What is Hydronephrosis?

Due to the obstruction of the urinary system, the renal pelvis and calves are dilated, and the retention of urine is collectively referred to as hydronephrosis. Due to the accumulation of urine in the kidneys and increased pressure, the renal pelvis and calves are enlarged and the renal parenchyma is atrophied. If the retained urine becomes infected, it is called infectious hydronephrosis; when the kidney tissue becomes necrotic and loses function due to the infection, the renal pelvis is filled with pus, which is called pyoderma or pus kidney. The main cause of hydronephrosis is obstruction at the junction of the pelvis and ureter.

Basic Information

English name: hydronephrosis
Visiting department: Nephrology
Common locations: kidney

Common causes: Segmental nonfunction, intrinsic ureteral stenosis, ureteral distortion, adhesion, band or valvular structure
Common symptoms: Abdominal mass and bloating sensation with nausea, vomiting, bloating, oliguria, etc.

Causes of hydronephrosis

There are two causes of hydronephrosis, congenital and acquired, and hydronephrosis caused by extraurinary and lower urinary tract causes.

Cause of congenital obstruction

(1) Segmental nonfunction Due to segmental muscle absentness, hypoplasia, or anatomical structural disorder at the junction of the pelvis and ureter or upper ureter, it affects the normal peristalsis of this ureter and causes dynamic obstruction. If such a lesion occurs at the entrance of the ureter and bladder, a congenital giant ureter is formed, with the consequence of dilatation of the kidney, ureter, and effusion.

(2) Intrinsic ureteral stenosis mostly occurs at the junction of the pelvis and ureter. The narrow section is usually 1 to 2 mm, and can also be 1 to 3 cm in length, resulting in incomplete obstruction and secondary distortion. Under the electron microscope, it can be seen that there are too many collagen fibers around and between the muscle cells in the obstructed section, and the muscle cells are damaged for a long time. The inelastic narrow section mainly composed of collagen fibers hinders the transfer of urine and forms nephropathy. water.

(3) ureteral distortion, adhesion, girdle or valvular iliac structure may be congenital or acquired. It often occurs at the junction of the pelvis and ureter and the ureteral waist. Children and infants account for almost 2/3.

(4) Ectopic vascular compression is located in front of the pelvic ureteral junction. Others include horseshoe-shaped kidneys and impeded kidney rotation during embryonic development.

(5) The high opening of the ureter can be congenital, or due to asymptomatic renal pelvis dilation due to fibrosis around the pelvis or bladder ureter return, which causes the pelvic ureter junction to migrate relatively upward, and no stenosis can be found during the operation.

(6) Other congenital ureteric ectopic, cysts, double ureters, etc.

Acquired acquired obstruction

(1) Post-inflammatory or ischemic scars lead to local fixation.

(2) ureteral distortion caused by bladder and ureteral reflux, and fibrosis around the ureter eventually forms the pelvic ureteral junction or ureteral obstruction.

(3) Neoplasms such as tumors and polyps of the renal pelvis and ureter may be primary or metastatic.

(4) Ectopic kidney.

(5) Stones and trauma and scar scar after trauma.

3. Obstruction caused by foreign causes

Mainly include lesions of arteries and veins; lesions of the female reproductive system; tumors and inflammations of the pelvic cavity; gastrointestinal diseases; retroperitoneal diseases (including retroperitoneal fibrosis, abscesses, bleeding, tumors, etc.).

4. Obstruction caused by various diseases of the lower urinary tract

Such as benign prostatic hyperplasia, bladder and neck contractures, urethral strictures, tumors, stones, and even phimosis, etc., will also cause difficulty in emptying the upper urinary tract and cause hydronephrosis.

Clinical manifestations of hydronephrosis

Patients are often asymptomatic for a long period of time and are not noticed until abdominal masses and lumbar swelling are present. Most of the masses are found unintentionally, and they are generally sexy. The pain is usually mild or even completely painless. However, in cases of intermittent hydronephrosis (due to ectopic blood vessel compression or caused by renal droop), renal colic, severe pain, and radiation along the costal margin and ureter can be seen. It is often accompanied by nausea, vomiting, bloating, and oliguria. It usually resolves in a short time or hours, and a large amount of urine is subsequently discharged. The enlarged kidney can be touched during the examination. If it is huge hydronephrosis, its tension is not great.

Hydronephrosis is complicated by infections with pyuria and systemic poisoning symptoms such as chills, fever, headache, and gastrointestinal disorders. Some patients have urinary tract infection as the initial symptom. Patients who do not respond well to urinary tract infection must pay attention to the existence of obstruction factors. When the obstruction is severe, inflammatory exudates cannot be excreted through the urine, and there are no white blood cells in the urine, but local pain and tenderness are more obvious in this case.

Swelling hydronephrosis is more susceptible to trauma, and minor injuries may cause rupture and bleeding. Urinary flow into the retroperitoneal space or peritoneal cavity causes severe reactions, including pain, tenderness, and systemic symptoms.

Hydronephrosis test

1. Type B ultrasound

The B-ultrasound method is simple and non-invasive, which helps to make the diagnosis clear. It can also show the morphology of the remaining kidney tissue in the hydronephrosis kidney, and it is also helpful for understanding the urinary tract condition (pelvis, calyx, and proximal ureter in obstruction).

2.Diuretic kidney diagram

Diuretic nephrogram is a test that has been attached great importance in the diagnosis of hydronephrosis in recent years. It is helpful to determine the early stage of the disease (with or without hydronephrosis), to determine whether hydronephrosis requires surgical treatment and the state of impaired renal function. Especially the single hydronephrosis is relatively light, or the double hydronephrosis is severe on one side and lighter on the other side. It is more valuable if the lighter hydronephrosis requires surgery. The diuretic renal map can also be used as a monitoring method for functional recovery after surgery (pyeloplasty).

3. Measurement of renal pelvis flow pressure

It is also one of the examination methods considered clinically valuable in recent years, and its significance is similar to that of diuretic nephrogram.

4. Urography and other examinations

It is extremely important to estimate the status of hydronephric renal function. Whether the operation needs to be performed, the surgical method, and the opportunity for recovery of renal function after surgery are of great significance.

5. Imaging examination

If the thickness of the remaining renal parenchyma of the stagnant kidney exceeds 1.5cm, the kidney has a reserved value.

Hydronephrosis diagnosis

Diagnosis can be made based on clinical manifestations, the location of the obstruction, the time, the speed of occurrence, the presence or absence of secondary infection and the nature of the primary lesion.

Hydronephrosis treatment

Surgical treatment of hydronephrosis should be performed early. Appropriate use of plastic surgery to correct abnormalities in the pelvic ureteral junction and strive for greater recovery of renal function. Severe hydronephrosis and severe damage to renal function, and those with normal contralateral kidneys can be treated with hydronephrosis.

The principle of surgery is light obstruction. If the pelvis and pelvis enlargement is not serious, simple orthopedic surgery is performed. If the expansion is obvious, the narrow section of the lesion and the over-expanded renal pelvis should be removed and then anastomosis;

Hydronephrosis should be treated with greater care, and every effort should be made to preserve the kidneys. There are several situations:

1. Severe hydronephrosis on one side

Lighter side: The severe side can be treated first. In order to avoid the occurrence of renal insufficiency, safety can be increased for contralateral surgery after successful surgery. The lighter side should be carefully judged for surgical indications and can be closely observed if necessary.

2. Severe hydronephrosis on both sides

Can be treated in stages, but it is better to treat the heavier side first.

3. Light hydronephrosis on both sides

Careful analysis is needed to determine the indications for surgery.