B-Late changes In severe degree of obstruction : The intrapelvic pressure becomes closure or higher than the glomerular filtration rate(6-12mm Hg), -less urine can be secreted.

-Glomerular filtration rate and renal plasma flow are reduced. -Concentration ability is gradually reduced. -In severe unilateral obstruction fluid and soluble substances reabsorbed through either the tubules or the lymphatic and will excreted by other kidney.

• Irreversible progression of loss of function may occur as early as 7days(dilatation and necrosis of the proximal tubules.

• Recovery of renal function may take up to 4weeks after release of complete obstruction.• The extent of recovery is difficult to asses before release of

the obstruction.

• Common causes of urinary tract obstruction: 1-Lower &Mid tract: Urethral stricture. B.P.H. Neurogenic bladder. Bladder neck Tumor. Bladder neck stenosis.. In neonates posterior urethral valve. 2-Upper tract: Ureteropelvic junction stenosis,ureteral or renal pelvis stone,ureteral stricture.

• Symptoms: 1-Lower and mid tract symptoms: In stage of compensation :with hypertrophied detrusor the contraction is so strong producing symptoms of the irritable bladder: urgency, urge incontinence,and frequency,dysuria. In stage of decompensation :vesical tone become impaired, or urethral

resistance exceed detrussor power producing symptoms of obstruction: Hesitancy, week stream, urinary retention,terminal dribbling

• Upper and Lower tract symptoms: - Flank and radiated pain. -Gross hematuria. -Gastrointestinal symptoms. -Chills ,Fever. -Cloudy urine,Dysuria.

• Signs: 1-Lower &Mid tract : -Induration in urethra(Urethral stricture). -DRE: atony of the anal sphincter(damage to sacral nerve

roots). -Enlarged prostate. -Vesical distention. -Observation of the force and caliber of the urinary stream.

•2-Upper tract: -Enlarged kidney.

- Large pelvic mass(pregnancy,tumor).- Children's with advanced urinary tract

obstruction may develop ascites.•Laboratory Findings:

-Anemia. - Microscopic hematuria.

- In significant bilateral hydronephrosis: Urea-Creatinine ratio is above 10.

–X-RAY : Plain film of the abdomen:

Enlargement of the renal shadow. Calcified shadows :renal or ureteral,tumor or metastases to the bones of the pelvis or spine.

Intravenous pyelogram: Information about the function. degree and level of obstruction.

Radiopaque and radio lucent stones. Bladder trabeculation and and diverticuli.

Tumors Residual urine .

•Retrograde urethro-cystogram:

Ultrasound

Renal Isotopes scan

C.T

C.T

Treatment

1-Relief of the obstruction.

2-Eradication of the infection.