INTRODUCTION — The appropriate evaluation of a patient presenting with minimal bright red blood per rectum (BRBPR) must be guided by the risk of underlying serious pathology, and there are few available guidelines. This topic will review the evaluation of patients with BRBPR based on age and other risk factors for more serious etiologies of minimal BRBPR. The approach to patients who pass larger amounts of blood or blood intermixed with stool is discussed elsewhere. (See "Approach to acute lower gastrointestinal bleeding in adults".)
DEFINITION — Rectal passage of minimal bright red blood most commonly occurs in a chronic intermittent pattern and has also been referred to as "intermittent scant hematochezia" [1]. The term minimal bright red blood per rectum (BRBPR) is used in this topic to indicate small amounts of red blood on toilet paper after wiping or a few drops of blood in the toilet bowl after defecation. Small amounts of blood on the surface of the stool is also considered minimal BRBPR, but red blood intermixed with stool is not.
A history of minimal BRBPR suggests a lesion near the anal canal but must be differentiated from a history of melena (which implies upper gastrointestinal or slow proximal colonic bleeding) or maroon stool with intermixed bright red blood (which implies a proximal colonic or small intestinal source). However, patients' and clinicians' perceptions of stool color vary widely, even when assisted by a standardized color chart [2,3].
Benign etiologies of BRBPR are common and appear to account for 90 percent or more of all episodes of minimal BRBPR. The true proportion of benign etiologies may be even higher, since many young people with minimal BRBPR never present for care. However, scant rectal bleeding is also a common presenting symptom of serious diagnoses, such as colorectal cancer [4-6].
EPIDEMIOLOGY — By self-report, minimal bright red blood per rectum (BRBPR) occurs in approximately 15 percent of adults, and may be even more common in younger adults who may be less likely to seek medical consultation for this problem [7-9].
●A study of 202 community-dwelling adults ages 30 and older in Australia found that 14 percent reported seeing blood on the toilet paper and 2 percent reported seeing blood in the toilet bowl within the prior six months [7]. However, 43 percent reported that they seldom or never looked at either their stool or the toilet paper, suggesting that the true frequencies are higher.
●A community-based study of 1643 adults ages 20 to 64 found that 13 percent reported ever having blood on wiping [10]. The prevalence of any rectal bleeding was significantly higher in younger people. Only 14 percent of those with any rectal bleeding had seen a physician for bowel problems in the prior year.
ETIOLOGIES — The etiology of minimal bright red blood per rectum (BRBPR) is highly variable and depends upon the population studied. The specific cause of bleeding is often difficult to determine because multiple potentially culpable lesions may be found at endoscopy in an individual patient. Only when a lesion is witnessed to be actively bleeding can it be definitively considered the cause of bleeding.
Common causes and presentations of minimal BRBPR include:
●Hemorrhoids – Hemorrhoids are present in anywhere from 27 to 95 percent of cases [11-13]. Painless bleeding is usually associated with a bowel movement. Bright red blood typically coats the stool at the end of defecation. Blood may also drip into the toilet or stain toilet paper. (See "Hemorrhoids: Clinical manifestations and diagnosis".)
●Anal fissures – Anal fissures are often diagnosed from the clinical history. Affected patients describe a tearing pain with the passage of bowel movements. The passage of stool may be accompanied by bright rectal bleeding, usually limited to a small amount on the toilet paper or on the surface of stool. Some patients also complain of an itch or perianal skin irritation. (See "Anal fissure: Clinical manifestations, diagnosis, prevention".)
●Polyps – Polyps, including adenomatous polyps, are generally asymptomatic and are most often detected by colon cancer screening tests. Small adenomas do not typically bleed, but occult bleeding and minimal BRBPR can occur; minimal BRBPR is more likely with distal polyps. Colorectal neoplasms (mostly adenomas) have been found in 16 percent of patients who were concurrently diagnosed with an anorectal source of bleeding [4]. (See "Overview of colon polyps".)
●Proctitis – Patients with proctitis or proctosigmoiditis often present insidiously with intermittent rectal bleeding, passage of mucus, and mild diarrhea associated with fewer than four small loose stools per day. (See "Medical management of low-risk adult patients with mild to moderate ulcerative colitis".)
●Rectal ulcers – Rectal ulcers can present with bleeding, passage of mucus, straining during defecation, and a sense of incomplete evacuation. (See "Solitary rectal ulcer syndrome".)
●Cancer – The majority of patients with symptomatic colorectal cancer have hematochezia, abdominal pain, and/or a change in bowel habits. Patients with minimal BRBPR from colorectal cancer are likely to have left-sided lesions. (See "Clinical presentation, diagnosis, and staging of colorectal cancer".)
Diverticulosis is a common finding on endoscopy in older adults but is generally an incidental finding in the workup of chronic or recurrent minimal BRBPR, since diverticular bleeding is usually more acute and of greater volume [14].
CLINICAL ASSESSMENT — Relatively few studies have addressed the appropriate evaluation of patients with minimal bright red blood per rectum (BRBPR). The goal of the clinical assessment for patients who present with any BRBPR is to identify patients who are at risk for a serious cause of bleeding and who therefore require additional testing.
Careful clinical assessment, however, can be unreliable both for determining the site of bleeding and for ruling out significant pathology [4,11,12,15-17]. As an example, the presence of hemorrhoids does not exclude a more proximal culprit lesion, and could even mask the concomitant bleeding of an early neoplastic lesion [15]. A study of 145 patients ages 40 and older who had rectal bleeding of less than six month’s duration found that 11 of the 63 patients for whom the primary care provider had predicted an anal source of pathology had a colonic or rectal source [11].
The difficulties in clinical assessment were further illustrated in a study of primary care patients that identified 297 people who reported visible rectal bleeding on a review of systems questionnaire [4]. Of these patients, 201 underwent evaluation with sigmoidoscopy and barium enema; 24 percent were found to have serious pathology, including 13 percent with polyps, 6.5 percent with colon cancer, and 4 percent with inflammatory bowel disease (IBD). Among the 58 patients younger than 50 years, there were no cases of cancer, but 12 percent had polyps or IBD. Despite evaluating a number of clinical variables and anoscopic findings, it was not possible to identify a group of 15 or more patients whose risk of serious conditions was lower than 7 percent. Only older age, shorter duration of bleeding, and blood mixed with stool were associated with a serious cause of rectal bleeding.
Many patients presenting with minimal BRBPR will already have indications for colon cancer screening but will not have been investigated [18-22]. Further evaluation with colonoscopy can be recommended for such patients for screening purposes alone. For other patients with BRBPR, the history and physical examination, in combination with risk assessment for serious pathology based predominantly on age, can be used to guide the need for additional testing.
History — The history should be directed at confirming the diagnosis of scant rectal bleeding and at identifying potentially worrisome symptoms and historical risk factors.
Historical features that suggest an anorectal source include spots of blood seen on the toilet paper or blood dripping into the toilet after defecation. This pattern has been referred to as "outlet-type bleeding" [23].
Anal pain during or after defecation is usually due to anal fissures, but can also be present with rectal carcinoma (as well as infectious causes such as herpes) and so is not helpful in distinguishing benign from more serious etiologies. A history of recent rectal trauma from medical procedures like transrectal prostate biopsy or from anal receptive intercourse may suggest an obvious source of blood loss [24].
Systemic symptoms such as night sweats, fever, or weight loss suggest malignancy or chronic infection or inflammation; diarrhea preceding or accompanying passage of blood suggests colitis; tenesmus can be present with proctitis; and nonspecific abdominal pain indicates a process that may include, but is not limited to, the rectum. Lastly, change in the frequency or caliber of stools is suggestive of colonic malignancy [25]. The presence of any of these symptoms suggests that further evaluation should be performed.
Past medical history should consider previous gastrointestinal blood loss and investigations, as well as previously resected colon cancer or polyps. A history of inflammatory bowel disease is important because these patients are at increased risk of colonic neoplasm. A history of pelvic radiation therapy is noteworthy because radiation proctitis has been known to occur two to three years after therapy [26]. (See "Clinical manifestations, diagnosis, and prognosis of ulcerative colitis in adults", section on 'Dysplasia or colorectal cancer' and "Clinical manifestations, diagnosis, and prognosis of Crohn disease in adults", section on 'Cancer risk' and "Radiation proctitis: Clinical manifestations, diagnosis, and management".)
Age is a major risk factor for colorectal cancer. It is an infrequent diagnosis before the age of 40; the incidence begins to increase significantly between the ages of 40 and 50, and age-specific incidence rates increase in each succeeding decade thereafter (figure 1). (See "Colorectal cancer: Epidemiology, risk factors, and protective factors".)
A family history should be taken in detail to further stratify colorectal cancer risk and should include not only a history of confirmed colorectal cancers, but also a history of family members known to have colonic polyps or other malignancies that could be associated with familial colon cancer syndromes. (See "Screening for colorectal cancer in patients with a family history of colorectal cancer or advanced polyp".)
Physical examination — The physical examination should be directed at identifying possible or definite sources of bleeding and at finding worrisome distal lesions that may be detectable on examination. A detailed physical examination must include external inspection of the anus and a digital rectal examination. Having the patient bear down during the examination may induce prolapse of a hemorrhoid or bleeding of a surface lesion. (See "Approach to adult patients with anorectal complaints", section on 'Physical examination'.)
When available, office-based anoscopy or proctoscopy should be carried out in patients who present with acute minimal BRBPR, because these are simple maneuvers that do not require bowel preparation and because the yield of these tests is highest when performed during a bleeding episode. In fact, anoscopy has a higher sensitivity for the detection of hemorrhoids than flexible video endoscopy [13].
Laboratory testing — Laboratory testing contributes little information to the evaluation of very low risk patients, but may prompt more extensive investigation in patients at intermediate risk for colonic neoplasia. A complete blood count (CBC) and ferritin are reasonable preliminary tests in patients over age 40, or those with other risk factors for colonic neoplasia, such as family history.
Diagnostic tests — Colonoscopy or sigmoidoscopy are generally recommended when additional evaluation beyond the history and physical examination is warranted.
Barium enema has no role in the initial evaluation of minimal BRBPR as it is insensitive to small neoplasms, cannot identify acutely bleeding lesions, and does not evaluate the distal colon and rectum well.
Computed tomographic colonography (CTC) is not indicated in the initial investigation but may be useful in individual cases where colonoscopy is incomplete or contraindicated.
Sigmoidoscopy versus colonoscopy — Flexible sigmoidoscopy investigates the distal 60 cm of the colon (see "Tests for screening for colorectal cancer"). It has the advantages over colonoscopy that it can be done without sedation (although sedation is sometimes used for the procedure) and is widely available. The main disadvantage of sigmoidoscopy is the potential need for a colonoscopy if a source of bleeding is not found or if a distal adenomatous polyp is found, thus exposing the patient to two endoscopic procedures.
Colonoscopy is the definitive tool for evaluating the entire colon for neoplastic lesions and is also a sensitive tool for the detection of all other bleeding lesions in the lower gastrointestinal tract (see "Tests for screening for colorectal cancer"). Colonoscopy requires full bowel preparation and a facility where the test is available. It is often performed under conscious sedation.
Proponents of colonoscopy to evaluate scant rectal bleeding have cited concerns that patients may have proximal lesions that are out of the reach of the sigmoidoscope. Most studies that reported a high incidence of proximal neoplasms in patients with scant BRBPR have lacked detailed descriptions of the bleeding pattern and were either uncontrolled or reported retrospective data [2,4,11,17,27,28].
Other studies have found that sigmoidoscopy is a sufficient initial test for many patients [23,25,29]:
●In one of the largest prospective studies that looked specifically at patients with scant BRBPR, structured interviews of 4265 patients referred for colonoscopy found that 468 patients had scant BRBPR, 299 had occult rectal bleeding, and 57 reported dark red rectal bleeding [29]. Patients were excluded if they had IBD or a personal or family history of colorectal cancer. Colonic neoplasms were found in 18 percent of patients with minimal BRBPR and in 7.5 percent of controls. However, the majority of these lesions were within reach of a sigmoidoscope and patients with minimal BRBPR were at no increased risk for proximal lesions compared with controls. Among 89 patients who were age 40 years or younger, there were three cancers and five adenomas; no cancers and only two adenomas were found proximal to the reach of a sigmoidoscope. By comparison, the risk of proximal neoplasms was significantly increased in patients with either occult bleeding (odds ratio [OR] 3.1. 95% CI 1.8-5.5) or maroon-colored blood in their stool (OR 4.8, 95% CI 2.0-11.5).
●Similarly, a smaller study that included 115 patients with "outlet bleeding" (defined as bright red blood seen during or after defecation, on the toilet paper or in the toilet bowl) and no other symptoms or risk factors for colon cancer found that only one adenomatous polyp and no cancers would have been missed by sigmoidoscopy [23].
●In a study of 223 adult patients younger than 50 years referred for colonoscopy for nonurgent rectal bleeding (some of which was more than minimal BRBPR), four cancers and 22 adenomas were detected [30]. The only lesions found proximal to the reach of a sigmoidoscope were six adenomas smaller than 8 mm in size.
In addition to concerns about missing proximal lesions, one study found that sigmoidoscopy as an initial investigation of patients with bright red hematochezia was not cost-effective because it so often had to be followed with colonoscopy [2]. However, that study excluded patients with histories suggestive of outlet bleeding. A study of outcomes after clinicians selected what they believed to be the "best" test for patients presenting to hospitals with hematochezia found that colonoscopy identified a diagnosis in 90 percent of patients, but sigmoidoscopy yielded a conclusive diagnosis in fewer than 10 percent; although 69 percent of sigmoidoscopies were abnormal, further tests were required in 90 percent of the hospitalized patients who underwent sigmoidoscopy as their first investigation [31].
Sigmoidoscopy is recommended as a first investigation for bright red hematochezia by some authors for patients up to age 50 [25], and is an acceptable alternative for colorectal cancer screening. (See "Screening for colorectal cancer: Strategies in patients at average risk".)
The American Society for Gastrointestinal Endoscopy suggests that for healthy individuals less than 40 years with minimal BRBPR, a digital rectal exam and sigmoidoscopy may be sufficient evaluation [1]. However, the guidelines recommend colonoscopy for all patients for whom an anorectal source of bleeding is not found at initial evaluation, for all patients 50 years or older, or for patients who have other symptoms such as iron deficiency anemia, risk factors for colon cancer, or alarm symptoms. These are the only consensus recommendations, to our knowledge, that specifically address scant rectal bleeding, but other recommendations on lower gastrointestinal bleeding may be applied to this setting. As an example, The European Panel on Appropriateness of Gastrointestinal Endoscopy suggests that colonoscopy is inappropriate in patients under 50 years of age with an identified source of bleeding, but it is generally appropriate in patients with no identified source of bleeding [32].
Since most authors agree that colonoscopy is the test of first choice in patients age 50 years and older, and given that recommendations for colon cancer screening in patients with "average risk" also begin at age 45 years, we believe that patients ≥50 years of age with scant rectal bleeding should undergo colonoscopy regardless of the presence or absence of identified anorectal pathology. In patients age 45 and above, colonoscopy may be reasonable when no anorectal source of bleeding has been found. This age group is at lower risk of colorectal cancer but does have a significant incidence of precancerous adenomatous polyps, and recommendations by the USPSTF and American Cancer Society suggest initiating screening of average-risk patients at age 45 [21,22]. One study of screening colonoscopy in 906 patients aged 40 to 49 years, for example, found no cancers, but found adenomatous polyps in about 13 percent of those examined; 3.5 percent had advanced lesions [33]. Approaches to screening for colorectal cancer are reviewed in detail elsewhere. (See "Screening for colorectal cancer: Strategies in patients at average risk".)
We consider flexible sigmoidoscopy to be an alternative first line of investigation in patients with unexplained bleeding up to the age of 50 years; the choice of test in this group may be influenced by cost and availability of the procedure.
APPROACH TO THE PATIENT — In the absence of high quality data, our approach is based upon indirect evidence from studies on patients with rectal bleeding, though not strictly minimal BRBPR, as well as expert opinion.
Red flags — Patients with minimal BRBPR with the additional following features or risk factors should undergo additional testing regardless of age:
●Patients with melena, dark red blood per rectum, or postural vital sign abnormalities should be evaluated for upper gastrointestinal tract pathology first. Even if a lower gastrointestinal tract source is considered possible, these patients are more likely to have proximal rather than distal colonic lesions and should undergo colonoscopy after upper gastrointestinal tract investigations.
●Patients with symptoms suggestive of malignancy such as constitutional symptoms, anemia, or change in frequency, caliber, or consistency of stools, should undergo colonoscopy.
●Patients with fecal occult blood positive stools are known to derive mortality benefit from investigation with colonoscopy [34-36]. Hemorrhoids do not affect the prevalence of positive occult blood tests [13]. (See "Evaluation of occult gastrointestinal bleeding" and "Tests for screening for colorectal cancer".)
●Patients with family histories suggestive of familial polyposis or hereditary nonpolyposis colon cancer syndromes who present with bleeding per rectum should be investigated with colonoscopy. (See "Screening for colorectal cancer in patients with a family history of colorectal cancer or advanced polyp".)
Age 50 or older — Most authors agree that colonoscopy is the test of first choice in patients age 50 years and older. Colon cancer screening is recommended for patients with "average risk" beginning at age 50 years. For these reasons, patients age 50 years and older with scant rectal bleeding should undergo colonoscopy regardless of the presence or absence of identified anorectal pathology on clinical examination.
Patients who have had a technically adequate normal colonoscopy within the previous two years have had insufficient time to develop a clinically important neoplasm, and more limited investigations such as sigmoidoscopy can be considered to confirm an outlet source without reinvestigating the entire colon. Care should be taken to ensure that the prior colonoscopy reached the cecum with good visualization of all colonic anatomy. Ideally, in order to consider the prior study technically adequate, it should be documented that the terminal ileum was reached and the bowel preparation was satisfactory.
Ages 40 to 49 — Patients with minimal BRBPR who are aged 40 to 49 and who do not appear to be at increased risk for colorectal cancer based on their presentation and history should undergo at least a sigmoidoscopy. Although there is a lack of high-quality evidence to support this approach, we would generally suggest a colonoscopy for most patients, particularly those ≥45 years of age, if no cause of bleeding was identified on sigmoidoscopy. (See 'Sigmoidoscopy versus colonoscopy' above.)
Age less than 40 — Patients with minimal BRBPR younger than 40 years are at low risk of colorectal cancer (figure 1). Thus, further evaluation is not necessary, if the presentation and history do not suggest an increased risk of cancer and a potential source of bleeding (such as hemorrhoids or an anal fissure) is identified on physical examination or anoscopy/proctoscopy. If no potential source of bleeding is identified, such patients should undergo sigmoidoscopy or perhaps colonoscopy; there are no high-quality data to inform the approach, and further testing decisions should be made based upon shared clinical decision-making. (See 'Sigmoidoscopy versus colonoscopy' above.)
Persistent bleeding — Persistent passage of minimal BRBPR may require management somewhat different from that described above. However, some studies have suggested that a longer duration of bleeding is associated with a lower risk of cancer. In one study of patients with rectal bleeding, for example, the risk of cancer was higher among patients older than age 50 when bleeding had been present for less than two months (18 versus 6 percent) [4].
However, in the absence of definitive data or expert consensus, and given the possibility that a patient who has hemorrhoids or an anal fissure could also develop more serious pathology, we suggest a cautious strategy:
●Patients who continue to pass blood after the identification and definitive management of an anorectal lesion should generally undergo colonoscopy at least once during their workup to ensure that an additional or concurrent proximal lesion has not been missed.
●Patients with recurrent minimal BRBPR should be periodically reassessed for any change in symptoms or any development of new "red flags" that would require additional investigation. (See 'Red flags' above.)
●Patients over the age of 50 with persistent bleeding from a documented outlet source should be reassessed at least yearly for change in symptoms, or the development of anemia or iron deficiency that could prompt need for repeat colonoscopy. In the absence of anemia or a change in symptoms, average-risk patients (who would otherwise be candidates for colonoscopy screening every 10 years by guidelines) could be considered for closer surveillance with colonoscopies as frequently as every five years, depending on patient preference and the quality of previous colonoscopic evaluations.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topics (see "Patient education: Colonoscopy (The Basics)" and "Patient education: Bloody stools (The Basics)")
●Beyond the Basics topics (see "Patient education: Colonoscopy (Beyond the Basics)" and "Patient education: Flexible sigmoidoscopy (Beyond the Basics)" and "Patient education: Blood in the stool (rectal bleeding) in adults (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Definition and diagnostic implications – The term minimal bright red blood per rectum (BRBPR) is used to indicate small amounts of red blood on toilet paper after wiping or a few drops of blood in the toilet bowl after defecation. Small amounts of blood on the surface of the stool is also considered minimal BRBPR, but red blood intermixed with stool is not. Minimal BRBPR suggests a lesion near the anal canal but must be differentiated from a history of melena (which implies upper gastrointestinal or slow proximal colonic bleeding) or maroon stool with intermixed bright red blood. (See 'Definition' above.)
●Etiologies – Common causes of BRBPR include hemorrhoids, anal fissures, polyps, proctitis, rectal ulcers, and colorectal cancer. Diverticulosis is generally an incidental finding, since diverticular bleeding is usually of greater volume. (See 'Etiologies' above.)
●Clinical assessment – The goal of the clinical assessment for patients who present with BRBPR is to identify those who are at risk for a serious cause of bleeding and who therefore require additional testing; discriminating such patients can be challenging. The history should be directed to the type of bleeding pattern, systemic symptoms, age, family history, and known bowel conditions. The physical examination should include a digital rectal examination and, when possible, office-based anoscopy or proctoscopy. (See 'Clinical assessment' above.)
●Approach to diagnostic testing – Diagnostic testing for selected patients may involve either colonoscopy or sigmoidoscopy. Computed tomographic colonography (CTC) is not an appropriate initial investigation but may be useful when colonoscopy is incomplete or contraindicated. (See 'Diagnostic tests' above.)
•The decision whether to do colonoscopy or sigmoidoscopy may be based on the patient’s age and risks for colorectal carcinoma. We consider flexible sigmoidoscopy to be an alternative first line of investigation in patients with unexplained bleeding up to the age of 49 years; the choice of test in this group may be influenced by cost and availability of the procedure. (See 'Sigmoidoscopy versus colonoscopy' above.)
•The following signs and symptoms are considered “red flags” and indications for additional testing: melena, constitutional symptoms, change in bowel frequency or caliber, or a family history of a colon cancer syndrome.
•In the absence of red flags, we generally advise colonoscopy for patients with BRBPR who are age 50 and older; sigmoidoscopy or colonoscopy for patients 40 to 49 years of age; and, for patients younger than 40 years, no further evaluation if a source of bleeding is identified on physical examination, and sigmoidoscopy (or colonoscopy) if a bleeding source is not identified. (See 'Approach to the patient' above.)
●Persistent or recurrent bleeding – Patients with persistent or recurrent bleeding should undergo colonoscopy at least once and be periodically reassessed for any change in symptoms or development of red flags. (See 'Persistent bleeding' above.)
ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledge Sumit Majumdar, MD, MPH, now deceased, who contributed to an earlier version of this topic review.
