Hydronephrosis etiology

(A) the cause of the disease

Hydronephrosis can be divided into primary and secondary two. Primary hydronephrosis, also known as congenital hydronephrosis, spontaneous hydronephrosis, idiopathic hydronephrosis. The most important cause is the obstruction of the ureteropelvic junction, which is often due to the part of the muscle cells by a large number of collagen fibers separated, lost the normal arrangement, can not effectively transmit from the pacing cells of electrical activity, blocking the normal peristalsis The transmission.

Congenital hydronephrosis and more caused by mechanical obstruction, the main reasons are: ① ectopic blood vessels: such as from the lower pole of the vagal vasoconstriction; ② fiber cord; ③ ureteropelvic high insertion; ④ ureteropelvic junction stenosis (Obstruction of ureteropelvic junction, UPJO) and valvular; ⑤ membranous adhesions caused by local ureter tortuosity. Congenital hydronephrosis can also be caused by the cause of power, such as segmental non-dynamic dysfunction.Secondary hydronephrosis due to other diseases caused by the urinary system, through routine examination can generally find the primary disease, some diseases need to pass a special examination (such as CT, magnetic resonance imaging, etc.) to confirm the diagnosis. These diseases include: ① upper urinary tract obstructive lesions, tumors, polyps, stones, tuberculosis, inflammation, injury, deformity, diverticulum, renal ptosis, etc .; ② upper urinary tract external compression, abdominal, pelvic or retroperitoneal mass , Idiopathic retroperitoneal fibrosis, ectopic blood vessels, pregnancy and menstrual congestion of the ovarian vein compression; ③ lower urinary tract obstructive lesions, benign prostatic hyperplasia, prostate cancer, urethral stricture, vesicoureteral reflux and so on.

(B) the pathogenesis

The normal function of the urinary system is the formation, storage and discharge of urine. The formation of urine is composed of glomerular filtration, renal tubular secretion and reabsorption. Under normal circumstances, the renal pelvis contraction, diastolic coordination action, resulting in renal pelvis hydrostatic pressure of about 10cm H2O or so, to ensure the smooth passage of urine. When the urinary tract obstruction, the renal pelvic pressure can be increased to 50 ~ 70cm H2O, on the one hand to increase the capsule pressure, on the other hand to reduce the glomerular capillary pressure, the glomerular filtration pressure reduced until the stop. The back pressure of the urine of the renal tubular distal expansion, proximal degeneration, loss of the original secretion and reabsorption function. Due to increased intracranial pressure to the blood vessels pressure, especially the output of the glomerular artery after compression, renal tissue nutrition disorders, renal papillary degeneration atrophy, from convex deformity, renal tubular system degeneration and renal thinning, And finally atrophy into fibrous tissue cysts. Observation of the ureteropelvic junction with optical and electron microscopy, mainly in the wall muscle changes, such as collagen tissue proliferation, deposition and fibrous tissue infiltration, which may be caused by local stenosis and then the main reason for the formation of obstruction. Ureteral contraction of the rhythm, urine retention can also form an obstruction. This is part of the hydronephrosis in patients with renal pelvis and ureteral connection lumen although smooth but can still lead to obstruction reasons. Renal effusion is not static, but often cycle. In the water after 2 weeks, the renal ureter urine urea was significantly reduced, while the glucose and chloride has increased significantly. Renal pelvis and re-absorption of the way may be: ① calyx bulb venous reflux; ② renal tubular reflux; ③ interstitial reflux; ④ lymphatic reflux. So acute obstruction if within 5 to 6 weeks to lift the obstruction, renal function can still be restored, which also prompted us to hydronephrosis, especially acute obstruction, can not easily decide the line of renal resection. After the formation of obstruction after the formation of hydronephrosis, depending on the severity of obstruction (obstruction is to continue to develop), renal pelvis adaptability (buffer) and the rate of urine flow, if the relative balance, you can stop the development, Thus stabilizing in the mild hydronephrosis stage.