Differential Diagnosis for Bright Red Blood on Outside of Stool
- Single most likely diagnosis
- Hemorrhoids: This is the most common cause of bright red blood on the outside of stool, especially if there's no blood on the toilet paper. Hemorrhoids are swollen veins in the lowest part of the rectum or anus, and they can bleed when they become irritated or strained.
- Other Likely diagnoses
- Anal fissure: A small tear in the lining of the anus can cause bright red blood on the stool. The pain associated with an anal fissure often occurs during and after bowel movements.
- Rectal prolapse: Although less common, a rectal prolapse can cause bleeding, especially if there's a significant portion of the rectum protruding through the anus.
- Inflammatory bowel disease (IBD): Conditions like ulcerative colitis or Crohn's disease can cause rectal bleeding, though they often present with other symptoms like diarrhea, abdominal pain, and weight loss.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Colorectal cancer: Although less likely in younger individuals without risk factors, colorectal cancer can present with rectal bleeding. It's crucial to rule out this diagnosis, especially in individuals over 50 or those with a family history of colorectal cancer.
- Gastrointestinal bleeding from a upper source (e.g., diverticulosis, angiodysplasia): While the blood is on the outside of the stool, it's essential to consider that the source could be higher up in the gastrointestinal tract, especially if the amount of blood is significant or the patient has other symptoms like dizziness or abdominal pain.
- Rare diagnoses
- Rectal varices: Enlarged veins in the rectum, often associated with liver disease, can cause bleeding.
- Arteriovenous malformation (AVM): A rare condition where there's an abnormal connection between arteries and veins, which can cause bleeding.
- Infections (e.g., rectal tuberculosis, amoebiasis): Certain infections can cause rectal bleeding, though they are less common in many parts of the world and often present with other symptoms like weight loss, fever, or diarrhea.