6 PathophysiologyObstructed MegaureterLocalized deficien`cy of muscle fibres within the UVJHypertrophy of the circulr muscle bundles immediately promixal to the deficiency…………………Adynamic distal segment.Intramural part…… composed of circulatory fibres instead of longitudinal fibresDegree of obstruction= Percentage of circular fibresThree types of obstructed Megaureter:Dense collagen infiltration of terminal ureterDistal circular muscular hypertrophyDistal muscular dysplasia
7 Pathophysiology Primary obstructed ectopic ureter: Additional thick collar of smooth muscle Does not resolve spontaneously ? Require early interventionSpontaneous improvement of obstructed megaureter:Segmental maturational development of terminal ureterCorrelation with Transforming Growth Factor –β (TGF-β)depletion within the first 2 years of life.Gene assessment:↑Angiotensen II Type 2.Adrenergic regulation: contractile function of the smooth muscle wall of the megaureter.
8 Pathophysiology Refluxing Megaureter Laterally positioned, gaping ureteral orificeBladder filling and repeated cyclic voiding→ pressure transmitted to the ureter→ Megaureter.↑ Collagen Type III……..Less distensible fiber→Stiffer ureter→ ? ↓ success rate of operative correction of refluxing megaureter compared to obstructed megaureter.
9 Diagnosis Fetal Ultrasonography Pre Fetal US era: Children with HydronephrosisPUJ obstruction (22%)PUV (19%)Ectopic ureterocele (14%)Megaureter (8%)Fetal US era : Antenatal HydronephrosisPUJ Obstruction (41%)Megaureter (23%)
10 Diagnosis 1- ULTRASONOGRAPHY A Keyhole in the assessment of the Megaureter.Size, shape, tortuosity of the ureterAssessment of the renal pelvisTracing of the distal ureteric insertion→ectopic positionobstructed ureterocelePeristaltic wave of the urine→ obstructed distal segmentThe echogenicity of the kidney
11 Diagnosis 2- Voiding cystourethrography To diagnose VUR Anatomical appearance of the bladder, bladder neck, urethra and ureterCYCLICAL VUCG;When ectopic or sphincteric ureter is suspected
12 Diagnosis 3- Renography Diuresis renal scintigraphy provides the greatest quantitative information of functional and dynamic data.Renal uptake and excretionTime to peak activityTime to half peak after Frusemide washoutMAG3 depend on effective renal plasma flow (preferable)DTPA depend on glomerular filtration rate ( ↓ in neonates)Two sets of activity curves → one over the kidney→one over the ureter
13 Diagnosis 5- Percutaneous Perfusion Studies 6- Excretory urography 4-Magnrtic Resonance Urography(MRU)Provides greater insight into anatomic abnormalitiesGadolinium- enhanced MRU in renal insufficiencyLimited use → need for sedation/ GA→ ↑ expense5- Percutaneous Perfusion StudiesWhitaker test:→Invasive→ Sedation/ GA→ infusion rate 10 ml/min may overcomethe peristaltic flow potential of normalureterMonitoring of the renal pelvic pressure while documenting passage of the contrast material from the distal ureter into the bladder (≥ 14 cm water)6- Excretory urography
14 Treatment 1- Nonobstructed, Nonrefluxig Megaureter Initial Medical treatmentProphylactic antibioticOccur in 6-10% in infants with ANHSpontaneous resolution in 72%Grade I within 13 monthsGrade IIGrade IIIGrade IV &V