Primary obstructed megaureters

Case contributed by Dr Muhammad Yousaf


Bilateral hydroureteronephrosis on ultrasound.

Patient Data

Age: 7 years
Gender: Male

There is bilateral mild to moderate dilatation of the renal calyces and dilated tortuous ureters seen till distal 3rd. Peristaltic waves were seen in distal ureters. Few urinary bladder diverticula were also appreciated. No urinary bladder trabeculations.

A voiding cystourethrogram was advised to look for any posterior urethral valve or reflux.



Voiding cystourethrogram shows multiple urinary bladder diverticula likely to be congenital as there is no evidence of bladder outlet obstruction/posterior urethral valve and no abnormally thickened/trabeculated urinary bladder wall. Also, there is no evidence of reflux into the ureters.

An intravenous pyelogram was then advised to look for a distal ureteric obstruction.



An IVU/IVP shows mild dilatation of the bilateral renal calyces, dilated tortuous ureters with tapering of distal ends, and delayed filling/opacification of the urinary bladder.

Case Discussion

Ultrasound, voiding cystourethrogram (VCUG), and intravenous pyelogram (IVP) findings are most consistent with the primary obstructed megaureters.

This subtype of megaureters is due to an intrinsic abnormality of the juxtavesical segment of distal ureters which are adynamic and thus lead to distal obstruction analogous to the distal aperistaltic segment of the esophagus in achalasia (the underlying pathophysiology is different in these two disorders).

In 15-20 % of the patients, the abnormality is bilateral and occurs more often in males. Symptomatic and complicated cases may require surgical treatment where excision of the distal adynamic segment and reimplantation into the bladder is performed.

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