Approach to Suspected Lower Gastrointestinal Bleeding


Bleeding lesion

Frequency (%)

Diverticulosis

5–42

Ischemia

6–18

Anorectal (hemorrhoids, anal fissures, rectal ulcers)

6–16

Neoplasia (polyps and cancers)

3–11

Angioectasia

0–3

Postpolypectomy

0–13

Inflammatory bowel disease

2–4

Radiation colitis

1–3

Other colitis (infectious, antibiotic associated, colitis of unclear etiology)

3–29

Massive upper GI bleeding

3–13

Other causes

1–9

Unknown cause

6–23



LGIB can be categorized as severe, moderate, and scant and is manifested by hematochezia. The chronic passage of intermittent bright red blood, often associated with a bowel movement, with streaks of blood on the stool or toilet paper is common and can usually be attributed to hemorrhoids, anal fissures, or a slow-growing neoplastic lesion. Patients over the age of 40 or those with a strong family history of colon cancer should undergo a high-quality colonoscopic evaluation. In younger, healthy patients, a digital rectal exam, in addition to flexible sigmoidoscopy, may be sufficient for evaluation if a rectal outlet source of bleeding is identified. Moderate hematochezia is a frequent GI cause for hospitalization and usually requires inpatient evaluation and management. Severe acute hematochezia is the least common but potentially life-threatening condition. In this high-risk group, rapid diagnosis and therapy are essential to avoid associated morbidity and mortality. Massive upper GI bleeding can also manifest with hematochezia, and so exclusion of an upper GI source is important in the right clinical scenario. Hematochezia associated with upper GI bleeding is often accompanied by hemodynamic instability, with possible concurrent hematemesis and upper GI symptoms. Up to 15 % of patients presenting with massive hematochezia have been found to have an underlying upper GI bleeding source.



Clinical History and Clues as to the Source of Bleeding


The initial evaluation of a suspected LGIB source starts with a careful history and physical examination. Often, the patient history can provide vital clues as to the etiology of bleeding and help to risk stratify the patient and plan the initial management. For example, a patient presenting with hematochezia within 2 weeks of undergoing a colonoscopy with polypectomy may not require urgent endoscopic evaluation, since postpolypectomy bleeding is frequently self-limited. A visual inspection of the external anal opening and a digital rectal examination can identify bleeding rectal outlet lesions, such as hemorrhoids and anal fissures, as well as to confirm stool color and consistency.


Diverticular Bleeding


Diverticular bleeding typically presents in elderly patients (>60 years old) and is associated with a “painless gush” of bright red blood per rectum. Patients with diverticular hemorrhage commonly provide a history of rectal bleeding that is large in volume and sudden in onset. Diverticulosis is the most common cause of acute LGIB, accounting for 42–56 % of cases (Fig. 6.1). Diverticula occur in areas of weakness within the wall of the colon. Bleeding occurs when the thin diverticular wall herniates into an arterial blood vessel (usually in the dome of the diverticulum or at its antimesenteric margin). In Western countries, 75 % of diverticula occur in the left colon, and, when right-sided diverticula do occur, they are usually associated with concurrent left-sided diverticula. Right-sided diverticular bleeding may be more severe than left-sided diverticular bleeding. Diverticular bleeding ceases spontaneously in about 80 % of cases. Although endoscopic therapies to treat a bleeding diverticulum, such as epinephrine injection and/or clip application (Video 6.1), are effective, recurrent bleeding has been reported in up to 40 % of patients despite endoscopic therapy [5]. For this reason, we advocate application of an endoscopic tattoo to mark the site of bleeding anytime an actively bleeding diverticulum is identified, so as to facilitate endoscopic or surgical localization should rebleeding occur. Recent studies have identified factors, such as nonsteroidal anti-inflammatory drugs (NSAIDs), antiplatelet drugs, and hypertension, that may be associated with a higher rate of recurrence of colonic diverticular bleeding [6].

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Fig. 6.1
Actively bleeding colonic diverticulum located in the sigmoid colon


Ischemic Colitis


Ischemic colitis usually manifests with abdominal pain and hematochezia, typically in an elderly patient. Historical features that raise the suspicion for colonic ischemia include small to medium volume passage of blood per rectum and antecedent hypotension. The colitis tends to be segmental (Fig. 6.2) and more commonly affects areas of the colon where the blood supply from two vascular territories do not overlap (“watershed areas”), such as the splenic flexure (Video 6.2). The likelihood of colonic ischemia as the cause of hematochezia also increases in patients who are critically ill or have a history of severe peripheral vascular disease. A common clinical scenario for the occurrence of colonic ischemia is in the critically ill patient who is in an intensive care unit and who suddenly develops hematochezia. Obtaining an accurate history regarding current medications (e.g., vasopressor therapy) and trending the patient’s blood pressure measurements in the period leading up to the episode of hematochezia are key determinants.

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Fig. 6.2
Ischemic colitis at the splenic flexure in a hospitalized patient with hypotension and sepsis


Vascular Ectasias


Bleeding vascular ectasias , or angioectasias , can present with either melena (from a right colon source) or bright red blood per rectum (from a left colon source). They more commonly present with painless bleeding in elderly patients (Fig. 6.3), and the severity of bleeding is variable. Angioectasias can be acquired through aging and their formation has been associated with chronic renal failure as well as aortic stenosis. Angioectasias are flat lesions in the GI tract and, as a result, can be easily obscured by retained colonic material or remain hidden between the colonic folds. In these situations, the use of an endoscopic cap may help locate an actively bleeding colonic angioectasia and facilitate endoscopic therapies, such as epinephrine injection, clip application, and/or argon plasma coagulation (Video 6.3). Angioectasias should be suspected in patients with recurrent overt LGIB where the source of bleeding has not been identified on previous colonoscopic examinations or other diagnostic studies. Colonoscopy with a good quality bowel preparation and careful examination of the colonic mucosa is essential for the detection and treatment of these lesions.

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Fig. 6.3
Actively bleeding colonic angioectasia hidden between mucosal folds at the hepatic flexure identified using a cap-fitted colonoscope


Neoplasia


Overt LGIB due to colonic neoplasia is a relatively rare occurrence. Bleeding due to colonic neoplasia (Fig. 6.4) occurs more commonly in elderly patients and is more often a source of occult blood loss. Bleeding is usually of small volume and painless and tends to occur as a result of tumor neovascularization (Video 6.4). LGIB from colonic neoplasia can present as intermittent melena (from a right-sided colonic neoplasia) or hematochezia (from a more distal neoplasia). Factors that raise the suspicion for colonic neoplasia as the source of LGIB include a history of iron-deficiency anemia, weight loss, and a change in stool caliber.

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Fig. 6.4
Actively bleeding colonic neoplasia in the descending colon


Anorectal Lesions


Hemorrhoidal bleeding is a relatively common source of LGIB and can be seen in patients of any age. Small-volume hematochezia , characterized by bright red blood after a bowel movement with dripping into the toilet or streaking on the toilet paper, is most commonly caused by hemorrhoids, especially in patients under the age of 50. Hemorrhoidal bleeding tends to be of low volume and intermittent in nature and may be associated with constipation.

Anal fissures are typically associated with pain upon defecation and small volume bleeding. These may be associated with constipation and the passage of hard stools. There may also be a history of anal trauma antecedent to the episode of bleeding.

Rectal ulcers can be caused by severe or prolonged pressure and irritation within the rectum. This can be due to constipation and hard stool (stercoral ulcer) or by pressure from fecal management systems. Due to the rich blood supply of the rectum, bleeding from rectal ulcers (Fig. 6.5) can be severe if the ulcer erodes into an arterial vessel. This type of bleeding lesion may require multiple endoscopic modalities, such as epinephrine injection and clip application, in order to provide durable hemostasis (Video 6.5). The diagnosis of an anorectal source of LGIB requires a thorough examination of the anal canal, both internally and externally. A careful inspection of the external anal opening and a digital rectal exam should be performed. It is also imperative to perform a high-quality retroflexed endoscopic examination of the rectum when evaluating for potential anorectal sources of LGIB.

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Fig. 6.5
Distal rectal ulcer with a visible vessel and large overlying clot


Inflammatory Bowel Disease


Inflammatory bowel disease (IBD) can present with abdominal pain and/or pain with defecation. Patients with IBD can present with either small or large volume of rectal bleeding and tends to occur in younger patients. In patients with IBD, bleeding is usually due to diffuse inflammation of the colonic mucosa, and the severity of bleeding is correlated to the degree of mucosal inflammation. LGIB in a patient with IBD may be the initial presenting symptom of the disease and may be associated with weight loss, anemia, inflammatory biomarkers, and extraintestinal manifestations or a family history of IBD.


Miscellaneous Causes


Bleeding due to radiation proctopathy typically presents with the passage of bright red blood per rectum, which may be associated with tenesmus. A history of previous radiation exposure (i.e., radiation for prostate cancer in men or for uterine cancer in women) is essential in making the presumptive diagnosis of bleeding due to radiation proctopathy.

Patients with bleeding due to NSAID-induced colonic ulceration (Fig. 6.6) can present with either melena or hematochezia. In contrast to ischemic ulcers, NSAID-induced colonic ulcers may be isolated and can occur in any part of the colon. NSAID-induced ulcers generally are clean-based and resolve following cessation of the offending drug (Video 6.6).

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Fig. 6.6
NSAID-induced colonic ulcer in the descending colon. Note the long, linear, and clean-based appearance of the ulcer


Early Predictors of Severity in Acute Lower GI Bleeding


Although there have been multiple studies designed to evaluate prognostic factors of severity in patients with upper GI bleeding, few have evaluated predictive factors of severity in LGIB (Table 6.2) [4]. In one study, important hemodynamic predictors of severity in patients with upper GI bleeding, such as tachycardia and hypotension, were also key predictors in patients with LGIB [4]. This study also found that the abdominal examination can be predictive of severity. Severe LGIB was associated with a non-tender abdomen on palpation (e.g., diverticular hemorrhage).
May 30, 2017 | Posted by in GASTROENTEROLOGY | Comments Off on Approach to Suspected Lower Gastrointestinal Bleeding
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