A patient presents to your office with symptoms of bloating, abdominal distension, pain, cramping, and bouts of both diarrhea and constipation. An exam is unremarkable, and all labs are normal. A CT scan of the abdomen is normal, and both colonoscopy and EGD with biopsies are unremarkable.

What is the most likely diagnosis?

A) Irritable bowel syndrome (IBS)
B) Ulcerative colitis
C) Crohn's disease
D) Diverticular disease

The most likely diagnosis for a patient with abdominal pain, bloating, and alternating bouts of diarrhea and constipation, with all tests being normal, is Irritable bowel syndrome (IBS). Therefore, the correct answer is option A) Irritable bowel syndrome or IBS

Explanation:

Considering the symptoms presented by the patient and the fact that all tests including lab work, CT scans, and endoscopy results are normal, the most likely diagnosis is A) Irritable bowel syndrome or IBS. IBS is characterized by a group of symptoms rather than a disease, and it often involves abdominal pain, bloating, and changes in bowel movements. In the case of IBS, no permanent structural damage is visible in the large intestine, distinguishing it from other conditions like inflammatory bowel diseases such as Crohn's disease or ulcerative colitis. IBS symptoms can often be managed through diet changes, stress reduction, and medication. Therefore, the correct answer is option A) Irritable bowel syndrome or IBS