What is the most likely diagnosis for a patient with bloody diarrhea and crypt abscesses found on biopsy?

The most likely diagnosis is ulcerative colitis, particularly when considering the presence of bloody diarrhea and crypt abscesses found on biopsy. Ulcerative colitis is characterized by inflammation of the colonic mucosa and can cause symptoms like bloody diarrhea due to ulceration and erosion of the intestinal lining. The crypt abscesses, which are collections of neutrophils in the crypts of the colonic mucosa, are a classic histological feature of ulcerative colitis.

In ulcerative colitis, the inflammation is usually continuous and can affect the rectum and extend proximally in a contiguous manner, often leading to significant clinical manifestations such as bloody stools. The presence of crypt abscesses is a strong indicator of this condition, distinguishing it from other forms of colitis where such findings might not be present.

Other potential diagnoses like Crohn's disease, while it can also cause diarrhea and inflammation of the colon, typically has a non-continuous pattern of lesions and may not prominently feature crypt abscesses in the same way ulcerative colitis does. Diverticular colitis could present with some similar symptoms, but it is associated more with diverticular disease rather than the specific histopathological findings of crypt abscesses.