The 5 Minute Urology Consult 3rd Ed.

UROLITHIASIS URETERAL

Mohamed S. Ismail, MBChB, MRCS, PhD

Francis Xavier Keeley, Jr., MD, FRCS

 BASICS

DESCRIPTION

• Ureteral urolithiasis refers to a stone present in the ureter.

• Ureteral stones usually pressent with severe colicky pain that radiates from the loin (flank) to the groin as the stone passes to the lower ureter. Ureteral stone can cause obstructive uropathy as well as urosepsis which are a clinical emergency.

• Stone composition:

– Calcium oxalate 85%

– Uric acid 5–10%

– Calcium phosphate and oxalate 10%

– Struvite (infection stones) 2–20%

– Cystine 1%

EPIDEMIOLOGY

Incidence

• The incidence of ureteral stones is increasing worldwide

• 116 affected individuals per 100,000 in the United States

• Peak incidence reported age ranging from 40 to 49 yr

• Prevalence rates decrease in women over age 59 yr and men over age 69 yr

• 2.3% for women and 7% for men

• White > Hispanics > Asian > Blacks

Prevalence

The prevalence of stone disease in the United States is 5.2% which has doubled since the 1960s.

RISK FACTORS

• Genetic and environmental factors

• Diet and climate have the most significant impact on the prevalence

• Males are 3 times more affected than females

• Diet: Dehydration, high animal protein, high salt diet, vitamin D (too much?), vitamin C and (low?) calcium consumption

• Obesity, metabolic syndrome

• Previous history of stone formation

• Urinary tract infection: urease producing bacteria such as Proteus

• Family history: 3 times normal risk

• Drugs: Chemotherapy, corticosteroids

• Hot climate

Genetics

• Stone formation is common in Caucasian and Asians.

• 25% of kidney stone patients report a family history of stone disease

• Familial renal tubular acidosis and cystinuria predispose for stone formation

PATHOPHYSIOLOGY

• Supersaturation: The urine is supersaturated with salts when the concentration of the salt exceeds its solubility product (Ksp). Beyond this point crystallization start to form. The concentration at which crystallization occurs is called formation product (Kf).

• Supersaturation depends on urinary PH, ionic strength, solute concentration, and complexation.

• Inhibitors of crystallization: The presence of inhibitors allows urine to hold more solute in solution, inhibiting stone formation

– Calcium oxalate: Absorptive hypercalciuria, resorptive hypercalciuria, renal hypercalciuria, hypercalcemia, hyperuricosuria, hyperoxaluria, hypocitraturia, enteric hyperoxaluria

– Uric acid stones: Gout, myeloproliferative disorders, idiopathic uric acid stones, chemotherapy

– Calcium phosphate and oxalate stones: Distal renal tubular acidosis

– Struvite stones: Occur as a result of infection with urease-producing bacteria that breakdown urea into ammonia

– Cystine stones: Occur in patients with cystinuria an autosomal recessive disorder resulting in reduced absorption of cystine from the proximal tubules

– Medication stones (rare): Triamterene, indinavir.

ASSOCIATED CONDITIONS

• Primary hyperparathyroidism

• Medullary sponge kidney/nephrocalcinosis

• Distal (type 1) renal tubular acidosis

• Chronic diarrheal states: GI surgery: gastric bypass/banding, small bowel resection

• Gout

• Sarcoidosis

• Primary hyperoxaluria

• Cystinuria

GENERAL PREVENTION

• Adequate hydration

• Low protein diet

• Reduce dietary salt

• Allopurinol for uric acid stones

• Alkalinization of urine using potassium citrate

• Restrict oxalate consumption

 DIAGNOSIS

HISTORY

• Acute onset colicky pain that radiates from the loin to the groin

• Patient moves around trying to find a comfortable position

• Lower ureteral stone pain may radiate to the tip of the penis

• Microscopic haematuria and very rarely macroscopic haematuria

• Previous history of renal stones

• Urinary frequency, urgency, and urinary incontinence are associated with lower ureteral stones

ALERT

Obstructed infected kidney is a clinical emergency.

PHYSICAL EXAM

• The most important aspect of examination of patient with ureteral stone is core body temperature.

• Abdominal examination may reveal tenderness.

• Urosepsis is associated with high temperature, low blood pressure, and tachycardia.

DIAGNOSTIC TESTS & INTERPRETATION

Lab

• CBC to test for underlying infection (See General Measures).

• Serum creatinine to detect renal impairment.

• Urine analysis: To check for hematuria, nitrite, and leukocytes.

– Up to 30% of patients with ureteral stones have no blood in their urine.

Imaging

• Computed tomography: Non-contrast spiral CT is the imaging of choice for patient with suspected ureteral stone.

• Intravenous urography: Can document renal anatomy.

• X-ray KUB: Only in radio opaque stones. Most practical for conservative management.

• Ultrasound:

– Operator dependent. Very useful in pregnancy, patients with contrast allergy and children. Can miss small kidney stones. Normal examination does not rule out ureteral stone since hydronephrosis is a relatively late finding.

• MR urography: May be used to diagnose Ureteral stones due to ureteral dilatation, but stones usually not well seen. Cost and availability also limit its routine use.

Diagnostic Procedures/Surgery

Retrograde pyelography: Occasionally used in the diagnosis. Is used in conjunction with ureteroscopy.

Pathologic Findings

Depend on stone composition

DIFFERENTIAL DIAGNOSIS

• Abdominal aortic aneurysm

• Acute appendicitis

• Acute cholecystitis

• Pancreatitis

• Peritonitis

• Pyelonephritis

• Renal cell carcinoma

• Upper-tract TCC

• Ureteropelvic junction obstruction

 TREATMENT

GENERAL MEASURES

• Ureteral calculi which are associated with renal impairment and/or signs of infection are indication for emergency treatment with broad-spectrum antibiotics and decompression of the renal tract.

• Infected stones warrant close observation to limit morbidity and mortality. Systemic inflammatory response syndrome (SIRS) is the earliest manifestations of the continuum leading to sepsis and shock and these patients require intensive monitoring. These criterion for SIRS include 2 or more of the following (1):

– Temperature >38°C or <36°C

– Heart rate >90 BPM

– Respiratory rate >20 breaths/min

– WBC > 12,000/mm3 or <4000/mm3 or >10% bands

• Mortality is improved with decompression of an infected system (ureteral or percutaneous nephrsotomy tube [PCNT]) (2).

• Watchful waiting: Small ureteral stones will pass spontaneously and do not require any intervention (see rate of spontaneous stone passage).

• Indication of conservative management:

– Stone size less than 10 mm

– Well-controlled pain

– No clinical evidence of infection

– Adequate renal function reserve

• Spontaneous passage of stone depends on the stone size, shape, location, and associated ureteral edema

– 68% of stones 5 mm or less pass spontaneously

– 47% of stones 6–10 mm in diameter

– > 10 mm unlikely will pass

• Average stone passage time is 3 wk, stone has not passed within 2 mo is unlikely to pass.

MEDICATION

First Line

• Pain control: Nonsteroidal anti-inflammatory drugs, or opiate analgesia.

• Antiemetics: If the acute pain is associated with nausea and vomiting.

• Treat dehydration and avoid excessive fluid intake as it may increase discomfort.

• Broad-spectrum empiric antibiotic in the presence of infection, modified based on culture

– 3rd-generation cephalosporin, or a fluoroquinolone (ciprofloxacin, levofloxacin)

– Aminoglycoside or a carbapenem with high rate of fluoroquinolone resistance.

– For hospital-acquired urosepsis following urologic interventions, an antipseudomonal 3rd-generation cephalosporin or piperacillin/β-lactamase inhibitor in combination with an aminoglycoside or a carbapenem.

• Ureteroscopy: Fluoroquinolone, trimethoprim sulfamethoxazole, or aminoglycoside ± ampicillin or 1st/2nd-generation cephalosporin or amoxicillin/clavulanate (3).

• Percutaneous nephrolithotomy (PCNL): 1st/2nd-generation cephalosporin, or aminoglycoside + metronidazole or clindamycin or aminoglycoside/sulbactam or fluoroquinolone (3)

Second Line

• Medical expulsive therapy: α1-adrenergic adrenoceptor blockers (such as tamsulosin) cause smooth muscle relaxation and increase spontaneous stone passage rate by 1/3. However, it is not licensed yet for this purpose. It is contraindicated in the presence of infection.

• Oral chemolysis: High fluid intake and alkalinization of urine with potassium citrate is indicated in uric acid and cystine stones.

SURGERY/OTHER PROCEDURES

• Extracorporeal shock wave lithotripsy (ESWL): Using ultrasound shock wave to fragment the stone. The efficacy is related to the stone size and location. The clearance rate for stone <10 mm in the upper ureter is >80%

• Ureteroscopy and endoscopic lithotripsy: Has a higher clearance rate for upper ureteral stones >10 mm and all mid Ureteral and distal ureteral stones compared to ESWL.

• There are no significant differences between ESWL and ureteroscopy and the use of either treatment depend on local resources.

• Other treatment modalities such as percutaneous nephrolithotomy, open ureterolithotomy, laparoscopic ureterolithotomy are rarely used.

• The presence of infection requires emergency management Antibiotics with urinary diversion (stent or PCNT).

ADDITIONAL TREATMENT

Radiation Therapy

N/A

Additional Therapies

Prevention of further stone formation (see general prevention)

Complementary & Alternative Therapies

No alternative or complementary medications have been shown to be beneficial

 ONGOING CARE

PROGNOSIS

• The prognosis of ureteral calculi is excellent.

• Patient with recurrent stone formation needs metabolic workup.

COMPLICATIONS

• Infection, bleeding, and pneumothorax are the complications of the treatment

• Multiorgan failure

• Renal impairment

• Urosepsis

FOLLOW-UP

Patient Monitoring

• Patient is followed to detect any further stone formation

• Prevention measures to avoid further stone formation (see general prevention)

• Patients with septic stone picture require at least 14 days of culture appropriate antibiotics

Patient Resources

Urology Care Foundation: Kidney and Ureteral Stones. http://www.urologyhealth.org/urology/index.cfm?article=148

REFERENCES

1. Bone RC, Balk RA, Cerra FB, et al. ; ACCP/SCCM Consensus Conference Committee Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/ Society of Critical Care Medicine. Chest. 1992;101:1644.

2. Borofsky MS, Walter D, Shah O, et al. Surgical decompression is associated with decreased mortality in patients with sepsis and ureteral calculi. J Urol. 2013;189(3):946.

3. Best Practice Policy Statement on Urologic Surgery Antimicrobial Prophylaxis (2008). http://www.auanet.org/education/guidelines/antimicrobial-prophylaxis.cfm

ADDITIONAL READING

• Dellabella M, Milanese G, Muzzonigro G. Efficacy of tamsulosin in the medical management of juxtavesical ureteral stones. J Urol. 2003;170:2202–2205.

• Goldsmith ZG, et al. Cooling off Hot Stones AUA News, Volume 18; Issue 10; October, 2013.

• Preminger GM, Tiselius HG, Assimos DG, et al. ; EAU/AUA Nephrolithiasis Guideline Panel. 2007 guideline for the management of ureteral calculi. J Urol. 2007;178:2418–2434.

• Romero V, Akpinar H, Assimos DG, et al. Kidney stones: A global picture of prevalence, incidence, and associated risk factors. Rev Urol. 2010;12(2–3):e86–e96.

See Also (Topic, Algorithm, Media)

• Urolithiasis, Adult, General Considerations

• Urolithiasis, Pediatric, General Considerations

• Urolithiasis, Renal

• Urolithiasis, Ureteral Algorithm 

• Urolithiasis, Ureteral Image 

• Urosepsis

 CODES

ICD9

• 592.1 Calculus of ureter

• 599.0 Urinary tract infection, site not specified

• 599.60 Urinary obstruction, unspecified

ICD10

• N13.9 Obstructive and reflux uropathy, unspecified

• N20.1 Calculus of ureter

• N39.0 Urinary tract infection, site not specified

 CLINICAL/SURGICAL PEARLS

• In the setting of an infected obstructing ureteral calculus, there is no significant difference in outcome whether stented or treated by percutaneous drainage.

• Recent studies suggest that in unstable patients with very large stone burdens percutaneous drainage may be preferred.



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