A 70-year-old male patient presented to the emergency department with the massive acute painless passage of bright red blood per rectum with postural symptoms. He had no history of fever, weight loss, anorexia, or recent change in bowel habits. There was no significant history of drug ingestion. The patient was a chronic alcoholic and nonsmoker. There was no significant history of any medical or surgical illness.

Majority of patients with hematochezia bleed from the large bowel, but in 10–25% of patients, the small bowel is the source of bleeding, and it poses difficult diagnostic dilemma. Also, some patients with massive upper GI bleeding can present with hematochezia. Lower GI bleeding represents a diverse range of bleeding sources and severities, ranging from mild hemorrhoidal bleeding to massive blood loss from vascular small bowel tumors.

Step 1: Initiate evaluation and resuscitation

The evaluation of the hemodynamic status and resuscitation is the most important step in the initial treatment of patients with lower gastrointestinal (GI) bleeding:

•Initiate resuscitation as mentioned in Chap. 78.

•Massive lower GI bleeding is defined as any bleeding requiring more than 3–5 units of blood during 24 h to maintain hemodynamic stability.

•Effort should be made to identify patients with hemodynamic compromise. Postural changes, pallor, dyspnea, tachycardia, and hypotension suggest hemodynamic compromise.

S.S. Rana, M.D., D.M. (*) • D. K. Bhasin, M.D., D.M.

Department of Gastroenterology, Postgraduate Institute of Medical Education & Research, Chandigarh, India

e-mail: drsurinderrana@yahoo.co.in

•Two large-caliber peripheral venous lines or a central venous line should be placed in patients with hemodynamic compromise.

•Blood should be transfused if indicated.

Step 2: Make a diagnosis

•An initial history and clinical evaluation should be done to arrive at a list of possible differential diagnosis and plan further investigations.

•The use of anticoagulants or nonsteroidal anti-inflammatory drugs (NSAIDs), the presence of liver disease, and serious comorbid medical conditions like cardiac conditions should be assessed.

•The character and frequency of stool output should be noted, as it allows critical assessment of the severity of bleeding as well as likely source of bleeding.

•Hematochezia must be differentiated from melena, as melena is suggestive of an upper GI bleeding source (although bleeding from the cecum and right-sided colon occasionally presents with melena).

•Patients with brown or infrequent stools are unlikely to have brisk bleeding; those with frequent passage of red or maroon stool, however, may have ongoing bleeding.

•Careful digital rectal examination should be done to exclude anorectal pathology as well as confirm patient’s description of stool color. Hematochezia should also be differentiated from bloody diarrhea, by proper history.

•The most common etiologies of lower GI bleeding vary according to the age groups of the patients.

•In young adults and adolescents, the most common causes of bleeding are inflammatory bowel disease, Meckel’s diverticulum, and polyps.

•In adults younger than 60 years, the most frequent source of lower GI bleeding includes colonic diverticula, inflammatory bowel disease, and neoplasms, whereas angiodysplasia, diverticula, neoplasms, and ischemia are the most common cause of lower GI bleeding in the elderly.

•With history of 2–3 weeks of fever in the patient with lower GIT bleeding, rule out enteric fever in countries with high incidence.

Step 3: Send investigations

•Initial laboratory studies should include a complete blood count, coagulation profile, blood grouping, renal function tests, and serum electrolytes.

•Coagulopathy (international normalized ratio >1.5) or thrombocytopenia (<50,000 platelets/mL) should be treated using fresh frozen plasma or platelets, respectively.

Step 4: Risk stratification

•Risk stratification is important because diagnostic and therapeutic interventions are timeand resource-consuming and often involve risk and discomfort (i.e., bowel preparation) to the patient.

•In contrast to the upper GI bleeding, predictors of poor outcome in the lower GI bleeding are not well defined.

•Hemodynamic instability, ongoing hematochezia, and presence of comorbid illness have been associated with poor outcome.

•About 75% of patients stop bleeding spontaneously without any treatment and are unlikely to benefit from aggressive interventions.

Step 5: Rule out the upper GI tract as the source of bleeding

•About 10–15% of patients presenting with severe hematochezia have the bleeding source localized in the upper GI tract.

•Patients with hemodynamic compromise and bleeding per rectum should at least have a nasogastric (NG) tube, and if the NG aspirate is bilious, an upper GI source of bleeding is unlikely.

•If the aspirate is nondiagnostic (no blood or bile), or if there is a strong suspicion of an upper bleeding source (i.e., history of previous peptic ulcer disease or frequent NSAID use), or an abdominal aortic surgery, then an upper GI endoscopy should be done.

•Nasogastric tube also helps in further preparation of the colon.

•High blood urea nitrogen to creatinine ratio has also been shown to be helpful in predicting an upper GI source of bleeding.

Step 6: Colonoscopy

•Colonoscopy is the preferred next diagnostic step after stabilization in most of the patients with lower GI bleeding as it can provide both a diagnosis and hemostasis. The diagnostic yield of colonoscopy is more than radiographic tests like tagged RBC scan or angiography, which requires active bleeding at the time of the radiological examination. Colonoscopy is also better than the flexible sigmoidoscopy, which visualizes only the left side of the colon.

•The diagnostic yield of urgent colonoscopy in acute lower GI bleeding has been reported to be between 75% and 97%, depending on the definition of the bleeding source, patient selection criteria, and timing of colonoscopy.

•Thoroughly clean the colon with bowel preparation in acute lower GI bleeding, as this procedure facilitates endoscopic visualization, improves diagnostic yield, and improves the safety of the procedure by decreasing the risk of perforation. Bowel preparation is not believed to dislodge clots or precipitate bleeding.

•The cecum should be reached, if at all possible, because a substantial proportion of bleeding sites are located in the right hemicolon.

•An attempt should be made to intubate the terminal ileum, especially in nondiagnostic colonoscopy, as substantial number of causes of lower GI bleeding can be found in the terminal ileum.

•Unlike early endoscopy in upper GI bleeding, colonoscopy should be performed after bleeding has stopped owing to fear of increased complications, need for colon preparation, and lack of proven benefit. However, recent studies have suggested that performing colonoscopy shortly after presentation within 24 h is advantageous, but studies comparing this approach with traditional delayed colonoscopy are limited.

•Early colonoscopy also helps in identifying low-risk patients and thus reduces the need for prolonged hospitalization and costs of care.

•The following criteria have been suggested for identifying the site of bleeding from colonoscopy:

–Active colonic bleeding

–Nonbleeding visible vessels

–Adherent clot

–Fresh blood localized to a colonic segment

–Ulceration of diverticulum with fresh blood in adjoining area

–Absence of fresh bleeding in the terminal ileum with fresh blood in the colon

Step 7: Achieve hemostasis

•Endoscopic treatment modalities for lower GI bleeding include injection, contact and noncontact thermal coagulation, and mechanical devices such as metallic clips and band ligation.

•Endoscopic clipping is considered as a safer alternative to thermal contact methods. Hemoclips can be applied directly to the stigmata, visible vessels, or used to oppose the sides of small diverticula or postpolypectomy defects.

•Thermal coagulation in the colon should be performed using moderately low power settings in 1- to 3-s bursts with light to moderate pressure. Thermal coagulation should be used carefully in the right colon, in the dome of diverticula, and in the presence of mucosal defects.

•Epinephrine (dilution, 1:10,000 or 1:20,000) can be injected in 1–2-mL aliquots in four quadrants around the lesion in cases of active bleeding.

•Argon plasma coagulation (APC) is useful for diffuse lesions such as radiation proctitis and large or multiple angiodysplasia.

•Ligation with bands is used for bleeding hemorrhoids and bleeding rectal varices, and, in certain circumstances, for treatment of focal lesions that are less than 2 cm in diameter on nonfibrotic tissue.

•The amount of tissue suctioned into the cap before the application of the rubber band must be carefully monitored to avoid perforation.

Step 8: Investigate further if colonoscopy is unhelpful or not possible

•The following radiological investigations are used in the management of severe lower GI bleeding who cannot be stabilized for colonoscopy or for ongoing bleeding of obscure etiology:

–Angiography

–Radionuclide scintigraphy

–Computed tomography (CT) angiography

–Magnetic resonance (MR) angiography

•They are useful in brisk bleeding as there is no need for bowel preparation. However, in contrast to colonoscopy, these investigations require active bleeding at the time of examination for diagnosis and treatment. Barium studies are not required in patients with lower GI bleeding.

•Computed tomography (CT) angiography and MR angiography are evolving as the modality of choice before digital subtraction angiography (DSA) and surgery if upper GI endoscopy and colonoscopy are normal.

Angiography

•Angiography is the only radiographic modality that is both diagnostic and therapeutic but requires a bleeding rate of at least 0.5–1.0 mL/min to be positive.

•Systolic blood pressure of less than 90 mmHg and a requirement of at least 5 units of packed red blood cells within a 24-h period have been shown to predict positive mesenteric angiography.

•This should be reserved for patients who have massive bleeding with hemodynamic compromise that precludes colonoscopy or in patients where colonoscopy is nonconclusive and the patient continues to bleed.

•Vasopressin is the first therapeutic modality employed during angiography, and it controls bleeding in up to 91% of cases, but major complications occur in 10–20% of patients and include arrhythmias, pulmonary edema, hypertension, and ischemia.

•Rebleeding occurs in up to 50% of patients after cessation of the infusion, and, therefore, it is often used to stabilize a patient before surgery rather than as a definitive intervention.

•Early attempts at embolization occasionally cause bowel infarction, but technologic advances in coaxial microcatheters and embolic materials have enabled the embolization of specific distal arterial branches with increased success and fewer complications.

Radionuclide scintigraphy

•Nuclear scintigraphy is a more sensitive method than angiography for detecting GI bleeding as it detects bleeding as low as 0.1 mL/min.

•The major disadvantage of nuclear imaging technique is that it localizes bleeding only to an area of the abdomen and also has high false localization rates because the intraluminal blood is moved away by intestinal motility.

•Currently, it is recommended that scintigraphy should be used as a screening test for patients before the angiography or colonoscopy.

CT angiography/MR angiography

•Multidetector row CT (MDCT), where scan time is considerably reduced, has brought CT also into the diagnostic armamentarium for patients with lower GI bleeding.

•Reduction of scan time thus enables the accurate acquisition of arterial images, which can show contrast extravasation into any portion of the GI tract.

•Bleeding rates as low as 0.3–0.5 cc per minute have been detected using MDCT.

•The yield of MDCT is highest among patients with severe ongoing lower GI bleeding.

•The average yield of MDCT for lower GI bleeding is 60%, with yields ranging from 25% to 95%.

•Lack of therapeutic capability is a major limitation of MDCT. However, MDCT can guide further angioembolization.

•Recently, advances in MR have shown good results with MR angiography.