CHAPTER 10 Megaureter, Ectopic Ureter, and Ureterocele
True/False: The ureter during embryologic development undergoes solidification and later recanalization.
True. In the first 7 to 8 weeks of gestation, the fetal ureter looses its lumen and recanalizes. The reason for this is unknown, but it may help to explain the presence of ureteral dilation especially if the recanalization process is prolonged.
True/False: The mesonephric duct is necessary for the development of the ureter.
True. The ureteral bud arises from the mesonephric duct to interact with the metanephric blastema to form the future collecting system and renal parenchyma.
What happens if the mesonephric duct is absent or maldeveloped?
Absence or maldevelopment of the mesonephric duct will lead to ipsilateral renal agenesis along with absence of genital duct structures such as the vas deferens and seminal vesicles.
Define megaureter.
A megaureter is an antomical term referring to an enlarged ureter typically measuring greater than 1 cm in diameter. It is easily seen on ultrasound. The typical pediatric ureter is less than 5 mm in diameter and is rarely seen on ultrasound examination.
Describe the 4 types of megaureter.
Megaureters arise from an underlying pathology such as obstruction or vesicoureteral reflux. The 4 types of megaureter are the obstructed megaureter, the refluxing megaureter, the obstructed, refluxing megaureter, and the nonobstructed, nonrefluxing megaureter.
True/False: The nonobstructed, nonrefluxing megaureter requires surgical correction.
False. The nonrefluxing, nonobstructing megaureter is likely a result of previous reflux and/or obstruction that has resolved. It does not require immediate surgical correction and often resolves spontaneously over time.
True/False: The presence of hydroureteronephrosis on antenatal ultrasound usually indicates obstruction and can be the precursor to an obstructing megaureter.
False. Hydroureteronephrosis and hydronephrosis are common findings on antenatal ultrasound. The findings are usually benign and are referred to as physiologic hydronephrosis without obstruction. However, true obstruction or high-grade vesicoureteral reflux may be present and further studies such as serial ultrasounds, voiding cystourethrogram, and diuretic renal scans may be necessary.
Describe the surgical options and reasoning for reducing the diameter of a megaureter during surgical reimplantation.
The infant ureter has an impressive ability to distend in response to obstruction or high-grade vesicoureteral reflux thus creating a megaureter. Successful surgical repair requires tapering of that ureter to allow for efficient peristalsis of urine. Additionally, reducing the ureteral diameter will decrease the need for a longer submucosal tunnel to prevent vesicoureteral reflux. The primary methods for tapering include plication or excision of the redundant ureter.
Define an ectopic ureter.
An ectopic ureter simply refers to a ureter that does not terminate in the bladder.
What is the most common site for the termination of an ectopic ureter in a male?
The ectopic ureter can terminate in a variety of places but always proximal to the urethral sphincter. The most common site of termination is the prostatic urethra.
Name 3 potential sites of termination for an ectopic ureter in a female.
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