Renal colic 

Incidence of 131 cases per 100,000 population

Site of pain is notoriously inaccurate at predicting location of stone

Calculus size, location, and patient discomfort predict the likelihood of spontaneous stone passage.

Approximately 90% of stones less than 5 mm pass within four weeks. Up to 95% of stones larger than 8 mm can become impacted, requiring intervention to pass

History and Physical

• Patients experiencing renal colic may present in very severe pain. Classically, these patients are unable to find a comfortable position and are often writhing or constantly pacing around the examination table
• sudden onset of flank pain –> radiating laterally to the abdomen and/or to the groin
• dull constant level of pain + colicky episodes of increased pain.
  • dull constant pain
    • is often due to stretching of the renal capsule due to obstruction
  • colicky pain
    • caused by peristalsis of the ureteral smooth muscle
• associated nausea or vomiting, and some may report gross hematuria.
• As the stone migrates distally and approaches the bladder, the patient may experience
  • dysuria
  • urinary frequency
  • urgency
  • difficulty in urination.

Differential Diagnosis

• Angiomyolipomas
• Aortic aneurysms
• Biliary colic
• Iliac aneurysms
• Endometriosis
• Ovarian torsion
• Peritonitis
• Pyelonephritis
• Renal cancer
• Renovascular compromise
• Wunderlich syndrome (rare condition with spontaneous renal subcapsular and/or retroperitoneal bleeding and hematoma formation)

Workup

• Do urine MCS
  • Hematuria is present in 85% of acute renal colic cases caused by calculi.
  • While the presence of hematuria is suggestive of a stone, it is not definitive and neither does the absence of hematuria conclusively prove that a stone is not present
• Chemistry screen
• serum uric acid
• calcium
• parathyroid
  • if hypercalcemia is present and therefore primary hyperparathyroidism
• Stone analysis if available

• Imaging for patient presenting with ureteric colic:
  • CT KUB noncontrast
    • gold standard for the initial diagnosis of suspected renal colic
    • sensitivity of 98%
    • specificity of 100%
    • negative predictive value of 97%
    • allows rapid identification of stone, provides information as to the location and size of the stone, and any associated hydroureter, hydronephrosis, or ureteral edema, and can give information regarding potential other etiologies of pain (e.g., abdominal aortic aneurysm, malignancy
    • Concerns regarding radiation dose are well founded so plain KUB Xray should be performed in addition to CT at the time of presentation
  • Xray Abdomen
    • Only calcium carbonate stones are visible on plain Xray
    • 10% to 20% of renal calculi are radiolucent
    • provide little information regarding hydronephrosis, obstruction, or the renal anatomy. Additionally, bowel gas, the bony pelvis, and abdominal organs may obstruct stone
  • Intravenous pyelogram
    • used rarely, however contrast CT urogram sometimes used in treatment planning
  • Ultrasound
    • used to establish hydronephrosis
    • Sensitivity 60% – 76%
    • miss stones smaller than 5 mm in size
    • not a reliable imaging modality for visualizing ureteral calculi
    • reserved for assessment of loin pain in pregnant women
    • Ultrasound may also be used in follow up to ensure signs of obstruction have resolved or to monitor stone size in asymptomatic patients
  • No role for MRI in urolithiasis

• Treatment
  • Conservative
    • Majority of stones that migrate to the ureter will pass spontaneously = <5mm should pass
    • Up to 70% of stones less than or equal to 6mm in transverse diameter will pass spontaneously
    • Increases to 90% with addition of Tamsulosin 400mcg /day (nonPBS)
      • alpha blockade medications (tamsulosin or nifedipine) is theorized to facilitate stone passage by decreasing intra-ureteral pressure and dilating the distal ureter.
    • Paracetamol/NSAID
      • celecoxib 200mg daily
      • indomethacin 50mg TDS
    • Strain urine – avoid imaging if passed, stone analysis
    • No evidence for increasing oral fluids, only has role in prevention
    • Silent (asymptomatic) obstruction should be considered, need repeat imaging after 6 weeks to ensure that the stone has passed

• Indications for hospital admission
  • significant renal stone in a solitary kidney
  • severe kidney injury
  • infected renal stone
  • intractable pain or nausea
  • urinary extravasation
  • hypercalcemic crisis

• Urology review if
  • Infected/sepsis
  • Obstructed/infected
  • Drop in GFR
  • Uncontollable pain
  • Complete obstruction
  • Single kidney
  • With significant CKD
  • >6mm unlikely to pass

Interventional

• Absolute
  • Infection (pyonephrosis)
    • fever or history of fever, infection in an obstructed system can result in life threatening Gram negative sepsis. Antibiotics alone cannot readily treat, drainage of the upper tract required by retrograde stenting and percutaneous nephrostomy
  • Renal failure deteriorating
    • renal function mainly an issue for patients with a solitary kidney, early intervention offered for this group
• Relative
  • Ongoing or recurrent pain-  patients may choose to have surgery after a trial of conservative management
  • stone larger than 6mm unlikely to pass or take longer to pass may benefit from early intervention
  • occupational / social some – occupations require complete removal of stones (eg. airline pilots) before they can return to work, planned overseas holidays particularly to remote locations

• Definitive treatment of stones in the kidney
  • Currently most patients that require intervention for ureteric stones will have ureteroscopic laser lithotripsy
  • Intervention for a stone is recommended by 4 weeks with no changes even if the patient is asymptomatic.
  • This is due to the likelihood of scarring and other complications

Stone Prevention

• Type of stone
  • Recurrence rates are high following first stone 50% within 5 yrs
  • At first presentation urinalysis, serum calcium uric acid and electrolytes
  • Stone analysis if available
  • Stone type can also be inferred from the radiological findings
  • Stone recovery pee into white ice cream container and recover stone, improves compliance over straining all urine
• Prevention
  • increasing fluid intake, especially water to maintain dilute urine output
  • avoiding added salt
  • maintaining a well balanced diet
  • patients with calcium oxalate stones should be advised to keep a low oxalate diet (the majority of published evidence now favors dietary salt and oxalate reduction rather than calcium)
  • Common oxalate rich foods include tea, chocolate, spinach, beetroot, rhubarb, peanuts, cola and vitamin C (most supplementary vitamin C is converted to oxalate)