Jennifer E. Heckman, MD, MPH
Stephen Y. Nakada, MD, FACS
BASICS
DESCRIPTION
• Ureteral obstruction can be an anatomic or functional blockage of the ureter and further classified as:
– Congenital or acquired
– Acute or chronic
– Benign or malignant
– Intrinsic or extrinsic
– Unilateral or bilateral
• Impact of obstruction dependent on:
– Degree and duration of obstruction
– Baseline renal function
– Potential for reversibility
• Associated definitions:
– Hydronephrosis
Dilation of renal pelvis and calyces
Can occur with or without obstruction (obstruction may be anywhere in urinary tract, from urethral meatus to calyces)
– Hydroureteronephrosis
Dilation of renal pelvis, calyces, and ureter
– Obstructive uropathy
Impedance to urinary flow anywhere in urinary tract
– Obstructive nephropathy
Renal parenchymal damage from urinary tract obstruction
• Urinary tract infection and sepsis may be superimposed
EPIDEMIOLOGY
Incidence
• No data available in unselected populations
• Etiology-dependent
Prevalence
• Can occur during fet al development, childhood, or adulthood
– Occurrence increases with increasing age
• Unilateral > bilateral
• Hydronephrosis may be surrogate marker for obstruction
– Overall prevalence in autopsy series: 3.1% (1)
RISK FACTORS
• Renal or ureteral calculi
• Malignancy
– Genitourinary
– Gynecologic
– Abdominopelvic
• Trauma
• Radiation
Genetics
• No specific associated familial or hereditary disorders, but cause may be congenital
• 30–50% of children with end-stage renal disease have obstructive uropathy associated with congenital anomalies
PATHOPHYSIOLOGY
• Ureter blockage results in elevated ureteral intraluminal pressure
• With increased pressures in proximal tubule and Bowman capsule, glomerular filtration rate (GFR) decreases
• Persistent obstruction leads to decreased renal blood flow and subsequent ischemia and nephron loss
• Three major points of anatomic ureteral narrowing:
– Ureteropelvic junction (UPJ)
– Where ureter crosses iliac vessels
– Ureterovesical junction (UVJ)
ASSOCIATED CONDITIONS
• Congenital
– Ureterocele
– Megaureter
– UPJ obstruction
– Stricture
• Inflammatory
– Abscess
– Amyloidosis
– Tuberculosis
– Fungal bezoars
• Malignancy
– Ureteral cancer
– Bladder cancer
– Metastatic disease
• Vascular
– Aneurysms
– Aberrant vessels
• Other
– Urolithiasis
– Pregnancy
– Trauma
– Retroperitoneal fibrosis
GENERAL PREVENTION
Dependent on underlying etiology
DIAGNOSIS
HISTORY
• Presentation reflects underlying etiology
• May be asymptomatic
• Acute obstruction may cause significant pain
– Ureteral colic
Flank pain (proximal obstruction)
Pain radiating to ipsilateral groin (distal obstruction)
• Inquire about history of urinary tract infections, renal failure, urolithiasis, malignancy, radiation therapy
PHYSICAL EXAM
• Pyrexia if associated with infection
• Hypertension possible
• Costovertebral angle tenderness
• Abdominal tenderness
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Serum studies:
– Creatinine
Often elevated, though may be normal in setting of normal contralateral kidney
– Electrolytes
• Urine studies:
– Urinalysis
May see hematuria, pyuria, or crystals
May see elevated pH secondary to nephron destruction in affected kidney
– Urine electrolytes
Imaging
• Renal ultrasound
– Screening test of choice (inexpensive, no radiation or contrast required)
– Can identify parenchymal thickness, urinary tract dilation
• Intravenous pyelogram/excretory urography
– Provides anatomic and functional information
– Low false-positive rate
– Requires contrast (limit use in renal insufficiency)
• Retrograde pyelogram
– Delineate collecting system anatomy
• Nuclear renal scan
– Assess relative renal function and degree of obstruction
T1/2 >20 minutes consistent with obstruction
– No contrast required
• Computed tomography (urography)
– Determine location of obstruction
– Highly sensitive
– Requires contrast (limit use in renal insufficiency)
Diagnostic Procedures/Surgery
Perform Whitaker test (pressure flow test) in equivocal cases
Pathologic Findings
• Gross
– Pelviureteric dilation
– Papillary blunting
– Cortical and medullary atrophy
– Parenchymal edema
– Enlarged, cystic appearance if total obstruction
• Microscopic
– Collecting duct, tubular, and lymphatic dilation
– Interstitial edema and fibrosis
– Tubular basement membrane thickening
DIFFERENTIAL DIAGNOSIS
• Intrinsic
– Urolithiasis
– Sloughed papilla
– Malignancy
• Extrinsic
– Abdominopelvic tumors
– Retroperitoneal fibrosis
– Pregnancy
– Vascular anomalies
• Anomalous course of ureter (circumcaval, retrocaval)
• Stricture disease (congenital or acquired)
• Inflammatory disorder
• Neuromuscular dysfunction
• In children:
– Posterior urethral valves (males)
– UPJ obstruction
– UVJ obstruction
– Ectopic ureter
– Megaureter
– Ureterocele
TREATMENT
Ureteral obstruction, if high-grade, bilateral, or associated with renal failure or infection warrants urgent decompression
GENERAL MEASURES
• Early recognition important in preventing irreversible renal functional impairment
• Management of acute obstruction directed at establishing drainage
• After initial stabilization and drainage, determine location and cause of obstruction
• Ureteral obstruction does not always require intervention
– May observe (e.g., terminally ill patient with normal contralateral kidney, normal serum Cr, and electrolytes)
• Supportive care (pain control, correction of electrolyte abnormalities)
MEDICATION
First Line
• Pain management (oral or parenteral)
– 1st line: Non-steroidal, anti-inflammatory medications
– 2nd line: Narcotic medications
Second Line
N/A
SURGERY/OTHER PROCEDURES
• Renal drainage:
– Retrograde ureteral stent placement
– Percutaneous nephrostomy tube placement
– Similar health-related quality of life (2)[C]
– Preferred technique depends on clinical scenario (e.g., stent preferred if uncorrectable coagulopathy, stent not as effective for extrinsic ureteral obstruction) (3)[C]
• After management of acute obstruction, definitive management directed by cause, renal function, and patient condition
– Urolithiasis
Ureteroscopy with laser lithotripsy/stone extraction, percutaneous nephrolithotomy, or extracorporeal shockwave lithotripsy (location- and calculus-dependent)
– UPJ obstruction
Open or laparoscopic pyeloplasty
– Vascular lesions (e.g., aortic aneurysm)
May require urgent operative intervention
• May consider nephrectomy if affected kidney contributes <10% to global renal function
ADDITIONAL TREATMENT
Radiation Therapy
N/A
Additional Therapies
N/A
Complementary & Alternative Therapies
N/A
ONGOING CARE
PROGNOSIS
• Progressive renal damage may occur
• Poor if untreated bilateral obstruction
COMPLICATIONS
• Acute renal failure
• Chronic renal failure
• Postobstructive dieresis in setting of bilateral ureteral obstruction
FOLLOW-UP
Patient Monitoring
• Serum creatinine
• Serum electrolytes
• Renal ultrasound
• Nuclear renal scan
Patient Resources
MedlinePlus: Unilateral hydronephrosis http://www.nlm.nih.gov/medlineplus/ency/article/000506.htm
REFERENCES
1. Bell ET. Obstruction of the urinary tract—Hydronephrosis. In: Renal Diseases. 2nd ed. Philadelphia, PA: Lea & Febiger; 1950:117–145.
2. Joshi HB, Adams S, Obadeyi OO, et al. Nephrostomy tube or ‘JJ’ ureteric stent in ureteric obstruction: Assessment of patient perspectives using quality-of-life survey and utility analysis. Eur Urol.2001;39:695–701.
3. Docimo SG, Dewolf WC. High failure rate of indwelling ureteral stents in patients with existing obstruction: Experience at 2 institutions. J Urol. 1989;142:277–279.
ADDITIONAL READING
Tseng TY, Stoller ML. Obstructive uropathy. Clin Geriatr Med. 2009;25(3):437–443.
See Also (Topic, Algorithm, Media)
• Bladder Tumors, Benign and Malignant, General Considerations
• Filling Defect, Upper Urinary Tract (Renal Pelvis and Ureter)
• Hydronephrosis/Hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Adult
• Hydronephrosis/Hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Pediatric
• Hydronephrosis/hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Prenatal
• Megaureter, Congenital
• Pregnancy, Urinary Tract Obstruction
• Retrocaval/Circumcaval Ureter
• Ureter and Renal Pelvic Tumors, General Considerations
• Ureter, Obstruction Image 
• Ureter, Stricture
• Ureteral Stricture Following Urinary Diversion
• Ureter, Stone Passage Statistics
• Ureterocele
• Ureteroenteric Anastamotic Stricture
• Ureteropelvic Junction Obstruction
• Urolithiasis, Adult, General Considerations
• Urolithiasis, Obstructing
• Urolithiasis, Pediatric, General Considerations
• Urolithiasis, Ureteral
• Urosepsis
• Whitaker Test
CODES
ICD9
• 591 Hydronephrosis
• 593.3 Stricture or kinking of ureter
• 753.20 Unspecified obstructive defect of renal pelvis and ureter
ICD10
• N13.1 Hydronephrosis w ureteral stricture, NEC
• N13.5 Crossing vessel and stricture of ureter w/o hydronephrosis
• Q62.39 Other obstructive defects of renal pelvis and ureter
CLINICAL/SURGICAL PEARLS
• Hydronephrosis is an anatomic, not functional, diagnosis.
• Renal scan best study if renal function adequate.
• Bilateral ureteral obstruction, ureteral obstruction in a solitary kidney, and ureteral obstruction associated with renal failure or infection warrant immediate renal drainage.