Gastrointestinal Bleeding, Lower

Sara Karjoo

Chris A. Liacouras

INTRODUCTION

The presence of blood in the gastrointestinal tract is always abnormal. Blood in the stool can occur in several forms: hematochezia (bright red blood on the stool), “currant-jelly” stools (thickened brick-red blood on the stool), melena (dark or black stools), or occult bleeding (normal-appearing stools that test positive by Hemoccult or guaiac testing).

Blood acts as a cathartic that decreases intestinal transit time. Therefore, hematochezia usually signifies colonic disease (i.e., bleeding from a site between the distal colon and the terminal ileum), but it may be the result of profuse proximal gastrointestinal tract bleeding. Melena usually signifies profuse upper intestinal bleeding (above the ligament of Treitz), whereas currant-jelly stools commonly occur when there is shedding of the intestinal mucosa as a result of an active Meckel diverticulum or intussusception. Normal-appearing stools that test positive for blood suggest slow gastrointestinal tract bleeding. Table 34-1 lists causes of bloody stools by site.

DIFFERENTIAL DIAGNOSIS LIST

The following are common causes of hematochezia and melena:

Infectious Causes

Bacterial Infection

Salmonella

Shigella

Campylobacter

Yersinia

Enterohemorrhagic Escherichia coli

Aeromonas

Plesiomonas

Clostridium difficile

Parasitic Infection

Entamoeba histolytica

Balantidium coli

Necator americanus (hookworm)

Strongyloides stercoralis

Ascaris lumbricoides

TABLE 34-1 Causes of Bloody Stools by Site

Site	Cause
Nasopharynx	Epistaxis, gum disease, oral or nasal trauma, tonsillectomy, adenoidectomy
Esophagus	Esophageal stricture, esophagitis, ulcer, varices, eosinophilic enteritis, graft-versus-host disease (GVHD)
Stomach	Gastritis, ulcer, foreign body, vascular anomaly, tumor, duplication, polyp, infection
Duodenum	Ulcer, celiac disease, malrotation, vascular anomaly, post-viral enteritis, parasitic infection
Small bowel	Inflammatory bowel disease, celiac disease, volvulus, malrotation, necrotizing enterocolitis, infection, Henoch-Schönlein purpura, duplication, Meckel diverticulum, vascular anomaly, tumor, eosinophilic enteritis
Colon	Polyp, inflammatory bowel disease, infection, Hirschsprung disease, trauma, sexual abuse, hemorrhoid, tumor, hemolytic uremic syndrome, Henoch-Schönlein purpura, milk-protein or soy-protein allergy, rectal varices, intussusception, volvulus, fissure, solitary rectal ulcer, foreign body, vascular anomaly, GVHD

Viral Infection

Adenovirus

Rotavirus

Cytomegalovirus

HIV

Neoplastic Causes

Leiomyoma

Lymphoma

Adenocarcinoma

Carcinoid

Traumatic Causes

Anal fissure

Foreign body

Sexual abuse

Congenital or Vascular Causes

Meckel diverticulum

Enteric duplication

Arteriovenous malformation (AVM)

Hemangioma

Hemorrhoids

Rectal varices

Esophageal varices (rapid flow)

Hirschsprung enterocolitis

Inflammatory Causes

Juvenile polyps

Polyposis syndromes

Inflammatory bowel disease

Lymphonodular hyperplasia

Necrotizing enterocolitis

Milk- or soy-protein allergy

Eosinophilic gastroenteritis

Graft-versus-host disease

Vasculitis (systemic lupus erythematosus)

Miscellaneous Causes

Rapid upper gastrointestinal bleeding

Intussusception

Volvulus

Solitary rectal ulcer

Coagulopathy

Thrombocytopenia

Anticoagulant drug therapy

Henoch-Schönlein purpura

Hemolytic uremic syndrome

TABLE 34-2 Foods and Drugs Mimicking Blood in the Stool

False Hematochezia	False Melena	False Heme-Positive Stools
Foods that contain red dye	Spinach	Red meat
Juice	Blueberries	Cherries
Candy	Licorice	Tomato skin
Kool-Aid	Purple grapes	Iron supplements
Jell-O	Chocolate
Tomatoes	Grape juice
Beets	Bismuth subsalicylate
Cranberries	Iron supplements
Cefdinir

DIFFERENTIAL DIAGNOSIS DISCUSSION

C. Difficile Colitis (Pseudomembranous Colitis, Antibiotic-Induced Colitis)

Etiology

The toxins produced by C. difficile have cytotoxic effects on the colonic mucosa. Although C. difficile colitis is usually associated with an imbalance of the gastrointestinal flora following the administration of broad-spectrum antibiotics (e.g., clindamycin, amoxicillin, cephalosporin), it can develop in patients with underlying intestinal disorders (e.g., inflammatory bowel disease) and those who have undergone recent abdominal surgery, institutionalized patients (as a result of cross-infection), and, sporadically, in otherwise healthy patients. Although C. difficile can also cause disease in young infants, this age group can have C. difficile carriage in the stool without symptoms. After 2 years of age, C. difficile toxin-positive stools are pathologic.

Clinical Features

C. difficile is associated with a wide variety of clinical symptoms. Patients may be asymptomatic, or they may experience frequent, painful, bloody diarrhea, a sign of severe, life-threatening colitis. Typically, children present with abdominal pain and frequent bloody, mucus-streaked, foul-smelling, watery stools. Some patients may be dehydrated.

Evaluation

Fresh stool specimens (transported on ice or frozen) should be collected and evaluated for the presence of C. difficile toxins A and B. In patients with persistent bloody diarrhea and a negative microbiologic evaluation, colonoscopy should be performed. Colonoscopy often reveals the classic mucosal pseudomembrane formation (raised yellow plaques).

Treatment

Treatment includes discontinuation of the inciting antibiotic and therapy with oral metronidazole (see Chapter 27, “Diarrhea, Acute”). Typically, oral metronidazole is the first-line therapy, and can be used for a second course if the symptoms recur. Vancomycin is an alternative antibiotic that is used when patients do not respond to metronidazole. Use of vancomycin as first-line therapy is discouraged because there is potential for creating vancomycin-resistant organisms. Symptoms usually resolve within 3 to 5 days. Recurrent episodes may occur following cessation of therapy; in this situation, repeat treatment and further evaluation for other underlying systemic disorders (e.g., inflammatory bowel disease) are indicated. Good hand-washing with water and soap should be encouraged because the C. difficile spores are resistant to regular alcoholic hand rubs. Dehydrated patients require intravenous fluids and the short-term introduction of clear liquids.

Only gold members can continue reading. Log In or Register to continue