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Duplex Kidney and Related Abnormalities
Urol Sci 2010;21(2):96−98
P R AC T I C A L U RO R A D I O LO GY
Duplex Kidney and Related Abnormalities Jia-Hwia Wang1,2* 1
Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan School of Medicine, National Yang-Ming University, Taipei, Taiwan
2
*Corresponding author. Department of Radiology, Taipei Veterans General Hospital, 201, Shih Pai Road, Section 2, Taipei 112, Taiwan. E-mail: [email protected]
Accepted: April 13, 2010
There are 2 CME questions based on this article
A 20-year-old woman felt right flank pain 2 years previously. At this time, she went to a local medical clinic where an abnormal urinary tract on the right side was found by imaging examinations. Surgical intervention was recommended, but she did not want to have surgery at that time. During those 2 years, intermittent right flank pain (three times per month) still bothered her. Therefore, she went to the outpatient department of our hospital. Sonography of the kidney was carried out, revealing duplex bilateral kidneys with hydronephrosis of the upper moiety of the right duplex kidney. Abdominal computed tomography was then carried out, which revealed the following: (1) a right complete duplex kidney with an ectopic ureteral orifice and ureterocele, hydronephrosis and hydroureter of the upper moiety of the right complete duplex kidney; and (2) a left incomplete duplex kidney (Figure 1). Right retrograde pyelography (Figure 2) and cystography (Figure 3) were carried out, which confirmed the computed tomography findings of the abdomen. Two right ureteral orifices were found with cystoscopy: one was near the bladder neck, and the other associated with the ureterocele was over the trigone. Surgical intervention was recommended. She was admitted to our hospital for further management. Physical examination did not show any abnormalities. Laboratory examinations showed that all parameters were within normal limits. Surgical removal of the upper moiety and its ureter of the right complete duplex kidney was performed. The postoperative course was unremarkable. The patient was discharged in a stable condition, and outpatient department follow-up was recommended. A duplex (duplicated) kidney is a kidney that has two pyelocalyceal systems and is associated with a bifid ureter 96
(incomplete duplication) or two ureters (double ureters) that empty separately into the bladder (complete duplication). A duplex kidney occurs in 12% of the population and may be unilateral or bilateral.1 Usually the lower moiety is dominant and drains most of the kidney, and a large renal pelvis drains the lower moiety via multiple calyces. The upper moiety may have only a single calyx and
Figure 1 Coronal view of contrast-enhanced computed tomography of the abdomen shows (1) ectopic ureteral orifice with ureterocele over the trigone of the urinary bladder, hydronephrosis and hydroureter of the upper moiety of a right complete duplex kidney; (2) downward displacement of the normal collecting system of the lower moiety of a right complete duplex kidney by hydronephrosis of the upper moiety of the right complete duplex kidney (drooping lily sign); and (3) a left incomplete duplex kidney. ©2010 Taiwan Urological Association. Published by Elsevier Taiwan LLC.
Duplex kidney and related abnormalities A
B
Figure 2 Right retrograde pyelography shows (A) a right complete duplex kidney with hydronephrosis and hydroureter of its upper moiety, and (B) a normal collecting system and ureter of its lower moiety.
F
Figure 3 Cystography shows ectopic ureteral orifice with ureterocele (arrow) over the trigone of the upper moiety of a right complete duplex kidney. F = Foley’s catheter.
Figure 4 Non-contrast computed tomography of the kidneys shows “faceless kidney” of a left incomplete duplex kidney and hydronephrosis of the upper moiety of a right complete duplex kidney.
a single infundibulum, and no renal pelvis. Each ureter has its own vesical orifice. The ureter that drains the upper moiety is ventral to the lower one, but crosses over and empties into the bladder in a lower, more medial ectopic location (Weigert-Meyer rule). In males, the ureter may open into the seminal vesicles, the vas deferens, the ejaculatory duct or the posterior urethra. In females, the ureter may open into the urethra, the lateral vulvar wall, the uterus, the vagina, or rarely, the rectum. In patients with complete ureteral duplication, obstruction at the ureterovesical junction with hydronephrosis and ectopic ureteral orifice associated with ureterocele may occur in the upper moiety. Vesicoureteral reflux into the lower moiety occurs in 50% of patients with lower moiety ureteropelvic junction obstruction.2,3
The most common symptoms of duplex kidney are flank pain and hematuria caused by obstruction and infection of the upper moiety of duplex kidney.4 Ectopic ureteral orifice is usually associated with urinary incontinence in females, resulting from insertion of the ureteral orifice below the urethral sphincter. The imaging findings of duplex kidney depend on the degree of obstruction. If both moieties of duplex kidney remain functioning, the diagnosis is usually achieved by intravenous urography. However, the upper moiety commonly becomes obstructed and enlarged, resulting in a nonfunctioning upper moiety mass effect (hydronephrosis). The opacified calyces of the lower moiety may be displaced by the large nonfunctioning upper moiety hydronephrosis (drooping lily sign) (Figure 1).5 Retrograde pyelography may confirm the diagnosis.
Vol. 21, 96–98, June 2010
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J.H. Wang Computed tomography is an excellent method for detecting obstruction in either moiety of a duplex kidney.6 It can also determine whether the orifice of an obstructed upper moiety ureter is intravesical or extravesical. “Faceless kidney” has been reported as a computed tomography sign of duplex kidney (Figure 4).6 Cystography or cystoscopy may be needed to locate the ureteral orifices of duplex kidneys. However, sometimes ectopic ureteral orifices cannot be located, and one may need to rely on antegrade pyelography or an operation for identification. We conclude that complete duplex kidney associated with ectopic ureteral orifice and hydronephrosis of the upper moiety should be treated by surgical removal of the upper moiety and its ureter.
98
References 1. 2.
3. 4.
5. 6.
Hartman GW, Hodson CJ. The duplex kidney and related anomalies. Clin Radiol 1969;20:387–400. Fernbach SK, Zawin JK, Lebowitz RL. Complete duplication of the ureter with ureteropelvic junction obstruction of the lower pole of the kidney: imaging findings. AJR Am J Roentgenol 1995;164:701–4. Fernbach SK, Feinstein KA, Spencer K, Lindstrom CA. Ureteral duplication and its complications. Radiographics 1997;17:109–27. Amitai M, Hertz M, Jonas P, Apter S, Heyman Z. Ectopic ureterocele in adults with a comparison of the anomaly in children. Urol Radiol 1992;13:181–6. Callahan MJ. The drooping lily sign. Radiology 2001;219:226–8. Cronan JJ, Amis ES, Zeman RK, Dorfman GS. Obstruction of the upper-pole moiety in renal duplication in adults: CT evaluation. Radiology 1986;161:17–21.
Vol. 21, 96–98, June 2010
P R AC T I C A L U RO R A D I O LO GY
Duplex Kidney and Related Abnormalities Jia-Hwia Wang1,2* 1
Department of Radiology, Taipei Veterans General Hospital, Taipei, Taiwan School of Medicine, National Yang-Ming University, Taipei, Taiwan
2
*Corresponding author. Department of Radiology, Taipei Veterans General Hospital, 201, Shih Pai Road, Section 2, Taipei 112, Taiwan. E-mail: [email protected]
Accepted: April 13, 2010
There are 2 CME questions based on this article
A 20-year-old woman felt right flank pain 2 years previously. At this time, she went to a local medical clinic where an abnormal urinary tract on the right side was found by imaging examinations. Surgical intervention was recommended, but she did not want to have surgery at that time. During those 2 years, intermittent right flank pain (three times per month) still bothered her. Therefore, she went to the outpatient department of our hospital. Sonography of the kidney was carried out, revealing duplex bilateral kidneys with hydronephrosis of the upper moiety of the right duplex kidney. Abdominal computed tomography was then carried out, which revealed the following: (1) a right complete duplex kidney with an ectopic ureteral orifice and ureterocele, hydronephrosis and hydroureter of the upper moiety of the right complete duplex kidney; and (2) a left incomplete duplex kidney (Figure 1). Right retrograde pyelography (Figure 2) and cystography (Figure 3) were carried out, which confirmed the computed tomography findings of the abdomen. Two right ureteral orifices were found with cystoscopy: one was near the bladder neck, and the other associated with the ureterocele was over the trigone. Surgical intervention was recommended. She was admitted to our hospital for further management. Physical examination did not show any abnormalities. Laboratory examinations showed that all parameters were within normal limits. Surgical removal of the upper moiety and its ureter of the right complete duplex kidney was performed. The postoperative course was unremarkable. The patient was discharged in a stable condition, and outpatient department follow-up was recommended. A duplex (duplicated) kidney is a kidney that has two pyelocalyceal systems and is associated with a bifid ureter 96
(incomplete duplication) or two ureters (double ureters) that empty separately into the bladder (complete duplication). A duplex kidney occurs in 12% of the population and may be unilateral or bilateral.1 Usually the lower moiety is dominant and drains most of the kidney, and a large renal pelvis drains the lower moiety via multiple calyces. The upper moiety may have only a single calyx and
Figure 1 Coronal view of contrast-enhanced computed tomography of the abdomen shows (1) ectopic ureteral orifice with ureterocele over the trigone of the urinary bladder, hydronephrosis and hydroureter of the upper moiety of a right complete duplex kidney; (2) downward displacement of the normal collecting system of the lower moiety of a right complete duplex kidney by hydronephrosis of the upper moiety of the right complete duplex kidney (drooping lily sign); and (3) a left incomplete duplex kidney. ©2010 Taiwan Urological Association. Published by Elsevier Taiwan LLC.
Duplex kidney and related abnormalities A
B
Figure 2 Right retrograde pyelography shows (A) a right complete duplex kidney with hydronephrosis and hydroureter of its upper moiety, and (B) a normal collecting system and ureter of its lower moiety.
F
Figure 3 Cystography shows ectopic ureteral orifice with ureterocele (arrow) over the trigone of the upper moiety of a right complete duplex kidney. F = Foley’s catheter.
Figure 4 Non-contrast computed tomography of the kidneys shows “faceless kidney” of a left incomplete duplex kidney and hydronephrosis of the upper moiety of a right complete duplex kidney.
a single infundibulum, and no renal pelvis. Each ureter has its own vesical orifice. The ureter that drains the upper moiety is ventral to the lower one, but crosses over and empties into the bladder in a lower, more medial ectopic location (Weigert-Meyer rule). In males, the ureter may open into the seminal vesicles, the vas deferens, the ejaculatory duct or the posterior urethra. In females, the ureter may open into the urethra, the lateral vulvar wall, the uterus, the vagina, or rarely, the rectum. In patients with complete ureteral duplication, obstruction at the ureterovesical junction with hydronephrosis and ectopic ureteral orifice associated with ureterocele may occur in the upper moiety. Vesicoureteral reflux into the lower moiety occurs in 50% of patients with lower moiety ureteropelvic junction obstruction.2,3
The most common symptoms of duplex kidney are flank pain and hematuria caused by obstruction and infection of the upper moiety of duplex kidney.4 Ectopic ureteral orifice is usually associated with urinary incontinence in females, resulting from insertion of the ureteral orifice below the urethral sphincter. The imaging findings of duplex kidney depend on the degree of obstruction. If both moieties of duplex kidney remain functioning, the diagnosis is usually achieved by intravenous urography. However, the upper moiety commonly becomes obstructed and enlarged, resulting in a nonfunctioning upper moiety mass effect (hydronephrosis). The opacified calyces of the lower moiety may be displaced by the large nonfunctioning upper moiety hydronephrosis (drooping lily sign) (Figure 1).5 Retrograde pyelography may confirm the diagnosis.
Vol. 21, 96–98, June 2010
97
J.H. Wang Computed tomography is an excellent method for detecting obstruction in either moiety of a duplex kidney.6 It can also determine whether the orifice of an obstructed upper moiety ureter is intravesical or extravesical. “Faceless kidney” has been reported as a computed tomography sign of duplex kidney (Figure 4).6 Cystography or cystoscopy may be needed to locate the ureteral orifices of duplex kidneys. However, sometimes ectopic ureteral orifices cannot be located, and one may need to rely on antegrade pyelography or an operation for identification. We conclude that complete duplex kidney associated with ectopic ureteral orifice and hydronephrosis of the upper moiety should be treated by surgical removal of the upper moiety and its ureter.
98
References 1. 2.
3. 4.
5. 6.
Hartman GW, Hodson CJ. The duplex kidney and related anomalies. Clin Radiol 1969;20:387–400. Fernbach SK, Zawin JK, Lebowitz RL. Complete duplication of the ureter with ureteropelvic junction obstruction of the lower pole of the kidney: imaging findings. AJR Am J Roentgenol 1995;164:701–4. Fernbach SK, Feinstein KA, Spencer K, Lindstrom CA. Ureteral duplication and its complications. Radiographics 1997;17:109–27. Amitai M, Hertz M, Jonas P, Apter S, Heyman Z. Ectopic ureterocele in adults with a comparison of the anomaly in children. Urol Radiol 1992;13:181–6. Callahan MJ. The drooping lily sign. Radiology 2001;219:226–8. Cronan JJ, Amis ES, Zeman RK, Dorfman GS. Obstruction of the upper-pole moiety in renal duplication in adults: CT evaluation. Radiology 1986;161:17–21.
Vol. 21, 96–98, June 2010