A Woman With DVT After a Flight, Anemia, and Bowel Changes

Jun H. Lee, MD; Marc D. Basson, MD, PhD


June 29, 2021

Endoscopy and biopsy is the criterion standard for diagnosing UC. Colonoscopy is more often used because it provides a more thorough view of the whole colon. The gross appearance on endoscopy and histology is used to differentiate between UC and other types of colitis.[4] Still, differentiating or even confirming a diagnosis of IBD is difficult. One study showed that more than 40% of people who were initially diagnosed with indeterminate colitis were found to have UC later on.[8] In that study, 9% of patients initially diagnosed with UC or Crohn disease (CD) had their diagnosis changed, and about 5% of people initially diagnosed with UC were rediagnosed with CD.[8] Vigilance for any changes in symptoms or signs that may warrant re-evaluation of the patient is important.

Key points to differentiate between different causes of colitis are as follows:

  • UC: Continuous inflammation extending proximally from rectum, erythematous, friable, granular appearance, shallow ulcerations, mucosal or submucosal involvement only, crypt abscesses, lymphocytes in lamina propria; most always involves rectum; varying severity of diarrhea

  • CD: Skip lesions, cobblestone appearance, granulomas, transmural inflammation; rectum less commonly involved, can involve any part of the gastrointestinal tract; perianal disease; abdominal pain common; diarrhea less severe

  • Ischemic colitis: Acute onset, petechial hemorrhage within areas of pallor, dusky, mucosal fibrosis, crypt atrophy; elderly patients; vascular disease; often painful

  • Infectious colitis: Acute onset, mucosal erosions, positive serology and stool examination; travel history; food poisoning

  • Pseudomembranous colitis: Multiple yellow mushroom-like plaques; recent antibiotic use; C difficile toxin-positive stool

Efforts have been made to determine if serologic markers can be used to differentiate between UC and CD. Determinations of perinuclear antineutrophilic cytoplasmic antibodies and anti-Saccharomyces cerevisiae antibodies together were specific but not sensitive for diagnosing UC.[9] Thus, no validated blood tests can facilitate the diagnosis of UC at this time.

The histologic results and the gross appearance within the colon in this patient's case correspond best with UC. The continuous nature of the lesion with a granular pattern and crypt abscesses are textbook diagnostic criteria for UC. Although this patient has a background of thrombophilia and was admitted with a DVT, ischemic colitis is more commonly due to arterial blockage rather than venous thrombosis. The thrombotic episode may have been secondary to the ongoing inflammatory state as patients with IBD are at higher risk of developing a thrombotic episode.[10] She also does not have a history of vasculopathy or signs of dehydration, as her blood urea nitrogen/creatinine ratio and urine-specific gravity are normal. Thus, ischemic colitis is less likely in this case. Infectious or pseudomembranous colitis are also less likely because of the negative stool test and lack of recent antibiotic use or trip abroad in her history. Although differentiating between UC and CD is difficult with history and examination alone, perianal disease is more commonly seen in patients with CD, which makes the diagnosis of CD less likely here. Lastly, colon cancer is unlikely in this case due to the shorter history of presentation and no associated weight loss or palpable mass.


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