Differential Diagnosis

The patient presents with lower back pain, bloating, and gastrointestinal symptoms including bright blood in the stool and altered stool color, which has recurred. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Inflammatory Bowel Disease (IBD): Conditions like Ulcerative Colitis or Crohn's Disease can cause recurring episodes of bloody stools, abdominal pain, bloating, and changes in bowel habits. The recurrence of symptoms and the presence of bright blood are particularly suggestive of IBD.

• Other Likely Diagnoses

  • Gastroenteritis: Infections can cause similar symptoms, including bloody stools, especially if caused by certain bacteria like E. coli or Salmonella. However, the recurring nature and the specific combination of symptoms might make this less likely.
  • Anal Fissure: Can cause bright red blood, especially if the fissure is acute and painful. However, it might not fully explain the bloating and altered stool color.
  • Hemorrhoids: Could cause bright red blood, but typically wouldn't cause changes in stool color or significant bloating.

• Do Not Miss Diagnoses

  • Intussusception: A condition where a part of the intestine slides into an adjacent part, which can cause bowel obstruction and ischemia. It's a surgical emergency and can present with bloody stools, abdominal pain, and changes in bowel habits.
  • Infectious Colitis: Certain infections (e.g., Clostridioides difficile) can cause severe colitis, presenting with bloody diarrhea, abdominal pain, and systemic symptoms. Missing this diagnosis could lead to severe complications.
  • Colon Cancer: Although rare in young individuals, it's crucial not to miss, especially if there's a family history. Symptoms can include changes in bowel habits, blood in the stool, and abdominal pain.

• Rare Diagnoses

  • Meckel's Diverticulum: A congenital anomaly of the small intestine that can cause gastrointestinal bleeding, but it's more common in children and might not explain all the symptoms.
  • Angiodysplasia: Vascular malformations in the gut that can cause bleeding, but this is more common in older adults and might not fully account for the patient's symptoms.
  • Ehlers-Danlos Syndrome: A genetic disorder that can affect the gastrointestinal system, among other systems, and cause symptoms like those described, but it's rare and would likely be accompanied by other systemic symptoms.