, these involvements were rare. The risk of injury of the muscularis propria was significant only in the colon when argon plasma coagulation was em-ployed.CONCLUSION: Tissue damage after argon plasma coagulation is deeper than bipolar electrocoagulation. Both of them depend on the amount of energy used.     

Low power interstitial Nd YAG laser photocoagulation in normal and neoplastic rat colon.

The effects of low power (1-2 Watts), long exposure (30-400 seconds), interstitial Nd YAG laser therapy on dimethylhydrazine induced rat colonic neoplasms and normal rat colon have been studied. After a single exposure with appropriate laser parameters, dimethylhydrazine induced rat colonic neoplasms underwent coagulative necrosis, sloughed off over a four day period, and left an ulcer which healed within 28 days. Inadequate laser energy resulted in incomplete tumour necrosis whilst excessive laser power or energy increased the likelihood of perforation. Treatment of normal colon with 1 Watt for 30 seconds or longer resulted in coagulative damage which healed by granulation. Mean colonic bursting pressures were significantly decreased one hour after treatment with 1 Watt for 75 or 100 seconds compared with untreated colon (p less than 0.05 and p less than 0.001 respectively) but not in colon treated with 1 Watt for 30 or 50 seconds. In animals treated with 1 Watt for 100 seconds mean bursting pressures were significantly lower than untreated animals when the animals were killed two, four, and seven days after lasering (p less than 0.001 in each case) but not in animals killed at 11, 17, or 21 days. The technique may be of value in the treatment of some inoperable colorectal cancers and sessile polyps in man.     

黏膜切除术治疗结直肠广基隆起性腺瘤性息肉98例临床研究

目的探讨内镜下黏膜切除术(endoscopic mucosal resection,EMR)治疗结直肠广基隆起性腺瘤性息肉患者的疗效。方法回顾性分析98例结直肠广基隆起性腺瘤性息肉(息肉直径0.6~2.0 cm)患者的临床资料并行EMR治疗。结果 98例均经电子结肠镜检查及术前病理诊断为腺瘤性息肉,均为广基隆起性病变,共120枚,行EMR,留取完整标本病理检查,创面均给予钛夹封闭。术后病理诊断为腺瘤性息肉113例,高级别瘤变4例,局部癌变3例,7例切缘均无癌细胞,未追加外科手术。1个月后复查见病变部位黏膜光滑,未见息肉及病变黏膜残留。高级别瘤变及局部癌变7例随访3年,未见肿瘤复发及它处转移。结论对于广基隆起性腺瘤性息肉行EMR较既往单纯的高频电灼或氩离子凝固术有助于发现早期癌,改善患者的预后。     

Status evaluation: hot biopsy forceps. American Society for Gastrointestinal Endoscopy. Technology Assessment Committee.

Monopolar hot biopsy forceps were developed for simultaneous tissue biopsy and electrocoagulation. Many endoscopists used these forceps for coagulation of diminutive polyps of the colon. The rationale for diminutive polyp eradication is to destroy neoplastic tissue and possibly prevent colon cancer. However, convincing data to document a reduction in the incidence of colorectal cancer or even complete obliteration of all treated diminutive polyps with hot biopsy forceps are lacking. Complications of hot biopsy include hemorrhage, perforation, and post-coagulation syndrome. Tissue injury is deeper with monopolar hot biopsy forceps than bipolar forceps. The right colon is particularly susceptible to transmural injury and perforation. For small polyp obliteration, comparative studies of hot biopsy (monopolar and bipolar) with other techniques such as cold biopsy combined with thermal probes, large cup cold biopsy removal, and snare electrocoagulation are warranted. The necessity to biopsy typical appearing angiomata does not seem warranted on a routine clinical basis. The expected obliteration rates of small angiomata or rates of controlling lower gastrointestinal bleeding from colon angiomata after monopolar hot biopsy electrocoagulation have not been well documented. Heater probe or bipolar electrocoagulation have been safely and effectively applied to bleeding colon angiomata. These newer coagulation probes are recommended as an alternative to hot biopsy forceps for treatment of bleeding colonic angiomata.     

The pathogenesis of inflammatory polyps

Eighty-six consecutive colonic resection specimens for inflammatory bowel disease were studied to determine the modes of inflammatory polyp formation. The two major groups of inflammatory polyps were (1) polypoid mucosal tags due to undermining ulceration and (2) mature inflammatory polyps composed of mucosa, muscularis mucosae, and a submucosal core. Mature inflammatory polyps were derived from polypoid mucosal tags after regeneration and the adjacent mucosa showed regenerative changes and submucosal scarring. The study confirms that ulceration which undermines the muscularis mucosae is the major precursor of inflammatory polyps. Presented at the meeting of the International Academy of Pathology, Toronto, Canada, March 1985. Supported by the Pencer Fund and the Foothills Hospital Foundation.     

Serum and colon mucosa micronutrient antioxidants: differences between adenomatous polyp patients and controls

OBJECTIVES: Micronutrient antioxidants, by virtue of their free radical scavenging properties, are potential chemopreventive agents against colon cancer. Yet, little is known about the actual concentration of these antioxidants in colonic mucosa. It is also not known whether a relationship exists between serum and mucosal tissue antioxidant levels. Previous studies evaluating the occurrence of polyps after supplementation with vitamin E and beta-carotene have yielded mixed results. The aim of this study was to determine the concentrations of seven micronutrient antioxidants (alpha- and gamma-tocopherol, lutein, beta-cryptoxanthin, lycopene, and alpha- and beta-carotene) in colonic mucosa and to determine whether serum levels of each antioxidant could predict levels of that antioxidant in the right and left colon of patients with normal mucosa or in those with adenomatous polyps. METHODS: Mucosal tissue concentrations and serum levels of antioxidants were determined in 10 patients with adenomatous polyps and 15 control subjects (GI patients with normal colonic mucosa). Mucosal tissue samples were obtained from both the right and left colon in all patients. RESULTS: Patients with polyps similar serum antioxidant status similar to that of control. However, polyp patients had significantly lower concentrations of all seven antioxidants in both the right (p < 0.0070) and left colon (p < 0.0026) than did controls. Finally, serum antioxidant levels predict right and left colon antioxidant levels in controls but not in patients with polyps. CONCLUSIONS: Patients with adenomatous polyps have low levels of micronutrient antioxidants in their colon mucosa. Because the serum levels of these antioxidants were similar in controls and polyp patients, our findings suggest an increased level of free radical activity in patients with polyps compared to normal subjects.     

The tissue effect of second generation argon plasma coagulation (VIO APC) in comparison to standard APC and Nd:YAG laser in vitro

BACKGROUND: The aim of this study was to evaluate the effect of 2nd generation argon plasma coagulation (VIO APC) with respect to the tissue destruction capacity, and to compare it with standard APC and Nd:YAG laser. METHODS: 2nd generation APC (VIO APC2, Erbe, Germany), standard APC (APC 300/Erbotom ICC 200, Erbe) and Nd:YAG laser (KTP/YAG XP 800; Laserscope, San Jose, California) were applied in 35 porcine livers. Using APC, power settings (30-120 W), application time (2 and 5 sec) and gas flow (1 and 2 l/min) were varied. Using Nd:YAG laser, 30-60 W were applied (flow 21/min). Diameter and depth of tissue coagulation were evaluated. RESULTS: Using VIO APC, maximum coagulation depth was 6 mm (maximum diameter 15 mm). In comparison to standard APC, the coagulation effect was significantly higher (p < 0.001). There was no significant difference in the mean depth achieved by VIO APC and Nd:YAG laser using 30- 60 W and an application time of 2 sec (p < 0.05). Using maximum energy available for the 2 systems, maximum depth achieved by VIO APC (6 mm) was higher than the one caused by Nd:YAG laser (4 mm). CONCLUSIONS : VIO APC was more effective than standard APC. Using medium power and a limited application time, it was as effective as Nd:YAG laser. The high effectiveness of VIO APC should be a topic of clinical education.     

Argon vs. neodymium YAG laser photocoagulation of experimental canine gastric ulcers

A neodymium YAG (Nd:YAG) laser was evaluated in a dog ulcer model used in the same manner as is recommended for bleeding patients (power 55 W, divergence angle 4 degrees, with CO2 gas-jet assistance). The experiments were performed during sterile laparotomy in heparinized dogs. Bleeding gastric ulcers were photocoagulated until bleeding stopped and then examined histologically 7 days later when depth of tissue injury was maximal. In the first series of experiments, the Nd:YAG laser was compared with the 7-W argon laser in the same dogs. Both lasers stopped bleeding from all experimental ulcers. The 55-W Nd:YAG laser caused full-thickness injury to the gastric wall beneath 11 of the 14 treated ulcers, whereas the 7-W argon laser caused no full-thickness injury beneath 14 treated ulcers. In a second series of experiments, we tried to determine whether varying exposure times with the 55-W Nd:YAG laser would make it less injurious; it did not. In a third series of experiments, the 55-W Nd:YAG laser was tested with and without CO2 gas-jet assistance in order to determine if this would affect the depth of injury; it did not. In the final series of experiments, the wattage of the Nd:YAG laser was varied to see if this would reduce depth of injury; lower wattage did not stop bleeding, and intermediate and higher wattages did stop bleeding but did not reduce depth of injury. We conclude that the 55-W Nd:YAG laser as it is currently used clinically produces deeper tissue damage than the argon laser in our animal model. This damage is not reduced by changes in power, duration of exposure, or the presence of gas-jet assistance.     

POLYPOID COLONIC HAMARTOMATOUS INVERTED POLYP

We herein present a unique polyp diagnosed as polypoid colonic hamartomatous inverted polyp. Colonoscopic examination revealed a clover‐like submucosal tumor about 30 mm in size with a long stalk at the mid‐transverse colon. The polyp consisted of elongated crypts with cystic dilatation located in the submucosal layer. To the best of our knowledge, there have been no previous reports of the same type of pedunculated colonic polyp, similar in appearance to inflammatory myoglandular polyps but covered with a layer of normal mucosa possessing the muscularis mucosae at the uppermost surface of the polyp.     

Randomized controlled study of injury in the canine right colon from simultaneous biopsy and coagulation with different hot biopsy forceps

Background: Monopolar hot biopsy forceps (HBF), bipolar HBF, and cold biopsy forceps (CBF) followed by bipolar electrocoagulation are used clinically to simultaneously perform a biopsy and coagulate diminutive colon polyps and angiomata. Our purpose was to conduct a randomized, controlled study to evaluate the safety of these different techniques in the canine right colon.Methods: After right colotomy in 8 mongrel dogs, colonic mucosa was grasped en face, tented, and biopsy performed in randomized order. The dogs were sacrificed after nine days and the biopsy sites were identified and histologically examined.Results: Monopolar HBF caused an overall mean rate of acute serosal whitening of 29% compared with 0% for bipolar HBF and CBF and 6% for CBF/bipolar probe. Histologically confirmed transmural injury 9 days after biopsy occurred in 44% of monopolar HBF compared with 5% of bipolar HBF, 0% of CBF, and 50% of CBF/bipolar probe.Conclusions: Monopolar HBF had significantly higher rates of acute serosal whitening and histologic transmural damage than bipolar HBF or cold biopsy alone. On the basis of these results, monopolar HBF should be avoided for coagulation of small or flat right colon lesions such as diminutive polyps or angiomata. (Gastrointest Endosc 1995;42:573-8.)     

The potential and limitations of laser photoablation of colorectal adenomas.

Ablation of colorectal adenomas by Nd:YAG laser energy was investigated in 271 patients. Two hundred and forty-one patients, selected because of poor surgical and medical condition or refusal of surgery, presented with incompletely removed polyps or with lesions unsuitable for endoscopic polypectomy. Thirty patients with polyposis coli were treated for rectal stump polyps after subtotal colectomy and ileorectal anastomosis. Because of insufficient follow-up (28) or malignant degeneration (23), full evaluation was possible in 196 colon adenoma and 24 polyposis patients. Complete ablation with histologic confirmation for at least 12 weeks was achieved in 150 (82%) of the 183 colon adenomas. This declined to 141 (77%) because of later recurrences in prolonged follow-up. Treatment of large adenomas was less successful than that of intermediate and small lesions: ultimate ablation in 56, 85, and 93%, respectively. Impressive was the immediate relief in 100 symptomatic elderly patients, who were bothered by frequent diarrhea, excessive mucous discharge, and incontinence. All patients survived despite major complications (7%) that mainly consisted of stenosis and hemorrhage. Rectal stump polyps were eliminated in 20 patients with polyposis coli. The remaining four had an uneventful ileoanal anastomosis for ultimately uncontrollable growth of polyps. Malignancy was discovered in 22 adenoma patients and in 1 polyposis patient. We recommend laser ablation of colorectal adenomas for small and medium-sized polyps, that cannot be removed by endoscopic polypectomy in inoperable patients or in patients refusing operation. Laser treatment for extensive adenomas seems only appropriate for symptomatic relief.     

Current Status of Lasers for Arrhythmia Ablation

Current Status of Lasers for Arrhythmia Ablation. Wavelength specific effects and mode of laser operation allow either photocoagulation or tissue removal as a means of approaching arrhythmia ablation. Successful intraoperative ablation of ventricular tachycardias has been performed with the Nd: YAG laser (photocoagulation) and argon laser (tissue vaporization). The argon laser has been used intraoperatively for transection of accessory pathways. Experimental studies indicate a strong theoretical potential for Nd:YAG laser catheter ablation of ventricular tachycardia. Laser energy has been used experimentally to evaluate the possibility of AV junctional ablation/modification and accessory pathway ablation. Adaption of laser energy to effective catheter systems for arrhythmia ablation requires solutions to problems inherent in all catheter systems and some unique to laser energy. (J Cardiovasc Electrophysiol, Vol. 3, pp. 345–353, August 1992)     

In vivo characterization of colonic thermal injury caused by argon plasma coagulation

BACKGROUND: Argon plasma coagulation has been rapidly accepted for endoscopic obliteration of vascular lesions and superficial tumors. Depth of injury is thought to be limited through preferential discharge of energy to nondesiccated tissue. However, argon plasma coagulation-induced injury has not been well characterized. The aim of this study was to characterize argon plasma coagulation-induced colonic injury by using a porcine model. METHODS: Laparotomy was performed in 6 female swine and the colon exteriorized with the subjects under general anesthesia. Lesions were made with an argon plasma coagulation probe held perpendicular and 2 mm from the mucosa. Variables studied were as follows: power (45 W, 60 W, and 75 W) and duration (1, 2, or 3 seconds; n = 11 for each power/duration combination). Injury was graded as either superficial or deep, involving the muscularis propria. RESULTS: Circular muscle layer injury correlated closely with power (p = 0.02), duration (p = 0.001), and total energy delivered (r = 0.977). Longitudinal muscle damage was associated with duration of burn (p = 0.001) and total energy delivered (r = 0.855), but correlated poorly with power (p = 0.40). No perforations occurred. Submucosal injection of saline solution had a protective effect with reductions in circular (90% to 10%, p = 0.002) and longitudinal muscle injury (50% to 0%, p = 0.1). CONCLUSIONS: Injury to the muscularis propria occurs at recommended settings for argon plasma coagulation. Injury correlates with power setting, duration of burn, and total energy delivery. Protective arcing to nondesiccated tissue does not appear to be significant in vivo. Submucosal injection of saline solution protects against deep injury.     

Importance of the surrounding colonic mucosa in distinguishing between hyperplastic and adenomatous polyps during acetic acid chromoendoscopy

AIM： To examine the characteristics of colonic polyps, where it is difficult to distinguish adenomatous polyps from hyperplastic polyps, with the aid of acetic acid chromoendoscopy. METHODS： Acetic acid spray was applied to colonic polyps smaller than 10 mm before complete excision. Endoscopic images were taken before and 15-30 s after the acetic acid spray. Both pre- and post-sprayed images were shown to 16 examiners, who were asked to interpret the lesions as either hyperplastic or adenomatous polyps. Regression analysis was performed to determine which factors were most likely related to diagnostic accuracy. RESULTS： In 50 cases tested by the 16 examiners, the overall accuracy was 62.4% （499/800）. Regression analysis demonstrated that surrounding colonic mucosa was the only factor that was significantly related to accuracy in discriminating adenomatous from hyperplastic polyps （P 〈 0.001）. Accuracy was higher for polyps with linear surrounding colonic mucosa than for those with nodular surrounding colonic mucosa （P 〈 0.001）, but was not related to the shape, location, or size of the polyp. CONCLUSION： The accuracy of predicting histology is significantly related to the pattern of colonic mucosa surrounding the polyp. Making a histological diagnosis of colon polyps merely by acetic acid spray is helpful for colon polyps with linear, regularly patterned surrounding colonic mucosa, and less so for those with nodular, irregularly patterned surrounding colonic mucosa.     

Nature and extent of histological changes induced by argon laser photocoagulation in canine gastric mucosa.

The tissue changes in canine gastric mucosa caused by exposure to an argon laser beam vary from mild mucosal oedema to complete cell destruction. Intermediate degrees of damage cause an inflammatory cell response with the formation of granulation tissue, particularly in the submucosa. The rate of healing is similar to that after other forms of injury to the gastric mucosa. Cell destruction at the surface of the mucosa starts with energies greater than 8 Joules on any one spot, and occurs at greater depths as the energy is increased but, unless cells are actually destroyed, the extent of histological damage is limited to a zone 1 mm lateral to, or below, the area exposed to the laser beam. Haemostasis is achieved by thermal contraction of bleeding vessels and of the surrounding tissue, thrombosis only occurring as a secondary effect.     

Treatment of colonic polyps--practical considerations

The adenomatous colonic polyp, a neoplastic lesion, is the precursor of most if not all carcinomas of the colon and rectum. Confirmatory evidence is derived from epidemiological, histological and clinical data demonstrating a close parallelism between adenomas and cancer of the colon. Based on current knowledge, all colonic polyps should be removed to prevent the development of colonic cancer. However, since the risk of malignancy within an adenoma is related to its size, histology and the degree of dysplasia, practical considerations dictate that all polyps 1 cm in diameter or larger should be removed upon their detection by barium enema or colonoscopy since such adenomas are the ones most likely to contain malignancy. The endoscopic removal of colon polyps can be efficiently and safely accomplished when established principles of colonoscopy and electrosurgery are followed. This technique requires the proper equipment, a skilled endoscopy assistant, and an experienced endoscopist with the ability to adeptly perform colonoscopy, an understanding of the basic concepts of electrocautery and knowledge of the various structural configurations of colonic polyps. Colonoscopic polypectomy will avoid the need for surgical resection in most instances. Management of the malignant colonic polyp remains controversial. The patient with a sessile or pseudo-pedunculated polyp containing invasive cancer should undergo colonic resection. Surgery is not necessary for the majority of patients whose pedunculated adenomas contain invasive cancer, unless the malignancy is poorly differentiated, the cancer invades lymphatics or vascular channels, or tumour is seen at or near the resection margin. Surveillance colonoscopy after endoscopic polypectomy should be performed in most instances within one year to look for recurrent tumour, missed polyps or a metachronous adenoma. Subsequently, colonoscopy should be performed every two years in patients with multiple index polyps, and every three years after removal of a single index adenoma.     

In vivo evaluation of argon plasma coagulation in a porcine model

BACKGROUND: Argon plasma coagulation (APC) is a noncontact form of monopolar electrocautery. One purported advantage of APC includes a limit to the depth of injury. It is unclear from previous studies whether the depth of injury is limited to superficial tissue layers with the settings used in clinical practice. OBJECTIVE: To evaluate the depth and the area of APC-induced injury by using new modes of APC delivery in an in vivo porcine model in the setting of colonoscopy. DESIGN: Blinded quasi-experiment. SUBJECTS: Six swine. INTERVENTION: Colonoscopy with the swine under general anesthesia, with application of APC in 2 different pulsed modes and varying power settings and duration of application. MAIN OUTCOME MEASUREMENTS: Surface area and depth of colonic mucosal injury. Qualitative histologic analysis of each site of APC application was performed on formalin-fixed specimens after euthanizing the swine. RESULTS: Muscularis propria injury occurred in 22% of lesions with 10 W, 62% of lesions with 20 W, 86% of lesions with 40 W, and 80% of lesions with 60 W. Muscularis propria injury occurred in 42% of lesions at 1 second, 66% of lesions at 3 seconds, and 69% of lesions at 5 seconds. Depth of injury was significantly correlated with total energy delivered (P = .001, r = 0.75). Surface area was significantly associated with total energy delivered (P < .001, r = 0.81). LIMITATIONS: This study was performed in distal swine colon rather than human colon. Colon tissue response to APC injury may differ from swine to human colon. The application distance from the APC probe to the colonic tissue may have varied between applications. CONCLUSIONS: Muscularis propria injury occurs across a broad range of clinically used APC settings. The frequency of deep injury and the surface area of the lesion increases with total energy delivered. The lowest power settings (10-20 W) and the shortest durations have the lowest risk of deep tissue injury.     

Histological changes following Nd YAG laser photocoagulation of canine gastric mucosa.

Tissue changes produced in the dog stomach by exposure to a Nd YAG laser varied from mild mucosal oedema to cell vaporisation. Intermediate degrees of damage caused a marked inflammatory response leading to extensive fibrosis in the submucosa and muscularis propria. The true extent of tissue damage was not apparent immediately, and treated mucosa that initially appeared intact sometimes sloughed several days later to leave an ulcer. The extent of damage and the rate of healing depended on the amount of laser energy used. With pulses at optimum laser power (75 w) and exposure time (0.4 sec), however, haemostasis was achieved in induced ulcers with total energy concentrations that did not produce full thickness tissue damage nor alter the healing rate from that observed in untreated ulcers. Thermal contraction was the primary haemostatic mechanism, thrombosis only occurring as a secondary effect.     

Retroflexion in the colon: a useful and safe technique in the evaluation and resection of sessile polyps during colonoscopy

OBJECTIVE: Endoscopic polypectomy has become the standard management approach for colon polyps. Three factors can make endoscopic resection of colonic polyps difficult: size, configuration, and location. We describe the use of retroflexion in the colon as a useful and routine technique using a standard colonoscope for the resection of difficult sessile polyps. METHODS: Fifteen patients in whom the retroflexion technique was used for polyp removal were prospectively identified. Each polyp was visualized and resected using both a forward and retroflexed view. RESULTS: Nine women and six men were identified between the ages of 49 and 81 years. The 15 polyps were located in the cecum (3), ascending colon (3), hepatic flexure (3), splenic flexure (2), descending colon (2), and sigmoid colon (2). All the polyps were sessile and their largest diameter ranged from 20 mm to 50 mm. Retroflexion combined with forward viewing allowed for a better assessment of the size and extent of all the polyps compared with forward viewing alone. All polyps, except two, were completely resected during the first session, using both the prograde and retroflexion approaches. No complications from retroflexion of the colonoscope, including perforation or bleeding, occurred. CONCLUSION: Retroflexion complements the conventional prograde inspection of sessile polyps that are only partially visualized on prograde view alone. Retroflexion allows a complete assessment of the lesions' size and extent and aid in their complete removal.