Basics
Description
- Urinary tract obstruction
- Intermittent distention of the renal pelvis of proximal ureter produces pain
- Kidney stones:
- Most common cause of renal colic
- Stone composition:
- 80%: Calcium stones (calcium oxalate > calcium phosphate)
- 5% uric acid
- Others: Magnesium ammonium phosphate (struvite), cystine
- Associated with infections caused by urea-splitting organisms (e.g., Pseudomonas, Proteus, Klebsiella) along with an alkalotic urine
- 90% of urinary calculi are radiopaque
Etiology
- 6 " 12% lifetime risk in the general population
- Twice as common in men as women
- Peak incidence between 40 and 60 yr old
- Theories on stone formation:
- Urinary supersaturation of solute followed by crystal precipitation
- Decrease in the normal urinary proteins inhibiting crystal growth
- Urinary stasis from a physical anomaly, catheter placement, neurogenic bladder, or the presence of a foreign body
- Recurrence rate of 40% at 5 yr and 75% at 20 yr
- Associated with chronic kidney disease, hypertension, type 2 diabetes mellitus, metabolic syndrome, and an increased risk of coronary artery disease
- Rare in children
- When present, often is an indication of a metabolic or genetic disorder
- 60% present with flank or abdominal pain though up to 30% only present with hematuria
- Pediatric patients <16 yr comprise ¢ ¼7% of all cases of renal stones.
- 1:1 sex distribution
- Causes of stone formation:
- Metabolic abnormalities (50%)
- Urologic abnormalities (20%)
- Infection (15%)
- Immobilization syndrome (5%)
Diagnosis
Signs and Symptoms
History
- Sudden onset of severe pain in the costovertebral angle, flank, and/or lateral abdomen
- Colicky or constant pain:
- Patient cannot find a comfortable position
- Hematuria:
- Gross hematuria in 1/3 of patients
- Nausea/vomiting
- Diaphoresis
- History of prior stone formation
Physical Exam
- Vital signs:
- Fever suggests an occult infection.
- Hypotension with an altered mental status suggests urosepsis
- Abdominal exam:
- Tenderness to palpation, rebound tenderness, or guarding suggests a more serious intra-abdominal process
- Palpate the abdominal aorta for tenderness or pulsatile enlargement suggestive of an aneurysm
- Genitourinary exam:
- Examine the genitalia for evidence of hernia, epididymitis, torsion, or testicular masses
Essential Workup
- Urinalysis
- Microscopic hematuria present in >80%
- Gross hematuria
- Absent urinary blood in 10 " 30%
- WBC/bacteria suggests infection
- No correlation between the amount of hematuria and the degree of urinary obstruction
Diagnosis Tests & Interpretation
Lab
- CBC:
- WBC >15,000 suggests concomitant infection
- Urine culture
- Electrolytes, glucose, BUN, creatinine
- Pregnancy test when suggestive
Imaging
- CT:
- Helical CT has replaced IV pyelogram (IVP) as test of choice
- Detects calculi as small as 1 mm in diameter
- Directly visualizes complications, such as hydroureter, hydronephrosis, and ureteral edema
- Advantages over IVP:
- Performed rapidly
- Does not require IV contrast media
- Detects other nonurologic causes of symptoms, such as abdominal aortic aneurysms (AAAs)
- Disadvantages:
- Does not evaluate flow or renal function
- Nonenhanced helical CT in the evaluation of renal colic:
- Sensitivity 95%
- Specificity 98%
- Accuracy 97%
- Indications:
- 1st-time diagnosis
- Persistent pain
- Clinical confusion with pyelonephritis
- IVP:
- Establishes diagnosis in 95%
- Demonstrates the severity of obstruction
- Scout film prior may localize stones that would otherwise be obscured by the dye.
- Postvoiding film
- Useful to identify stones at the ureteral vesicular junction or distal ureter that are obscured by a full bladder
- Kidney, ureter, and bladder (KUB) radiograph:
- Indicated when allergy to IVP dye and when renal scanning and US not available
- Distinguishes calcium-bearing stones (radiopaque) from noncalcium stones
- Assists in locating radiopaque stones and the exclusion of other pathologies in nonpregnant patients
- Difficult to distinguish radiopaque body:
- Phlebolith
- Bowel contents
- Obstruction within the urinary tract on the KUB
- Oblique films assist in localizing suspicious calcifications.
- US:
- Useful in the detection of larger stones and hydronephrosis
- Provides anatomic information only
- Helpful in diagnosing obstruction and localizing stones in the proximal and distal portions of the ureter
- Ability to detect hydronephrosis:
- Sensitivity 85 " 94%
- Specificity 100%
- Limitations:
- May miss stones <5 mm in size
- May miss an obstruction in the early phase of renal colic
- Time delay until the onset of pyelocaliectasis even after total obstruction
- Every effort should be made to minimize ionizing radiation exposure to the fetus
- US is the imaging modality of choice
Diagnostic Procedures/Surgery
Ureteroscopy, shock-wave lithotripsy, percutaneous nephrolithotomy
Differential Diagnosis
- Dissecting or rupturing AAA
- Pyelonephritis
- Papillary necrosis (sickle cell disease, NSAID analgesic abuse, diabetes, or infection)
- Renal infarction (vascular dissection or arterial embolus)
- Ectopic pregnancy
- Ovarian cyst/torsion
- Appendicitis
- Intestinal obstruction
- Biliary tract disease
- Musculoskeletal strain
- Lower lobe pneumonia
- Malingering or narcotic dependence (diagnosis of exclusion)
Treatment
Pre-Hospital
Parenteral opiates may be required for pain control with long transport times
Initial Stabilization/Therapy
- Rapid dipstick urine test for blood:
- Positive test in conjunction with clinical findings sufficient to begin analgesic therapy
- Provide adequate analgesia when diagnosis suspected on clinical and lab findings
Ed Treatment/Procedures
- Hydration:
- Initiate IV crystalloid infusion with 1 L of normal saline infused over 30 " 60 min followed by 200 " 500 mL/h
- Bolus volume compromised patients with 500 mL increments until urine output adequate
- Analgesics (morphine, ketorolac):
- Combination of IV NSAIDs and opioids decrease ED stay and provide better pain control than either alone
- Antiemetics (prochlorperazine, ondansetron, droperidol, hydroxyzine)
- α-Blockers (tamsulosin) or calcium-channel blockers (nifedipine) have been shown to decrease time to spontaneous stone passage:
- Most efficacious for stones <5 mm in diameter
- Tamsulosin and nifedipine equally effective
- Prescribe on discharge
Avoid NSAIDs in pregnancy, particularly in 3rd trimester
Medication
- Hydromorphone (Dilaudid): 1 " 4 mg (peds: 0.015 mg/kg/dose) IM/IV/SC q4 " 6h PRN. Reduce dose in opiate-naive patients.
- Hydroxyzine hydrochloride (Vistaril): 25 " 50 mg (peds: 0.5 " 1 mg/kg/dose) IM (not IV) q4 " 6h
- Ketorolac (Toradol): 30 " 60 mg IM or 30 mg (peds: 0.5 mg/kg/dose up to 1 mg/kg/24 " 48 h) IV (alone or with opiates); reduce dose to 30 mg IM or 15 mg IV if >65 yr or <50 kg.
- Morphine sulfate: 2 " 10 mg (peds: 0.1 " 0.2 mg/kg/dose q2 " 4h) IM/IV/SC q2 " 6h PRN; may redose more frequently if needed
- Nifedipine 30 mg PO daily.
- Ondansetron (Zofran): 4 mg (peds: 0.1 mg/kg 1) IM/IV, not to exceed 8 mg/dose IV.
- Prochlorperazine (Compazine): 5 " 10 mg IM/IV q4 " 6h; 25 mg suppository PR
- Promethazine (Phenergan): 12.5 " 25 mg (peds: 0.25 " 1 mg/kg not to exceed 25 mg) IM/IV/PR q4 " 6h
- Tamsulosin (Flomax) 0.4 mg PO daily for 4 wk
Follow-Up
Disposition
Admission Criteria
- Obstruction in the presence of infection mandates immediate urologic intervention.
- Intractable pain with refractory nausea and vomiting
- Severe volume depletion
- Urinary extravasation
- Hypercalcemic crisis
- Solitary kidney and complete obstruction
- Relative admission indications (discuss with urologist):
- High-grade obstruction
- Renal insufficiency
- Intrinsic renal disease
- Stones of size <5 mm usually pass spontaneously; those >8 mm rarely do.
Discharge Criteria
- Normal vital signs
- No evidence of concomitant urinary tract infection
- Adequate analgesia
- Able to tolerate PO fluids to maintain hydration status
- Reliable patient with an adequate home situation
- Appropriate outpatient follow-up arranged
- Normal renal function
- Provide a urine strainer to collect the stone for possible future stone analysis
- Arrange urologic follow-up
Issues for Referral
Imaging if pain persists and diagnosis not established in ED
Followup Recommendations
All patients should have urology follow-up, especially:
- 1st episode of renal stone
- Large stone >5 mm
- Patients who fail to pass a stone after 4 wk of conservative therapy
Pearls and Pitfalls
- Do not miss a vascular catastrophe mimicking as renal colic
- Aggressive pain management and hydration promote passage of stones
- The absence of hematuria does not exclude the diagnosis of acute renal colic
Additional Reading
- Hollingsworth JM, Rogers MA, Kaufman SR, et al. Medical therapy to facilitate stone passage: A meta-analysis. Lancet. 2006;368:1171 " 1179.
- Marx JA, Hockberger RS, Walls RM, eds. Rosens Emergency Medicine: Concepts and Clinical Practice. 7th ed. St. Louis, MO: Mosby; 2009.
- Schissel BL, Johnson BK. Renal stones: Evolving epidemiology and management. Pediatr Emerg Care. 2011;27(7):676 " 681.
- Teichman JM. Clinical practice. Acute renal colic from ureteral calculus. N Engl J Med. 2004;350:684 " 693.
- Worcester EM, Coe FL. Clinical practice. Calcium kidney stones. N Engl J Med. 2010;363(10):954 " 963.
Codes
ICD9
- 592.0 Calculus of kidney
- 592.1 Calculus of ureter
- 788.0 Renal colic
ICD10
- N20.0 Calculus of kidney
- N20.2 Calculus of kidney with calculus of ureter
- N23 Unspecified renal colic
SNOMED
- 95570007 Kidney stone (disorder)
- 266556005 Calculus of kidney and ureter
- 7093002 Renal colic (finding)
- 427649000 Calcium renal calculus
- 274401005 Uric acid renal calculus (disorder)