Differential Diagnosis for 18yo Female with Stomach Aches, Nausea, Loss of Appetite

Single Most Likely Diagnosis

• Irritable Bowel Syndrome (IBS): This is a common condition characterized by chronic abdominal pain, bloating, and alteration of bowel habits in the absence of any mechanical, inflammatory, or biochemical abnormalities. The symptoms of stomach aches, nausea, and loss of appetite can be associated with IBS, especially if there's a pattern of exacerbation with certain foods or stress.

Other Likely Diagnoses

• Gastroesophageal Reflux Disease (GERD): GERD can cause stomach aches, nausea, and loss of appetite due to the reflux of stomach acid into the esophagus, leading to discomfort and pain.
• Peptic Ulcer Disease: Ulcers in the stomach or duodenum can cause pain, nausea, and decreased appetite. The pain is often described as burning and can be relieved by eating or worsened by hunger.
• Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can present with chronic abdominal pain, nausea, loss of appetite, and changes in bowel habits. Although less common in the general population, they are significant due to their impact on quality of life and potential complications.
• Functional Dyspepsia: This condition involves recurring signs and symptoms of indigestion that have no obvious cause. Symptoms can include pain or discomfort in the upper abdomen, early satiety, and difficulty swallowing, among others.

Do Not Miss Diagnoses

• Appendicitis: Although the classic presentation involves acute onset of abdominal pain, nausea, and vomiting, atypical presentations can occur, especially in young females. Missing appendicitis can lead to perforation and severe complications.
• Ectopic Pregnancy: In females of childbearing age, ectopic pregnancy must be considered, especially if there's a history of missed periods or positive pregnancy test. It can present with abdominal pain and nausea.
• Pancreatitis: Acute pancreatitis can cause severe abdominal pain, nausea, and vomiting. It's crucial to identify and treat promptly to avoid complications.
• Ovarian Torsion: This is a gynecological emergency that can present with acute abdominal pain, nausea, and vomiting. Prompt diagnosis and treatment are essential to preserve ovarian function.

Rare Diagnoses

• Gastric Cancer: Although rare in young individuals, gastric cancer can present with non-specific symptoms like abdominal pain, nausea, loss of appetite, and weight loss.
• Celiac Disease: An autoimmune reaction to gluten can lead to malabsorption and symptoms like abdominal pain, diarrhea, fatigue, and weight loss.
• Gastroparesis: A condition where the stomach takes too long to empty its contents, leading to nausea, vomiting, feeling full after eating only a small amount of food, and abdominal bloating.

Each of these diagnoses requires a careful history and physical examination, along with targeted diagnostic tests to confirm the diagnosis and guide treatment.