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Acute Renal & Uretic Colic

Red Flags

  • Evidence of sepsis (an obstructed infected kidney is a surgical emergency)
  • Uncontrolled pain
  • AKI / Anuria
  • Concern over diagnosis (possibility of peritonitis / ruptured AAA)

Refer to RCHT for urgent assessment. This allows for timely confirmation of diagnosis (non-contrast CT KUB), pain control and appropriate management.

Key Messages

  • Cases presenting less acutely with adequate analgesia in the community should be imaged and managed as per this guidance.
  • At least one in 5 referrals to Urology is for suspected renal stones
  • Referrals for suspected stones are increasing
  • With the correct imaging, many of these patients do not have stones and are discharged back to primary care

The majority of RENAL stones of 4mm or less do not need further treatment

Almost all patients with a ureteric stone have at least a trace of blood in their urine within the first 24hrs,but up to 10% of patients with a stone may not, if presentation delayed.

If an USS suggests stones a CT KUB will then be required (unless pregnant).

(If an outside provider has reported the USS please attach report to the CT request).

A negative USS does not exclude stones

Primary Care Management

History

  • Severe, sudden onset loin pain, not associated with movement, typically intermittent waves, the patient “cannot get comfortable”.
  • If renal stones suspected, consider diet (esp. if chronic), time spent in hot dry climate, fluid intake and family history of stones. Include in the referral.
  • Please indicate in referral if renal impairment present or a solitary kidney

 

Examination

An appropriate physical examination, including vital observations and abdominal assessment to detect alternative diagnoses eg musculoskeletal pain especially costal margin/lower ribs, paravertebral muscles, sacroiliac joints, AAA

 

Actue Investigations

Blood tests

  • U&E, FBC, Calcium, Phosphate and Uric acid

Urine tests

  • Dipstick for blood – Most patients with a stone have at least a trace of blood in their urine but up to 10% of patients with a stone may not.
  • Urine pH can show acidity which may inform Urologists with onward management.
  • If white blood cells or nitrites found , especially if the history suggests infection, please send MSU and treat infection

Imaging – CT KUB

  • Low dose non-contrast CT KUB (CT Renal Colic) has more than 95% PPV and NPV (positive and negative predictive values) for diagnosing stones in the renal tract

Imaging - USS

  • USS is a good screening test for significant stones in the kidney, not great for seeing ureteric stones but if hydronephrosis present then proceed with CT.
  • For women under 40 years of age an USS is the primary investigation of choice. USS can be useful when there is no clear diagnosis for the abdominal pain
  • A negative USS does not exclude stones. If there is a high index of suspicion, consider CT.  Occasionally ureteric stones can be present with no, or only mild, hydronephrosis.
  • If an USS suggests stones a CT KUB will then be required (unless pregnant).

If an outside provider has reported the USS, please attach report to the CT request and referral to secondary care. The site and size of the stone will allow the receiving urologist to make the correct management decision

Stone analysis

  • If the patient passes the stone and is able to retrieve it this should be sent for analysis (Clinical Biochemistry form stone sent in sterile dry pot)
  • Analysis may provide a metabolic cause.

Management

Immediate

  • Pain relief with NSAIDs – when safe to use
  • Normal fluid intake recommended – enough to keep urine clear / colourless. i.e aiming for good normal hydration. Pushing fluids won’t “flush” the stone
  • If pain not well managed consider acute referral 

Post-imaging

  • The majority of RENAL stones of 4mm or less do not need further treatment
  • The majority of URETERIC stones <4mm will pass spontaneously though this may take up to 6 weeks. If symptoms persist they should be referred.
  • Ureteric stones >7mm will almost always need intervention.
  • It is also worth noting that stones within the renal calyces are unlikely to cause pain (occasionally if large, >10mm) so alternative diagnoses should be considered.
  •  If recurrent stone former or have a strong FH then consider referral.

 

Referral Criteria  - the following information is required when making a referral

  • Urinalysis, including ph
  • U&E, FBC, Bone Profile (for Calcium and Phosphate), urate
  • CTKUB unless  < 40 year old female in which case USS

 

References

National Institute Of Clinical Excellence.  Acute Renal or ureteric colic.  Clinical Knowledge Summaries, April 2015