Differential Diagnosis for Abdominal and Back Pain

The patient presents with a complex set of symptoms including abdominal pain, back pain, increased urinary frequency, and nausea. The following differential diagnoses are considered based on the provided history and symptoms:

• Single Most Likely Diagnosis
  • Irritable Bowel Syndrome (IBS) exacerbation: Given the patient's history of IBS, the description of abdominal pain as dull aching/shooting, and the presence of bloating, an exacerbation of IBS is a plausible explanation. The absence of blood in stool, normal bowel movements, and lack of significant changes with food intake also support this diagnosis.
• Other Likely Diagnoses
  • Ovarian cysts: The patient's history of ovarian cysts and the description of pain being more pronounced on the left side could suggest a possible ovarian cyst causing the symptoms.
  • Interstitial cystitis flare: The increased urinary frequency and history of interstitial cystitis could indicate a flare of this condition, contributing to the patient's symptoms.
  • Musculoskeletal back pain: The lower back pain radiating to the hips could be indicative of musculoskeletal issues, possibly exacerbated by or unrelated to the abdominal symptoms.
• Do Not Miss Diagnoses
  • Ectopic pregnancy: Although the patient has had a tubal ligation and ablation, the possibility of an ectopic pregnancy, however small, cannot be entirely ruled out without further investigation, given the presentation of abdominal pain and the potential for rare failures of sterilization procedures.
  • Appendicitis: While the pain is described as more left-sided and there's no mention of migratory pain or rebound tenderness, appendicitis can sometimes present atypically, especially if the appendix is in an unusual location.
  • Kidney stones: The increased urinary frequency and abdominal pain could be indicative of kidney stones, which would require prompt diagnosis and treatment to prevent complications.
  • Diverticulitis: Although less likely given the absence of fever, changes in bowel habits, or blood in stool, diverticulitis could present with left lower quadrant pain and should be considered.
• Rare Diagnoses
  • Endometriosis: Given the patient's history of ovarian cysts and abdominal pain, endometriosis could be a rare consideration, especially if the pain is cyclic and related to menstrual periods, though this is not clearly indicated.
  • Inflammatory bowel disease (IBD): While the patient had a colonoscopy at 18, the possibility of a new diagnosis of IBD (Crohn's disease or ulcerative colitis) cannot be entirely ruled out without further investigation, especially if the symptoms worsen or do not respond to IBS management.

Each of these diagnoses should be considered and investigated based on the patient's specific symptoms, history, and physical examination findings, with the goal of providing an accurate diagnosis and appropriate management plan.