Answer:
Urinary flow obstruction may be a consequence of intrinsic or extrinsic mechanical blockage, as well as functional alterations not accompanied by fixed occlusion of the urinary drainage system. Mechanical obstruction can occur anywhere in the urinary device, from the renal calyces to the external urethral meatus. Normal narrowing sites, such as ureteropelvic and ureterovesical junctions, bladder neck and urethral meatus, are frequent sites of obstruction. When the latter is proximal to the bladder, it produces unilateral dilatation of the ureter (hydroureter) and the pielocaliceal system (hydronephrosis); lesions in the bladder or distance to a causal cause bilateral involvement.
Table 343-1 lists the frequent forms of obstruction. Pediatric causes include congenital malformations, such as ureteropelvic junction stenosis and abnormal insertion of the ureter into the bladder, which is the most frequent origin. Vesicoureteral reflux in the absence of urinary infection or bladder neck obstruction often resolves with age. Reintegration of the ureter into the bladder is indicated if reflux is severe and spontaneous improvement is unlikely, when renal function deteriorates or urinary infections recur despite chronic antimicrobial treatment. Vesicoureteral reflux can cause prenatal hydronephrosis and, if severe, causes recurrent urinary infections and renal scarring in childhood. Posterior urethral valves are the most common cause of bilateral hydronephrosis in boys. In adults, urinary tract obstruction is mainly due to acquired anomalies; Pelvic tumors, analysis and urethral stenosis predominate. Ligation or injury of the ureter during pelvic or colonic surgical procedures can cause hydronephrosis, which, when unilateral, can go unnoticed. Also, obstructive uropathy may be the result of extrinsic neoplasia (cervical or colonic carcinoma) or inflammatory disorders. Lymphomas and pelvic or colonic tumors with retroperitoneal involvement are causes of ureteral obstruction. Up to 50% of men> 40 years old may have lower urinary tract symptoms derived from benign prostatic hypertrophy, although these symptoms may also have symptoms without obstruction