What is the cause of diarrhea lasting 15 days and a single episode of bright red blood per rectum (BRBPR) without fever, with normal vitals and no abdominal pain?

From the Guidelines

For a patient with diarrhea for 15 days and bright red blood per rectum (BRBPR) for 1 day, without fever, with normal vitals and no abdominal pain, I recommend a comprehensive workup to rule out inflammatory or infectious causes. The patient's symptoms of prolonged diarrhea and BRBPR without fever or abdominal pain suggest a possible inflammatory or infectious process rather than simple viral gastroenteritis, which typically resolves within 3-5 days 1.

Initial Evaluation

Initial evaluation should include:

• Stool studies (culture, ova and parasites, Clostridioides difficile toxin) to identify potential bacterial, viral, or parasitic pathogens 1
• Complete blood count, comprehensive metabolic panel, and inflammatory markers like C-reactive protein and fecal calprotectin to assess for signs of inflammation or infection 1

Further Testing

The patient should undergo colonoscopy within 1-2 weeks to evaluate for inflammatory bowel disease, ischemic colitis, or malignancy, as these conditions can present with similar symptoms 1.

Symptomatic Treatment

While awaiting these results, symptomatic treatment with loperamide 2mg after each loose stool (maximum 8mg/day) can be offered, along with oral rehydration and electrolyte replacement to manage symptoms and prevent dehydration 1.

Dietary Modifications

Diet modification to include low-fiber, non-spicy foods and avoiding dairy, caffeine, and alcohol is advised to help manage symptoms and reduce the risk of exacerbating the condition 1.

Potential Causes

Recent antibiotic use, travel history, and dietary changes should be explored as potential causes of the patient's symptoms, as these can increase the risk of developing infectious diarrhea 1. The presence of blood with prolonged diarrhea raises concern for inflammatory or infectious processes, and the absence of fever and abdominal pain is somewhat reassuring against severe inflammatory conditions, but the duration and bleeding warrant thorough investigation 1.

From the Research

Possible Causes of Diarrhea and BRBPR

• Diarrhea lasting 15 days and a single episode of bright red blood per rectum (BRBPR) without fever, with normal vitals and no abdominal pain can be caused by various factors, including infectious agents 2, 3, 4, 5, 6
• The presence of BRBPR suggests a possible invasive or inflammatory cause, such as Shigella, Salmonella, Campylobacter, or Shiga toxin-producing Escherichia coli (STEC) infections 3, 4

Diagnostic Approach

• A diagnostic workup, including stool culture and testing for Clostridium difficile, may be necessary to determine the cause of the diarrhea and BRBPR 3, 4, 6
• The absence of fever and abdominal pain does not rule out the possibility of an infectious cause, and further evaluation may be needed to determine the underlying cause 2, 5

Treatment Options

• Symptomatic therapy, including oral rehydration, is the mainstay of treatment for most cases of infectious diarrhea 2, 4, 5, 6
• Antibiotic therapy may be considered in certain cases, such as severe or prolonged diarrhea, or in patients with underlying comorbidities or immunosuppression 2, 3, 4, 5, 6
• However, routine empirical use of antibiotics is not recommended for most adults with mild, watery diarrhea, due to the risk of antibiotic resistance and the self-limited nature of most cases 2, 5, 6