Differential Diagnosis for Lower Abdominal Pain

Given the symptoms of intermittent lower abdominal pain occurring at night and not relieved by eliminating dairy, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Irritable Bowel Syndrome (IBS): This condition is characterized by recurrent abdominal pain associated with changes in bowel habits, such as diarrhea or constipation. The pain often improves with bowel movements. The nocturnal nature of the pain and its intermittent pattern could fit with IBS, especially if other symptoms like bloating or changes in stool are present.

• Other Likely Diagnoses

  • Appendicitis: Although appendicitis typically presents with constant pain, some cases can have intermittent pain, especially in the early stages. The pain often starts near the navel and then moves to the lower right abdomen. Nocturnal pain and the lack of relief from eliminating dairy make this a consideration.
  • Ovarian Cysts: In women, ovarian cysts can cause intermittent lower abdominal pain, especially if the cysts rupture or bleed. The pain can occur at any time, including nighttime.
  • Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause abdominal pain, often accompanied by changes in bowel habits, weight loss, and sometimes blood in the stool. The pain can be intermittent and worsen at night.

• Do Not Miss Diagnoses

  • Ectopic Pregnancy: In women of childbearing age, an ectopic pregnancy can cause severe, intermittent abdominal pain, often accompanied by vaginal bleeding and missed periods. This is a medical emergency.
  • Intestinal Obstruction: This condition involves a blockage of the intestine, which can cause severe, intermittent abdominal pain, vomiting, and constipation. It requires immediate medical attention.
  • Kidney Stones: While kidney stones often cause flank pain, they can also cause lower abdominal pain, especially if the stone is moving down the ureter. The pain can be severe and intermittent.

• Rare Diagnoses

  • Endometriosis: This condition, where tissue similar to the lining inside the uterus grows outside of it, can cause chronic pelvic pain, heavy bleeding, and infertility. The pain can be intermittent and worsen during menstruation.
  • Diverticulitis: Inflammation of the diverticula in the digestive tract can cause lower abdominal pain, usually on the left side, accompanied by changes in bowel habits and fever.
  • Intussusception: A condition where a part of the intestine slides into an adjacent part, causing bowel obstruction. It's rare in adults but can cause intermittent abdominal pain, vomiting, and blood in the stool.