Differential Diagnosis for Daily Nausea and Pain in Lower Right Abdomen

Given the symptoms of daily nausea and pain in the lower right abdomen, especially after eating, with no gallstones, no celiac disease, a clear endoscopy, and a clear abdominal ultrasound, but with mild inflammation in the stomach, the differential diagnosis can be broken down into the following categories:

• Single Most Likely Diagnosis (40%):
  • Irritable Bowel Syndrome (IBS): This condition is characterized by chronic abdominal pain, bloating, and alteration of bowel habits in the absence of any mechanical, inflammatory, or biochemical abnormalities. The presence of symptoms after eating and the absence of other findings make IBS a plausible diagnosis.
• Other Likely Diagnoses (40%):
  • Functional Dyspepsia: Characterized by persistent or recurrent upper abdominal pain or discomfort that is not exclusively relieved by defecation or associated with the onset of a bowel movement. The mild inflammation in the stomach could contribute to this diagnosis.
  • Inflammatory Bowel Disease (IBD): Although the endoscopy was clear, IBD (including Crohn's disease and ulcerative colitis) can sometimes present with subtle or patchy inflammation that might not be detected on a single examination. The symptoms of abdominal pain and nausea, especially after eating, could be indicative of IBD.
  • Gastroesophageal Reflux Disease (GERD): Could be considered if the nausea and pain are related to eating and possibly worsened by lying down or certain food types, despite the lack of typical heartburn symptoms.
• Do Not Miss Diagnoses (15%):
  • Appendicitis: Although the pain is described as being in the lower right abdomen, which is consistent with appendicitis, the chronic nature of the symptoms and the clear ultrasound make this less likely. However, appendicitis can present atypically, especially in retrocecal appendicitis, and is a diagnosis that must be considered due to its potential severity.
  • Ovarian Cysts or Torsion: In female patients, ovarian pathology must be considered, especially if the pain is severe and acute. The absence of a clear finding on ultrasound does not entirely rule out ovarian issues, as some conditions might not be visible or might develop rapidly.
• Rare Diagnoses (5%):
  • Chronic Intestinal Pseudo-Obstruction: A rare condition characterized by recurrent episodes of abdominal pain, nausea, vomiting, and altered bowel habits in the absence of any mechanical obstruction.
  • Eosinophilic Gastroenteritis: A rare inflammatory condition of the gastrointestinal tract that could present with abdominal pain, nausea, and vomiting, often related to food intake.
  • Gastric or Small Bowel Cancer: Although extremely rare, especially in younger individuals, these conditions can present with nonspecific symptoms like abdominal pain and nausea after eating. The mild stomach inflammation could be a red flag, but the clear endoscopy and ultrasound reduce the likelihood.

Each of these diagnoses has a different set of diagnostic criteria and may require further testing for confirmation. The percentages assigned are approximate and based on the information provided, reflecting the relative likelihood of each condition given the symptoms and test results.