1993-01-25-14 Ureterocele, ectopic © Malisch www.thefetus.net/
Timothy W. Malisch, MD, Philippe Jeanty, MD, PhD
* Address correspondence to Timothy W. Malisch, MD, Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, 21st and Garland Ave, Nashville, TN 37232-2675. Ph 615-322-0999 Fax 615-322-3764
Prevalence: The prevalence of duplex collecting systems varies between 1.7 - 4.2%1, roughly 50% have associated ureteroceles3. Ectopic ureterocele: M1:F46; simple ureteroceles M1:F1. First order relatives of a child with a duplex system have a 12% risk of duplication anomaly.
Definition: Congenital cystiform dilatations of the terminal submucosal ureter occurring with single or duplicated collecting systems. Simple ureteroceles drain in the bladder, ectopic ureteroceles in the bladder neck or proximal urethra. Ectopic ureteroceles nearly always involve the upper pole ureter of a duplicated system.
Etiology and pathogenesis: The following mechanisms have been suggested to result in ureteroceles:1,4 1) dilatation secondary to distal obstruction by a persistence of Chwalla membrane, 2) longer than usual course with delayed formation of the distal lumen, leading to increased intraluminal pressure, 3) intrinsic muscular defect in the ureteral wall, 4) the ectopic ureteral orifice lies closer to the internal urethral sphincter and contraction of this sphincter, causes a physiologic obstruction of the distal ureter.
Associated anomalies: Duplicated contralateral upper tract in 30-40% of cases1, crossed-fused ectopia, dysplastic kidneys, abnormal testes and cardiac abnormalities11.
Resulting anomalies: Urinary tract infection, urosepsis, renal dysplasia, obstruction, vesicoureteral reflux, inefficient voiding, diminished bladder storage capacity, incontinence, and decreased function of ipsilateral upper and/or lower pole moiety or contralateral kidney.
Differential diagnosis: ..of upper pole hydronephrosis: ureteropelvic or ureterovesical junction obstruction, posterior urethral valve, renal cyst or cystic mass. ...of ureterocele: hydrometrocolpos, seminal vesicle "cyst" caused by ectopic ureter inserting into seminal vesicles.
Prognosis: Mostly excellent after surgical resection.
Recurrence risk: Not known to be increased, but it has been reported in mono- and dizygotic twins, among brothers and in a mother and daughter pair12-15.
Management: No modification of in utero management, unless there is evidence of degrading renal function. Our attempt at laceration of a ureterocele did not provide long-term decompression. Prophylactic antibiotic administration from birth until surgical correction to prevent infections. The surgical procedure depends on the function of the ipsilateral upper and lower pole as well as contralateral kidney, the presence of reflux or obstruction and age of patient (see text).
MESH Ureterocele MIM 191650 ICD9 753.2 CDC 753.480
The patient is a 30-year-old gravida 2 para 1 married white patient, previously delivered by C-section. Ultrasonography at an outside institution showed a single intrauterine pregnancy at 16 weeks with questionable renal abnormalities. The patient was referred to our institution at 25 weeks gestation. The examination showed considerable distension of both upper urinary systems and a septation within the bladder (fig 1,2).
Figure 1: The ureterocele (U) occupies a large portion of the bladder. Marked bilateral hydronephrosis (H) is also noted. The amniotic fluid (A) (only partially visible on this view) was within normal limits.
Figure 2: Coronal view of the ureterocele.
This suggested a right ureterocele prolapsing into the bladder neck. It was believed to cause intermittent obstruction of the urethra, producing the contralateral hydronephrosis yet allowing the amniotic fluid volume to be normal. Three days later the patient underwent a fetal blood sampling and transabdominal puncture of the fetal ureterocele with a 21 gauge needle (fig 3).
Figure 3: Laceration of the ureterocele. The needle is in place in the collapsed ureterocele.
The procedure decompressed the ureterocele, but within a week it had returned to its preprocedure appearance (fig 4).
Figure 4: Within a few days, however, the ureterocele has returned to its original appearance.
The temporary decompression of the urinary system allowed visualization of the upper pole of the left kidney which was not obstructed (fig 5).
|Figure 5: After the procedure, the non-obstructed upper left pole is visible (arrow), suggesting the existence of an ectopic ureter terminating below the bladder neck.|
It was thus concluded that the fetus had a duplicated collecting system on the left, and that, since the left upper pole was not obstructed, it must have drained through a ureter with ectopic implantation below the bladder neck, probably in the vagina.
At 37 weeks gestation, a 2920g female infant was delivered by repeat C-section. Postnatal radiographic studies revealed bilateral duplex systems with a large right ureterocele and bilateral hydronephrosis. There was good function of the right lower pole and left upper pole. Repeat incision of the ureterocele was performed and a definitive procedure consisting of left lower pole and right upper pole heminephrectomy with bilateral ureteral reimplantation and reconstruction of the bladder floor is tentatively planned when the patient is about 12-18 months of age.
A small non-obstructive left ureterocele was detected in a 19 week fetus (fig 6).
Figure 6: Case #2. A faintly visible ureterocele (arrow) is seen.
No associated anomalies were detected aside from a duplicated left kidney. Postnatally, the ureterocele was surgically removed in an elective procedure and the young girl was asymptomatic and without sonographic anomalies at the 6 month follow-up examination.
The prevalence of duplex collecting systems varies between 1.7 - 4.2%1. Few cases have been diagnosed prenatally2-3,7, 18-19. Studies of infants and children with duplex systems and hydronephrosis showed that roughly 50% had associated ureteroceles.3 Ectopic ureterocele has a 4:1 predilection for girls6 (the prevalence of simple ureteroceles is independent of sex). Siblings and parents of a child with a duplex system have a 1 in 8 chance of having some duplication anomaly.
A ureterocele is a congenital cystiform dilatation of the terminal submucosal ureter. Ureteroceles are classified by whether they occur with single or duplicated systems (ureters) and by the location of ultimate drainage. Simple (also called adult or orthotopic) ureteroceles drain into the bladder at the lateral angle of the trigone. The ureteral orifice is stenotic, and the lesion may be bilateral. Ectopic (infantile) ureteroceles usually drain into the bladder neck or proximal urethra; however, numerous other sites of drainage occur as described below. It is usually unilateral (less than 10% are bilateral) and may cause renal failure from obstruction. Both simple and ectopic ureteroceles are more likely to be associated with duplicated systems. In fact, ectopic ureteroceles nearly always involve the ureter draining the upper pole of a duplicated system.
The ureterocele occurs in the terminal ureter as it courses deep to the bladder mucosa, within the bladder wall, and as it dilates it projects farther into the bladder lumen. Ureteroceles are more common on the left side, and 10-15% are bilateral11. The possible sites of ureteral drainage in ectopy are dependent on the patient"s sex. The sites in girls include urethra (35%), vestibule (34%), vagina (25%), cervix or uterus (5%) and Gartner"s duct or urethral diverticulum. In boys, they include posterior urethra (47%), seminal vesicle (33%), prostatic utricle (10%), ejaculatory duct (5%) and vas deferens (5%).1
Etiology and pathogenesis
Ureteroceles are the result of abnormal embryogenesis. The exact mechanism of formation is still unclear; however, the following four theories have been proposed:1,4
- Ureteroceles form because of dilatation secondary to distal ureteral obstruction by a persistence of Chwalla membrane, which fails to desquamate.
- Ectopic ureters follow a longer than usual course and have delayed formation of the distal lumen. This delay results in increased hydrostatic pressure, in turn causing ureteral expansion.
- Ureteroceles result from an intrinsic muscular defect in the ureteral wall.
- The ectopic ureteral orifice lies closer to the internal urethral sphincter, and contraction of this sphincter causes a physiologic obstruction of the distal ureter.
Figure 7: Ureteral drainage of ectopic ureters, in girls (above) and boys (below)1.
The contralateral upper tract is duplicated in 30-40% of cases1. Triplication of the ureter has been reported16-17. Other anomalies include crossed-fused ectopia, dysplastic kidneys, abnormal testes and cardiac abnormalities11.
Prolapse into the bladder outflow tract may result in obstruction, renal dysplasia, vesicoureteral reflux, inefficient voiding, diminished bladder storage capacity and decreased function. After birth these may induce urinary tract infection, urosepsis and incontinence.
Ureteroceles appear as echolucent thin-walled cyst-like structures within or about the bladder. Although duplex systems with upper pole hydronephrosis and a ureterocele have been diagnosed prenatally by sonography, this degree of diagnostic precision is probably the exception rather than the rule. A recent study3 showed that prenatal sonography identified only 30% of cases of duplex system with upper pole hydronephrosis and only 5% of ureteroceles. The authors describe difficulties including the ureterocele being mistaken for bladder if the bladder is empty and a full bladder effacing the ureterocele. Another difficulty in identifying duplex systems is the small tissue mass of the upper pole. Some authors point out that precise prenatal diagnosis of duplex system with ureterocele is not necessary for effective surgical treatment. Detection of hydronephrosis is sufficient to begin prophylactic antibiotics at birth and continue them until surgical correction, thus reducing urosepsis and urinary tract infection.
The differential diagnosis of upper pole hydronephrosis includes renal cyst or cystic mass. The differential diagnosis of ureterocele includes hydrometrocolpos and seminal vesicle "cysts" caused by an ectopic ureter inserting into seminal vesicles.
Most patients with ureterocele are relieved of all symptoms by the definitive surgery, with long-term follow-up studies showing no evidence of obstruction, reflux, urinary tract infection or renal function deficit. These excellent results are not, however, universal and depend upon prompt diagnosis of ureterocele, antibiotic prevention/treatment of infections and appropriate choice of surgical procedure.
Not known to be increased, but it has been reported in mono- and dizygotic twins, among brothers and in a mother and daughter pair12-15.
The management depends on function of the ipsilateral upper and lower poles as well as the contralateral kidney, findings of reflux or obstruction and age of patient. The options include:
- Upper pole nephrectomy alone or in combination with excision of ureterocele and/or cross trigonal reimplantation of lower pole ureter.
- Endoscopic decompression incision of ureterocele with or without Teflon injection20.
- Unroofing decompression procedure (performed in adulthood).
- "Marsupialization" of the ureterocele rather than enucleation6.
The prenatal detection of hydronephrosis of the upper pole of a duplex system allows administration of prophylactic antibiotics from birth until surgical correction. This effectively decreases the risk of urinary tract infection, urosepsis and irreversible loss of renal function. Yet a precise prenatal diagnosis of accompanying ureterocele is not necessary for efficient postnatal management3.
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