Differential Diagnosis for Acute Onset Abdominal Pain

The symptoms described, including acute onset dull aching abdominal pain radiating to the back, increased nausea with excessive salivation, and mucoid stool, suggest a range of possible diagnoses. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Pancreatitis: The pain radiating to the back and the presence of nausea and vomiting are classic symptoms of pancreatitis. Excessive salivation could be related to the pain or a reflex response. Mucoid stool might not be directly related but could indicate gastrointestinal upset.

• Other Likely Diagnoses

  • Gastroenteritis: Could cause abdominal pain, nausea, vomiting, and changes in stool, including mucoid stools. The back pain might be less typical but could occur due to referred pain or muscle strain from vomiting.
  • Intestinal Obstruction: Early signs can include abdominal pain, nausea, vomiting, and changes in bowel habits, which could include mucoid stools. The pain radiating to the back might be less common but possible, especially if the obstruction involves the lower parts of the intestine.
  • Cholecystitis: Inflammation of the gallbladder can cause right upper quadrant abdominal pain that might radiate to the back, along with nausea and vomiting. While less directly linked to mucoid stools, the overall gastrointestinal upset could contribute to such symptoms.

• Do Not Miss Diagnoses

  • Appendicitis: Although the pain typically starts around the navel and then moves to the lower right abdomen, atypical presentations can occur, especially in children or the elderly. Nausea, vomiting, and changes in bowel habits can be present. It's crucial to consider appendicitis due to the potential for severe complications if not promptly treated.
  • Mesenteric Ischemia: This condition involves insufficient blood flow to the intestines and can present with severe abdominal pain out of proportion to the physical examination, along with nausea and vomiting. While less common, it's a critical diagnosis to consider due to its high mortality rate if not promptly addressed.
  • Ectopic Pregnancy: In women of childbearing age, ectopic pregnancy can cause abdominal pain, nausea, and vomiting. The pain can radiate to the back, and while mucoid stools are not a typical symptom, any severe abdominal pain in this demographic warrants consideration of ectopic pregnancy due to its potential for severe consequences.

• Rare Diagnoses

  • Carcinoid Syndrome: This condition, caused by a neuroendocrine tumor, can lead to a variety of gastrointestinal symptoms, including abdominal pain, diarrhea (which might occasionally appear mucoid), and flushing. However, it's much less common and typically presents with a more chronic course.
  • Pseudomyxoma Peritonei: A rare condition characterized by recurrent mucinous ascites causing abdominal distension and pain. It might present with mucoid stools if there's involvement of the intestines, but it's an uncommon diagnosis.