Differential Diagnosis for Melena with Normal Coloscopy and Endoscopy
Single Most Likely Diagnosis
- Angiodysplasia: A vascular malformation in the gastrointestinal tract that can cause bleeding, which may not be visible on initial endoscopy or coloscopy, especially if the bleeding has stopped. The fact that there was no recurrence of melena since the initial episode suggests a possible self-limiting condition like angiodysplasia.
Other Likely Diagnoses
- Mallory-Weiss Tear: A tear in the mucous membrane or lining of the lower end of the esophagus, where it connects to the stomach, which can cause bleeding. Although endoscopy was normal, a Mallory-Weiss tear could have healed by the time of the procedure.
- Gastric or Duodenal Ulcer: Although endoscopy was reported as normal, it's possible that a small ulcer was missed, especially if it was not actively bleeding at the time of the procedure. Ulcers can heal on their own, explaining the lack of recurrence.
- Hemorrhoids: Internal hemorrhoids can cause melena, and if they were not prolapsed or significantly bleeding at the time of examination, they might have been overlooked.
Do Not Miss Diagnoses
- Gastrointestinal Cancer: Although less likely given the normal coloscopy and endoscopy, it's crucial not to miss a diagnosis of gastrointestinal cancer. Some cancers might not be visible or might be in a location that's difficult to reach with standard endoscopy or coloscopy.
- Vascular Disorders (e.g., AV Malformations): Similar to angiodysplasia, other vascular disorders could cause bleeding that might not be evident on initial examination.
- Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause bleeding. The fact that there was no recurrence doesn't rule out IBD, as these conditions can have periods of remission.
Rare Diagnoses
- Dieulafoy's Lesion: A rare cause of gastrointestinal bleeding characterized by a small, usually solitary mucosal defect with an exposed, often large caliber, persistent artery at its base. It can be easily missed on endoscopy if not actively bleeding.
- Intussusception: Although more common in children, intussusception (the telescoping of one portion of the intestine into another) can occur in adults and cause bleeding. It might not be visible on standard endoscopy or coloscopy.
- Meckel's Diverticulum: A congenital diverticulum of the small intestine that can cause bleeding due to the presence of ectopic gastric mucosa. It's a rare cause of melena and might not be detected by standard endoscopy or coloscopy.