Ectopic insertion of a duplicated ureter into prostatic urethra: Demonstration by 3D multi-detector computed tomography urography

1Introduction

Ectopic insertion of the ureter is defined as abnormal insertion of the ureter [2]. The incidence of ectopic ureter is about 1 : 2000 [3], and it occurs more frequently in females than in males at a ratio of approximately 6 : 1 [3–5]. In women, the ectopic orifice is either suprasphincterically or infrasphincterically, thus the ectopic insertion sites may locate at lower bladder, urethra, vestibule, vagina, uterus, or Gartner duct cyst [5, 6]. In men, the extravesical ectopic orifice is always suprasphincterically and the ectopic orifice sites may be in bladder neck, seminal vesicle, vas deferens, prostate or epididymis [7]. Normal urination together with continuous incontinence are patognomic features for infrasphincteric ureteral openings [8].

Ectopic ureteral insertion is most commonly associated with complete duplication and obstruction [2]. The challenge in the diagnosis of ectopic insertion of the ureter is to find its insertion opening [7]. MDCT urography with 3D imaging techniques can improve temporal and spatial resolutions of the latest CT scanners and be able to acquire isotropic datasets with identical resolutions in all three planes. It provides results that are equivalent, and almost certainly superior, to those of conventional excretory urography in the evaluation of the upper urinary tracts for transitional cell carcinoma [1]. Herein, we present a young male patient with ectopic insertion of a duplicated ureter was diagnosed by MDCT urography.

2Case report

A 27-year-old male patient presented with intermittent lower left flank pain over 3 years. Routine urine and blood examinations were within normal limits. Initially, ultrasonography (USG) demonstrated double collecting system in left kidney, and moderate hydroureteronephrosis of the collecting system draining upper pole of the left kidney. MDCT urography demonstrated the ureter draining the upper pole of the kidney was dilated (Fig. 1a) and opened into the prostatic urethra (Fig. 1b and c), while other ureter draining the lower pole of the left kidney was normal. As the upper pole of the left kidney remaining function, ureteric re-implantation on the left posterior bladder wall was performed for the ectopic ureter and its distal stump was ligated. The patient’s postoperative course was uneventful and his symptoms resolved completely.

3Discussion

Ectopic insertion of the ureter in the genitourinary tract is often accompanied with ureteral duplication [2]. Partial duplication of the collecting system results from the branching of the ureteral bud before it connects with the metanephric blastemal [9]. Complete duplication occurs when two separate ureteric buds arise from the mesonephric duct. According to Weigert-Meyer law, the upper-moiety ureter usually inserts into the inferior and medial portion of the urinary bladder, while the lower-moiety ureter usually inserts into the bladder trigone [9].

Several imaging modalities are available in diagnosis of the congenital defect in the genitourinary tract system. Each of the methods has its own advantages and disadvantages (Table 1). ^99mTc-DMSA scintigraphy is mainly used for the functional study of choice in identifying poorly functioning renal tissue [10]. Magnetic resonance imaging offers dilated collecting system, ectopic ureter and its extravesical insertion point [6]. Most of the partial duplications and uncomplicated complete duplication are incidentally detected on USG or intravenous urography (IVU), while ectopic ureteral insertion sites may not be easily visible [4, 11]. The early diagnosis of potential complications of this anomaly should be made in order to prevent permanent renal damage. Therefore, sufficient information about ectopic ureteral orifice site (suprasphincterical or infrasphincterical levels) and complications (with or without hydronephrosis) could be obtained by MDCT urography [11].

MDCT urography utilizes 3D analysis technology along with the administration of intravenous contrast to create images similar those obtained with IVU [11, 12]. Volume rendering is the visualization and manipulation of objects represented as sampled data in three or more dimensions [1]. The maximum intensity projection technique displays the pixels of greatest intensity along a predefined axis of the image [1, 13]. The detail information is useful for the depiction of urinary tract anatomy when there is a large difference between attenuation values of urinary tract opacified by contrast agent, and the surrounding tissues [12, 14]. Rotated volume rendering reconstruction images and continual thinner maximum intensity projection reformatted images can be observed in the videos, and can offer good delineation of the ectopic ureteral orifice and its associated ureteral duplication.

The surgical management of ectopic ureter aims at preserving renal function, eliminating infection, and maintaining continence [10]. In a functioning upper pole, the procedures that can be done are distal and proximal uretero-ureterostomy (end-to-side), or upper polar ureteric re-implantation. In cases of nonfunctional moiety, an upper polar nephrectomy may be performed to prevent the risk of infection. In this case, the upper polar renal function remaining was considered sufficient to justify ureteric re-implantation.