Tag Archive for: megaureter

1. Department of Urology, Great Western Hospital, Swindon, UK

2. Department of Urology, Knappschaft Hospital, Sulzbach, Germany

Ureteric duplication refers to the presence of two complete and separate ipsilateral ureters. The kidney on the affected side may have a duplicated pelvicalyceal system or there may be two separate kidneys.

The reported incidence of ureteral duplication is 1 in 125, or 0.8%.

Unilateral duplication occurs about six times more often than bilateral duplication, with the right and left sides being involved about equally. In duplicated ureters, the two orifices are characteristically inverted in relation to the collecting systems they drain. The orifice to the lower pole ureter occupies the more cranial and lateral position, and that of the upper pole ureter has a caudal and medial position (the Weigert-Meyer law). [1]

No specific clinical signs are associated with ureteric anomalies. Most children present with an abnormal finding on routine prenatal ultrasound before associated symptoms or infection develops. Some patients present with urinary tract infections (UTIs ), an abdominal mass or haematuria. Children with primary megaureters may also present with cyclic abdominal  or flank pain, or, less commonly, in an acute pain crisis. [2]

A 16 year-old girl was initially referred to the Paediatric team with recurrent UTIs and chronic pelvic pain causing many school absences. Ultrasound scan revealed a hypoechoic area on the right side of the pelvis, thought to be a right-sided hydrosalpinx. (Figure 1)

A diagnostic laparoscopy and cystoscopy performed after failure of conservative measures to control the pain revealed a normal uterus, ovaries, fallopian tubes and an inflamed bladder. An  intravenous urogram (IVU) demonstrated a dilated right ureter, reduced number of calyces in the right kidney, and normal left kidney and ureter. (Figure 2)

More detailed investigation with contrast enhanced magnetic resonance imaging (MRI) demonstrated complete ureteric duplication with a widely distended upper moiety pelvic ureter opening in close proximity to the bladder neck, and a moderately distended lower moiety ureter opening superio-laterally to its twin ureter. (Figure 3)

The distended and tortuous ectopic ureter was the source of the recurrent urinary tract infections, and pelvic pain.

On reviewing the ultrasound images of the right kidney in retrospect, the two moieties could be identified separately as shown in Figure 4.

Furthermore, on reviewing MAG3 renogram images also performed for functional assessment, a truncated looking right kidney was demonstrated, indicating little or no function in the upper obstructed moiety. (Figure 5)

The term megaureter (MGU) is simply a descriptive name that conveys the picture of a dilated ureter. It implies no particular unifying pathophysiologic principles but merely groups together a spectrum of anomalies associated with increased ureteric diameter, usually wider than 7 to 8 mm. [1]

MGU can be associated with complete ureteric duplication –as demonstrated in this case. The latter has a propensity for vesicoureteric reflux into the lower pole and obstruction of the upper pole. This can be a source of recurrent urinary tract infections and repeated hospitalization. [2]

Postnatal abdominal ultrasonography is the best initial screening study. Disparate hydronephrosis in the upper and lower pole of a kidney suggests ureteral duplication, especially with upper pole dilation associated with an obstructed or ectopic ureter or with a ureterocele. [3,4]

IVU findings are mostly diagnostic. Difficulty may arise when function is poor or absent in one of the moieties. [3] An obstructed, poorly functioning upper pole moiety of a duplex kidney –as demonstrated in this case- can exert a mass effect on the lower pole collecting system which causes lateral displacement of the lower pole moiety giving rise to the so called drooping lily sign; the appearance of the lower pole collecting system is reminiscent of a lily flower that is wilting or drooping. (Figure 2)

Magnetic resonance (MR) urography may be used as the primary diagnostic method for assessing a duplex ectopic ureter, as well as the complications associated with duplex kidneys, however it is rarely the initial study of choice due to cost considerations. [5,6]

Mercaptoacetyltriglycine (MAG-3) renal scintigraphy provides information on segmental renal function, allowing comparison of the upper pole moiety to the lower. It may aid in the determination of salvageability and selection of operative technique. [7]

With salvageable renal function, a number of surgical options are available, depending on the cause, the degree of dilatation, and whether one or both ureters are abnormal.

When only one ureter of a duplex system needs to be addressed options include: ureteroureterostomy and ureteropyelostomy. When both ureters require correction, they can be mobilized within the bladder as a common sheath and reimplanted by a standard technique to complete the repair. [1]

In cases in which there is no function, as represented in this case, excision of the MGU is performed in concert with heminephrectomy, which could be performed laparoscopically in selected centers. [1]

This girl underwent laparoscopic heminephrectomy and had a good recovery.

Complete duplex ureters should always be considered in any child, teenage or adult with intractable urinary tract infections.

Ultrasonography and excretory urography (IVP) are usually diagnostic; however, renal scintigraphy and contrast enhanced MRI greatly aid the diagnosis in cases of uncertainty or when there is a poorly functioning moiety.

Radiologists can occasionally miss some subtle features of a duplex system, which reiterates the importance of clinical correlation and more involvement in radiological interpretation by urologists.

[1] Wein AJ, Kavoussi LR, Novick AC, et al, eds. Campbell-Walsh urology, 9th ed. Philadelphia: WB Saunders; 2007:3413-3481

[2] Gatti J, Murphy P, Williams J, et al. Ureteral Duplication, Ureteral Ectopia, and Ureterocele. Emedicine.medscape.com/article/1017202

 [3] Khan AN, Chandramohan M, MacDonald S, et al. Duplicated Collecting System Imaging. Emedicine.medscape.com/article/378075

[4] Adiego B, Martinez-Ten P, Perez-Pedregosa J, et al. Antenatally diagnosed renal duplex anomalies: sonographic features and long-term postnatal outcome. J Ultrasound Med. Jun 2011;30(60):809-15.

[5] Avni FE, Nicaise N, Hall M, et al. The role of MR imaging for the assessment of complicated duplex kidneys in children: preliminary report. Pediatr Radiol. Apr 2001;31(4):215-23.

[6] Yanagisawa N, Yajima M, Takahara T, et al. Diagnostic magnetic resoncance-urography in an infant girl with an ectopic ureter associated with a poorly functioning segment of a duplicated collecting system. Int J Urol. May 1997;4(3):314-7.

[7] Wu F, Snow B, Taylor A Jr. Potential pitfall of DMSA scintigraphy in patients with ureteral duplication. J Nucl Med. Jul 1986;27(7):1154-6.