Renal colic

• Arrange immediate hospital admission if:

  • The person has signs of systemic infection (such as fever or sweats) or sepsis. 
  • The person is at increased risk of acute kidney injury, for example, if they have pre-existing chronic kidney disease or a solitary or transplanted kidney, or bilateral obstructing stones are suspected.
  • The person is dehydrated and cannot take oral fluids due to nausea and/or vomiting. 
  • The diagnosis is doubtful.
• For all other people with suspected renal or ureteric colic:

  • Offer urgent (within 24 hours of presentation) imaging to confirm the diagnosis and assess the likelihood of spontaneous stone passage. 
  • For most adults, offer low-dose non-contrast CT (computed tomography).
  • If a woman is pregnant, offer ultrasound instead of CT.
• For pain relief, offer a nonsteroidal anti-inflammatory drug (NSAID) by any route.  

  • Per rectum NSAIDs are very effective for renal colic
  • If NSAIDs are contraindicated or are not giving sufficient pain relief, offer intravenous (IV) paracetamol if available.
• Management of renal or ureteric stones includes :  

  • Watchful waiting — this is considered for asymptomatic renal stones in adults, children, and young people if the stone is:  
  • Less than 5 mm.
  • Larger than 5 mm and the person (or their family or carers, as appropriate) agrees to watchful waiting after an informed discussion of the possible risks and benefits.
• Medical expulsive therapy — this involves the use of an alpha-blocker to facilitate spontaneous stone passage during the observation period. It is considered for people with distal ureteric stones less than 10 mm. 
• Renal calculi do not ordinarily cause pain when they remain in the kidney, however when those stones drop into the ureters it can be excruciating
• Stasis of urine in a blocked kidney can lead to superimposed infection which can cause rapid onset sepsis.
• Micro-abrasions caused by a hard stone passing through the ureter cause microscopic haematuria
• The ureter lies close to the genitofemoral nerve (branch of lumbar plexus) which can lead to referred testicular pain
• Common locations of obstruction:

  • Pelvis ureteric junction - between the renal pelvis and ureter
  • Pelvic brim - where the ureter crosses above the common iliac vessels into the pelvis
  • Vesicoureteric junction - between the ureter and bladder
• Risk factors:

  • Dehydration - most important modifiable risk factor
  • Previous stones or family history
  • Metabolic conditions - primary hyperparathyroidism, gout
  • Medications - diuretics, anti-retrovirals, PPIs
  • Obesity
  • Bowel conditions
  • Idiopathic - most common
• History:

  • Sudden onset, severe, loin to groin pain
  • Pain in waves - usually sharp
  • Nausea
  • Systemic symptoms (fever/rigors) suggests an infected, obstructed system
  • Colic patients typically cannot lie still (in contrast to peritonism where they want to lie still)
  • Abdominal exam usually normal - may have severe unilateral flank pain which indicated infected urinary system
• Bedside investigations:

  • Vitals - mild tachycardia due to pain. Look for signs of sepsis
  • Urine dipstick - microscopic haematuria is common
  • Urine MC&S
• Lab investigations:

  • FBC - neutrophilia can occur in renal colic. in isolation, it is not enough evidence of infection
  • U&Es - reduction in renal function
  • CRP
  • Lactate
  • Calcium
• Conservative management:

  • small stones
  • Fluids
  • analgesia (NSAIDs)
  • Review in 4 weeks to ensure stone is passed (abdominal x-ray)
• If stone with infected urinary system - urgent relief of obstruction via sent or nephrostomy:

  • Stent - sits in ureter and allows the passage of urine. Inserted under general anaesthetic
  • Nephrostomy - tube placed percutaneously straight into the kidney
  • These patients will still need treatment of their stones at a later date with a ureteroscopy and laser fragmentation
• • Shockwave lithotripsy (SWL) — a non-invasive outpatient treatment that focuses shock waves on the stone to break it up. Stone particles are passed spontaneously.
• • Percutaneous nephrolithotomy (PCNL) — a procedure in which a nephroscope is passed percutaneously into the collecting system and the stone is fragmented and extracted through the nephroscope.
• • Ureteroscopy (URS) — involves the use of various energy sources (such as lasers) to break up the stone.
• Nephrolithiasis = stones within the kidney

  Ureterolithiasis = stones within the ureter

  Urolithiasis = stones in any part of the urinary tract
• For patients with suspected renal or ureteric colic who do not have features warranting urgent hospital admission:

  • Offer urgent (within 24hrs) imaging to confirm diagnosis and assess the likelihood of spontaneous stone passage
  • Most adults - non contrast CT
  • Pregnant and young people - ultrasound
• Medial expulsive therapy using an alpha-blocker can be used to facilitate spontaneous stone passage. Considered for people with distal ureteric stones less than 10mm

  Not used much clinically
• Surgical treatment:

  • Offered to adults with ureteric stones and renal colic within 48 hours of diagnosis if pain is ongoing and not tolerated or the stone is unlikely to pass
  • Shockwave lithotripsy
  • Percutaneous nephrolithotomy
  • Ureteroscopy
  • Open surgery
• Initially the stones are lodged in the renal pelvis, where they can be asymptomatic and don't cause any obstruction of urine flow

  Passage into the ureter causes spasms and colicky pain

  When stones reach the bladder they can irritate and obstruct the bladder, leading to frequent or painful urination - can lead to hydronephrosis and decrease in renal function
• Obstruction of a ureter can be life-threatening to patients. The stasis of urine in a blocked kidney can lead to superimposed infection, which can cause rapid-onset sepsis. 
• The majority of stones are calcium oxalate and are radio opaque

  • most cases are idiopathic
  • Urinary stasis
  • Infection
  • Hyperparathyroidism
• Causes of calcium stones:

  • Most common type (80%)
  • Dehydration
  • Hypercalcaemia
  • High salt diet (sodium and calcium share same transport in kidney)
• Causes of struvite stones (magnesium ammonium phosphate)

  • Often large soft stones, can cause staghorn calculi
  • Form when urine becomes more alkaline
  • Urease producing organisms (e.g. proteus and klebsiella) make the urine more alkaline so urine infections due to these organisms can cause struvite stones
• Causes of urate stones:

  • The only radiolucent stones
  • When there are high levels of uric acid in the blood
  • High purine diet (breaks down into uric acid) - red meats, seafoods
  • Haematological disorders - uric acid is product of red blood cell break down
  • Classically seen in patients with gout
• Cysteine stones are typically associated with familial disorders affecting cystine metabolism e.g. homocystinuria
• How to prevent calcium stones:

  • Check PTH to exclude primary hyperparathyroidism
  • Keep hydrated
  • Reduce salt intake (means less calcium excreted into urine)
  • Drink less fizzy drinks (fizzy drinks increase uric acid and calcium in urine)
  • Add fresh lemon juice to drinking water (Increases urine citrate which inhibits stone formation)
• Formation of renal stones is multifactorial but put simply when the balance of the following factors isn’t right renal stones can form

  1. Increased levels of material in urine that can form stones: calcium, phosphate, uric acid etc

  2) Decreased levels of material in urine that inhibit crystallization/stone formation e.g. citrate

  3) Urinary pH
• Medications for calcium stones:

  • Potassium citrate - increases urinary citrate which inhibits formation of calcium stones - use in patients with calcium stones with hypercalciuria or hypocitraturia
  • Thiazide treatment - increases calcium reabsorption in distal renal tubule therefore lowering urinary calcium - use in patients with calcium oxalate stones and hypercalciuria who's not responded to reducing salt intake
• How to prevent struvite stones:

  • Antibiotics to prevent infection
  • Medication to prevent bacteria making urine alkaline (acetohydroxamic acid AHA)
• How to prevent urate stones:

  • Avoid high purine foods e.g. red meat and shellfish
  • Urate-lowering medication e.g. allopurinol
  • Drink less fizzy drinks (fizzy drinks increase uric acid and calcium in urine)
• Bedside investigations:

  • Urine dipstick and culture
  • Haematuria occurs in 90% of cases, typically microscopic
  • Can also look for evidence of infection
• Lab investigations:

  • FBC
  • CRP
  • U+Es
  • Urate and calcium levels
  • PTH
• Imaging:

  • Gold standard is non contrast CT KUB
  • Ultrasound first line in pregnant women and children
  • Plan AXR - most stones are radiopaque - can be used for follow up/surveillance
• If a patient ever passes a stone in micturition ask them to retrieve it so it can be sent for analysis
• Analgesia:

  • 1st choice = NSAID
  • 2nd choice = IV paracetamol
  • 3rd choice = opioid