Loin Pain

Differential Diagnosis

Common Diagnoses

Occasional Diagnoses

  • Gynaecological Causes (e.g. Ectopic Pregnancy, PID, Ruptured or Torted Ovarian Cyst)
  • Gastrointestinal Causes (e.g. Appendicitis, Biliary Colic)
  • Other Urological Causes in Men (e.g. Epididymitis, Prostatitis)
  • Pelvi-Ureteric Obstruction
  • Radicular Pain (e.g. from Osteoarthritis or Disc Prolapse)

Rare Diagnoses

  • Leaking Abdominal Aortic Aneurysm
  • Retroperitoneal Fibrosis
  • Renal Infarction
  • Renal Tumour (Either Directly or by Causing a Blood Clot in the Ureter)
  • Acute Papillary Necrosis
  • Factitious (e.g. Addicts Seeking Opioids)
  • Idiopathic Loin Pain Haematuria Syndrome

Ready Reckoner

Key distinguishing features of the most common diagnoses

Acute Musculoskeletal PainRenal or Ureteric StoneAcute PyelonephritisRIB PainShingles
Urinary SymptomsNoPossiblePossibleNoNo
Macro or Microscopic HaematuriaNoPossiblePossibleNoNo
Pain w Worse with MovementYesNoNoPossibleNo
Pain ColickyNoYesNoNoNo

Possible Investigations

Likely:Urinalysis, MSU.

Possible:U&E, sieving urine, renal imaging.

Small Print:Metabolic screen (usually secondary care); other hospital-based investigations.

  • Urinalysis: The presence of microscopic haematuria would support your diagnosis of renal/ ureteric colic (though its absence does not rule it out); urinalysis may also reveal evidence of urinary infection or acute papillary necrosis (blood and white cells in the latter).
  • MSU: To confirm suspected infection; also might suggest acute papillary necrosis (blood and sterile pyuria).
  • U&E: To assess renal function when underlying renal issue suspected.
  • Sieving urine: To retrieve stone in renal/ureteric colic for subsequent analysis.
  • Renal imaging: Non-contrast helical CT is the hospital investigation of choice in suspected renal/ureteric colic; depending on how acute the presentation is, and on local pathways and guidelines, plain abdominal X-ray or US may be helpful. Renal imaging may also be required in acute pyelonephritis (especially if recurrent), possible renal tumour and in suspected pelvi-ureteric obstruction. Ultrasound, IVU, CT or MRI may be needed to diagnose retroperitoneal fibrosis.
  • Metabolic screen such as blood and 24 hour urine for calcium, phosphate and urate in stone formers.
  • Other hospital-based investigations: Required to clarify the diagnosis in those admitted, and will depend on whether the cause seems urological, gynaecological or gastrointestinal.

Top Tips

  • Remember that many patients fear kidney problems. They may value reassurance that all is well renally as much as your positive diagnosis of musculoskeletal pain.
  • Take care during busy telephone triaging sessions – be sure to check that the apparently simple case of cystitis isn’t actually a developing case of acute pyelonephritis.
  • The absence of microscopic haematuria does not rule out renal/ureteric colic but should certainly prompt a consideration of alternative diagnoses.
  • Patients with genuine renal/ureteric colic tend to writhe about in pain.
  • Think of shingles, particularly in elderly patients with an otherwise unexplained short history of burning loin pain, and warn them of the possibility of a rash developing – the pain may precede the skin manifestations by a few days.

Red Flags

  • Beware of a first diagnosis of renal/ureteric colic (especially left sided) in older men – a leaking abdominal aortic aneurysm can cause very similar symptoms.
  • Some cases of renal/ureteric colic can be managed – at least initially – in the community. But those with fever, prolonged or unresponsive pain, or known renal compromise should be admitted.
  • Remember that acute pyelonephritis in men and children, and recurrent episodes in women, require investigation to exclude any underlying urological problem.
  • Be cautious about using strong analgesics for possible renal/ureteric colic in patients with past histories of drug addiction – this used to be a favoured way of engineering a free opioid fix, although the increasing use of diclofenac as the urgent treatment of choice has reduced this problem.
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