Urolithiasis

Background

• Renal damage
  • Irreversible renal damage can occur w/in 3wk w/ complete obstruction
  • Most pts have no rise in Cr b/c unobstructed kidney functions at up to 185% of its baseline capacity
    • Rise in Cr suggests solitary kidney or preexisting renal disease (such that the unobstructed kidney is unable to compensate)
• Infection
  • 8-15% of kidney stones have urinary co-infection
  • Fever, pyuria >10 WBC/hpf, and peripheral WBC >11.3 (any one) best predictors of concomitant UTI

Pass Rate

• <5mm - 98% will pass w/in 4wk
• 5-7mm - 60% will pase w/in 4wk
• >7mm - 39% will pass w/in 4wk

Types

• Calcium (75%)
  • Hyperparathyroidism, hypercalcemia of malignancy, sarcoidosis, increased absorption, loop diuretics, IBD
• Struvite (magnesium-ammonium-phosphate) (15%)
  • Proteus, klebsiella, pseudomonas, staph
• Uric Acid (10%)
  • 25% of pts w/ gout develop kidney stones

Risk Factors for Poor Outcome

1. Renal function at risk
   1. DM
   2. Hypertension
   3. Renal insufficiency
   4. Single kidney
   5. Horseshoe kidney
   6. Transplanted kidney
2. History of difficulty with stones
   1. Extractions
   2. Stents
   3. Ureterostomy tubes
   4. Lithotripsy
3. Symptoms of infection
   1. Fever
   2. Hypotension
   3. Systemic illness
   4. UTI

Diagnosis

Clinical Features

• Pain
  • Acute onset, crampy, intermittent
  • Location of pain depends on location of stone:
    • Upper ureter: flank pain
    • Mid ureter: lower anterior quadrant of abdomen
    • Distal ureter: groin pain
    • UVJ: Can mimic a UTI (frequency, urgency, dysuria)
• N/V (50%)
• Hematuria (85%)
  • Cannot be used to rule-in or rule-out stone (25% of pts w/ flank pain and hematuria do not have stone)

Work-Up

Labs

1. UA
2. UCx
   1. Consider for all patients
3. Urine pregnancy
4. Chemistry
5. CBC (if concern for infection)

Imaging

• Consider CT for:
  • 1st time stone
• Consider US for:
  • Pregnant pt
  • Repeat stone (to avoid CT)

Differential Diagnosis

1. Vascular
   1. AAA
      1. Nephrolithiasis is most common misdiagnosis given to pts w/ rupturing AAA
      2. Stones don't usually present in men >60yr, never cause hypotension
   2. Renal artery embolism
   3. Renal vein thrombosis
   4. Aortic Dissection
   5. Mesenteric Ischemia
2. Renal
   1. Pyelonephritis
   2. Papillary necrosis
   3. Renal cell carcinoma
   4. Renal infarct
   5. Renal hemorrhage
3. Ureter
   1. Blood clot
   2. Stricture
   3. Tumor (primary or metastatic)
4. Bladder
   1. Tumor
   2. Varicose vein
   3. Cystitis
5. GI
   1. Biliary Colic
   2. Pancreatitis
   3. Perforated peptic ulcer
   4. Appendicitis
   5. Inguinal Hernia
   6. Diverticulitis
   7. Cancer
   8. Bowel obstruction
6. Gynecologic
   1. Ectopic Pregnancy
   2. PID/TOA
   3. Ovarian Cyst
   4. Ovarian Torsion
   5. Endometriosis
7. GU
   1. Testicular Torsion
   2. Epididymitis
8. Other
   1. Shingles
   2. Retroperitoneal hematoma/abscess/tumor

Treatment

• Pain
  • NSAIDs are agent of choice
    • Ketorolac 30mg IV
  • Morphine
  • Metoclopramide (provides pain relief equivalent to morphine)
• Infection
  • Inpatient:
    • Gentamicin 1-2.5mg/kg + ampicillin 1-2gm q4hr OR
    • Piperacillin-tazobactam 3.375 gm q6hr OR
    • Cefepime 2gm q8hr OR
    • Ciprofloxacin 400mg q12hr (if local sensitivities do not predict treatment failure)
  • Outpatient:
    • Ciprofloxacin 500mg PO BID x10-14d OR
    • Levofloxacin 500mg PO daily x10-14d OR
    • Cefpodoxime 200mg PO BID x10-14d
• Expulsion
  • Alpha blockers a/w increased rate of expulsion, decreased time to expulsion, and decreased pain
    • Tamsulosin 0.4mg PO daily up to 4wk
• Surgery
  • Considered for:
    • Persistent obstruction
    • Failure of stone progression
    • Increasing or unremitting colic
    • Staghorn calculi (abx penetration is poor)

Disposition

Admission

1. Absolute
   1. Intractable pain or vomiting
   2. Urosepsis
   3. Single or transplanted kidney with obstruction
   4. Acute renal failure
   5. Hypercalcemic Crisis
   6. Severe medical comorbidities
2. Relative
   1. Fever
   2. Solitary kidney or transplanted kidney without obstruction
   3. Obstructing stone with signs of urinary infection
   4. Urinary extravasation
   5. Significant medical comorbidities
   6. Stone unlikely to pass (large stone (>5mm) in proximal ureter)

Consultation

1. Renal insufficiency
2. Severe underlying disease
3. Stone >6 mm
4. Sloughed renal papillae
5. Associated UTI without sepsis

Discharge

• Small stone, adequate analgesia, able to arrange urology f/u w/in 7d

Source

Tintinalli