History and Examination

GP should work through a recommended scheme of assessment for suspected kidney stones.

This may include one or all of the following:

History

• Appropriate clinical history to evaluate if symptoms are due to kidney stones or other differential diagnoses.
• If renal stones are suspected, questions about diet, time spent in a hot dry climate, fluid intake and a family history of stones should be included in the referral.

Examination

• Appropriate physical examination, including vital observations and abdominal assessment to detect alternative diagnoses e.g. abdominal aortic aneurysm (AAA).

Indications for acute referral

• Temperature or signs of infection (an obstructed infected Kidney is a surgical emergency)
• Pain not controlled in the community
• Concern over the diagnosis (possibility of ruptured AAA)

Acute presentation with significant pain can be referred to emergency department or surgical assessment ward

Blood tests

• RFT
• FBC
• Calcium
• 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 regarding onward management.
• If white blood cells or nitrites found , especially if the history suggests infection, please send MSU and treat infection.

Imaging

• Low dose non-contrast low dose non contrast CT KUB has more than 99.5% PPV and a 90% NPV (positive and negative predictive values) for diagnosing stones in the renal tract. Low dose non contrast CT KUB should be arranged in primary care to ensure the patient gets seen in the right clinic.
• 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 an USS suggests stones, a low dose non contrast CT KUB will then be required (unless pregnant)
  • If an outside provider has reported the USS please attach report to the low dose non contrast CT KUB request
• The site and size of the stone will allow the receiving urologist to make the correct management decision which may be a secondary care referral or advice on management in the community.

Stone analysis

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

Immediate management:

Pain relief with NSAIDs; where safe to use, and consider timely follow up with urgent imaging.

If pain not well managed consider acute referral.

Post-imaging:

The majority of renal stones of 4mm or less do not need further treatment, but should be referred via pre-choice triage for an opinion and may not require a face-to-face appointment.

The majority of ureteric stones less than 4mm will pass spontaneously though this may take up to 6 weeks. If symptoms persist they should be referred.

Ureteric stones greater than 7mm will almost always need intervention.

It is also worth noting that stones within the renal calyces do not cause pain so alternative diagnoses may need to be considered.

Referral Criteria

Pre-choice triage will assess the clinical information including the site and size of the stone which will then determine whether the patient needs to be seen for a face-to-face appointment.

NB Please attach radiology results as part of the referral as it cannot be guaranteed that the triaging consultant will be able to access the results.

Pre referral criteria

Referrals sent without the following information may be returned

• Urinalysis
• RFT, FBC, Calcium and Uric acid
• Low dose non contrast CT KUB unless under 40 year old female in which case USS

Referral Instructions

e-Referral service selection:

• Specialty: Urology
• Clinic Type: Urinary Calculus
• Service: DRSS-Western-Urology - Devon ICB - 15N

Referral Form

DRSS referral form

Pathway Group

This guideline has been signed off on behalf of NHS Devon.

Publication date: March 2018