Differential Diagnosis for Rectal Bleeding in a Patient with Psoriatic Arthritis
Single Most Likely Diagnosis
- Inflammatory Bowel Disease (IBD): Given the patient's history of psoriatic arthritis, an autoimmune condition, there's an increased likelihood of also having IBD, such as Crohn's disease or ulcerative colitis, which are known to cause rectal bleeding.
Other Likely Diagnoses
- Gastrointestinal Infections: Infections can cause rectal bleeding and are more common in patients with compromised immune systems, which might be the case if the patient is on immunosuppressive therapy for psoriatic arthritis.
- Diverticulosis: A common condition in adults that can cause rectal bleeding, especially if the patient is over 40 years old.
- Hemorrhoids: Very common and can cause rectal bleeding, especially with straining during bowel movements.
- Anal Fissures: Can cause painful rectal bleeding, especially if the fissure is deep.
Do Not Miss Diagnoses
- Colorectal Cancer: Although less likely in younger patients, the presence of rectal bleeding necessitates ruling out colorectal cancer, especially if there are other risk factors present.
- Ischemic Colitis: Reduced blood flow to the colon can cause rectal bleeding and is a medical emergency.
- Infectious Colitis (e.g., C. difficile): Especially if the patient has been on antibiotics, which can disrupt normal gut flora and lead to an overgrowth of harmful bacteria.
Rare Diagnoses
- Intussusception: A condition where a part of the intestine slides into an adjacent part, which can cause bowel obstruction and bleeding.
- Angiodysplasia: Vascular malformations of the gastrointestinal tract that can cause recurrent bleeding.
- Solitary Rectal Ulcer Syndrome: A condition that can cause rectal bleeding, typically associated with chronic constipation and straining during bowel movements.
- Ehlers-Danlos Syndrome: A group of disorders that affect connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues, which can lead to gastrointestinal complications including rectal bleeding.