Paediatric unilateral giant hydroureteronephrosis from idiopathic ureterovesical stricture: a case report

Abstract

A congenital type of ureterovesical junction obstruction may be present in the fetus or at any stage during childhood, more commonly associated with urinary tract infections and other secondary causes. We present the case of a 6-year-old boy who suffered from colic and side pain, which was worsening monthly. He suffered from a giant hydroureteronephrosis resulting from idiopathic ureterovesical junction obstruction, with no clinical or laboratory signs of urinary tract infection or other secondary causes of obstruction. Indications for surgery were a decrease in kidney function (<40%) at scintigraphy, severe hydronephrosis (>30 mm), and the coexistence of symptoms (colic pain). After surgery, kidney function returned to almost completely normal. Unexpectedly an obstruction may become symptomatic late in infancy, especially in patients with normal prenatal ultrasound screening and postnatal life, as was the case for our patient in whom the only clinical sign was pain at flank.

BACKGROUND

Megaureters account for approximately 20% of cases of hydronephrosis in newborns, and approximately 15–25% of them are bilateral.¹ Ureteral dilation can be divided into four categories: non-refluxing non-obstructed ureter, refluxing non-obstructive ureter, refluxing obstructive ureter, and non-refluxing obstructed ureter. Primary ureterovesical junction (UVJ) obstruction is rare among the different aetiologies of hydroureteronephrosis. UVJ obstruction is frequently associated with an aperistaltic segment of the distal ureter at the UVJ. Routine ultrasound screening during pregnancy detects most dilations of the urinary tract,^2,3 but diagnosis and treatment of primary UVJ obstructions are done during early infancy. It is unlikely that patients with primary UVJ obstruction remain asymptomatic until childhood.

We report the case of a child with unilateral hydronephrosis caused by UVJ stricture with no risk factors or signs of secondary aetiology or any signs of kidney damage. The stricture resulted in monolateral symptomatic giant dilatation which developed later in infancy; almost total resolution of the kidney dysfunction was achieved following correction of the obstruction.

CASE PRESENTATION

A 6-year-old boy was born at term with normal prenatal and postnatal clinical history. The child was admitted to the hospital when recurring left sided colic pain continued to worsen monthly.

INVESTIGATIONS

Laboratory tests showed only mild signs of infection (C reactive protein 9.3–34.7 mg/dl, white blood cells 7140–6960 cell/mm³). Blood pressure (98/54 mm Hg) and renal function were normal (table 1). Urine analysis showed isolated microhaematuria. The microbiological urinalysis was negative for urinary tract infection (UTI). However, ultrasound of the abdomen revealed an enlargement of the left kidney, pelvis and ureter. The polo–polar length of the left kidney was 160% longer than normal and the left cortical thickness was thinner than on the right side. Doppler of the left renal artery disclosed enhanced resistive index. The voiding cysto-ureterogram was normal. Dynamic scintigraphy MAG-3 showed a dilated left kidney with reduced scintigraphic uptake (fig 1A) and delayed radioactive urine formation. The urinary upload was very low and elimination after diuretic furosemide was quite delayed (fig 1A). In particular, the radioactive urine appeared 8 min later. Finally, the scintigraphic results indicated UVJ stenosis (table 1).

Table 1.

Kidney function and renal parameters by magnetic resonance imaging before and after surgery

	Before surgery		Eight months after surgery
Creatinine (mg/dl)	0.67		0.48
GFR (ml/min/1.73 mq)	96.8		140
Kidney	Left (obstructed)	Right	Left (operated)	Right
Ultrasound (cm)	14.3	9.5	11	9.5
Pelvis (mm)	40	–	8	–
Ureter (mm)	35	–	–	–
Cortical thickness (mm)	3	16	7	16
Resistive index	0.62	0.53	0.55	0.52
Scintigraphy (%)	38	62	48	52
ERPF (ml/min)	150	250	183	198

ERPF, effective renal plasma flow; GFR, glomerular filtration rate by Swartz formula.

Figure 1.

Renal MAG3 scintigraphy before and after surgery. (A) Urinary upload was very low and elimination after diuretic furosemide was quite delayed. (B) Kidney function was similar between kidneys; the urine washout was almost complete after diuretic stimulus. ERPF, effective renal plasma flow.

Multiple magnetic resonance imaging (MRI) was performed in both basal condition and with gadolinium. MRI showed enlargement of the left kidney with marked reduction of the cortical thickness and an enlarged pelvis and ureter until right before the UVJ (fig 2). Finally, MRI showed considerably delayed washout of medium into bladder.

Figure 2.

Magnetic resonance imaging urography showing an enlargement of the left kidney with marked reduction of cortical thickness and giant pelvis and ureter, until just before the ureteral vesical junction.

TREATMENT

Finally, surgical correction of the UVJ obstruction was successful. Histological analysis confirmed fibrosis of tissues removed at surgery.

OUTCOME AND FOLLOW-UP

Three months after surgery the estimated kidney function by Schwartz’s formula was 150 ml/min/1.73 mq. Ultrasound follow-up showed a reduction of the enlarged left kidney and an improvement in cortical thickness. Dynamic scintigraphic scan with MAG3 performed 8 months later confirmed that the left kidney was less enlarged than before surgery, but did not confirm homogeneous parenchyma. The accumulation of urine was slightly prolonged with ameliorated slope, similar to that of the other normal kidney. We observed slightly less radioactive urine production although it was better in an orthostatic position and, after diuretic stimulus, the urine washout was almost complete (−84%). The radioactive urine flux from ureter to bladder was normal. Scintigraphic renal function was similar for both kidneys (fig 1B).

DISCUSSION

We report a case of a giant hydroureteronephrosis in a 6-year-old boy caused by UVJ stricture presenting worsening of side pain. Causes of paediatric obstructive hydroureteronephrosis may include primary or congenital UVJ obstruction and a secondary form of UVJ obstructions (that is, calculus, ureterocele, tumours, ureteral reimplantation, retroperitoneal fibrosis). Ultrasound during pregnancy enabled the physician to make an early diagnosis of primary UVJ obstruction, which involved 4% of the total fetal hydronephrosis,⁴ which required a postnatal u1trasound for confirmation and follow-up. Furthermore, MRI techniques made it possible to see the anatomical details of the obstruction level from the third trimester of pregnancy to postnatal life.^5,6 Surgical treatment consisted of excision of the distal ureteric segment, tapering of the ureter and reimplantation or insertion of a JJ stent.⁷

Since there was reduced scintigraphic renal function, the boy underwent surgery because patients with UVJ obstruction are at risk of kidney failure. Of the 27% of paediatric patients with kidney failure due to obstructive uropathy, the obstructive megaureter accounts for 3.5% of cases.^8,9 In our patient’s case, the indications for surgery were a decrease in renal function (<40%) at scintigraphy, severe hydronephrosis (>30 mm) and coexistent symptoms (colic pain). Postoperative imaging showed an improvement in renal functional (+10%) and did not show severe hydroureteronephrosis,¹⁰ but only slight dilation of the pelvis.

Finally, our case was typical of an idiopathic UVJ obstruction with late manifestation and no clinical or laboratory signs of UTI except colic side pain. Further examination excluded other secondary causes of obstruction (calculi, compression of the ureter from mass, etc). Terminal ureteral obstruction may result from progressive cell deficiency in the cloaking muscular coat and fibrosis of the ureter, which can lead to an anatomical obstruction. After surgery, kidney function had almost returned to normal.

LEARNING POINTS

• A congenital type of UVJ obstruction may be present at any stage during childhood.

• UVJ obstruction is commonly associated with UTIs or other secondary causes, although not always.

• Primary obstruction may become symptomatic late in infancy, especially in patients with normal prenatal ultrasound screening and postnatal life, as was the case with the present patient in whom the only clinical sign was pain at flank.