I. What is hydronephrosis?
Congenital hydronephrosis (CHn) refers to an abnormal dilatation of the renal collecting system that is present in fetal life. It is defined by the International Fetal Urological Association as a separation of the renal collecting system of more than 12.5 px before 24 weeks of fetal age, and a separation of more than 25 px after 24 weeks and in the neonatal period as the diagnostic criteria for hydronephrosis.
Second, what are the causes of hydronephrosis?
The etiology of congenital hydronephrosis is complex, with obstructive and non-obstructive hydronephrosis. The former causes include ureteropelvic junction obstruction (44%), uretero-vesical junction obstruction (21%), ureteral cyst and ectopic ureter (12%), neurogenic bladder, posterior urethral valves (9%), urethral atresia, and vaginal uterine effusion; the latter includes primary vesicoureteral reflux (14%) and physiologic pelvic calyces and Prune-Belly syndrome. The latter includes primary vesicoureteral reflux (14%) and physiological pelvic calyx dilatation, Prune-Belly syndrome.
Ureteropelvic junction obstruction (UPJO) hydronephrosis refers to the inability of urine to enter the upper ureter from the renal pelvis, causing progressive dilatation of the renal collecting system and kidney damage; UPJO is the most common cause of hydronephrosis in newborns, accounting for more than 85% of cases. It is more common in males than females, and the ratio of males to females is 2:1. It is more common on the left side than on the right side. Bilateral cases account for about 10%, and occasionally isolated hydronephrosis is seen.
Third, what are the common clinical symptoms of hydronephrosis?
In the early stage, there are no special clinical symptoms, and those with serious obstruction may have the following manifestations.
1.May not have any symptoms Occasionally, hematuria is found after trauma.
2.Abdominal mass More than half of newborns and infants are seen with asymptomatic abdominal masses. 75% of children can find a mass in the lumbar abdomen. The mass is smooth, non-pressure, moderately tense, and occasionally fluctuates. In some cases, there is a change in the size of the mass, such as sudden onset of abdominal pain with abdominal mass, and the mass shrinks after heavy urination is an important diagnostic basis.
3. Intermittent pain in the lower back and abdomen The vast majority of children can state epigastric or periumbilical pain. Older children can clearly point out that the pain comes from the affected lumbar region. Intermittent episodes often suggest intermittent hydronephrosis. The pain can be triggered by heavy drinking and is often accompanied by nausea and vomiting. It is often misdiagnosed as a gastrointestinal disorder. The pain is caused by elevated renal pelvis pressure and enlargement of the renal pelvis to stimulate the peritoneum.
4. Hematuria can be caused by rupture of renal medullary vessels or minor abdominal trauma or combined with urinary tract infection and stones. The incidence is 10%-30%, and it is visual or microscopic hematuria.
5.Urinary tract infection is characterized by frequent urination, urgent urination and difficulty in urination, often accompanied by systemic toxic symptoms such as high fever, chills and sepsis. The incidence is less than 5%.
6.Hypertension The dilated collecting system compresses the blood vessels in the kidney leading to renal ischemia, which reflexively causes an increase in renin secretion and causes an increase in blood pressure.
7, polyuria and polydipsia symptoms After the kidney concentration function decreases, it can be manifested as low specific gravity urine, polyuria and polydipsia symptoms.
8.Rupture of kidney The rupture of dilated renal pelvis occurs by external force and manifests as acute abdomen.
9.Uremia Bilateral or isolated hydronephrosis may appear in late stage with azotemia and renal insufficiency. The child has slow growth, growth retardation, feeding difficulties or anorexia, etc. This kind of symptom is very rare clinically.
Clinical diagnosis strategy of hydronephrosis
The diagnosis of hydronephrosis is not difficult. The disease should be considered when the above clinical manifestations are met. Diagnosis of hydronephrosis generally requires one or more of the following tests. Among them, ultrasound, ECT and intravenous urography (IVU) are most commonly used, CT urography (CTU) and magnetic resonance urography (MRU). CT urography (CTU) and magnetic resonance urography (MRU) are the next most common tests, and other tests are used as needed. For most children with hydronephrosis, ultrasound and ECT can be used to make a clear diagnosis.
V. Regression of hydronephrosis
Hydrocele can have 3 regressions.
1, transient hydronephrosis: such as mild hydronephrosis found in the fetal period, some can disappear completely a few weeks after birth.
2, no progressive impairment of renal function hydronephrosis: In addition to mild hydronephrosis, the child has no progressive impairment of renal function and no clinical symptoms. Such patients account for about 1/3 of congenital hydronephrosis and need long-term follow-up.
3, progressive damage to renal function type hydrocele (loss of compensatory phase): UPJ obstruction is more serious, progressive increase in hydrocele, progressive damage to renal function.
Six, the treatment principles of hydronephrosis
1, treatment principles: mild hydronephrosis, incidentally found during physical examination without obvious clinical symptoms, can be observed for follow-up. If there is obvious evidence of ureteropelvic junction obstruction (UPJO), progressive increase of hydronephrosis or progressive damage of renal function, or clinical comorbidities such as abdominal pain, infection and stone, timely surgery should be performed. If the hydronephrosis kidney is severely atrophied, losing function or combined with severe infection, hydronephrectomy can be considered if the contralateral kidney is normal. Clinically, nephrectomy is a prudent option especially for infants and young children with massive hydronephrosis, which can be preceded by nephrostomy and followed by isotope 99mTc-DTPA renal dynamic imaging in three months after surgery. According to our clinical experience, the younger the child is, the greater the chance of restoring kidney function, and most of them do not need nephrectomy.
2.Observation and follow-up: For hydrocele found in the fetal period, regular follow-up is especially important in understanding the regression of hydrocele in the fetus. Do not worry too much about hydrocele found in the fetus, there is no need to terminate the pregnancy in a hurry, it should be followed up regularly by ultrasound in B, and then ultrasound review about five days after birth, about 1/3 of the affected children may return to normal after birth.
3. There is a correlation between the amount of renal pelvis separation and the degree of renal function damage: generally, when the renal pelvis separation is <20mm, renal function damage rarely occurs; when the renal pelvis separation is <30mm, renal function damage is <60%. When the renal pelvis separation is >50 mm, the impairment of renal function can reach 100%. Therefore, when renal pelvis separation is <30 mm or isotope 99mTc-DTPA renal dynamic imaging score renal function >40%, treatment should be conservative observation. When there is progressive enlargement of hydronephrosis (pelvic separation >30mm) or isotope 99mTc-DTPA renal dynamic imaging score renal function <40%, it proves that the child has obvious renal function impairment, surgical intervention should be promptly treated, and the cost of waiting is the sacrifice of renal function.
VII. Indications for surgery in hydronephrosis
1, with obvious obstructive symptoms such as abdominal pain or lumbar abdominal pain.
2, with total renal impairment or fractional renal impairment with isotonic fractional renal function less than 40%.
3, combined with the occurrence of urinary stones or infection / hypertension, etc.
Eight, hydronephrosis surgery and prognosis
Disconnected pyeloureteroplasty (Anderson-Hynes pyeloplasty) is the most commonly used surgical method. Open surgery and laparoscopic surgery are available, and each has its own advantages and disadvantages. However, for hydrocele in children over 1 year of age, laparoscopic surgery is more advantageous, with its advantages of less trauma and faster recovery.
The success rate of hydrocele surgery is more than 95%, and the surgical result is ideal. The hospitalization period is usually about one week.
Whether ureteral stent tube (double J tube) needs to be implanted for hydronephrosis surgery
There are many options of ureteral drainage for hydronephrosis surgery, and each unit has a different choice. We (pediatric urology of Xinhua Hospital, Shanghai Jiao Tong University Medical College) choose to implant a double J tube intraoperatively, drain for 4-8 weeks, and then remove the double J tube under cystoscopy (no anesthesia is needed, and our original method of removal is used). For some children with thick ureteric ducts, we choose not to place a double J tube.
The common complications of leaving a double J tube and other ureteral drainage tubes are: hematuria, urinary tract infection (which is more likely to occur in infants and children), etc.
Post-operative follow-up of hydronephrosis
The original symptoms can disappear after the obstruction is lifted, and the renal function and the thickness of renal parenchyma can be restored to some extent. Except for early mild hydronephrosis, the morphology and function can be restored after surgery, but in most cases, the expanded renal calyces, renal pelvis and parenchymal thickness cannot be restored to normal. Ultrasound is usually reviewed 3 months after surgery, and ultrasound and isotope are reviewed 6 months after surgery. Kidney function generally recovers most obviously 3-6 months after surgery, and is basically fixed 1 year after surgery.
For children without indwelling double J-tube, the hydronephrosis may be larger than preoperative at 1 month after surgery (the anastomosis will be edematous after surgery), which can be temporarily observed if there are no symptoms and will mostly subside gradually.