Differential Diagnosis for Left Lower Back Pain Radiating to the Abdomen

Single Most Likely Diagnosis

• Musculoskeletal Strain: Given the worsening of pain with movement and the absence of urinary symptoms (other than normal frequency), a musculoskeletal strain is the most likely diagnosis. The use of heat/ice for relief and the negative urinalysis further support this diagnosis.

Other Likely Diagnoses

• Lumbar Disc Herniation: The radiation of pain to the front of the abdomen could be indicative of a lumbar disc herniation, especially if the pain worsens with movement. However, the lack of specific neurological symptoms (e.g., numbness, tingling) makes this less likely.
• Kidney Stone (small, non-obstructing): Although the urinalysis is negative, small kidney stones might not always show up on initial testing. The pain radiating to the abdomen could be consistent with a kidney stone, but the absence of other urinary symptoms and the negative urinalysis make this less likely.

Do Not Miss Diagnoses

• Abdominal Aortic Aneurysm (AAA): Although less common, an AAA can present with back pain radiating to the abdomen. This is a medical emergency, and missing the diagnosis could be fatal. The patient's age and risk factors (if any) would increase the likelihood of this diagnosis.
• Pyelonephritis or Kidney Infection: Despite the negative urinalysis, a kidney infection could present with back pain and abdominal radiation. This diagnosis is critical to not miss due to the potential for severe complications if left untreated.
• Pancreatitis: Acute pancreatitis can cause severe back pain radiating to the abdomen. The absence of other gastrointestinal symptoms does not rule out this diagnosis, and it is crucial to consider due to its potential severity.

Rare Diagnoses

• Spinal Tumor or Metastasis: Tumors of the spine can cause back pain that radiates, including to the abdomen. This would be a rare cause of the patient's symptoms but is important to consider, especially if there are risk factors or if the pain does not respond to typical treatments.
• Retroperitoneal Hematoma: A collection of blood in the retroperitoneal space can cause back and abdominal pain. This is a rare condition but could be life-threatening, depending on the cause and size of the hematoma.