Overview: Fibrotic regression of the urachus typically extends from the umbilicus toward the bladder, resulting in the formation of the median umbilical ligament.1,2 Failure of the urachus to normally regress results in one of four disorders: (1) patent urachus (50%), (2) urachal sinus (15%), (3) urachal diverticulum (3-5%), and (4) urachal cyst (30%) (Fig. 121-1).³ Clinical symptoms include umbilical discharge, local infection, lower abdominal pain, and urinary tract infection.⁴

Imaging: Abdominal ultrasound, voiding cystourethrography (VCUG), and fistulography are the primary imaging diagnostic tools for initial evaluation of suspected urachal anomalies.⁵ In a patent urachus, the urachus fails to obliterate, resulting in a vesicoumbilical fistula (Fig. 121-2). The diagnosis may be confirmed by catheterization of the bladder through the umbilicus (Fig. 121-3) or by VCUG with films in the lateral projection. In urachal sinus, the urachus is closed at the level of the bladder but remains patent at the umbilicus (e-Fig. 121-4). The diagnosis of urachal sinus can be made only by catheterization and opacification of the umbilical fistula. In urachal diverticulum, the urachus is obliterated at the level of the umbilicus but communicates with the bladder. Ultrasound readily demonstrates this, but urachal diverticula are best shown on a cystogram in the lateral projection (Fig. 121-5). In urachal cyst, the urachus is obliterated at both ends but remains patent in its midportion. Multiple small urachal cysts may occur as a result of segmental urachal obliteration (e-Fig. 121-6).¹

Treatment: Urachal remnants in children younger than 6 months are likely to resolve with nonoperative management. However, if symptoms persist or the urachal remnant fails to resolve after 6 months of age, it should be excised to prevent recurrent infection.1,2,6

Overview: Bladder diverticula, which may be primary (congenital), secondary, or iatrogenic (postoperative) (Box 121-1),⁷ are the most common, are seen more often in males than in females, may be single or multiple, and occur most frequently in the trigonal area.^8,9 Secondary bladder diverticula are the result of chronically increased intravesical pressure and occur most commonly in the paraureteral area. Iatrogenic diverticula are seen most often in the anterior wall of the bladder at the site of a previous vesicostomy or suprapubic drainage catheter, and at the ureterovesical junction after ureteral reimplantation. Patients present with recurrent urinary tract infection, urinary retention, incontinence, stone formation, vesicoureteral reflux, and ureteral and bladder outlet obstruction.¹⁰

Imaging: VCUG is the most efficient method of detection.¹¹ Bladder diverticula may become visible only during voiding when contractions of the bladder force urine into the diverticulum (Fig. 121-7). A paraureteral diverticulum or Hutch diverticulum¹² is located laterally and cephalad to the ureteral orifice (e-Fig. 121-8). If the diverticulum is large, it may engulf the ureteral meatus and the ureter may empty into the diverticulum. Associated vesicoureteral reflux is present in about half of the cases (e-Fig. 121-9).¹³

Treatment: Surgical diverticulectomy may be performed by an intravesical, extravesical, or combined approach with satisfactory results.¹⁴ The muscular defect in the bladder wall should be meticulously repaired. Surgical diverticulectomy often restores normal voiding dynamics.^10,15,16

Overview: Rhabdomyosarcoma (RMS) is the most common and important neoplasm of the lower genitourinary tract and accounts for about 20% of all RMS seen in children. RMS is the most frequent bladder neoplasm in children in the first two decades of life, presenting typically at ages 2 to 6 years or 15 to 19 years.17,18 In males, more than 50% of the cases arise from the prostate. In females, RMS arises from the vagina and the uterine cervix. Histologically, the tumor is divided into three subtypes: (1) embryonal, (2) alveolar, and (3) polymorphic. Embryonal RMS is further subdivided into three categories: (1) classic embryonal, (2) botryoid, and (3) spindle cell. The embryonal form is, by far, the most common, accounting for approximately 90% of all RMS. The embryonal botryoid subtype accounts for one fourth of the cases and has a lobulated, polypoid appearance, resembling a bunch of grapes, hence the name sarcoma botryoides.^17,19–21

RMS spreads by local extension from the bladder, prostate, and vagina into regional and retroperitoneal lymph nodes and muscle. Lymph node involvement or distant tumor spread is found at initial diagnosis in 10% to 20% of patients.²² Although RMS can metastasize to almost any site, it does so most commonly to the lungs, cortical bone, and lymph nodes, and less frequently to the bone marrow and liver. Hematuria, dysuria, frequency, urinary retention, and obstruction are the most frequent clinical manifestations. An abdominal mass may be palpated in some cases. In females, a vaginal tumor may manifest as a prolapsing mass in the introitus.¹⁹

Imaging: On ultrasound, RMS is hyperechoic or hypoechoic, compared with surrounding healthy tissue, with or without focal anechoic regions representing necrosis and hemorrhage. Color and duplex Doppler evaluation show hypervascularity.²² VCUG shows a filling defect in the posteroinferior aspect of the bladder (e-Fig. 121-10). When originating in the prostate (Fig. 121-11 and e-Fig. 121-12), the cystogram shows an upward displacement of the bladder floor or a smooth, lobulated mass at the base of the bladder.^19,22 Contrast-enhanced CT identifies RMS of the prostate or bladder base as a bulky pelvic mass of heterogeneous attenuation that may invade periurethral and perivesical tissues or may extend into the ischiorectal fossa. Calcification is rare. Vaginal tumors often arise high in the anterior vaginal vault and may be indistinguishable from a primary bladder tumor.¹⁹ On magnetic resonance imaging (MRI) scans, RMS demonstrates nonspecific, low signal intensity on T1-weighted sequences and high signal intensity on T2-weighted sequences. After the administration of MRI contrast, RMS typically enhances heterogeneously.

Treatment: The Children’s Oncology Group and Intergroup Rhabdomyosarcoma Study staging and clinical system for neoplasms of the genitourinary system is given in Box 121-2.¹⁸ Treatment combines surgical removal of as much of the tumor as possible, chemotherapy, and radiation therapy. Tumors of the urinary bladder and prostate have an overall 5-year survival rate of approximately 70%. Tumors originating in nonbladder or prostatic sites (paratesticular, vagina, and cervix) have better 5-year survival rates, between 84% and 89%.²³ Botryoid histology has the most favorable prognosis compared with all other histologies.²⁴

Overview and Imaging: Hemangioma of the bladder is probably the most common benign neoplasm (0.6% of all bladder tumors). Hemangioma presents as a discrete solitary mass of variable size (<1 cm to more than 10 cm), usually projecting from the posterior or lateral walls of the bladder.²⁵ Hematuria is the most common clinical presentation. Ultrasound will demonstrate bladder wall thickening, intramural anechoic spaces, and occasional calcification. CT and MRI may be required to fully define the extent of the lesion and for preoperative planning, since cystoscopy may only reveal a small portion of the mass.²⁶

Nephrogenic adenoma is a rare benign papillary lesion of the bladder. In most cases. a history of upper urinary tract infection, inflammation, trauma or recent surgery (ureteral re-implantation), calculi, or catheterization is present. The bladder is the most common site in children.²⁷ The female to male ratio in children is 3 : 1. Clinical presentation includes hematuria, frequency or urgency, and nocturia. Ultrasound demonstrates a nonspecific, echogenic papillary mass projecting from the bladder wall (Fig. 121-13).²⁸ Most nephrogenic adenomas are less than 1 cm in size; however, they may be as large as 7 cm.²⁹ Treatment consists of transurethral resection and fulguration. The recurrence rate in children is 80%, with peak recurrence at approximately 4 years after treatment.^28,30

Overview: Posterior urethral valves (PUVs), more recently considered congenital obstructive posterior urethral membranes, are the most common cause of congenital bladder outlet obstruction.31–34 The valves are identified at the base of the verumontanum, and the obstruction leads to posterior urethral dilation and chronic bladder outlet obstruction. The degree of urethral obstruction, however, is variable.^32,35–37 When detected prenatally, varying degrees of renal dysplasia result from pressure damage to the developing renal pelvis, collecting ducts, and parenchyma. If the fetus survives, up to 45% will develop renal insufficiency or end-stage renal disease requiring renal dialysis or transplantation before 5 years of age.^38–41 Those children who escape antenatal detection may present in the first months or years of life with urinary tract infections, sepsis, voiding disorders, hematuria, vomiting, failure to thrive, urinary retention, hydronephrosis, ascites, and congestive heart failure. At the other end of the spectrum are patients with late presentation of PUVs. These patients have a mild form of disease, and detection may be delayed as late as adolescence. These children may present with functional voiding disorders or urinary tract infections.^42,43

Imaging: Ultrasound shows varying degrees of hydroureteronephrosis and bladder wall thickening (e-Fig. 121-14). Dysplastic kidneys with increased echogenicity, decreased corticomedullary differentiation, and cortical cyst formation may be seen. Perinephric fluid collections (urinomas) are usually related to forniceal rupture (Fig. 121-15 and e-Fig. 121-16). When unexplained ascites is discovered in a male newborn, the diagnosis of urinary tract obstruction caused by PUVs should be strongly considered. Associated hydroureteronephrosis may not be present because the forniceal rupture and communication to the peritoneal cavity act as a “pop off” mechanism, allowing one or both kidneys to decompress. Transperineal ultrasound can show the dilated posterior urethra, especially if the child is voiding at the time of the examination (e-Fig. 121-17).^44–50

VCUG is the diagnostic study of choice for PUVs (Fig. 121-18 and e-Fig. 121-19). VCUG directly shows the PUVs and their effect on the urinary bladder; wall thickening, trabeculation with cellulae and sacculi, diverticula, and hypertrophy of the interureteric ridge (e-Fig. 121-20). Vesicoureteral reflux occurs in about one half to two thirds of male children with PUV, of whom approximately two thirds have unilateral reflux (e-Fig. 121-21) (Box 121-3).^34,35,51,52

Treatment: Transurethral resection or fulguration of the obstructing valvular structures is the recommended treatment for PUVs. Residual valve tissue with obstruction is not uncommon, and stricture formation at the site of previous urethral valves or in the membranous urethra as a complication of surgery may occur. Urethroscopy is usually more reliable than the urethrogram in the diagnosis of these lesions.53–63

Overview: Urethral polyps typically arises from the posterior urethra and consist of an elongated, freely movable mass on a long stalk originating from the region of the verumontanum (Box 121-4).⁶⁴ The lesion is typically diagnosed in the first decade of life at a mean age of 8 to 10 years. The classic symptoms are those of intermittent urethral obstruction with straining on voiding, abnormal voiding pattern, and urinary retention.^65,66 Hematuria (30%–60%) and urinary tract infections may also be observed.^64–67

Imaging: VCUG remains the imaging gold standard. Before voiding, the tip of the polyp is frequently located at the level of the bladder neck, causing a small rounded filling (Fig. 121-22 and e-Fig. 121-23). In the voiding phase, the polyp moves downward into the distal posterior urethra and occasionally into the bulbar urethra. At the end of voiding, the polyp is displaced backward to the level of the bladder outlet by the contraction of the external urethral sphincter. Ultrasound may demonstrate a mobile pedunculated mass at the bladder base and indirect signs of bladder outlet obstruction (hydronephrosis and large bladder with or without bladder wall hypertrophy.^65–69

Treatment: Therapy of urethral polyps includes surgical resection (either by the transurethral endoscopic approach or through the suprapubic open cystostomy), transurethral fulguration, or laser (Nd:YAG, or neodymium-doped yttrium aluminum garnet).⁶⁵

Overview: The prostatic utricle is an epithelium-lined diverticulum of the prostatic urethra, the remnant of the fused caudal ends of the müllerian ducts. It is located in the verumontanum between the openings of the two ejaculatory ducts. When secretion or resistance to müllerian inhibitory factor is deficient, regression of the müllerian ducts is incomplete, resulting in an enlarged prostatic utricle and varying degrees of hypospadias (secondary to incomplete androgen-mediated closure of the urogenital sinus). The increasing severity of the hypospadias correlates with the increasing size of the utricle.⁷⁰ Poor emptying leads to urine retention and stasis. Clinically, this presents as lower urinary tract voiding symptoms, urinary retention, epididymitis, urethral discharge caused by urinary infection or stone formation, or postvoid dribbling caused by delayed utricle drainage.⁷¹

Imaging: VCUG and retrograde urethrography (RUG) define the utricular size and its origin from the prostatic urethra, and associated hypospadias (Fig. 121-24). Direct catheterization of the bladder during VCUG may be difficult secondary to preferential passage into the utricle (e-Fig. 121-25). Transabdominal ultrasound may demonstrate a retrovesical cystic mass, with or without internal debris, tapering to the expected location of the posterior urethra. CT and MRI imaging will demonstrate a thin-walled cystic lesion originating from the prostatic urethral region, with or without associated mass effect on the bladder and ureters.^72,73

Treatment: Surgical excision is the definitive treatment of symptomatic müllerian duct remnants. Surgical management remains challenging because of the intimate association of these lesions to the ejaculatory ducts, pelvic nerves, rectum, vas deferens, and ureters.⁷⁴

Overview: Bulbourethral (Cowper’s) glands are two pea-sized bodies on either side of the membranous urethra between the two layers of the urogenital diaphragm (Fig. 121-26). Their ducts are 2 to 3 cm in length and are directed forward through the bulb of the corpus spongiosum to end in the ventral aspect of the bulbar urethra. These accessory sexual organs secrete a clear mucous substance that acts as a lubricant for spermatozoa.^75–78

Imaging: Both the ducts and glands may opacify during VCUG when the distal orifice is patulous. A contrast medium–filled tubular structure is seen paralleling the undersurface of the bulbous urethra (e-Fig. 121-27). This finding, as a rule, is of no clinical significance. When the ductal orifice becomes stenotic, a dilated Cowper’s gland (syringocele) and duct are formed. The diagnosis can be made at VCUG by demonstrating a smooth extrinsic mass effect along the ventral surface of the bulbous urethra (Fig. 121-28).^75,76,79,80

Treatment: At urethroscopy, these lesions appear cystic. Transurethral marsupialization or incision demonstrates these lesions to be filled with clear or blood-tinged fluid.81,82

Overview: These uncommon anomalies of the male urethra are considered together because of common features and transitional forms suggesting a spectrum of related deformities.⁸³ The difference resides in their relationship to the corpus spongiosum. The urethral arch accompanying valves may take on a “pseudodiverticular” appearance but remains bordered by the corpus spongiosum. In contrast, a true diverticulum develops outside the corpus spongiosum, which is completely absent from the margin of the diverticular pouch. The urethral diverticulum may be more anatomically linked to the megalourethra, in which the corpus spongiosum (scaphoid megalourethra), corpora cavernosa (fusiform megalourethra), or both are deficient.⁸⁴

Overview: Anterior urethral diverticulum is a saccular outpouching of the ventral aspect of the anterior urethra into the corpus spongiosum, usually near the penoscrotal junction.83,85,86 The corpora cavernosa are intact. During voiding, urine distends the diverticulum and displaces the anterior lip of the diverticulum forward and against the dorsal wall of the urethra, obstructing the flow of urine. A tense bulge on the ventral aspect of the penis at the level of the diverticulum may be observed during voiding. The clinical symptoms depend on the degree of obstruction and include urinary retention, poor urinary stream, dribbling of urine, enuresis, and urinary tract infection.^87,88

Imaging: VCUG is the diagnostic tool of choice. Imaging of the urethra in an anterior oblique position will demonstrate a wide-mouthed, focal outpouching of the ventral urethra of variable size (up to 3 to 5 cm in diameter).⁸⁴ The urethra proximal to the diverticulum is dilated, with a sharp demarcation with the unobstructed distal urethra (Fig. 121-29). The proximal margin of the urethral diverticulum forms an acute angle with the floor of the ventral urethra.⁸³ The lesion is not clearly visualized on a retrograde urethrogram.⁸⁹

Treatment: Transurethral resection of the distal margin of the diverticulum with a hooked, single-wire or electrocautery knife is often successful. Open primary reconstruction, with diverticulectomy and urethroplasty, provides a more homogeneous caliber to the urethra. In the presence of infection, marsupialization of the diverticulum and urinary diversion followed by secondary repair is recommended.83,85,87

Overview: Anterior urethral valves (AUVs) are congenital mucosal folds located distal to the membranous urethra.⁹⁰ The valvular tissue is directed backward and is anchored laterally such that it is raised up against the dorsal aspect of the urethra during voiding, obstructing the flow of urine. It differs from a urethral diverticulum in that it lacks a posterior lip and usually causes a lesser degree of localized swelling of the ventral aspect of the penis during micturition.⁸⁴ No abnormalities of the corpus spongiosum or corpora cavernosa are present. The clinical manifestations and complications are the same as those described for anterior urethral diverticula but are often milder.

Imaging: VCUG is the diagnostic tool of choice. The urethra has a more fusiform dilation proximal to the valve and is narrow distally. A thickened band of valvular tissue is seen at the transition, assuming an iris-like, semi-lunar, or cusp-like configuration (Fig. 121-30 and e-Fig. 121-31).^87,91 AUVs may produce a proximal dilation of the urethra that mimics a diverticulum. However, in “pseudodiverticula” formation caused by AUVs, the proximal end of the urethral dilation forms an obtuse angle with the ventral floor of the urethra, unlike the acute angle seen in a true urethral diverticulum.^83,91

Treatment: Transurethral valve ablation with the help of a pediatric resectoscope is the treatment of choice. Open urethrotomy and excision of the valve or segmental urethrectomy of the valve-bearing area along with a primary end-to-end anastomosis are alternative options.⁹¹

Overview: The scaphoid megalourethra is much more common than the fusiform type. It consists of a saccular dilatation of the penile urethra, caused by the absence or underdevelopment of the corpus spongiosum. Ventrally, the penis is soft and baggy with redundant skin. During voiding, the affected part of the urethra balloons markedly, causing a large, smooth bulge in the ventral surface of the penis. The penis and pendulous urethra assume a scaphoid (boat-shaped) configuration. The patient voids with a poor stream.35,92

Fusiform megalourethra, less common and more severe than the scaphoid form, is characterized by a diffuse ectasia of the penile urethra secondary to the absence or partial deficiency of the corpus spongiosum and corpora cavernosa. The penis is large, misshapen, and flabby, with redundant and wrinkled skin.³⁵ During voiding, the urethra and penis become markedly distended. The patient voids with a poor urinary stream. Clinical symptoms and the prognosis vary with the severity of the associated anomalies (e.g., “prune belly syndrome”).

Imaging: On VCUG or RUG, the dilated ventral segment of the scaphoid urethra dilates and blends gradually with a normal urethra distally and proximally. The fusiform megalourethra is markedly dilated, tapering both distally and proximally into a relatively normal urethra (Fig. 121-32). The proximal urethra may be dilated. Sometimes, the anomaly affects only a small portion of the urethra (e-Fig. 121-33).^93,94

Overview: A single unifying theory does not exist to explain all the various forms of duplication, and more than one classification scheme exists in the literature. These developmental anomalies are characterized by the presence of a complete or partial accessory urethral channel arising from the bladder to the distal urethra. Incomplete duplications arise from the penile surface or from the urethral channel but end blindly in the periurethral tissue.95–98 Sagittal plane duplication is most common with a ventral and dorsal urethra (one urethra atop the other). It is important to remember that in almost all cases, the ventral urethra is the functioning channel and contains the urethral sphincter and verumontanum. According to the location of the accessory urethral opening on the dorsal or ventral aspect of the penis, urethral duplications are divided into epispadic (the most common type) and hypospadic types, respectively.^99–101

In the epispadic type, an incomplete accessory channel has a dorsal opening in the penis and ends blindly. The complete or partial forms originate from the bladder or proximal urethra and course through the dorsal aspect of the penis to end in an epispadic position anywhere between the glans and the root of the penis, or rarely they originate from a minute cavity (nonfunctional sagittal plane duplicated bladder) located behind the pubic symphysis and in front of the normal bladder. The ventral urethra is normally positioned and ends in the glandular meatus (although rarely is hypospadic).96,98–101

In the hypospadic type, an incomplete accessory channel has a ventral opening in the penis and ends blindly or originates from the normal proximal urethra and ends blindly in the periurethral tissue, similar in appearance to a urethral diverticulum or Cowper’s duct. Complete or partial duplications arise from the bladder or proximal urethra and course through the ventral aspect of the penis to end in a hypospadic position along the shaft.96–98,102

An important form of urethral duplication of the hypospadic type is referred to as Y-type duplication. The ventral urethra originates from the midprostatic urethra and terminates in the anal canal or in the perineum along the anterior anal margin. Urine flows preferentially through this ventral channel and is considered the normal urethra as it traverses the sphincter mechanism. A normally positioned dorsal urethra is usually stenotic or partially atretic.103–106

The congenital urethroperineal fistula has a similar location to the Y-type duplication, but is a distinctly different developmental anomaly (Fig. 121-34 and e-Fig. 121-35). The normally positioned dorsal channel is the functioning urethra in this case, and micturition is normal. Clinically, only a few drops of urine are present at the perineal opening.^107–109

Accessory urethras may be asymptomatic or may cause a double urinary stream, urinary incontinence, urinary tract infections, and urinary retention.

Imaging: Appropriate evaluation or urethral duplication includes anatomic evaluation of all channels, recognition of the functional urethra and identification of associated anomalies.95,96,98 VCUG is adequate if both urethral channels can be clearly identified (Fig. 121-36 and e-Fig. 121-37). RUG may be necessary for hypoplastic channels not visualized on VCUG. Cystoscopy may be performed to confirm the radiographic findings and to precisely identify which urethra contains the sphincteric mechanism and normal verumontanum.^97,102

Treatment: Preservation and reconstruction of the functional urethral channel is the primary goal of treatment. Ventral channel excision in congenital urethroperineal fistula is curative.96,97,102,103,110

Overview: Iatrogenic strictures, which account for about two thirds of the cases, are located predominantly near the penoscrotal junction, an area that is particularly vulnerable to internal trauma. Pelvic fractures, penetrating injuries, direct blows to the perineum, and straddle injuries are the most common forms of external trauma. Urethral infections are uncommon causes of urethral strictures in children as opposed to young adults, in whom urethral strictures are often due to Neisseria gonorrhoeae infection.111–115 Urethral strictures of unknown cause in symptomatic boys are not rare. They may be the result of unrecognized external trauma or urethritis, Cowper’s duct infection, or rupture of a Cowper’s duct cyst, or they may be secondary to incomplete dissolution of the urogenital membrane at the junction of the cloaca and genital groove (Cobb’s collar).^116,117 The clinical manifestations of urethral strictures include poor urinary stream, straining to void, urinary retention, painful urination, hematuria, urinary infections, and recurrent epididymitis.

Imaging: The diagnosis is readily established by VCUG when the bladder can be catheterized. Compression of the distal penis during voiding (choke urethrogram) or RUG results in distention of the normal urethra and a better delineation of the true extent of the stricture. The membranous urethra is the area most often injured, owing to its fixation by the urogenital diaphragm. Strictures from straddle injuries are usually located in the bulbar urethra (Fig. 121-38 and e-Fig. 121-39). Congenital strictures are located most often in the bulbar urethra and are usually very short and diaphragm-like (Fig. 121-40). An alternative to fluoroscopic evaluation is ultrasound of the urethra, which provides information about the urethra as well as periurethral tissues. In the interpretation of the urethrogram, it is important to keep in mind those normal areas of narrowing at the level of the urogenital diaphragm or narrowing caused by spasm of the bulbocavernosus or external sphincter muscles that may simulate a stricture.^{111,115,118–121}

Treatment: Three major forms of treatment exist for urethral stricture: (1) urethral dilation, which is the oldest and simplest treatment; (2) open reconstruction with urethroplasty, which is regarded as the gold standard; and (3) internal urethrotomy by incising or ablating the stricture transurethrally.122,123