Differential Diagnosis for Lower Abdominal Pain with Nausea and Vomiting

Single Most Likely Diagnosis

• Appendicitis: This is often the first consideration for lower abdominal pain, especially if the pain starts near the belly button and then moves to the lower right abdomen. Nausea and vomiting are common accompanying symptoms.

Other Likely Diagnoses

• Gastroenteritis: Inflammation of the stomach and intestines, usually due to infection, can cause lower abdominal pain, nausea, and vomiting.
• Urinary Tract Infection (UTI): While UTIs more commonly cause pain in the flank or suprapubic area, they can also cause lower abdominal pain, especially if the infection involves the lower urinary tract.
• Ovarian Cyst or Torsion: In women, ovarian cysts can cause lower abdominal pain, and if the cyst ruptures or the ovary becomes twisted, the pain can become severe, accompanied by nausea and vomiting.
• Diverticulitis: Inflammation of the diverticula in the digestive tract can cause lower abdominal pain, usually on the left side, along with nausea and vomiting.

Do Not Miss Diagnoses

• Ectopic Pregnancy: A pregnancy that develops outside the uterus can cause severe lower abdominal pain, nausea, and vomiting. This is a medical emergency.
• Ruptured Aneurysm: Although less common, a ruptured abdominal aortic aneurysm can cause severe abdominal pain, nausea, and vomiting, and is immediately life-threatening.
• Intestinal Obstruction: Blockage of the intestine can cause severe abdominal pain, nausea, vomiting, and constipation, and requires prompt medical attention.
• Pelvic Inflammatory Disease (PID): Infection of the female reproductive organs can cause lower abdominal pain, nausea, and vomiting, and if left untreated, can lead to serious complications.

Rare Diagnoses

• Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can cause chronic lower abdominal pain, nausea, and vomiting, but are less common causes of acute presentations.
• Endometriosis: A condition where tissue similar to the lining inside the uterus grows outside of it, leading to pain, especially during menstruation, and can sometimes cause nausea and vomiting.
• Mesenteric Ischemia: Reduced blood flow to the intestines can cause severe abdominal pain, nausea, and vomiting, but is relatively rare and usually occurs in older adults or those with cardiovascular disease.