Colonic telangiectasia. Endoscopic views before and after argon plasma therapy
Hemangiomas and vascular malformations (Figs. 34.2, 34.3, and 34.4): GI hemangiomas are uncommon benign vascular tumors. They may occur as a single or multiple lesions along the intestinal tract; the small bowel is the most common site of occurrence, followed by the colon. Association with syndromes such as a rubber bleb nevus or Kippel-Trenaunay syndrome has to be investigated in cases of multiple lesions. Most are pedunculated, polypoid intraluminal masses, but they may also have an infiltrative growth pattern. Insidious or acute bleeding is the major complication .
Colonic angiomatosis. (a) Enhanced axial multidetector computed tomography showing rectosigmoid wall thickening with multiple clusters of phleboliths. (b) Endoscopic view
Small-bowel hemangioma in a 40-year-old adult. Enhanced coronal multidetector computed tomography showing a lobulated mass with phleboliths (arrow)
Arteriovenous malformation of the right colon. (a) Endoscopic view. (b) Axial MIP enhanced axial MDCT view. Enhanced vascular wall lesion with arterial and venous abnormal vessels (arrow). (c) Coronal MIP vascular reconstruction. (d, e) Digital selective angiography before and after selective embolization
Postradiation colitis: This is a major complication of pelvic organ radiotherapy, especially following cervical or prostate cancer. Radiation induces endarteritis obliterans, fibrosis of the submucosal layer of the bowel, ischemic endarteritis, and neovascularization associated with the development of telangiectasis in 5–20 % of cases. Four to 13 % of patients report rectal bleeding following radiation therapy for prostatic carcinoma, most often several years after therapy.
Ischemic colitis: This is a common cause of lower GI bleeding and typically affects the elderly. Risk factors include atherosclerosis, embolic disease, chronic renal failure, insufficient flow, or recent high-risk surgery . The splenic flexure and rectosigmoid junction are typically affected. Stercoral colitis is a specific condition that typically affects old patients. Overdistension of the rectal lumen by severe fecal impaction leads to rectal ischemia, bleeding, and perforation .
Neoplasias: Most neoplasias are responsible for occult or chronic lower GI bleeding. They account for 2–9 % of hematochezia . Hemorrhage originates from tumor erosion and mucosal ulceration. In the case of high-stage carcinoma with local invasion, involvement and erosion of adjacent arteries may lead to acute lower GI bleeding.
Postpolypectomy bleeding: This is the most frequent complication of colonoscopy and has been reported in 2–8 % of acute lower GI bleeding. Risk factors include the size and gross morphology of the polyp, the cutting mode of the electrosurgical current, inadvertent cutting before the current was applied, associated comorbidity, and the experience of the endoscopist .
Inflammatory bowel disease: Acute bleeding is rare in inflammatory bowel disease, with an incidence of 0.9–6 %. Acute bleeding is more frequent in Crohn’s disease because ulcers form deeper in the wall compared with ulcerative colitis with respectively 1.2 % and 0.1 % of hospitalization stay use eventually Hospitalization. Spontaneous cessation occurs in 50 % of cases, but rebleeding will occur in 35 % of cases.
34.3 Anorectal Lesions
Rectal varices may occur in the setting of cirrhosis and portal hypertension, with a prevalence between 40 % and 77 %, but these are rarely responsible for acute lower GI bleeding (Fig. 34.5). In 2–9 % of patients, hemorrhoids are responsible for the bleeding .
Recurrent lower gastrointestinal bleeding in a 60-year-old adult. Colonic varices (arrow) caused by segmental venous mesenteric hypertension are complicating a small-bowel carcinoid tumor with a retractile mesenteric mass (arrowheads). Endoscopic view and enhanced coronal Maximum Intensity Projection (MIP) multidetector computed tomography view
Dieulafoy lesion, a typical lesion of the upper stomach, may be discovered in the rectum. Bleeding is caused by a tiny erosion of an abnormally large submucosal end artery within a minute mucosal defect. Contrary to peptic ulcer, the absence of inflammation at the point of erosion and the small size of the mucosal defect make it difficult to locate in the absence of active bleeding .
34.4 Small-Bowel Lesions
A majority of lower GI bleeding arises from the colon and rectum. Nevertheless, 10–25 % of these bleeds may arise from the small bowel or proximal to the angle of Treitz.
Angiodysplasia is the most common source of small-bowel bleeding, found in 30–60 % of reported cases, followed by tumors in 5–10 % of cases.
In children, special attention should be devoted to Meckel diverticulum, which occurs in 2–3 % of the population. Lifetime risk of developing complications has been estimated at 4 % up to the age of 20 years, 2 % up to the age of 40 years, and 0 % in the elderly population. Hemorrhage is the most common complication, especially in the pediatric population. Ectopic gastric mucosa located inside the diverticulum produces gastric acid and may induce mucosal damage and bleeding.
34.4.1 Chronic versus Acute Bleeding
A wide range of underlying diseases may be the source of lower GI bleeding. Diagnosis and management differ depending on the type of bleeding (Tables 34.1 and 34.2).
Assess the severity of a lower gastrointestinal bleeding
Massive bleeding per anum of red blood with or without clots + Haemodynamic compromise
Blood pressure ≤100 mmHg
± Pulse rate ≥100/min
± Hemoglobin <10 g/dL
± 6–8 units of blood required to stabilize the patient
Chronic lower GI bleeding
Minor, melena, or hematochezia
Acute lower GI bleeding
Brisk, significant bleeding
Occurring in the past 3 days
Self limited; resolves spontaneously, allowing for investigations
Massive lower GI bleeding
Massive and continuous hemorrhage with the need for urgent resuscitation
Rule out an upper GI cause of bleeding (10–15 % of cases)
Occult/obscure lower GI bleeding
Cause not found, even with advanced investigations
5 % of cases
Could be massive and intermittent
In the case of chronic or recurrent bleeding, determining the origin of the bleeding may be challenging. Diagnostic tools include endoscopy, radionuclide imaging, abdominal multidetector computed tomography, wireless capsule endoscopy, and double-balloon enteroscopy.
Acute lower GI bleeding has been defined as a recent bleeding situation (within 3 days) and may result in instable vital signs, anemia, or the need for a blood transfusion. Although patients with lower GI bleeding classically present with less hemodynamic instability compared with patients with upper GI bleeding, anemia and hemodynamic instability are present in one-half of patients and cardiovascular collapse in 9 % . Factors predicting a severe course include hemodynamic instability (heart rate ≥100 bpm, blood pressure <100 mmHg), syncope, initial hematocrit ≤35 %, active gross bleeding from the rectum, and more than two active associated comorbid conditions [15, 16].
In the presence of acute lower GI bleeding, clinical evaluation and resuscitation should be initiated before diagnostic evaluation . This take into account the patient’s history, intake of antiplatelet or anticoagulant therapy, vascular disease, and the duration and frequency of previous bleedings. Physical examination should focus on the patient’s vital signs. In the case of clinical evidence of acute bleeding or associated high comorbidity, patients should be monitored in an intensive care unit . Management includes treatment of coagulopathy, volume replacement, and transfusions before the source of bleeding is investigated. In contrast to acute upper GI bleeding, only a few risk scores have been developed to accurately forecast the outcome of a patient with acute lower GI bleeding in terms of risk of recurrent bleeding, intensive management, and mortality. Useful tests include the Bleed classification system (based on ongoing bleeding, low systolic blood pressure, elevated prothrombin time, erratic mental status, and unstable comorbid disease), clinical risk factors, and an artificial neural network [19–21].
34.4.2 Investigations and Treatments
The goals of investigations for lower GI bleeding are (1) to identify the source of the bleed and (2) to allow its permanent treatment. Endoscopic and imaging techniques (nuclear scintigraphy, computed tomography angiography, and catheter angiography) are both of interest. Today they not only play a role in localizing and identifying the cause of bleeding but also are an important part of bleeding management; each of these approaches addresses the various types of bleeding. Because only specialist centers can offer the full range of these advanced procedures, patients who specifically require them must be identified. An algorithm addresses this selection process  (Fig. 34.6).
Management algorithm for massive lower gastrointestinal bleeding
34.5.1 Diagnostic Endoscopy
Endoscopy is considered as the investigation of choice. In acute lower GI bleeding, pan–upper GI endoscopy is mandatory to rule out a potential source of bleeding in the upper GI tract . The use of a nasogastric tube and gastric lavage to exclude an upper GI source of bleeding is no longer recommended. Colonoscopy has been proposed as the first-line modality for diagnosis and therapy of lower GI bleeding. Because 80 % of hemorrhages will cease spontaneously, an elective colonoscopy is often indicated after standard bowel preparation. The accuracy of colonoscopy in identifying definitively the source of bleeding varies between 45 % and 90 % . In the case of acute bleeding, the timing of colonoscopy is urgent. It may be hampered by incomplete preparation or poor observation of the colonic wall as a result of a massive hemorrhage. Urgent endoscopy has been defined as occurring within 12–48 h of admission. Earlier completion of colonoscopy has been associated with greater yield and shorter length of hospital stay . Rapidly purging the colon through a nasogastric tube or by mouth has been recommended to facilitate mucosal observation and improve diagnostic yield. Although urgent colonoscopy can be performed without preparation, Jensen et al.  reported a significant reduction in sensitivity in cases of insufficient preparation and successful treatment in as few as 21 % of cases.
34.5.2 Therapeutic Endoscopy
Diagnostic colonoscopy can be associated with endoscopic hemostasis. Depending on the site and cause, several modalities are available, including thermal coagulation, injection of hemostatic agents, and mechanical devices. Thermal coagulation with bipolar electrocoagulation, argon plasma, and laser-mediated coagulation are the preferred methods for vascular lesions, especially angiodysplasia. Epinephrine injection and metal clips are recommended for diverticular disease or bleeding after polypectomy, with a limited risk of complication. The accuracy of hemostasis by endoscopic therapy in diverticular hemorrhage is 95 %, without morbidity, but recurrent bleeding is observed in more than 25 % of cases .
Rectal varices and hemorrhoids are best treated with rubber bands and a sclerosing injection.
34.5.3 Wireless Capsule Endoscopy
In the case of negative upper and lower GI endoscopies, the small bowel should be investigated. Wireless capsule endoscopy is a painless tool that allows a noninvasive evaluation of the entire small bowel. A high diagnostic yield – more than 90 % – has been reported. Angiodysplasia is the most frequently observed lesion, found in up to 49 % of patients . The best results were obtained in cases of ongoing obscure-overt bleeding (>90 %) and dropped to 12.9 % in cases of previous overt bleeding, in parallel with the duration of the interval since the bleeding episode began. Wireless capsule endoscopy seems to be superior to push-enteroscopy. The main contraindication is a bowel stricture. A 5 % rate of non-natural excretion has been reported.