Renal Calculi

Guidance for medical examiners when assessing a patient for either a general topic or condition - Renal Calculi.

Aeromedical implications 

Effect of aviation on condition

• Low fluid intake, especially in hot conditions

Effect of condition on aviation

• Overt incapacitation from severe pain and vomiting
• Distraction due to treatment and symptoms
• High recurrence rate of calculi

Effect of treatment on aviation

• Post-lithotripsy symptoms

Approach to medical certification

Based on the condition

• Absence of calculi in any part of the collecting system, determined by:
  • low-dose CT scan
  • via renoscopy `
  • ultrasound ONLY acceptable for confirming clearance of ureteric stones in applicants under 35yrs with BMI 24 or less
• Identification of high risk stone-formers:
  • genetic (e.g. Renal tubular acidosis), familial and early onset renal calculi
  • recurrent episodes of renal colic or calculi despite preventative measures
  • evidence of parenchymal calcification or Randall’s plaques.
  • primary hyperparathyroidism
  • gastric bypass procedures and inflammatory bowel disease
  • sarcoidosis
  • obesity
  • diabetes
  • gout with persistently acid urine.

Based on treatment

• Renoscopic confirmation of stone clearance (assuming good visualisation)
• Preventative strategies in place (fluids / allopurinol / citrate / thiazides etc)

Risk assessment protocol - information required

New cases

• Confirmed diagnosis
• Clinical status and symptoms
• Investigations conducted
  • pre and post episode ultrasound and CT scan reports
  • results of metabolic studies
  • stone analysis if available
• Management
  • treatment
  • side-effects
  • monitoring
• Follow-up plan.

Renewal

• Low dose CT scan as per protocol

Indicative outcomes

• Unrestricted certification is only possible for pilots who have no stones in the collecting system
• Parenchymal calcification and Randall’s plaques are considered to increase the risk of calculus formation
• High risk stone-formers will require imaging more frequently

Favourable

• CT KUB: calculus-free
• Nephroscopic clearance and visual confirmation of clearance of all calculi 

Unfavourable

• Any calculi in the collecting system (irrespective of location)
• Ureteric obstruction
• High risk stone-former where risks are not actively managed

Pilot and controller information

• Acute colic mandates grounding and must be reported to the DAME
• If CT is required, low dose CT imaging greatly reduces radiation exposure
• Any calculus passed should be submitted for laboratory analysis. This assists the specialist in advising how to reduce the risk of recurrence
• If treatment is required, the most effective method should be discussed with the specialist. Lithotripsy is associated in some circumstances with a higher need for follow-up procedures and does not guarantee clearance of calculi - a pre-requisite for certification.