Urinary Tract Obstruction
Can happen anywhere from urethral meatus to calyx
Upper causes hydronephrosis (Ex renal mass, flank pain)
Lower causes retention +/- hydronephrosis (Ex suprapubic mass/pain, poor stream)
Pain can cause nausea and vomiting
Etiology
Ix
Antenatal US hydronephrosis graded 1-4
Renal US
MAG-3 to asses differential function and drainage (supercedes IVP)
Complications
Pelviureteric junction obstruction
Posterior urethral valves
Upper causes hydronephrosis (Ex renal mass, flank pain)
Lower causes retention +/- hydronephrosis (Ex suprapubic mass/pain, poor stream)
Pain can cause nausea and vomiting
Etiology
- Congenital (posterior / anterior UV, diverticula, stenosis/atresia (PUJ see below), ureterocele, megaureter, ectopic ureter, retro(IV)cava ureter, phimosis)
- If lower UT or bilateral UT, can cause oligohydroamnios, which can cause pulmonary hypoplasia
- Trauma (Haematoma, Urinoma, stricture, foreign body)
- Neoplasia (extrinsic Wilm's, Neuroblastoma, lymphoma, polyp)
- Calculi
- Inflammation (intrinsic TB, extrinsic IBD/ chronic granulomatous disease, retroperitoneal fibrosis)
- Iatrogenic (Lymphocele )
- Neurogenic bladder
Ix
Antenatal US hydronephrosis graded 1-4
Renal US
- Renal parenchymal thickness/cysts
- Hydronephrosis
- Dilation
- Bladder wall thickening
- Post-void residual
- Stones
MAG-3 to asses differential function and drainage (supercedes IVP)
- first 3 mins show differential uptake (ie function)
- unobstruction clears from pelvis by 15mins (15-20min indeterm) >20mins = obstruction
- Frusemide 1mg/kg
- IDC if VUR to prevent prolonged exposure to radionucleotide
- Difficult to interpret <1mo at immature kidneys clear slowly
Complications
- congenital: from cortical dysplasia to multicystic dysplastic kidneys
- MCDK (hypoplasia (reduced nephrons), dysplasia, cysts.
- unilateral (v Polycystic KD = bilateral), as bilateral = still born
- Risk of wilms and HTN = annual US/BP v nephrectomy
- MCDK (hypoplasia (reduced nephrons), dysplasia, cysts.
- aquired: from minimal tubular changes to dilation of Bowman’s space, glomerular fibrosis, and interstitial fibrosis ie scarring
- Urinary stasis
- Pyelonephritis
- Calculi
- Urinary ascites (after tract rupture)
- Patent urachus if congenital and lower (persistant allantois that drained to bladder to the umbilical cord)
Pelviureteric junction obstruction
- hydronephrosis without ureteric dilation
- 60:40 L:R, 2:1 M:F, 10% bilateral, 50% have scarring
- MAG-3 after d3 (neonatal oliguria
- MCUG (15% have VUR)
- Pyeloplasty for Gr 3-6 (95% success)
Posterior urethral valves
- 1:8,000 boys
- fan distally from prostatic urethra to external urinary sphincter
- prostatic urethra dilations, bladder distention/trabeculation, VUR (50%), renal scarring, Renal insuff (30%)
- Rx temporary vesicostomy until urethra large enough for transurethral ablation of the leaflets