A ureterocele is a cystic dilation of the terminal ureter that balloons into the bladder. About 80% of ureteroceles are associated with ureteral duplication, occurring in the ureter that drains the upper pole (see Plate 2-23). About 10% of ureteroceles are bilateral.
A ureterocele is known as “intravesical” if it extends only into the bladder, and “ectopic” if it reaches the bladder neck or urethra. The oriﬁce is termed “stenotic” if a pinpoint opening is seen and “sphincteric” if it lies distal to the bladder neck. If the oriﬁce possesses both of these characteristics, it is known as “sphincterostenotic.”
The overall incidence of ureteroceles is difﬁcult to estimate because many small ureteroceles are not identiﬁed. The clinical incidence of ureterocele, however, appears to range from 1 in 5000 to 1 in 12,000. In contrast, one autopsy series reported the incidence to be as high as 1 in 500. For unknown reasons, there is a female : male ratio of 4 : 1, and most cases occur in whites.
The embryologic basis for ureteroceles is unknown, but several theories have been proposed. One is that ureteroceles result from incomplete breakdown of the Chwalla membrane, a normally transient structure that divides the ureter from the bladder. Although this theory explains ureteroceles with stenotic oriﬁces, it does not explain those with patent oriﬁces. Another theory is that the terminal ureter is lined with an inadequate number of smooth muscle cells, which causes it to become dilated.
Presentation And Diagnosis
A ureterocele may be asymptomatic, but it can also cause ureteral obstruction, especially when it is associated with a duplicated system. If large enough, the ureterocele can obstruct the bladder neck or even the contralateral ureteric oriﬁce.
If a ureterocele is not diagnosed using prenatal ultra-sound, it may become apparent during infancy. The most common presentation is a urinary tract infection, which results from urinary stasis in the obstructed system. Less often, a ureterocele can cause failure to thrive, ﬂank pain, or hematuria. If the ureterocele lies within the bladder neck, voiding dysfunction may occur. If the obstruction and associated hydronephrosis are severe, the kidney may become a palpable abdominal mass.
The diagnosis of ureterocele is typically established using ultrasound. In most cases, ureteral duplication is also seen. Hydroureteronephrosis may be seen if there is an obstruction. The diagnosis may be missed if the bladder is overdistended with urine because the ureterocele may become effaced. In addition, it is important to distinguish between a ureterocele, which is separated from the bladder lumen by its own thin wall, and a dilated ectopic ureter, which is separated from the bladder lumen by the thicker bladder walls.
A VCUG is helpful for further characterizing the size and location of a ureterocele, which becomes visible as a discrete, smooth ﬁlling defect near the trigone. In duplicated systems, the ipsilateral lower pole ureter often exhibits vesicoureteral reﬂux. The reﬂux is related both to the short intramural course of the lower pole ureter (see Plate 2-21) and to the deforming effect of the ureterocele on the trigone. In rare cases, the ureterocele itself may exhibit reﬂux. Again, it is essential to obtain images during early bladder ﬁlling because high intravesical pressures can cause the ureterocele to become effaced.
An intravenous pyelogram or contrast-enhanced CT can also be performed to characterize a ureterocele. An obstructed ureterocele that is associated with a poorly functional renal unit, as often seen in a duplicated system, will not ﬁll with contrast and will appear as a ﬁlling defect in the bladder. In contrast, a nonobstructed ureterocele associated with a functional renal unit, as may be seen in a nonduplicated system, will ﬁll with contrast. The ureterocele wall will then form a visible halo in the bladder.
If the ureterocele is large, it may be difﬁcult to determine from which side it originates. In such cases, it is helpful to directly visualize the ureterocele using a cystoscope; intubate it with a ureteral catheter and perform a retrograde pyeloureterogram, generally at the same time that deﬁnitive repair is planned.
Once a ureterocele has been identiﬁed, the patient should be started on antibiotic prophylaxis to reduce the risk of urinary tract infection. In addition, a radionuclide renal scan should be performed to determine the functional status of the associated renal parenchyma, especially if there is a duplicated system, because the results will determine the optimal surgical approach.
The goals of surgical intervention include relief of obstruction, infection, and reﬂux. The standard options include endoscopic incision of the ureterocele, as well as various open or laparoscopic procedures, such as heminephrectomy, ureteropyelostomy, ureterostomy, and ureteral implantation.
It is impossible to offer a simple algorithm for the management of ureteroceles. In each case, the plan must take into account numerous variables, including patient age, the size and position of the ureterocele, history of urinary tract infections, the presence or absence of reﬂux, the presence of a single or duplicated collecting system, and the d gree of function in the associated renal parenchyma.