UPJ obstruction

Incidence

Most common congenital urinary obstruction (1 in 1250 births)

More common in boys (2:1), two-thirds occur on the left side

Bilateral dilation in 5-10% of patients

Etiology

Intrinsic Causes

Failure of transmission of peristaltic waves across UPJ

Ineffective peristaltic waves causing hydronephrosis

Extrinsic Causes

Aberrant renal vessels, bands, adventitial tissues, and adhesions causing angulation or compression of UPJ

Intraluminal Causes

ureteral valves, benign fibroepithelial polyps

Secondary PUJ obstruction

severe vesico-ureteric reflux (VUR)

15% - 30% of children who have ipsilateral PUJ obstruction

ureter may kink proximally

Antenatal Diagnosis

Prenatal ultrasound detects hydronephrosis and abnormal anatomy

Features suggestive of UPJ obstruction

unilateral pelviectasis

Low amniotic fluid volume

no evidence of ipsilateral ureteral dilation

normal thickness of the bladder wall

CP

Older children and adults may present with

Most infants asymptomatic, often detected through prenatal screening

Episodic flank or abdominal pain

Palpable flank mass

Hematuria

Recurrent UTIs

Radiological evaluation

Renal and Bladder US

at least 2 days after birth. (false negative)

Exception: For a male neonate with bilateral hydronephrosis and a thickened bladder wall, suggestive of a more urgent problem like bladder outlet obstruction (e.g., posterior urethral valves).

Features:

Dilated calyces depicted as multiple intercommunicating cystic spaces leading to a larger cystic structure at the hilum, representing the dilated renal pelvis.

Peripheral to the dilated calyces, the renal parenchyma is usually thinned with normal or increased echogenicity.

Renal Scintigraphy (99mTc-MAG3)

MAG3 is the radionuclide of choice, both filtered and secreted by renal tubules.

The drainage curve of an obstructed kidney fails to decline even after diuretics administration, with a half-life (t½) greater than 20 minutes.

Magnetic Resonance Urography (MRU)

Recently advocated for its non-ionizing radiation and superior three-dimensional views of anatomic obstruction.

Gd-MRU provides dynamic, gadolinium-enhanced images.

Some investigators consider MRU a more reliable determinant of renal anatomy and function in UPJ obstruction.

Treatment

Goal of Surgery for UPJ Obstruction:

Preserve renal function by facilitating unobstructed drainage of the renal pelvis.

Indications for Surgery:

Differential function of less than 40%.

An obstructed curve on renogram with T½ longer than 20 minutes.

Severe calyceal dilatation with anteroposterior (AP) pelvic diameter > 40mm.

Worsening hydronephrosis on follow-up ultrasound.

Cortical thickness of less than 3 mm.

Clinical symptoms attributable to UPJO: pain, hypertension, or recurrent febrile urinary tract infections (UTI).

Surgical Approaches:

Conventional Pyeloplasty

Several techniques available, approached via lumbotomy, flank, or anterior extraperitoneal incision.

Flap Techniques: Includes Y-V-plasty, which uses renal pelvic tissue to augment the narrowed UPJ segment.

Dismembered Pyeloplasty (Anderson Hynes Pyeloplasty): Involves complete removal of the narrowed (dysfunctional) segment, tailoring of the renal pelvis if necessary, and re-approximation of the ureter to the renal pelvis in a dependent position.

Both techniques can provide a solution to UPJ obstruction with success rates exceeding 90-95%.

Endourological Pyeloplasty

Involves the use of balloon dilatations either via percutaneous antegrade endopyelotomy or retrograde ureteroscopic endopyelotomy.

Laparoscopic Techniques

Laparoscopic dismembered pyeloplasty yields results comparable to the open technique.

Follow-Up:

Follow-up ultrasound may be performed 3-6 months after the operation when maximum improvement can be seen.

Follow-up radionuclide scan should be done 6-8 months following pyeloplasty to evaluate an improvement in renal function and drainage.

follow up

Follow-up ultrasound may be performed 3-6 months after the operation when maximum improvement can be seen.

Follow-up radionuclide scan should be done 6-8 months following pyeloplasty to evaluate an improvement in renal function and drainage.