Differential Diagnosis for a 45-year-old Male with Bright Red Blood in Stool and Associated Symptoms

Single Most Likely Diagnosis

• Diverticulitis or Diverticulosis: The presence of bright red blood in the stool, a feeling of a "wet" rectum, and the inability to wipe completely are common symptoms associated with diverticular disease. The mild epigastric pain could be related to the diverticulitis if it's complicated or if there's an associated condition like gastritis.

Other Likely Diagnoses

• Rectal Ulcer or Proctitis: These conditions can cause rectal bleeding and a sensation of incomplete evacuation or a feeling of wetness due to mucous or blood.
• Inflammatory Bowel Disease (IBD): Conditions like ulcerative colitis or Crohn's disease can present with rectal bleeding, abdominal pain, and changes in bowel habits.
• Gastrointestinal Infection: Certain infections can cause similar symptoms, including rectal bleeding, abdominal pain, and changes in stool consistency.

Do Not Miss Diagnoses

• Colorectal Cancer: Although less common in a 45-year-old without a family history, it's crucial to rule out colorectal cancer due to its potential severity and the fact that symptoms can sometimes be non-specific.
• Ischemic Colitis: This condition can present with sudden onset of abdominal pain and rectal bleeding, and it requires prompt diagnosis and treatment to prevent complications.
• Infectious Colitis (e.g., Clostridioides difficile): Especially if the patient has recently been on antibiotics, C. difficile infection can cause severe diarrhea, abdominal pain, and potentially life-threatening complications.

Rare Diagnoses

• Angiodysplasia: A vascular anomaly of the gastrointestinal tract that can cause bleeding, more commonly seen in the elderly.
• Solitary Rectal Ulcer Syndrome: A condition characterized by rectal bleeding, mucous discharge, and a feeling of incomplete evacuation, often associated with chronic straining during defecation.
• Dieulafoy's Lesion: A rare cause of gastrointestinal bleeding due to a mucosal ulceration overlying a persistent arteriole, which can be found in various parts of the GI tract, including the rectum.

Each of these diagnoses should be considered and evaluated based on the patient's complete medical history, physical examination, and appropriate diagnostic tests to determine the underlying cause of the symptoms.