Christopher E. Keel, DO
Raju Thomas, MD, MHA, FACS
BASICS
DESCRIPTION
• Ureteropelvic junction obstruction (UPJO) is a restriction of urine flow from the renal pelvis to ureter
• Most common cause of significant dilation of collecting system in fet al kidney
EPIDEMIOLOGY
Incidence
• 1:500–1000 newborns
– 25% diagnosed by 1 yr, 50% by 5 yr
• Adult presentation usually in 3rd–4th decade
Prevalence
• Left > right side (67%)
• Male > female (>2:1) (1)
RISK FACTORS
• Familial disposition
• Congenital renal anomalies:
– Contralateral UPJO: 10–40% risk
– Vesicoureteral reflux (VUR): 0.5–5% risk
– Renal duplication: 6% risk
– Horseshoe kidney: 15% risk
– Ectopic kidney: 35% risk
PATHOPHYSIOLOGY
• Congenital (most common etiology):
– Intrinsic etiologies:
Adynamic ureteral segment due to ureteral smooth muscle maldevelopment; the most common cause of pediatric UPJO
Intrinsic stenosis due to inadequate ureteral recanalization during fet al development
Persistent valvular mucosal folds
– Extrinsic etiologies:
Crossing accessory lower-pole vessel; most common cause of adult UPJO
High ureteral insertion into renal pelvis
Horseshoe, ectopic, or malrotated kidney causing kinking at ureteropelvic junction (UPJ)
• Acquired:
– Severe VUR can cause ureteral tortuosity and kinking at UPJ
– Inflammation and scarring from trauma, urolithiasis, instrumentation, infected urinoma, retroperitoneal fibrosis
ASSOCIATED CONDITIONS
• 50% associated with another congenital anomaly:
– Contralateral renal dysplasia or multicystic dysplastic kidney (MCDK)
– Contralateral UPJO: Most common
– Horseshoe or ectopic kidney
– Incomplete renal duplication
– Unilateral renal agenesis
– VACTER/VACTERL syndrome
– Vesicoureteral reflux (9–18%)
GENERAL PREVENTION
None
DIAGNOSIS
HISTORY
• Prenatal/neonatal presentation:
– Hydronephrosis seen on antenatal US
– Typically asymptomatic; but occasionally see feeding difficulties, failure to thrive, sepsis
• Childhood presentation:
– Episodic abdominal complaints or ipsilateral colicky flank pain
– Cyclic nausea and vomiting
– Gross hematuria, classically after minor abdominal or flank trauma
– UTI
• Adult presentation:
– Episodic ipsilateral colicky flank pain, classically after diuretic or alcohol intake (aka Dietl crisis)
– Cyclic nausea and vomiting
– UTI or pyelonephritis
PHYSICAL EXAM
• Prenatal/neonatal or childhood presentation:
– Palpable abdominal mass
– Fever, failure to thrive
• Childhood presentation:
– Costovertebral (CVA) tenderness
– Palpable abdominal mass in small children
• Adult presentation:
– CVA tenderness
• Hypertension (HTN): Due to acute pain or activation of renin–angiotensin–aldosterone system
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Serum BUN and creatinine
• Urine analysis:
– Microscopic hematuria, rarely gross
– Trace proteinuria
– Pyuria and bacteriuria
• Urine culture
Imaging
• Renal US:
– Most often used as initial screening study in pediatric population
– Useful to distinguish renal masses and ureterovesical junction obstruction from UPJO
• Defer until 2nd or 3rd day of life to avoid false-negative result secondary to physiologic oliguria
• Computed Tomography (CT):
– Most commonly employed diagnostic study after neonatal period
– When IV contrast given, findings include delayed opacification of collecting system, pyelocaliectasis, nonvisualization of ureter, cortical thinning
• Intravenous pyelogram; still occasionally performed
• Diuretic renal scintigraphy (Tc-99mm MAG3):
– Provides differential renal function
– T1/2 assesses for presence of obstruction:
Normal T1/2: <10 min
Indeterminate T1/2: 10–20 min
Obstruction T1/2: >20 min
Diagnostic Procedures/Surgery
• Cystoscopy with retrograde pyelography:
– Defines extent of ureteral involvement
– Allows for placement of temporary ureteral stent to relieve urinary obstruction
– If available endoluminal ultrasound can define crossing vessels intraoperatively
• Helical CT scan with 3D reconstruction:
– Allows visualization of collecting system and renal vasculature (crossing vessels)
• Whitaker test (WT): Rarely performed
– Reserved for equivocal IVP or MAG3
– Percutaneous catheter with pressure transducer placed in renal pelvis, another placed in bladder via urethra; fluid infused into renal pelvis at 10 cc/min; measure pressure differential:
Normal: <15 cm H2O
Equivocal: 15–22 cm H2O
Obstructed: >22 cm H2O
Pathologic Findings
• Hydronephrosis without hydroureter
• Elevated T1/2 >20 min on diuretic MAG3
• Pressure differential >22 cm/H2O on WT
• Crossing vessel on helical CT scan
DIFFERENTIAL DIAGNOSIS
• Obstructive dilation:
– Fungal balls
– Impacted urinary calculus
– Intraluminal benign or malignant neoplasm
– Sloughed papilla
• Nonobstructive dilation:
– Prune belly syndrome
– Renal or peripelvic cysts
– VUR
– Megaureter
TREATMENT
GENERAL MEASURES
• Prevent further deterioration in renal function
• Relieve symptoms of obstruction
MEDICATION
First Line
• Neonatal/newborn presentation:
– Prophylactic antibiotics to maintain sterile urine:
UTI prophylaxis: Ampicillin 25 mg/kg/d as neonates THEN
Trimethoprim-sulfamethoxazole 2 mg/kg/d OR nitrofurantoin 1–2 mg/kg/d beyond 2 mo of age
– Repeat imaging—to monitor for resolution or deterioration of function (2)
• Childhood and adult presentation:
– No medical therapy appropriate except to treat active infection
SURGERY/OTHER PROCEDURES
• Purpose: Restore renal function
– Especially in patients with bilateral obstruction, solitary kidney, or poorly functioning contralateral kidney
• Relieve severe symptoms:
– Percutaneous nephrostomy or ureteral stent
• Treat pyonephrosis if present:
– Culture-specific antibiotics
– Percutaneous nephrostomy or ureteral stent may be necessary to ensure adequate drainage of infected urine.
• Expectant treatment:
– Neonatal hydronephrosis: Obstruction associated with unilateral neonatal hydronephrosis is 15%; a majority of neonates with hydronephrosis can be initially managed nonoperatively.
– Asymptomatic adults with normal contralateral kidney and significant comorbidities
• Definitive operative treatment:
– Robotic assisted laparoscopic pyeloplasty
Gaining more acceptance and is now becoming the standard approach, even in the pediatric population, with increasing access to robotic surgical technology (3).
Employs the same techniques as those performed both open and laparoscopic
Comparative outcomes to open techniques approaching >95%
Ease in surgical dissection and suturing techniques, management of associated calculi and crossing vessels, has increased its popularity (4).
Offers decreased morbidity, better cosmesis, and quicker return to daily activities
– Laparoscopic pyeloplasty: Success rate >90%; transabdominal or retroperitoneal approach; employs dismembered or Y-V plasty technique;
Utilized when robotic technology is not available. Technical demands of laparoscopic suturing techniques is a major drawback.
Open pyeloplasty: Procedure of choice in pediatric patients:
Dismembered (Anderson-Hynes) pyeloplasty: Most common open technique; success rate >90%; appropriate for high insertion, accessory vessels, massive dilation, long ureteral involvement; excise anatomic and functionally abnormal segment
Foley Y-V plasty: Appropriate for high ureteral insertion
Spiral or vertical flap: Appropriate for large extrarenal pelvis and long segment of narrowed ureter
Ureterocalycostomy: Appropriate for rotational anomalies or reoperation after failed pyeloplasty; partial lower pole nephrectomy is required to prevent anastomotic stenosis.
Simple nephrectomy: May be appropriate for ipsilateral poor renal function and normal contralateral renal function, especially if differential renal function <10–15%, extensive stone disease, chronic infection, multiple failed repairs
– Endoscopic procedures: Minimally invasive alternative to open procedures in adults: (5)
Antegrade cold-knife incision endopyelotomy: Success rate >60%; requires percutaneous access; nephrostomy tube left indwelling 24–48 hr, ureteral stent left indwelling 6 wk; appropriate for adult patients with stricture <2 cm, UPJO associated with renal calculi, children with secondary UPJO
Retrograde ureteroscopic laser incision: Success rate in small series 85–90%; allows direct visualization of incision; requires specialized ureteroscopic equipment and endourologic expertise; ureteral stent left indwelling 6 wk
– Chronic percutaneous nephrostomy or ureteral stent: Reserved for patients who are not candidates for definitive operative treatment
ONGOING CARE
PROGNOSIS
• Prenatal/neonatal presentation:
– Often does not require definitive operative treatment, due to propensity for self resolution or to remain stable
– Intervention in severe cases can result in greatly improved renal function
• Childhood and adult presentation:
– Recent investigations demonstrate excellent long-term success rates with pyeloplasty (>90%) verses 60–70% with endoscopic techniques.
COMPLICATIONS
• Recurrent stricture
– Usually managed endoscopically or by repeat pyeloplasty
– Ureterocalycostomy
• Urinary leak/fistula
• Infection
• Rarely sepsis/HTN
FOLLOW-UP
Patient Monitoring
• Expectant management in the neonate:
– Renal US or MAG3 at 1 mo, followed at 3–6 mo
– Operative intervention is recommended if >10% difference in renal function, worsening of obstruction or renal function or worsening hydronephrosis
• Postoperative Management
– Renal US or MAG3 6–12 wk postop
91% of children will have improvement in renal function
Adults generally will not improve function but will have improvement in drainage.
REFERENCES
1. Carr MC, Casale P. Anomalies and surgery of the ureter in children. In: Wein AW, et al., eds. Campbell-Walsh Urology. 10th ed. Philadelphia, PA: Elsevier-Saunders; 2012.
2. Ross SS, Kardos S, Krill A, et al. Observation of infants with SFU grade 304 hydronephrosis: worsening drainage with serial diuresis renography indicates surgical intervention and helps prevent loss of renal function. J Pediatr Urol. 2011;7(3):266–271.
3. Barbosa JA, Kowal A, Onal B, et al. Comparative evaluation of the resolution of Hydronephrosis in children who underwent open and robot-assisted laparoscopic pyeloplasty. J Pediatr Urol.2013;9(2):199–205.
4. Boylu U, Oommen M, Lee BR, et al. Ureteropelvic Junction Obstruction Secondary to Crossing Vessels—To Transpose or Not? The Robotic Experience. J Urol. 2009;181:1751–1755.
5. Kmi EH, Tanagho YS, Traxel EJ, et al. Endopyelotomy for pediatric ureteropelvic junction obstruction: a review of our 25-year experience. J Urol. 2012;188(4 Suppl):1628–1633.
ADDITIONAL READING
None
See Also (Topic, Algorithm, Media)
• Hydronephrosis/Hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Adult
• Hydronephrosis/Hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Pediatric
• Hydronephrosis/Hydroureteronephrosis, (Dilated Ureter/Renal Pelvis), Prenatal
• Megaureter, Congenital
• Ureter, Obstruction
• Ureteropelvic Junction Obstruction Image 
CODES
ICD9
• 592.1 Calculus of ureter
• 593.4 Other ureteric obstruction
• 753.21 Congenital obstruction of ureteropelvic junction
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
• Purpose is to relieve obstruction and preserve kidney function.
• Open or laparoscopic surgical repair remains the best option for treatment.