Multimodality approach in duplex renal moiety with vaginal ectopic ureterocele.

Clinical History

A 19-year-old married female complained of urinary incontinence since childhood along with recurrent episodes of urinary tract infection. She was nulliparous and had no significant surgical or obstetric history.

Imaging Findings

A 19-year-old married female complained of urinary incontinence and recurrent urinary tract infection since childhood. The patient underwent Intravenous Urography (IVU) and ultrasonography.

Bilateral nephrograms and right excretory system were normal on IVU. However, a suspicion of left sided duplex system with non excreting upper moiety was kept due to non visualization of left upper calyces and presence of “drooping lily sign” (Fig. 1). Bilateral ureters were normal in course and caliber.

Ultrasound abdomen showed focal hydronephrosis of upper calyces along with upper renal cortex thinning (Fig. 2a). Pelvic scans showed persistent fluid in vaginal canal. Transvaginal ultrasound showed dilated upper moiety ureter draining into the vagina with terminal cystic dilatation and change in caliber on straining (Fig. 2b & 2c).

Contrast enhanced computed tomography (CT) with delayed scans and MIP were obtained which vividly showed poorly functioning upper moiety with ectopic vaginal ureterocele (Fig. 3a & 3b). The lower moiety had normal insertion into bladder trigone. Delayed CT scans also picked up excretion of contrast into upper calyces indicating some preserved function as against IVU (Fig. 3c).

MR imaging was done using single shot long TE sequences in axial and coronal planes along with 3D static MR Urography. The images vividly demonstrate obstructed upper moiety and the ectopic vaginal ureterocele as hyperintense structures due to heavy T2 weighting (Fig 4a & 4b). Post Gadolinium scans show non excreting upper moiety and normally functioning lower moiety (Fig. 4c).

Discussion

Complete duplication of ureters occurs in 0.2% of live births. Most are left-sided but about 10% are bilateral. Bilateral duplication occurs in 15-40% of individuals with complete duplication.

In a duplex system, 80% of ureteroceles are associated with the upper pole moiety. Most ureteroceles in adults are orthotopic, whereas in children they are commonly ectopic. In women, ectopic ureters can terminate at a level distal to the bladder neck and external sphincter, resulting in incontinence. Two major types of ectopic ureteroceles have been described: the stenotic and sphincteric. The most common is the stenotic type, which has a congenitally small orifice distally and is particularly prone to become obstructed, resulting in hydronephrosis of an upper pole moiety. The sphincteric type, which travels submucosally through the bladder neck and opens into the urethra, is particularly prone to cause vesicoureteral reflux [1].

A duplex kidney with complete ureteral duplication results when two ureteral buds arise from the Wolffian duct. The ureteral bud that is associated with the future lower pole separates first from the Wolffian duct, and the orifice progresses superiorly and laterally. The common excretory duct, with the remaining ureter still attached, is taken up into the urogenital sinus. This combined with persistence of the distal mesonephric duct, which ruptures vaginally, accounts for vaginal ureteral ectopia and incontinence.The orifice of the ureter that drains the upper pole opens medial and inferior to the orifice that drains the lower pole - the “Weigert Meyer law” (Fig. 3b).

On IVU, recognition of “drooping lily sign” and careful examination of delayed images is necessary for suspicion of duplex moiety [2]. The enlarged, obstructed upper pole moiety exerts a mass effect on the remaining lower portion of the kidney, which results in inferolateral displacement of the lower pole moiety and lateral displacement of the most superior calyces of the lower pole collecting system. This lack of upper pole excretion, combined with visualization of a decreased number of calyces oriented in an abnormal axis, are the fundamental components of the drooping lily sign.

Ultrasonography recognises the non functioning renal parenchyma and pelvicalyceal system. Persistent appearance of fluid in vagina in a symptomatic woman should be examined for possible ectopic ureter insertion and must be evaluated further. Transvaginal examination often helps in diagnosis and must be performed whenever applicable.

CT Urography with 3D reconstruction also gives excellent anatomical details but has high radiation exposure and risk of allergy to the contrast [3].

MRU as a single investigation gives excellent anatomical description of the duplex renal moieties even if non-functioning. It is a non invasive technique and being ionisation free can be safely used in children and does not require iodinated contrast. Disadvantages are cost, time and need for sedation in children [4].

Teaching points:
1.Upper moiety frequently obstructs. Lower moiety undergoes vesico-ureteral reflux.
2.“Drooping lily” sign – suspect intrarenal mass effect.
3.Persistent fluid in vagina in symptomatic female – suspect vaginal ectopic
4.MR Urography is single best investigation for duplex renal moieties.

Differential Diagnosis List

Final Diagnosis

Left complete ureteral duplication with poorly functioning upper moiety with stenotic ectopic vaginal ureterocele.

URL:	https://www.eurorad.org/case/8126
DOI:	10.1594/EURORAD/CASE.8126
ISSN:	1563-4086