A 64-year-old man comes to the emergency department due to diarrhea and intermittent abdominal cramps for the past 6 weeks. The patient has had 4 or 5 bowel movements every day over this period, and the stools contain blood and mucus. He also reports poor appetite and fatigue and has lost 5.9 kg (13 lb). The patient has intermittent right knee swelling and tenderness that responds to ibuprofen. He has taken no antibiotics recently and has no other medical conditions. The patient was last seen by a physician 2 years ago; his last colonoscopy 4 years ago was normal. Family history is positive for colon cancer in his mother. Temperature is 38.1 C (100.6 F), blood pressure is 142/84 mm Hg, pulse is 98/min, and respirations are 16/min. Physical examination shows tenderness in the left lower quadrant without rebound or guarding. Digital rectal examination is positive for blood. Laboratory results are as follows:
| Leukocytes | 13,600 mm3 |
| Hemoglobin | 9.6 g/dL |
| Platelets | 314,000/mm3 |
| Erythrocyte sedimentation rate | 65 mm/hr |
Flexible sigmoidoscopy reveals erythematous, friable mucosa of the entire rectum and the majority of the sigmoid colon. Small, shallow ulcers are also seen. Which of the following is the most likely cause of this patient's current condition?
Inflammatory bowel disease subtype characteristics | ||
Crohn disease | Ulcerative colitis | |
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RLQ = right lower quadrant. | ||
This patient's symptoms are concerning for ulcerative colitis (UC), a subtype of inflammatory bowel disease (IBD). Similar to Crohn disease (CD), most patients develop UC between age 15 and 40, although it can be diagnosed at any age. UC is characterized by chronic idiopathic inflammation of the rectum and other portions of the colon with intermittent exacerbations. Patients commonly have abdominal pain, bloody diarrhea, tenesmus, fecal incontinence, fever, and, in severe cases, weight loss. Inflammatory arthritis, as seen in this patient, is a common extraintestinal manifestation of both UC and CD, and nonsteroidal anti-inflammatory drugs (eg, ibuprofen) used to treat arthritis symptoms may worsen underlying bowel inflammation.
Laboratory findings in UC can include leukocytosis, anemia (mixed iron deficiency and chronic disease), reactive thrombocytosis, and elevated inflammatory markers (eg, erythrocyte sedimentation rate). Colonoscopy or flexible sigmoidoscopy typically demonstrates erythematous and friable mucosa with ulcers; the lesions are usually continuous and circumferential (unlike in CD). Biopsy shows inflammation limited to the mucosa and submucosa (compared to transmural inflammation in CD).
(Choice A) Amebic dysentery presents with bloody diarrhea, abdominal pain, and elevated inflammatory markers, but exudative ulcerations and skip lesions (as opposed to continuous inflammation) are usually seen. This patient's flexible sigmoidoscopy findings are more consistent with UC.
(Choice B) Clostridioides difficile infection is classically associated with pseudomembranes on endoscopy. It usually causes pancolitis, presents with watery diarrhea, and occurs most commonly in patients with a history of recent antibiotic use.
(Choice C) Although weight loss, bloody stools, and anemia can be seen in colon cancer, this patient's flexible sigmoidoscopy findings are highly suggestive of UC, which also explains these findings. Furthermore, this patient had a normal colonoscopy 4 years ago, making colon cancer less likely.
(Choices D and E) Patients with chronic colonic ischemia or small vessel vasculitis can have bloody diarrhea and weight loss and may be initially misdiagnosed with UC. However, involvement of the rectum, which has a dual blood supply, makes atherosclerotic ischemic colitis less likely (watershed areas at the splenic flexure or rectosigmoid junction are usually affected). In addition, this patient's lack of other findings of small vessel inflammation (eg, skin, pulmonary, or renal involvement) reduces the likelihood of vasculitis.
Educational objective:
Ulcerative colitis most commonly develops between ages 15 and 40, but it can be diagnosed at any age. Symptoms include abdominal pain, bloody diarrhea, tenesmus, and fecal incontinence. Colonoscopy or flexible sigmoidoscopy demonstrates continuous colonic involvement with ulcers and erythematous, friable mucosa.