Clinical Presentation

In infectious diarrhea, symptoms will depend on the pathogenic properties of the organism involved. In IBD, the extent and severity of disease are the important factors. It is the chronicity of the patient's symptoms that will best help to distinguish infectious from idiopathic inflammation, as many features of the patient's history may be common to both conditions.

The setting in which the diarrhea develops is helpful in making a diagnosis. The history should include recent types of food eaten and places where food was obtained; presence of other affected individuals; recent travel history; recent antibiotic use or chemotherapy; recent hospitalizations; recent contacts with daycare centers, nursing homes, or mental institutions; and recent sexual contacts. Clearly the state of the host's immunity and underlying defense mechanisms must be considered, as impaired hosts are more susceptible to pathogenic GI infections. The presence of an immunocompromised state such as IgA deficiency, AIDS, steroid or immunosuppressive drug use, status post organ transplant, sickle cell disease, or neutropenic cancer patients may change the differential diagnosis.

The infectious inflammatory diarrheal syndrome is usually characterized by small-volume mucoid bloody stool rather than pure rectal bleeding. The bleeding component of the syndrome may be preceded by several days of watery diarrhea. Infectious causes of significant bleed-

Table 1 Infectious Agents Causing Acute Gastrointestinal Bleeding


Campylobacter Clostridium difficile Enterohemorrhagic E. coli Salmonella Shigella

Vibrio parahaemolyticus Yersinia Parasitic

Crytposporidium Entamoeba histolytica Viral

Cytomegalovirus Herpesvirus ing along with diarrhea include Salmonella, Shigella, Campylobacter, enterohemorrhagic E. coli, enterinvasive E. coli, Clostridium difficile, Entamoeba histolytica, and Yersinia. Bleeding can also occur from viral agents, most commonly cytomegalovirus (CMV), which causes discrete ulcerations, herpes simplex virus (HSV), and human papillomavirus (HPV), which result in mass lesions that may bleed secondary to friability and trauma (Table 1).

The clinical features of infectious colitis can vary with the affected area of the GI tract. Organisms that are found in the colon cause lower abdominal pain, tenesmus, and mucoid bloody stool. Toxins and microorganisms that attack small bowel enterocytes cause crampy diffuse periumbilical pain and large volume (>1 L/day) watery diarrhea without tenesmus.

In IBD, symptoms are usually chronic, although bloody diarrhea may bring the patient to a physician's attention. Bloody diarrhea is a predominant symptom in approximately 10-46% of patients with Crohn's disease (3), but most patients with ulcerative colitis have bloody diarrhea. Acute life-threatening lower GI bleeding is reported in 6-10% of those emergency surgical resections for ulcerative colitis but in only in 0.6-2% for Crohn's disease (4,5). As part of the history, it is helpful to know whether the patient has a family history of IBD, as well as smoking status. Patients who recently quit smoking are at higher risk for increased disease activity in ulcerative colitis; patients with Crohn's disease tend to be smokers more often than the normal population (6).

Ulcerative colitis typically begins in the rectum and extends proxi-mally. Symptoms tend to develop gradually, with the predominant symptom of diarrhea, accompanied by blood. Occasionally it may begin with infrequent stools but pure rectal bleeding, secondary to the significant rectal inflammation, resulting in a functional right-sided constipation. The course is usually chronic, characterized by remission with intermittent episodes of relapse (7). Less commonly, the course may be continuous, with unrelenting symptoms and eventual surgery. The severity of the symptoms tends to parallel the severity of the inflammation, not necessarily the extent. In other words, a limited extent does not guarantee a more benign course. Symptoms range from occasional rectal bleeding even without diarrhea to profuse purulent bloody diarrhea. Patients may experience lower abdominal pain, urgency, tenesmus, and incontinence. With more severe inflammation, patients also have systemic complaints such as decreased appetite, weight loss, malaise, fatigue, weakness, or fevers. Extraintestinal manifestations of ulcerative colitis and Crohn's disease include arthralgias, skin rashes (pyoderma, gangrenosum, erythema nodosum), and uveitis.

In contrast to ulcerative colitis, in which diarrhea and bloody stools are present early in the disease, patients with Crohn's disease may have a less dramatic presentation, and the symptoms may be insidious. Patients may have vague abdominal pain and intermittent diarrhea for years before the diagnosis of Crohn's disease is considered. The predominant symptom usually correlates with disease location. In isolated small bowel disease (30% of patients with Crohn's disease), blood loss is usually occult (3). Forty percent of patients have ileocecal disease at initial presentation and have pain and diarrhea but rarely significant bleeding. Fortunately, acute hemorrhage is rare in patients with small bowel disease.

Twenty-five percent of patients with Crohn's disease have involvement limited to the colon. It is this group of patients that will present with symptoms similar to those of ulcerative or infectious colitis. Patients complain of abdominal pain, fever, weakness, and hemato-chezia. Again, the diarrhea may be associated with urgency, tenesmus, and incontinence. The presence of perianal disease (anal structuring, perirectal abscess, fistula formation) should alert the clinician to the distinct possibility of Crohn's disease.

The physical exam varies with the severity of the bleeding and its effect on the patient but will most likely be nonspecific. In mild cases of colitis, the physical exam may be unremarkable. In severe cases, fever, tachycardia, and pallor are consequences of dehydration, blood loss, and malnutrition. Mucous membranes may be dry and skin turgor diminished. An abdominal exam will determine tenderness or signs of peritonitis. Bowel sounds range from hypoactive (absence of peristalsis in toxic dilation) to hyperactive. A distended abdomen is of concern for toxic megacolon. Inflammatory masses may be palpable and suggestive of ileocecal Crohn's disease. A detailed perianal and rectal exam should be performed to assess for large skin tags, fistulae or abscess, mass lesions, and the gross appearance of stool. Other features that should be noted are the presence of oral ulcers, ocular inflammation, or skin lesions. These are systemic manifestations of certain infectious organisms or IBD.

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