What is Hydroureteronephrosis?
Hydroureteronephrosis is the simultaneous dilation of the renal pelvis, calyces, AND ureter, representing a more extensive form of obstruction than simple hydronephrosis (which involves only the kidney collecting system). 1
Anatomic Definition and Distinction
Hydroureteronephrosis specifically indicates that both the kidney collecting system (pelvis and calyces) and the ureter are dilated, distinguishing it from isolated hydronephrosis where only the renal pelvis and calyces are affected. 1
The condition develops secondary to urinary tract obstruction, leading to back-pressure buildup throughout the upper urinary tract. 1
Progressive dilation can lead to acute kidney injury and permanent nephron loss if not corrected. 2
Clinical Significance and Presentation
Most cases are clinically silent and discovered incidentally during imaging for unrelated causes. 1
When symptomatic, acute flank or abdominal pain is the hallmark presentation, especially with stone-related obstruction. 3
Bilateral hydroureteronephrosis is a medical emergency requiring urgent decompression, as serum creatinine will be elevated (unlike unilateral cases where the contralateral kidney compensates). 4
Common Etiologies
Urolithiasis (kidney stones) is the most common cause in adults, creating mechanical blockage of the ureter. 5, 4
Ureteropelvic junction (UPJ) obstruction predominates in antenatal and pediatric populations. 5, 4
Non-calculus causes include benign prostatic hypertrophy, urethral stricture, neurogenic bladder, retroperitoneal mass, and bladder outlet obstruction. 1
Malignant ureteral compression from pelvic or retroperitoneal tumors becomes increasingly important with age. 3
Prognostic Implications in Malignancy
In upper urinary tract urothelial carcinoma (UTUC), preoperative hydroureteronephrosis independently predicts worse overall survival, cancer-specific survival, and disease-free survival. 6
A meta-analysis of 22 studies involving 7,542 UTUC patients confirmed this association, though the definition of hydroureteronephrosis varies among studies with heterogeneity and potential confounding factors. 6
The presence of obstruction should be considered alongside other high-risk factors rather than used as the sole criterion for risk stratification. 6
Critical Complications
Pyonephrosis (infected obstructed kidney with pus) requires urgent decompression before definitive treatment to prevent sepsis. 3, 4, 7
Chronic hydroureteronephrosis can progress asymptomatically until significant renal damage occurs. 3
If left untreated, the condition may culminate in renal failure. 1
Diagnostic Approach
Ultrasound detects hydroureteronephrosis with sensitivity exceeding 90% and serves as the first-line imaging modality. 3
CT urography provides comprehensive assessment with 92% sensitivity and 95% specificity for identifying muscle-invasive disease in UTUC cases. 6
Color Doppler ultrasound helps differentiate obstructive from non-obstructive causes and can assess renal perfusion. 8