IS case 543: Primary megaureter, presenting in adulthood

Jeremy Duda, MD

University of Rochester

Imaging Sciences URMC 2010
Publication Date: 2010-09-17


Patient is a 42-year-old male presenting with left flank and suprapubic pain for three weeks.


Post-contrast images from a CT scan demonstrated dilated left distal ureter. The left distal ureter is ectatic and dilates to a diameter of 2.2 cm before abruptly tapering at its insertion in the bladder. There were no obstructing lesions. Left hydronephrosis was also noted.


Primary megaureter, presenting in adulthood


Primary megaureter is defined as an idiopathic, congenital condition leading to the dilation of the distal ureter above approximately 7 mm; the proximal ureter may also be involved. Each of the three types of primary megaureter exhibit a distinct mechanism, and should be differentiated from secondary, acquired causes of megaureter.


Obstructed: a short aperistaltic segment near the bladder causes proximal dilation, similar to aganglionic diseases like achalasia and Hirschsprung's. 2.

Refluxing: secondary to abnormality of vesicoureteral junction, such as an insufficiently small intravesical segment or ureter. In this type, studies have found a paucity of smooth muscle cells and an overabundance of collagen fibers in the region distal to the dilated segment. 3.

Non-refluxing unobstructed: a portion of ureter proximal to the bladder is dilated without associated stenosis or reflux, commonly seen in neonates.

Imaging of suspected genitourinary diseases of the neonate begins with VCUG and ultrasound depending on the clinical context, and may show the abnormality outright or may demonstrate hydronephrosis. When vesicoureteral reflux is ruled out as a cause, proceeding to functional studies such as perfusion studies and diuretic renography can evaluate for severity of obstructive nephropathy.

Pediatric patients may be treated conservatively in the absence of renal insufficiency, infections, and worsening hydronephrosis. Often symptoms will resolve, otherwise surgery is indicated. However in the adult population, such as in the present case, the literature supports active surgical intervention. Almost all adult patients are symptomatic (94% in one study) and do not spontaneously improve. Adults with functioning kidneys may undergo ureteral reimplantation, otherwise nephrectomy is indicated.


  1. Halachmi S, Pillar G. Congenital urological anomalies diagnosed in adulthood - management considerations. J Pediatr Urol. 2008 Feb;4(1):2-7. PMID: 18631884
  2. Blickman JG, Lebowitz RL. The coexistence of primary megaureter and reflux. AJR Am J Roentgenol. 1984 Nov;143(5):1053-7. PMID: 6333147 children: embryologic, radiologic, and pathologic features. Radiographics. 2002 Sep-Oct;22(5):1139-64. PMID: 12235344
  3. Berrocal T, López-Pereira P, Arjonilla A, Gutiérrez J. Anomalies of the distal ureter, bladder, and urethra in children: embryologic, radiologic, and pathologic features. Radiographics. 2002 Sep-Oct;22(5):1139-64. PMID: 12235344

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