Diagnosis: Bilateral Nephrolithiasis

The patient's CT urogram showed bilateral nephrolithiasis with a large obstructing calculus in the right ureteropelvic junction with associated moderate hydronephrosis. 

There is also a large staghorn calculus in the mid-to-upper pole of the left kidney, associated with severe left upper pole caliectasis. 

The patient underwent interventional radiology-guided right nephrostomy tube placement without complication. Following the procedure the patient's pain improved, was able to tolerate po and ambulate. She was discharged 2 days later. 

Nephrolithiasis

Epidemiology

• typically adults ages 20-50 years old
• 3:1 male:female ratio
• most stones are calcium oxalate or mixed calcium oxalate and phosphate 
• less common: struvite (magnesium-ammonium phosphate --> urea-splitting bacteria)
• Proteus, Klebsiella, Pseudomonas 
• less common: uric acid (i.e. gout) 
• 90% of stones < 5mm will pass spontaneously (> 5mm unlikely to pass) 
• 40% of symptomatic patients will have a recurrence 

Pathogenesis

• urine becomes supersaturated with a particular mineral 
• poor oral intake or excessive urinary losses 
• excess secretion of a mineral (i.e. hypercalciuria, hyperoxaluria)
• stones form in renal collecting system and pass into ureter 

Clinical Features

• abrupt onset of flank pain, radiates to abdomen and groin
• nausea and vomiting are common
• patient often unable to find a comfortable position
• fever is atypical --> consider alternative diagnoses if present
• abdomen usually nontender; consider abdominal aortic aneurysm if pulsatile mass palpated or bruit auscultated
• costovertebral angle tenderness is inconsistent

Urinanalysis 

• hematuria usually present, about 15% however will not have hematuria 
• WBCs and bacteria should raise concern for infection 
• pH >7.6 = concern for struvite and urea-splitting bacteria 

Blood work

• CBC and electrolytes typically are normal
• BUN and Creatinine are usually normal even in context of obstructive uropathy if other kidney is functioning
• Check calcium 

**Rule out vascular catastrophe! (i.e. AAA, iliac aneurysm, etc)** 

Imaging

• CT urogram = gold standard 
• sensitive and specific, can measure degree of obstruction if present, may detect alternative diagnoses, no IV contrast needed
• US
• great for detecting and measuring renal obstruction, can detect stones in the kidneys, often misses stones in the ureters

Management

• analgesia with NSAIDs (first-line), opioids, or both
• antiemetics 
• IV hydration 
• alpha-blocking agents such as Tamulosin to aid stone passage is controversial (currently recommended by the American Urological Association) 
• absolute indications for admission:
• intractable nausea and vomiting, or intractable pain 
• obstruction with infection
• relative indications for admission:
• stone >5 mm
• high-grade obstruction
• solitary kidney
• deteriorating renal function 

References: 

Lopez BL, Brooks M, Emergency Medicine: A Focused Review of the Core Curriculum, 1st Ed, 2008, Chapter 17: Renal and Urological Disorders, pages 989-994

Discite Exerceo Adservio