eMedicine Specialties > General Surgery > Colorectal

Lower Gastrointestinal Bleeding, Surgical Treatment: Workup

Author: Burt Cagir, MD, FACS, Assistant Professor of Surgery, State University of New York, Upstate Medical Center; Consulting Staff, Director of Surgical Research, Robert Packer Hospital; Associate Program Director, Department of Surgery, Guthrie Clinic
Coauthor(s): Elizabeth Cirincione, MD, Director of Colon and Rectal Surgery, Department of Surgery, Nassau University Medical Center
Contributor Information and Disclosures

Updated: Oct 29, 2009

Workup

Laboratory Studies

• Appropriate blood tests include CBC; serum electrolytes (sequential multiple analysis 7 [SMA7]); and coagulation profile, including activated partial thromboplastin time (aPTT), prothrombin time (PT), manual platelet count, and bleeding time.

Imaging Studies

• The role of nuclear scintigraphic imaging in the diagnosis and treatment of patients who present with lower GI bleeding remains controversial. Nuclear scintigraphy is a sensitive diagnostic tool (86%) and can detect hemorrhage at rates as low as 0.1 mL/min. Nuclear scintigraphy is reportedly 10 times more sensitive than mesenteric angiography in detecting ongoing bleeding. The scintigraphic imaging suffers from a low specificity (50%) due to its limited resolution; this has led many investigators to recommend that scintigraphic imaging be used primarily as a screening examination to select patients for mesenteric angiography. (See image below and Image 2.)

• No preparation is required for^99m sulfur colloid. This agent has a very short half-life (2.5-3.5 min) because it is rapidly cleared by the reticuloendothelial system. Because it enhances the liver and spleen, bleeding from both the hepatic flexures and the splenic flexures may be obscured.^99m Tc-labeled RBC scintigraphy is the preferred technique because its half-life is longer. Images delayed up to 24 hours can be taken with labeled RBC scanning.
• The sensitivity of the^99m Tc-labeled RBC scintigraphy is reportedly 20-95%. The bleeding site can be identified accurately when intraluminal accumulation of^99m Tc-labeled RBCs is observed during the dynamic phase of scanning. Although nuclear scintigraphy is sensitive enough to diagnose ongoing bleeding at a rate as low as 0.1 mL/min, it is not highly accurate in locating the bleeding point. The bleeding point is accurately localized in 52-90% of positive cases, with an average of 86% and incorrect localization of 14%, as reported in 24 publications. Because of the high false localization rate (10-60%) for the bleeding site, performing segmental resections based solely on scintigraphy results is not recommended.
• Ng and colleagues reviewed 86 patients with positive^99m Tc-labeled RBC scintigraphy findings.⁵ Patients with an immediate blush (within 2 min of the study) revealed a positive predictive value of 75% for angiography. Patients with a delayed blush (after 2 min of the study) had a negative predictive value of 93% for angiography. Thus, patients with delayed blush should proceed with colonoscopic evaluation instead of mesenteric angiography. Use^99m Tc-labeled RBC scintigraphy as a prescreening test for selective mesenteric angiography.
• In 1992, Ryan et al published their experience with^99m Tc-labeled RBC scintigraphy. In this study, 29 patients with lower GI bleeding were identified. Scintigraphy identified the site of bleeding accurately in 9 patients with massive lower GI bleeding. In 6 of 9 patients, the scintigraphy finding was positive in the first 5 minutes of the study. In 3 patients, the scintigraphy finding was positive at 14-45 minutes.
  • Another study was performed to evaluate the efficacy of RBC scintigraphy in confirming the location of the lower GI bleeding. Twenty-one patients with positive scintigraphy results were included in the study. Of these, the bleeding site was confirmed in 16 patients by various methods. RBC scintigraphy findings were positive within the continuous phase of the study in 10 of the confirmed studies and in none of the incorrectly localized studies. Therefore, in carefully selected cases, patients can undergo segmental resections only if scintigraphy findings are strongly positive in the very initial part of the test.
  • Cinematic^99m Tc-labeled RBC scintigraphy (real-time scanning) has been described as a noninvasive alternative to mesenteric angiography. Continuous dynamic imaging using sequential computer acquisition provides more accurate localization of the bleeding point because it enables cinematic playback. More studies are necessary to identify the success of real-time scintigraphic evaluations.
  • Recurrent lower GI bleeding occurs after negative^99m Tc-labeled RBC scintigraphy. Hammond et al conducted retrospective evaluations of 84 patients with negative^99m Tc-labeled RBC scintigraphy. The overall rebleeding rate was found to be 27% (n=23 patients). Hammond et al concluded that age, gender, bleeding source, use of anticoagulant/antiplatelet agents, length of hospital stay, admission Hct, Hct nadir, and transfusion requirements are not predictive of the patients who will rebleed.
• The use of¹¹¹ indium–labeled RBC scintigraphy to detect intermittent bleeding has been described in the medical literature in a handful of publications.
  • Ferrant and colleagues initially used¹¹¹ indium–labeled RBC scintigraphy in patients with lower GI bleeding in 1980; however, it remains underutilized because of a prolonged half-life of 67 hours. This scintigraphy is more expensive and also is a more labor-intensive technology than^99m Tc labeling. The image quality and localization of bleeding can be less than desirable because of the prolonged half-life and intestinal motility. However, the longer half-life of¹¹¹ indium–labeled RBC scintigraphy can be useful in locating intermittent bleeding points, particularly when conventional methods have failed.
  • Schmidt et al published a report on 6 patients in whom^99m Tc scanning was initially unrewarding.⁶ Subsequent scintigraphy with¹¹¹ indium–labeled RBCs located the site of bleeding in all patients.
  • Mole et al detected synchronous, small and large intestinal adenocarcinomas with¹¹¹ indium–labeled RBC scintigraphy in a 70-year-old patient with intermittent GI bleeding and profound blood loss anemia.⁷
• In 1965, Baum et al described selective mesenteric angiography in the diagnosis of GI bleeding.¹ Since then, the value of mesenteric angiography in the diagnosis and management of lower GI bleeding has been well established. The extravasation of contrast material indicates a positive study finding. Selective mesenteric angiography can detect bleeding at a rate of more than 0.5 mL/min. In a patient with active GI bleeding, the radiologist concentrates on the major mesenteric vessel most likely to be responsible (eg, the inferior mesenteric artery in bright red rectal bleeding). If no bleeding is identified, the other major mesenteric vessels, including the superior mesenteric artery and celiac axis, are studied. In some cases, aberrant vascular anatomy can contribute to colonic or small bowel circulation; in other cases, patients with upper GI bleeding may present in an uncommon clinical fashion.
• Helical CT scan of the abdomen and pelvis can also be used when routine workup fails to determine the cause of active GI bleeding. Multiple criteria, including vascular extravasation of the contrast medium, contrast enhancement of the bowel wall, thickening of the bowel wall, spontaneous hyperdensity of the peribowel fat, and vascular dilatations, are used to establish the bleeding site with helical CT. The presence of diverticula alone was not enough to define the bleeding site. Three-phase helical CT should be performed using intravenous contrast. Water can be used as an oral contrast in the workup of patients who are actively bleeding. Therefore, helical CT could be a good diagnostic tool in acute lower GI bleeding to help the physician identify the bleeding site.
• A pilot study was done in Sydney, Australia, to evaluate CT as a diagnostic tool for acute lower GI bleeding.
  • Helical CT was compared to selective mesenteric angiography and colonoscopy in the diagnosis and detection of a bleeding site. Seven patients with acute lower GI bleeding were included. All patients underwent mesenteric angiography following CT. Colonoscopies were also performed on 5 patients investigated with both CT and mesenteric angiography. Both modalities had concordant findings of 2 active bleeding sites, 1 nonbleeding rectal tumor, and 1 negative result. In 3 patients, the source of bleeding was found on CT, whereas the mesenteric angiography finding was negative. Colonoscopies performed in these 3 patients confirmed blood in the colon/ileum.
  • Sabharwal et al concluded that helical CT is a safe, convenient, and accurate diagnostic tool for acute lower GI hemorrhage.⁸ The authors proposed a new management algorithm for acute lower GI hemorrhage using CT as the preselective mesenteric angiography screening tool.
• Frattaroli et al examined the sensitivity of multi-detector row CT (MDCT) scanning in identifying the site and etiology of acute upper (11 patients) and lower (18 patients) GI bleeding.⁹ Comparing this modality with endoscopy, the investigators reported that, in terms of identifying the anatomic location and etiology of upper GI bleeding, MDCT had a sensitivity of 100% and 90.9%, respectively, while endoscopy had a sensitivity of 72.7% and 54.5%. For lower GI bleeding, MDCT had a sensitivity for site and etiology identification of 100% and 88.2%, respectively, while endoscopy had a sensitivity of 52.9% for both identifications.
• Once the bleeding point is identified, angiography offers potential treatment options, such as selective vasopressin drip and embolization. Thirteen publications reported experiences with selective mesenteric angiography. When 657 patients underwent mesenteric angiography, the percentage of positive study findings fluctuated between 27-86%, with an average of 45%. Because of the intermittent nature of lower GI bleeding, the number of positive study findings is significantly less with this invasive diagnostic modality.
• Emergency angiography as an initial study is indicated in a highly selected group of patients with massive ongoing lower GI bleeding. Browder et al used 2 criteria to triage patients for emergency angiography.¹⁰ The criteria were at least 4 units of blood transfusion in the first 2 hours following hospital admission and systolic blood pressure of less than 100 mm Hg with aggressive resuscitation. Fifty patients underwent emergency angiography, and bleeding was localized in 72% of patients. Vasopressin infusion was successful in 91%; however, half experienced bleeding following cessation of the vasopressin infusion. Thus, patients with ongoing hemorrhage, emergency angiography, and vasopressin infusion have improved operative morbidity, mortality, and outcome.
• Five to 10% of patients may present with recurrent episodes of massive lower GI bleeding without any diagnosis of the bleeding site. These patients experience multiple hospital admissions; they also undergo recurrent blood transfusions and several invasive studies repeatedly. Ryan et al performed 17 elective provocative bleeding studies for occult lower GI bleeding in 16 patients.¹¹ Although an abnormality was identified in 50% of patients, bleeding was provoked in 6 (37.5%) patients. Most of the positively provoked patients (ie, 5 patients) had a previously positive tagged red cell scintigraphy.¹¹ Of the 6 patients with provoked bleeding, 3 were treated with superselective embolization at the time of provoked bleeding, 2 were treated with estrogen therapy, and 1 was treated with palliative therapy.¹¹ Ten patients did not bleed during the provoked study.¹¹
• Widlus and Salis reported 9 patients who underwent provocative angiography with Reteplase, a new fibrinolytic agent.¹² An initial diagnostic visceral arteriogram was performed and failed to identify the source of bleeding in each patient.¹² Reteplase was administered, and provocative arteriography was repeated. Bleeding was identified in 8 (89%) patients, and these patients were treated with microembolization, segmental resection, or conservatively.¹² It was concluded that the use of Reteplase is safe and effective as a provocative agent, stimulating bleeding to allow localization, in patients with occult, recurrent, massive lower GI bleeding.¹²

Other Tests

• Double-contrast barium enema examinations can be justified only for elective evaluation of unexplained lower GI bleeding. Do not use barium enema examination in the acute hemorrhage phase because it makes subsequent diagnostic evaluations, including angiography and colonoscopy, impossible.
• Elective contrast radiography of the small bowel and/or enteroclysis is often valuable in investigation of long-term, unexplained lower GI bleeding.

Diagnostic Procedures

• Colonoscopy has an important role in the diagnosis and treatment of lower GI bleeding. Rapid colonic lavage with GoLYTELY clears the intraluminal blood, clot, and stool, providing an adequate environment for visualization of the lower GI mucosa and lesions. GoLYTELY can be administered orally or by nasogastric tube. The best candidates for colonoscopic evaluation are patients who are bleeding slowly or who have already stopped bleeding.

Histologic Findings

Most colonic diverticula are false pulsion diverticula and are composed only of mucosa and submucosa herniated through the colonic wall musculature. Hemorrhage associated with diverticula comes from perforated vasa rectae located at the neck or the apex of the diverticula.

Colonic angiodysplasias are vascular ectasias commonly located on the right side of the colon. Microscopically, vascular ectasia consists of dilated thin-walled venules and capillaries localized in the submucosa of the colonic wall.

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