Differential Diagnosis for Chronic Functional Epigastric Pain and IBS

Given the patient's history of chronic functional epigastric pain, irritable bowel syndrome (IBS), and previous negative endoscopies, the differential diagnosis can be organized into the following categories:

• Single Most Likely Diagnosis
  • Irritable Bowel Syndrome (IBS) with abdominal pain and diarrhea: This is the most likely diagnosis given the patient's history of IBS and the presentation of abdominal pain and diarrhea. The fact that the patient has undergone multiple endoscopies without finding any structural abnormalities supports this diagnosis.
• Other Likely Diagnoses
  • Functional Dyspepsia: This condition is characterized by chronic epigastric pain or discomfort without any evidence of organic disease. Given the patient's history of chronic functional epigastric pain, this is a plausible diagnosis.
  • Small Intestine Bacterial Overgrowth (SIBO): This condition can cause abdominal pain, diarrhea, and bloating, and is often associated with IBS. The patient's symptoms could be consistent with SIBO.
  • Inflammatory Bowel Disease (IBD) (e.g., Crohn's disease, ulcerative colitis): Although the patient has had multiple negative endoscopies, it is possible that the disease is limited to a segment of the bowel that was not visualized or is in remission.
• Do Not Miss Diagnoses
  • Gastrointestinal Cancer: Although the patient has had multiple negative endoscopies, it is essential to consider the possibility of gastrointestinal cancer, particularly if there are any "red flag" symptoms such as weight loss, bleeding, or anemia.
  • Celiac Disease: This autoimmune disorder can cause abdominal pain, diarrhea, and malabsorption, and can be associated with IBS-like symptoms.
  • Ischemic Bowel Disease: This condition can cause abdominal pain and diarrhea, particularly in older patients or those with risk factors for vascular disease.
• Rare Diagnoses
  • Eosinophilic Gastroenteritis: This rare condition is characterized by eosinophilic infiltration of the gastrointestinal tract, which can cause abdominal pain, diarrhea, and other symptoms.
  • Mastocytic Enterocolitis: This condition is characterized by an increased number of mast cells in the gastrointestinal tract, which can cause abdominal pain, diarrhea, and other symptoms.
  • Chronic Intestinal Pseudo-Obstruction: This rare condition is characterized by recurrent episodes of intestinal obstruction without any mechanical obstruction, which can cause abdominal pain, diarrhea, and other symptoms.

Each of these diagnoses should be considered in the context of the patient's history, physical examination, and laboratory results to determine the most appropriate diagnosis and treatment plan.