Differential Diagnosis for Rectal Bleeding and Anal Symptoms

The patient's symptoms of bright red rectal bleeding, excruciating pain with defecation, and constant anal itching can be evaluated based on the provided options and other potential diagnoses. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Thrombosed Hemorrhoid: This condition is characterized by severe pain, especially during defecation, and is often accompanied by bright red bleeding. The sudden onset of symptoms and the nature of the pain and bleeding make this a highly plausible diagnosis.

• Other Likely Diagnoses

  • Anal Fissure: Although not listed among the options, anal fissures can cause severe pain during and after defecation and can lead to bright red bleeding. The constant anal itching could be secondary to the fissure or another condition.
  • Condylomata Acuminata (Genital Warts): While these can cause itching and discomfort, they are less likely to cause the severe pain and bright red bleeding described. However, they should be considered in the differential due to the symptom of itching.

• Do Not Miss Diagnoses

  • Anal Tumor: Although less common, an anal tumor (such as anal cancer) could present with bleeding, pain, and itching. It's crucial to rule out malignancy due to its significant implications for treatment and prognosis.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause rectal bleeding, pain, and itching. While the acute onset might be less typical, IBD should be considered, especially if other symptoms like diarrhea or weight loss are present.

• Rare Diagnoses

  • Proctitis: Inflammation of the rectum can cause bleeding, pain, and itching. This could be due to infectious or inflammatory causes and is less common but should be considered if other diagnoses are ruled out.
  • Solitary Rectal Ulcer Syndrome: This condition can cause rectal bleeding and pain, often associated with straining during defecation. It's less common and might not fully explain the itching, but it remains a rare consideration.