Summary

Renal Colic is the acute onset of severe abdominal pain caused by the passage of a urinary stone (calculus) from the kidney into the ureter. It is a common emergency, affecting 10% of the population. The classic presentation is "loin to groin" colicky pain associated with nausea and vomiting. The patient is typically restless (visceral pain). The diagnostic gold standard is Non-Contrast CT KUB. Management is stratified by urgency: Infected Obstruction (Stone + Fever) is a UROLOGICAL EMERGENCY requiring immediate decompression (Stent or Nephrostomy) to prevent septic shock. Simple colic is managed with NSAIDs (Diclofenac) and conservative waiting for spontaneous passage (highly likely for stones <5mm). Larger or unpassable stones require intervention (Ureteroscopy/ESWL).

Key Facts

• Lifetime Risk: 10-15%. Men > Women (3:1).
• Most Common Stone: Calcium Oxalate (80%).
• Gold Standard Imaging: CT KUB (Non-Contrast).
• Best Analgesia: NSAIDs (Diclofenac PR). Superior to Opioids due to prostaglandin inhibition.
• Emergency: Obstruction + Infection = Pus under pressure = Sepsis. Time is Nephrons.

Clinical Pearls

"The Rolling Patient": A patient with Peritonitis (Appendicitis) lies perfectly still. A patient with Renal Colic cannot sit still; they writhe and pace. This "Restless" sign is nearly diagnostic.

"Loin to Groin": The classics hold true. Upper ureter = Flank. Mid ureter = Iliac fossa. Distal ureter (UVJ) = Labia/Scrotum/Penis tip pain + Urinary Frequency (mimics cystitis).

"The Single Kidney Trap": If a patient has only one kidney and blocks it, they will produce NO URINE (Anuria). Creatinine will skyrocket. This is a silent emergency. Always ask: "How many kidneys do you have?"

"Diclofenac is Magic": It works by inhibiting renal prostaglandin synthesis, which reduces glomerular filtration rate and ureteric pressure. It treats the cause of the pain (capsular stretch), not just the perception.

        PATIENT WITH FLANK PAIN
                   ↓
      ANALGESIA (Diclofenac PR) + CT KUB
                   ↓
      ┌────────────┼────────────┐
   STONE CONFIRMED          NO STONE
      ↓                     (Look for other
   IS IT COMPLICATED?        causes e.g.
  (Fever/Sole Kidney/        AAA, Appx)
   Uncontrollable Pain)
      ↓            ↓
     YES           NO (Simple Colic)
      ↓            ↓
  ADMIT UROLOGY    MANAGEMENT BY SIZE
  + Decompress     (See below)
  (Stent/Neph)

1. Acute Management (Simple Colic)

• Analgesia: NSAIDs (Diclofenac 100mg PR or IM). Opiates second line.
• Fluids: Normal hydration. (Forcing fluids increases pain by increasing pressure).
• Medical Expulsive Therapy (MET): Tamsulosin (Alpha-blocker). Relaxes distal ureter. Increases passage rate for stones >5mm.

2. Management by Size

• less than 5 mm: 90% pass spontaneously. Discharge with analgesia and sieve.
• 5 - 10 mm: 50% pass. Trial of conservative management or early intervention.
• > 10 mm: Unlikely to pass. Needs intervention.

3. Emergency Decompression

• Indications:
  • Infected Obstructed Kidney (Sepsis).
  • Obstructed Solitary Kidney (Anuria).
  • Intractable Pain / Vomiting.
• Methods:
  • JJ Stent: Internal tube from kidney to bladder. (Inserted cystoscopically).
  • Nephrostomy: Percutaneous tube through the back into kidney. (Interventional Radiology).

1. ESWL (Extracorporeal Shockwave Lithotripsy)

• External shockwaves focused on stone to fragment it.
• Pros: No surgery, no anaesthetic.
• Cons: Takes weeks to pass fragments ("Steinstrasse"). Not for hard stones (Cystine) or Obese patients.

2. Ureteroscopy (URS) + Laser

• Rigid or Flexible scope passed up urethra -> Ureter -> Kidney.
• Holmium Laser blasts stone to dust.
• Pros: Clearance in one session.
• Cons: GA, Stent discomfort post-op.

3. PCNL (Percutaneous Nephrolithotomy)

• Keyhole surgery through the back. Track made into kidney.
• For Large Stones (>2cm) or Staghorns.

Technique (Retrograde Stent)

1. Position: Lithotomy.
2. Cystoscopy: Identify ureteric orifice (UO) in bladder.
3. Guide Wire: Hydrophilic wire passed up ureter, past the stone, into renal pelvis (Confirm on Fluoroscopy).
4. Stent: Pushed over wire.
5. Deployment: Wire removed. "Pigtail" curls form at both ends (Renal pelvis and Bladder) to prevent migration.
6. Function: Does not remove stone. Allows urine to bypass the obstruction, relieving pressure and pain.

Recurrent Formers (50% recur at 5 years).

Landmark Trials

1. SUSPEND Trial: Questioned efficacy of Tamsulosin for small stones. (Still widely used for >5mm distal stones).
2. MIMIC Study: NSAIDs vs Opioids. Confirmed NSAIDs superior for colic.

NICE NG118

• Gold standard imaging: Low-dose non-contrast CT.
• Pain relief: NSAID first line.
• Observe stones <5mm.
• Treat infected stones with decompression immediately.

What is a Kidney Stone?

It is a hard crystal formed from waste chemicals in the urine (calcium, oxalate). It forms in the kidney. When it falls out of the kidney and gets stuck in the narrow tube (ureter) leading to the bladder, it blocks the flow of urine.

Why does it hurt so much?

The blockage causes urine to back up. The kidney swells and stretches its sensitive capsule. This causes the severe agony, often worse than childbirth.

Is it dangerous?

The pain is horrible but rarely dangerous unless there is infection. If you have a temperature/shivering with the pain, the backed-up urine has turned to pus. This creates "poisoning of the blood" (sepsis) and needs emergency surgery to drain it.

How do you treat it?

• Small stones: We give you painkillers and you pee it out at home.
• Large stones: We may use shockwaves (from outside) or a laser (telescope up the water pipe) to break it.