Pelvic ureteral junction obstruction
Pelviureteric junction obstruction PUJO
Pelviureteric junction obstruction is a common cause of pediatric congenital hydronephrosis. Pelviureteric junction obstruction causes hydronephrosis, which can lead to atrophy of renal parenchyma and impairment or even loss of renal function.
[Etiology and pathogenesis
The causes of obstruction are: ① proximal ureteral stenosis; ② vagal vascular compression; ③ tortuous ureter; ④ ureteral opening at high level of renal pelvis; ⑤ intra-ureteral valve; ⑥ intra-ureteral polyp; ⑦ dynamic obstruction. The volume of renal pelvis in pediatric patients varies with age, from 1 ml/year for those under 5 years of age to 5-7 ml for those over 5 years of age. hydronephrosis can cause elongation of renal medullary vessels and ischemia of renal parenchyma under pressure, resulting in impaired renal function, which is irreversible in severe cases.
Diagnosis
(A) Symptoms and signs
1. Abdominal masses More than half of newborns and infants are seen with asymptomatic abdominal masses, but there are also those who present with large abdominal bulges. The mass is often palpated on the affected side of the abdomen, and is mostly a cystic mass with smooth surface and no pressure pain. The mass increases during the onset of abdominal pain and decreases after extensive urination.
Intermittent pain in the lower back and abdomen Except for infants and young children, the majority of children present with pain in the upper abdomen or around the umbilicus, and older children may point out that the pain comes from the affected side of the lower back. The pain may be accompanied by nausea and vomiting and other gastrointestinal symptoms.
The incidence of hematuria is between 10%-30%.
4.Urinary tract infection Occurrence rate is less than 5%, once it appears, it is often accompanied by high fever, chills and other systemic symptoms.
5, hypertension may be due to the dilated renal collecting system compression of intrarenal vessels, causing renal ischemia and renin production.
6, renal rupture manifested as acute abdomen, with a large amount of urine in the abdominal cavity. It is due to the kidney rupture caused by direct violence or fall of the sick child.
7, renal insufficiency Bilateral hydronephrosis or single kidney with hydronephrosis may have renal insufficiency, manifested as growth retardation, loss of appetite and other gastrointestinal symptoms.
(B) Laboratory tests
1.B ultrasound can detect hydronephrosis before delivery, most of which are obstruction of the pelvic ureteral junction. ultrasound as a preliminary imaging examination, the pelvic calyces can be seen dilated, and then combined with the undilated ureter, suspicious diagnosis of obstruction of the pelvic ureteral junction, and the thickness of the renal parenchyma can be measured for future comparison.
2. X-ray examination
(1) Plain radiographs to understand the presence of concomitant renal calculi.
(2) Intravenous urography (IVU) to understand the morphology and function of the kidney. Dilatation of the renal pelvis and calyces can be seen, and the contrast agent abruptly terminates at the pelvic ureteral junction. Delayed films may provide a clear picture of kidney morphology and the presence or absence of dilated ureters in those with more impaired renal function.
Retrograde pyelogram and percutaneous nephrostomy: can understand the site of obstruction, because it is an invasive test, it is currently used only when necessary.
(3) renal nuclide scan to understand fractional renal function for later comparison.
(4) Magnetic Resonance Imaging (MRU) is a more satisfactory test to understand the site and morphology of renal and ureteral obstruction. It is more expensive and does not allow understanding of renal function if contrast is not used.
(iii) Differential diagnosis
It is mainly distinguished from retroperitoneal masses, such as nephroblastoma, teratoma and neuroblastoma. However, the latter are mainly substantial lesions and can be clearly diagnosed after IVU, CT, ultrasound and other examinations.
【Treatment
For hydronephrosis detected by perinatal ultrasound, ultrasound and IVP should be repeated after delivery to understand the function and morphology of the kidney, and regular follow-up ultrasound monitoring should be performed. Most of the hydronephrosis may not require treatment because it is an artifact or the renal function is back to normal. For mild hydronephrosis without significant progress, surgery can be considered after 6 months of age. For clearly diagnosed pelvic ureteral junction obstruction, especially in symptomatic cases, surgery should be performed, and the surgical method is disconnected pyeloplasty, i.e. Anderson-Hynes procedure.
Bilateral dissection pyeloplasty may be considered in one stage depending on the response of the patient during the procedure.
Percutaneous nephrostomy is only indicated for single or bilateral hydronephrosis complicated by uremia and severe infection.
Nephrectomy is only indicated in cases where the contralateral kidney is normal and the kidney has less than 10% renal function after drainage.
Complications and treatment
The presence of anastomotic stenosis should be considered for dissection pyeloplasty, and ultrasound and IVP should be performed 3-6 months after surgery.
[Prevention
There is no way to prevent the occurrence of obstruction at the pelvic ureteral junction.