The most common causes of lower gastrointestinal bleeding are diverticulosis, colonic polyps and cancer, angiodysplasia and ischemia. Diverticular disease is the most common cause of life threatening lower GI bleeding. Although ischemia has been found to be the third or fourth most common cause of colonic bleeding, it rarely causes life threatening bleeding. The etiology of acute colonic ischemia can be classified as either occlusive or nonocclusive. The causes are numerous and include congestive heart failure and arrythmias, chronic renal insufficiency, vasculitis, and hematologic disorders.
The outcome depends on the severity of the clinical presentation with the highest mortality associated with gangrenous colitis. Local ischemia has a very low morbidity and bleeding requiring urgent surgical intervention is rare.
We report an unusual case of right-sided focal ischemic colitis presenting as an isolated ulcer causing massive lower GI bleeding requiring surgical intervention.
A 72-year-old man with history of hypertension, ischemic cardiomyopathy, chronic atrial fibrillation treated with coumadin, CVA and chronic renal insufficiency, presented with a 1-day history of 2 episodes of large volume, painless hematochezia.
He gave a history of intermittent vomiting without hematemesis in the preceding week. On admission he was hemodynamically unstable.
The physical examination was remarkable for maroon color blood on rectal examination. Laboratory evaluation revealed an initial hematocrit of 25%, platelet of 317 k/Ál, leucocyte 11 k/Ál, prothrombin time/INR 14.25/1.74, BUN/Cr 71/4.4. Nasogastric lavage did not reveal any fresh or altered blood. The patient was admitted to the ICU and after initial volume resuscitation with crystalloids and PRBCs, an upper GI endoscopy was performed which was normal. Colonoscopy revealed a single 2x2cm ulcer with an adherent clot and 2 visible vessels in the proximal transverse colon (Figure 1). The vessels were injected with epinephrine and bicapped.
On the fourth day post endoscopic therapy he had 2 episodes of large painless hematochezia. The nasogastric lavage was negative. Swan Ganz monitoring was compatible with hypovolemic shock. An emergency laparotomy was performed. The ascending colon was full of blood, the liver was congested with moderate ascites, the extra hepatic biliary system, gallbladder and pancreas were normal.
A right hemicolectomy with an ileo-colic anastomosis to the distal transverse colon was performed. Intraoperatively, the patient was anuric and hypotensive with an estimated additional blood loss of ~400cc. Perioperatively he received 6 units of packed RBC and 4 units of fresh frozen plasma and dopamine infusion.
The immediate postoperative course was unremarkable, however about 8 hours postoperatively he went into cardiac arrest and died. The surgical pathology revealed findings compatible with ischemic colitis (Figure 2).
Colonic ischemia is the most common vascular pathology in the GI tract. The immediate precipitating factor is not usually identified and no clinical symptoms are automatically associated with the etiology or the anatomical location. The colon is susceptible to ischemia because of systemic low flow states that are secondary to diseases such as cardiomyopathy and nonocclusive events that affect the collaterals in the "watershed" areas. Our patient had massive bleeding from right-sided ischemia that presented as an isolated ulcer. He had a number of systemic problems that could explain the acute ischemia. He also had chronic atrial fibrillation which could have precipitated an embolic event. Although massive bleeding from ischemia, especially focal ischemia is rare, previous reports have described a worse prognosis from right-sided ischemia and a higher mortality rate.
Medina et al.  reported 53 cases of ischemic colitis and identified hypertension as the main risk factor associated with ischemic colitis. Peripheral vasculopathy and right colonic involvement were risk factors for a severe outcome. In their report 5 out of 53 patients died and 4 of these 5 patients had right colonic involvement. Flobert et al.  reported 60 cases and identified chronic renal failure, hemodialysis and right colonic involvement as the main risk factors. Right colonic involvement was the only factor independently associated with severity. Scharf et al.  reported 129 cases of ischemic colitis and the overall mortality was 29%. Ischemic colitis was associated with chronic renal failure and atherosclerosis and the absence of colonic infarction did not ensure a favorable outcome. Patients who were candidates for nonoperative therapy had significant high mortality rates.
Additional etiologies have been reported for ischemic colitis including cocaine use, antiphospholipid syndrome or vasculopathy, vascular intervention, atheroemboli and radiation [4-8]. The most common presentation is abdominal pain, diarrhea and hematochezia. In most cases the bleeding is mild and can be managed conservatively with medical treatment and supportive care. Krishikawa et al.  reported a case of chronic ischemic proctitis as a cause of massive lower GI bleeding that also required surgical intervention. The patient died after a complicated hospital course. Our patient had massive right-sided bleeding from an ulcer with a visible vessel which is even more unusual.
It is widely accepted that colonoscopy is a useful first test for lower GI bleeding. The endoscopic findings of ischemic colitis frequently include pale mucosa with patchy bleeding and submucosal hemorrhagic nodules which are equivalent to "thumbprints" detected on radiologic studies. A single linear ulcer running along the longitudinal axis of the colon "the single-stripe sign" has been reported in a few cases.
In summary we report a rare case of focal ischemic colitis which presented as an isolated colonic ulcer and massive gastrointestinal bleeding. Clinicians should maintain a high suspicion for ischemia in patients with established risk factors. It is unlikely that our clinical management would have been different if we had identified this case initially as focal ischemia instead of an isolated ulcer. Although Scharf's study  suggests that non-operative treatment has a higher mortality in patients with right-sided colitis, those patients did not present with massive bleeding. Mortality is high in the studies that have looked at ischemia involving the right colon and this case is another example of that with an unusual clinical presentation. Patients with right-sided ischemia need to be monitored closely throughout their course and patients who present with bleeding may need to have the resolution of the ischemia documented to prevent rebleeding.
This case was first published on GastroHep.com in 2005.
Bhavna Balar MD
Sabo Tanimu MD
Rohan Clarke MD
Lisa A Ozick MD
Division of Gastroenterology, Department of Internal Medicine, Harlem Hospital Center, Columbia University Medical Center, New York, NY 10037, USA.
Dr Bhavna Balar MD
Harlem Hospital Center, Department of Medicine, Division of Gastroenterology RM 13106, 506 Lenox Avenue, New York, NY 10037, USA.
Phone +1 (212) 939-1430
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This article was first published on GastroHep in March 2005.