What does sigmoidoscopy really miss?

The relative effectiveness of flexible sigmoidoscopy compared with colonoscopy to screen for colorectal cancer depends on the magnitude of the association between findings in the proximal and distal colon and the false-negative rate of screening sigmoidoscopy for proximal neoplasia. Lewis et al. performed a systematic review and meta-analysis of screening colonoscopy studies. Published studies through July 31, 2000 of asymptomatic patients undergoing screening colonoscopy were identified from the MEDLINE database. The authors generated pooled estimates of the odds ratio for the association between findings in the distal and proximal colon and the prevalence of isolated proximal adenomatous neoplasia. With the sigmoid–descending colon junction used to identify the beginning of the distal colon, the pooled odds ratio for the association between distal adenomatous polyps and any proximal neoplasia was 2.40 (95% confidence interval [Cl] = 1.42–4.05). Diminutive distal adenomatous polyps were also associated with proximal neoplasia (odds ratio = 2.36; 95% CI = 1.30–4.29). Distal hyperplastic polyps were not associated with proximal neoplasia (odds ratio = 1.44; 95% CI = 0.79–6.62). The prevalence of isolated advanced proximal neoplasia in the three studies was 2%, 3%, and 5%, respectively. When the sigmoid–descending colon junction is used to identify the beginning of the distal colon, this yields a pooled estimate of isolated proximal neoplasia of 16.3% (95% CI = 13.6%–19.1%). Distal adenomatous polyps, including diminutive distal adenomatous polyps, are associated with an increasing prevalence of synchronous proximal neoplasia. From 2% to 5% of patients undergoing screening colonoscopy might have isolated advanced proximal neoplasia.     

Detection of proximal adenomatous polyps with screening sigmoidoscopy: a systematic review and meta-analysis of screening colonoscopy

BACKGROUND: The relative effectiveness of flexible sigmoidoscopy compared with colonoscopy to screen for colorectal cancer depends on the magnitude of the association between findings in the proximal and distal colon and the false-negative rate of screening sigmoidoscopy for proximal neoplasia. To address this, we performed a systematic review and meta-analysis of screening colonoscopy studies. METHODS: Published studies through July 31, 2000, of asymptomatic patients undergoing screening colonoscopy were identified from the MEDLINE database. We generated pooled estimates of the odds ratio for the association between findings in the distal and proximal colon and the prevalence of isolated proximal adenomatous neoplasia. RESULTS: Using the sigmoid-descending colon junction to identify the beginning of the distal colon, the pooled odds ratio for the association between distal adenomatous polyps and any proximal neoplasia was 2.40 (95% confidence interval [CI], 1.42-4.05). Diminutive distal adenomatous polyps were also associated with proximal neoplasia (odds ratio, 2.36; 95% CI, 1.30-4.29). Distal hyperplastic polyps were not associated with proximal neoplasia (odds ratio, 1.44; 95% CI, 0.79-2.62). The prevalence of isolated advanced proximal neoplasia in the 3 studies was 2%, 3%, and 5%. Using the sigmoid-descending colon junction to identify the beginning of the distal colon yields a pooled estimate of isolated proximal neoplasia of 16.3% (95% CI, 13.6%-19.1%). CONCLUSIONS: Distal adenomatous polyps, including diminutive distal adenomatous polyps, are associated with an increased prevalence of synchronous proximal neoplasia. Two percent to 5% of patients undergoing screening colonoscopy may have isolated advanced proximal neoplasia. Even more patients may have isolated nonadvanced proximal neoplasia.     

The Sentinel Hyperplastic Polyp: A Marker for Synchronous Neoplasia in the Proximal Colon

We prospectively screened 129 asymptomatic subjects (mean age 64 yr) with flexible sigmoidoscopy. Colonoscopy was performed at a later date, regardless of the sigmoidoscopic result. Our intent was 1) to establish the prevalence of proximal neoplasms in patients with and without hyperplastic polyps within reach of the 60-cm sigmoidoscope and 2) to determine whether a distal (sentinel) hyperplastic polyp predicts the presence of synchronous neoplastic polyps higher up in the colon. Our results show that 15% of asymptomatic adult subjects without polyps on sigmoidoscopy have adenomas in proximal colonic segments that can be diagnosed only by colonoscopy. By comparison, proximal neoplasms were detected in 32% (p less than 0.05) and 37% (p less than 0.05) of patients when hyperplastic or adenomatous polyps, respectively, were present on the sigmoidoscopic examination. This finding suggests that a distal (sentinel) hyperplastic polyp by itself may be a marker for neoplastic polyps in proximal colonic segments. Also, the "index" adenoma and "sentinel" hyperplastic polyp may be equivalent for predicting the presence of proximal neoplasms. The observed detection rates for these polyps were both significantly higher than expected when compared to patients who did not have polyps in the distal colon or rectum. If these results can be confirmed by a larger prospective trial, then full colonoscopy for detection of proximal neoplasms may be indicated when either an index adenoma or sentinel hyperplastic polyp is detected by sigmoidoscopy.     

Hyperplastic Colonic Polyps as a Marker for Adenomatous Colonic Polyps

Hyperplastic colonic polyps are generally regarded as being of little or no clinical consequence. Recently, however, hyperplastic polyps have been found to share numerous functional similarities with colorectal carcinoma. To determine whether the presence of an isolated left-sided colonic hyperplastic (metaplastic) polyp could serve as a marker for more proximal synchronous adenomatous colonic polyps, we retrospectively analyzed all consecutive colonoscopic polypectomies performed over an 18-month period at two medical centers. It is the policy at both institutions to remove or biopsy all polyps, regardless of size. Indications for colonoscopy included known or previous colonic polyps or carcinoma, hemoccult positive stool, lower gastrointestinal bleeding, iron deficiency anemia, abnormal barium enema, inflammatory bowel disease, abdominal pain, and family history of colon cancer. The location of adenomatous polyps and hyperplastic polyps was recorded and compared. One hundred sixty-three of 845 consecutive patients (19.3%) had at least one colonic polyp. The prevalence of adenomatous polyps alone was 10.3%, hyperplastic polyps 9%, and both types 1.9%. The prevalence rate for an adenomatous polyp in patients without a hyperplastic polyp was 15%. In contrast, among patients with a hyperplastic polyp, 49% had a synchronous adenomatous polyp. Only 3.4% of patients had an adenomatous polyp proximal to the splenic flexure when no polyps were present in the left colon. Conversely, among the 29 patients in whom an isolated hyperplastic polyp was found in the left colon, there was a 32.5% prevalence of adenomatous polyps in the proximal colon (p less than 0.01). The results of this study suggest that left-sided hyperplastic colonic polyps (generally within the reach of a screening sigmoidoscopy) serve as a marker for neoplastic polyps.     

Screening for Colon Malignancy with Colonoscopy

Screening of asymptomatic individuals for colon malignancy has been advocated for the past 20 yr in the hopes of reducing colon cancer mortality. Although sigmoidoscopy is an important element of current screening recommendations, the sensitivity of this test in asymptomatic subjects has never been studied. The purpose of this study was to determine the prevalence and location of polyps and cancers in an asymptomatic population by performing full colonoscopy. We wished to assess the sensitivity of screening flexible sigmoidoscopy to 60 cm by determining how many patients with adenomas or cancer had "index" adenomatous polyps in the distal 60 cm. One hundred five healthy male outpatients, over 50 yr old, with negative examinations for occult blood in stools and no prior history of colon pathology, had full colonoscopy. Careful examination of the distal 60 cm was performed, followed by a full colon examination to the cecum. Forty-three patients (41%) had adenomatous polyps, and only 19 of these patients had an index adenomatous polyp in the distal 60 cm. Therefore, the sensitivity of sigmoidoscopy was 44%. The prevalence of adenomas increased with age. Patients were assigned to one of three groups based on the findings in the distal 60 cm. Group 1 (n = 65) had no polyps in the distal 60 cm, but 18 of these patients (28%) had adenomatous polyps in the proximal colon. Among 21 patients with only hyperplastic polyps in the distal 60 cm (group 2), six patients (29%) had proximal adenomas. In group 3, eight of 19 patients (42%) with adenomas in the distal 60 cm also had proximal adenomatous polyps. We conclude that adenomatous polyps are common in asymptomatic men who have negative tests for fecal occult blood. Sigmoidoscopy to 60 cm had a sensitivity of only 44% in this patient population, suggesting that this is an insensitive test for the detection of patients with adenomatous polyps.     

Hyperplastic polyps seen at sigmoidoscopy are markers for additional adenomas seen at colonoscopy

Asymptomatic individuals undergoing screening flexible sigmoidoscopy were prospectively studied. Polyps were found in 185 subjects. The endoscopist recorded an opinion on the polyps' histology based on endoscopic appearance. No polyps were removed at sigmoidoscopy. All subjects with rectosigmoid polyps then underwent colonoscopy and polypectomy. Of them, 99 subjects (54%) had at least one rectosigmoid adenoma, 69 (37%) had only hyperplastic polyps, and 17 (9%) had other findings. The endoscopists' opinion of the histopathology of polyps at sigmoidoscopy was correct for 61% of the lesions. Of subjects with adenomatous rectosigmoid polyps, 29% had additional adenomas at more proximal sites. Proximal adenomas were found in 28% of patients with hyperplastic rectosigmoid polyps. Patients with rectosigmoid hyperplastic polyps had the same risk for additional proximal adenomas as patients with rectosigmoid adenomatous polyps.     

Risk for colon adenomas in patients with rectosigmoid hyperplastic polyps

OBJECTIVE: To determine whether hyperplastic polyps found in the rectosigmoid area of the colon are associated with proximal adenomas, and to judge whether patients with distal hyperplastic polyps found during sigmoidoscopy might benefit from full colonoscopy. DESIGN: Data on patients having colonoscopy collected prospectively according to a set protocol. The size and location of all polyps were noted, and all polyps were biopsied. SETTING: Two university hospitals. PATIENTS: One thousand eight hundred and thirty-six consecutive patients referred for colonoscopy between 31 December 1987 and 31 August 1989. RESULTS: Of the 970 patients who met eligibility requirements, 274 (28.3%) had adenomas and 108 (11.1%) had hyperplastic polyps. The proportion of patients with distal hyperplastic polyps and proximal adenomas (31.9%) was similar to the proportion of those without distal hyperplastic polyps (23.0%) (crude odds ratio, 1.57; 95% CI, 0.77 to 3.06). After adjusting for age and sex, the results were unchanged (adjusted odds ratio, 1.53; CI, 0.82 to 2.88). Patients with distal adenomas, on the other hand, were three times more likely to have proximal adenomas than those without distal adenomas (adjusted odds ratio, 3.42; CI, 1.99 to 5.88). CONCLUSIONS: Distal hyperplastic polyps are not strong predictors of risk for proximal adenomas. Based on the magnitude of the risk difference, we do not believe that finding a hyperplastic polyp during sigmoidoscopy justifies doing a full colonoscopy to search for proximal adenomas. Because rectosigmoid adenomas are associated with proximal adenomas, however, small polyps seen during sigmoidoscopy should be biopsied to determine their type. Colonoscopy should be reserved for patients who are proved to have adenomas.     

Are tiny polyps important when found on sigmoidoscopy in asymptomatic people?

To determine the occurrence of synchronous large bowel polyps located proximal to the sigmoid, in persons undergoing screening flexible sigmoidoscopy, we examined those who had diminutive polyps (less than or equal to 0.5 cm) as the only finding in the distal colon by further colonoscopy. One hundred one asymptomatic persons (mean age 61 +/- 13 years) had 143 diminutive polyps; a single polyp was found in 76%, and 64% of all polyps were located in the rectum. Thirty (21%) were hyperplastic and 86 (60%) were neoplastic, including 14 with moderate and one with severe dysplasia. The others were inflammatory (five) or unclassified (hot biopsy changes or normal mucosa, 14 polyps), and eight were lost before processing. Colonoscopy revealed that 16 (16%) of the 101 patients had 21 additional polyps proximally, mostly less than 1 cm in diameter. These included one hyperplastic and 18 neoplastic polyps, and two specimens showed hot biopsy changes. Age, histological type, number or location of the index diminutive polyps, were not associated with proximal lesions. We question whether immediate colonoscopy is justified in asymptomatic patients with only diminutive polyps at flexible sigmoidoscopy.     

Multiple Large Hyperplastic Polyps of the Colon Coincident with Adenocarcinoma

Diminutive hyperplastic polyps are the most common non-neoplastic lesions of the colon. Typically, they are small (<0.5 cm) sessile lesions, lack cellular atypia, and are found predominantly in the rectosigmoid region of the colon. Multiple large hyperplastic polyps (>1 cm) are rare. Although the relationship between diminutive hyperplastic polyps and adenomatous polyps or carcinoma is controversial, even less data are available on the significance of large hyperplastic polyps. We report the case of a 56-yr-old man who was seen because of fatigue, anemia, and Hemoccult-positive stool. On air contrast barium enema study and colonoscopy, multiple polyps that were similar in appearance were found distributed symmetrically throughout the colon. However, histologic examination revealed 16 hyperplastic polyps 1–2 cm in size, multiple diminutive hyperplastic polyps, one adenomatous polyp, and one adenomatous polyp containing well-differentiated adenocarcinoma. Because multiple large hyperplastic polyps are rare, we suspect this entity may be distinct from diminutive hyperplastic polyps. In our patient, large hyperplastic polyps were distributed symmetrically throughout the colon and were associated with a synchronous carcinoma. Because large hyperplastic polyps may be coincident with adenomatous polyps and carcinoma of the colon, we recommend that patients found to have large hyperplastic polyps undergo removal of all polyps for histologic study.     

Diminutive colonic polyps: An indication for colonoscopy

A prospective study investigated the significance of solitary diminutive colonic polyps discovered during screening flexible sigmoidoscopy. Eighty-two patients with a solitary diminutive polyp (5 mm) underwent colonoscopy after cold biopsy of the index polyp. Of the patients with adenomatous index polyps, 42.5 percent had proximal neoplastic polyps. Of the patients with hyperplastic index polyps, proximal neoplastic polyps were found in 38.9 percent. These data suggest that diminutive polyps identified during flexible sigmoidoscopy, whether adenomatous or hyperplastic, place the patient in the intermediate risk group for colorectal neoplasia. We recommend that any patient with polyps seen during screening sigmoidoscopy, regardless of histopathology, should undergo colonoscopy.Read at the meeting of The American Society of Colon and Rectal Surgeons, St. Louis, Missouri, April 29 to May 4, 1990.     

Barium enema versus colonoscopy for patients with polyps found during flexible sigmoidoscopy

This prospective study compares the accuracy of barium enema examination performed by experienced radiologists to colonoscopy performed by experienced gastroenterologists blinded to the radiographic findings to detect proximal, synchronous lesions in patients with polyps detected during fiberoptic sigmoidoscopy. Three thousand six patients were examined, of whom 147 (5%) had polyps larger than 0.5 cm in diameter. Of 114 patients who completed the protocol, 46 patients (40%) had synchronous, proximal colonic lesions. There were no radiographic false positives, but the single-contrast barium enema missed polyps in 13 while detecting polyps in 2 patients (sensitivity = 13%). The double-contrast barium enema missed proximal polyps in 23 patients while detecting them in 8 (sensitivity = 26%). We conclude that patients with neoplastic polyps found during fiberoptic sigmoidoscopy should have colonoscopy without barium enema. If the entire colon cannot be examined at colonoscopy, we advise double-contrast barium enema.     

The association of multiple colonic adenomatous polyps with cancer of the colon

We reviewed our colonoscopy data for the past 10 yr for patients with five or more polyps to determine the association of multiple adenomatous polyps and colon cancer. During that period, 3,834 patients underwent colonoscopy. Fifty-two patients with five or more polyps at the initial colonoscopy were found. In 25 patients (group I) there were at least five synchronous adenomas, and in 27 patients (group II) a combination of adenomas and hyperplastic polyps totaling five or more. The number of polyps ranged from five to 30 (median, six). There was no significant difference in the location of polyps between groups I and II. Eight of 52 patients (15%) were found to have colon cancer at the initial colonoscopy. In group I, there were six cancers (24%), five of which were in the cecum. Two of 27 patients (7%) in group II had cancer, one of which was located in the cecum. Patients with five or more adenomas at the index colonoscopy are at high risk of having colon cancer that is particularly prone to arise from the right side of the colon.     

Predictive value of morphologic characteristics in rectosigmoid adenomatous polyps for the probability of synchronous polyps or cancer in the proximal colon.

BACKGROUND/AIMS: Sigmoidoscopy is performed more frequently than colonoscopy, especially for screening purposes and searching for colorectal neoplasm. The necessity of colonoscopy in patients with an adenoma ofor=11 mm) polyps. These groups were compared regarding the presence of proximal adenoma and advanced proximal neoplasia (>10 mm adenoma and/or villous histology and/or high grade dysplasia or cancer). Polyps found in the rectum and sigmoid colon were considered as distal polyps and polyps other than these were considered as proximal polyps. RESULTS: In this study, of 1124 consecutive patients who underwent colonoscopy between April 1997 and January 2002, 184 (16%) had 258 adenomatous polyps in the rectosigmoid area. The polyps were diminutive (or=11 mm) in 33 patients. Forty-one of the patients (39%) with diminutive polyps, 20 of the patients (43%) with small polyps and 19 of the patients (57%) with large polyps had neoplasm in the proximal bowel. In these patients, advanced proximal neoplasm was found in 8 (8%), in 6 (13%) and in 11 (33%), respectively. There was no difference regarding the presence of neoplasm in the proximal colon between these groups. The rate of advanced proximal neoplasm was found to be significantly higher in the group with large polyps in the rectosigmoid area than in the groups with small and diminutive polyps (p<0.05). In 104 patients (57%) with polyp(s) in rectum and sigmoid colon, no associated polyp or cancer was encountered in the proximal colon. CONCLUSION: Colonoscopy is indicated when adenomatous polyp, regardless of size, is found on rectosigmoidoscopy performed because of symptoms.     

Spatial clustering of multiple hyperplastic,adenomatous, and malignant colonic polyps in individual patients

Analysis of relative polyp locations in 426 consecutive patients with multiple colonic polyps found on colonoscopy showed novel findings. First, synchronous and metachronous neoplastic polyps showed spatial clustering in individual patients. For example, patients with their largest neoplasm in the cecum or proximal ascending colon, had 34.3 percent±4.6 percent (standard error) of their other colonic neoplasms in the same location. Second, hyperplastic polyps showed spatial clustering in individuals that was statistically significantly greater than expected from the increased hyperplastic polyp concentration in the rectum and sigmoid. Third, hyperplastic polyps showed spatial clustering with neoplastic polyps; this clustering was similar in magnitude to clustering for exclusively hyperplastic or neoplastic polyps. In contrast, lipomas were not spatially clustered with hyperplastic and neoplastic polyps. The magnitude of clustering between hyperplas and neoplasia showed a closer association between these histologic types than previously appreciated. Because of clustering, regions with prior polyps appear to merit closer surveillance. These findings suggest clinical study, using a randomized controlled clinical trial, of whether a patient who had only rectal and sigmoid adenomas on initial and follow-up colonoscopy should have surveillance with flexible sigmoidoscopy alternating annually with colonoscopy. A patient with a prior cecal adenoma should have surveillance only with a complete colonoscopy or adequate cecal views on barium enema.     

Significance of distal polyps detected with flexible sigmoidoscopy in asymptomatic patients.

BACKGROUND--Colorectal cancer is a frequent cause of death from cancer. To reduce the mortality associated with this disease, regular flexible sigmoidoscopy is recommended. However, the significance of diminutive polyps (adenomatous or hyperplastic) detected during flexible sigmoidoscopy remains controversial, as does the appropriate endoscope length (35 vs 60 cm) for colorectal cancer screening. METHODS--One hundred one consecutive patients with no history of colonic disease, gastrointestinal tract symptoms, or positive results of fecal occult blood testing underwent flexible sigmoidoscopy as part of a colorectal cancer screening program. All patients with distal polyps detected during flexible sigmoidoscopy underwent colonoscopy. RESULTS--More than 25% of these asymptomatic, predominantly male subjects had colonic neoplasms or polyps detected. Fifty percent more lesions could be detected with a 60-cm sigmoidoscope than with a 35-cm sigmoidoscope, and detection of any distal polyp, whether adenomatous or hyperplastic, was associated with at least one proximal colon adenoma in 20% of patients. "Extended flexible sigmoidoscopy" for colorectal cancer screening was well tolerated by patients, as evidenced by insertion to the hepatic flexure in 25% of patients, and provided significantly more information than could be obtained with a 35-cm sigmoidoscope. CONCLUSIONS--Colorectal cancer screening should be performed with a 60-cm flexible sigmoidoscope, and distal colonic polyps or neoplasms will be detected in 25% of asymptomatic patients.     

The role of colonoscopy and flexible sigmoidoscopy in screening for Colorectal Carcinoma

Six hundred thirty-two patients were referred to the Colorectal Clinic from February 1983 to February 1986 for screening with the Pentax 65 cm flexible sigmoidoscope. Forty-nine of these patients (8 percent) had adenomatous polyps. There were 27 males and 22 females. The mean distance examined by the 65 cm flexible sigmoidoscope was 55 cm. Five patients were excluded from analysis, leaving 44 patients who underwent colonoscopy to the cecum. At the time of colonoscopy, 15 of the 44 patients (34 percent) had one or more adenomatous polyps beyond reach of the 65 cm flexible sigmoidoscope. The remaining 29 patients who underwent colonoscopy had no polyps beyond reach of the 65 cm flexible sigmoidoscope. Thirty adenomatous polyps, one invasive carcinoma of the ascending colon, and one hyperplastic polyp were found in these 15 patients. In summary, 34 percent of patients found to have adenomatous polyps within reach of the 65 cm flexible sigmoidoscope harbored one or more adenomatous polyps in the proximal colon at the time of colonoscopy. A positive 65 cm flexible sigmoidoscope examination requires colonoscopy to identify and remove proximal premalignant lesions, thereby aborting the polyp-cancer sequence.     

Synchronous Proximal Polyps and Cancer in Patients with Polyps Detected at Sigmoidoscopy: Results of a Single, Rural-Based Sigmoidoscopy Clinic

The prevalence of polyps and cancer in the proximal colon among patients who have polyps detected on sigmoidoscopy was determined in a large rural referral hospital in north central Pennsylvania. Eleven thousand one hundred sixty patients underwent sigmoidoscopy between 1991 and 1997. Polyps were detected in 709 patients. Five hundred twenty-three patients who had a polyp at sigmoidoscopy and full colonoscopy completed within one year were included in this study. 120 patients (23%) had a proximal polyp detected at colonoscopy. The prevalence of proximal polyps and histologically advanced polyps was related to the size, number, and histology of the distal index polyp found at sigmoidoscopy. However, the absolute difference in prevalence of proximal polyps stratified by dings at sigmoidoscopy was small. A total of 5 adenocarcinomas were detected in the proximal colon. All proximal cancers detected at colonoscopy occurred in patients with a distal polyp less than 10 mm. Our data emphasize the importance of colonoscopy in all patients with a polyp detected at sigmoidoscopy independent of its size and histology.     

Is the distal hyperplastic polyp a marker for proximal neoplasia?

CONTEXT: The current literature is unclear about the association between distal hyperplastic polyps and synchronous neoplasia (adenomatous polyps and cancer) in the proximal colon. OBJECTIVE: To estimate the prevalence of proximal neoplasia associated with distal hyperplastic polyps. DATA SOURCES: Database searches (medline and embase from 1966 to 2001) and manual search of the bibliographies of included and excluded studies, case reports, editorials, review articles, and textbooks of Gastroenterology. STUDY SELECTION: Studies describing the prevalence of proximal neoplasia in persons with distal hyperplastic polyps. DATA EXTRACTION: Demographics, clinical variables, study design, and prevalence of proximal neoplasia associated with various distal colorectal findings. DATA SYNTHESIS: Of 18 included studies, 12 involved asymptomatic individuals in which the pooled absolute risk of any proximal neoplasia associated with distal hyperplastic polyps was 25% (95% confidence interval [95% CI], 21% to 29%). In 4 studies where colonoscopy was performed irrespective of distal findings, the absolute risk was 21% (95% CI, 14% to 28%). The relative risk of finding any proximal neoplasia in persons with distal hyperplastic polyps was 1.3 (95% CI, 0.9 to 1.8) compared to those with no distal polyps. Among 6 studies of patients with symptoms or risk factors for neoplasia, the absolute risk of proximal neoplasia was 35% (95% CI, 32% to 39%) in persons with distal hyperplastic polyps. In 2 studies of screening colonoscopy, advanced proximal neoplasia (cancer, or a polyp with villous histology or severe dysplasia, or a tubular adenoma >/=1 cm) was present in 4% to 5% of persons with distal hyperplastic polyps, which was 1.5 to 2.6 times greater than in those with no distal polyps. CONCLUSIONS: In asymptomatic persons, a distal hyperplastic polyp is associated with a 21% to 25% risk for any proximal neoplasia and a 4% to 5% risk of advanced proximal neoplasia, and may justify examination of the proximal colon. Further study is needed to determine the risk of advanced proximal neoplasia associated with size and number of distal hyperplastic polyps.     

Small colorectal polyps

The histology of small (≤0.5 cm.) colorectal polyps removed during total colonoscopy in 303 patients was reviewed to determine their clinical significance. There were 178 male patients and 125 females, with a median age of 64 years (range, 26 to 97 years). A total of 766 polyps were treated, 60 percent being adenomatous and 22 percent hyperplastic. Hyperplastic polyps were more common in the rectum (71 percent) while adenomas were more common in the colon (63 percent). Hyperplastic polyps in the colon were associated with adenomas in 75 percent of cases and hyperplastic rectal polyps were associated with proximal adenomas in 63 percent. There were six mixed hyperplastic/adenomatous polyps. Of the 458 adenomas, 449 were tubular, eight were tubulovillous, and one was villous. Moderate dysplasia was noted in 23 (5 percent) and severe dysplasia in four (0.9 percent). There were associated large adenomas in 84 patients. Small colonic polyps are usually adenomatous and should be destroyed. Biopsy may be important if no other neoplasm has been identified. Small rectal polyps are usually hyperplastic but may be associated with proximal adenomas. Because of the uncertain significance of hyperplastic polyps they should also be treated, and are a relative indication for total colonoscopy. Read at the meeting of the American Society of Colon and Rectal Surgeons, Washington, D.C., April 5 to 10, 1987.