Surgery for Pediatric Bladder Anomalies

The timing of altered embryogenesis leading to bladder anomalies has been a matter of speculation, and the embryologic cause of these lesions is unknown.

Bladder development occurs during weeks 5-7 of gestational development. Development depends upon many factors, such as proper mesenchymal differentiation, mesenchymal growth, urine production that stimulates bladder expansion, and detrusor contraction. Bladder cycling, the process of sequential expansion and contraction, is important in the anatomic and physiologic development of the normal bladder. Bladder ears are considered a normal variation, not a congenital anomaly.

Bladder diverticula are uncommon but not rare. In a series of over 5000 children studied, the approximate incidence was 1.7%. All of the other entities are uncommon or rare. In particular, megacystis, bladder duplication, and bladder septation are quite rare.[2, 3]  For example, as of 2021, only about 70 cases of bladder duplication had been reported in the English literature.[4]

Bladder anomalies are generally diagnosed in infancy or childhood. With the advent of antenatal ultrasonography (US), such abnormalities are fully evaluated after birth. When they are not detected by antenatal screening, they are most commonly discovered in the evaluation of a UTI or, in the case of urachal anomalies, periumbilical drainage or redness. All of these anomalies occur in both males and females. The data are insufficient to establish any reasonably accurate frequency differences between the sexes.

The prognoses for the various pediatric bladder anomalies are as follows:

• Bladder diverticula - Excellent
• Urachal sinus - Excellent
• Urachal cyst - Excellent
• Patent urachus - Excellent
• Vesicourachal diverticulum - Excellent
• Bladder ears - Excellent
• Bladder agenesis - Guarded
• Megacystis - Good
• Bladder duplication - Good to excellent
• Bladder septation - Variable, ranging from guarded to good, depending on the anatomy and the degree of renal dysfunction

Most of these pediatric bladder anomalies have a low mortality and are associated with little morbidity.

Bladder diverticula and vesicourachal diverticula often cause no symptoms, but in symptomatic cases, patients most often present with UTI. Rarely, bladder diverticula and vesicourachal diverticula may cause bladder outlet obstruction. Death from peritonitis due to a ruptured infected urachal cyst has been reported in a few cases, but most bladder anomalies are incidental findings, and patients are typically asymptomatic.

Patent urachal anomalies do not usually cause significant morbidity or mortality. However, adenocarcinoma has been reported in adults in urachal remnants, presumably from chronic inflammation and infection.[5]  The risk of later adenocarcinoma appears to be low in children with asymptomatic lesions.[6]

Bladder agenesis generally is incompatible with life.

The morbidity of megacystis, bladder duplication, and bladder septation is generally related to associated abnormalities (when present), such as high-grade VUR or renal dysplasia. Megacystis may occur as part of megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS; also referred to as Berdon syndrome), for which the prognosis is poor.[7]

In all of these conditions, an element of voiding dysfunction may exist. Parents should be educated regarding frequent and complete bladder emptying after the toilet training period to guard against infrequent and dysfunctional voiding patterns. In general, children should void approximately five or six times per day, which equates to voiding every 3 hours. Infrequent and dysfunctional voiding in the presence of an anatomic abnormality may place the child at increased risk for febrile UTIs and renal damage.

Bladder diverticula

Bladder diverticula are herniations of the bladder mucosa through bladder wall musculature (detrusor muscle).[8] Diverticular size can vary greatly, with some attaining a size equal to or greater than the volume of the bladder. Diverticula can be wide- or narrow-mouthed, as dictated by the size of the musculature (detrusor) defect. The size of diverticular openings has functional implications because narrow-mouthed diverticula often empty poorly. Stasis of urine within diverticula can also lead to stone formation or epithelial dysplasia.[9]

Depending on the size and location, bladder diverticula may cause ureteral obstruction, bladder outlet obstruction, or vesicoureteral reflux (VUR). Ureteral obstruction is unusual, occurring in approximately 5% of children with bladder diverticulum. Bladder outlet obstruction is rare. However, VUR is more common, affecting 8-13% of patients.[10]

Bladder diverticula most commonly occur lateral and superior to the ureteral orifices. They may also occur at the dome of the bladder, particularly in such disorders as bladder outlet obstruction (ie, posterior urethral valves) or Eagle-Barrett syndrome (prune belly syndrome).

Bladder diverticula may be congenital or acquired; in children, most are congenital.[11, 12] Congenital deficiency or weakness in the Waldeyer fascial sheath has been implicated as a cause. Congenital diverticula tend to be solitary and are located at the junction of the bladder trigone and detrusor. This location, close to the insertion of the ureter into the bladder, is important because large diverticula can impinge on or distort the ureteral orifices. Surgical excision of these diverticula must therefore be undertaken with care to avoid ureteral injury.[11]

Acquired diverticula are the result of obstruction, infections, or iatrogenic causes. They tend to be multiple and occur in trabeculated bladders. Examples of loci of obstruction include posterior urethral valves (PUVs), anterior urethral valves, urethral strictures, neuropathic bladder, and external sphincter dyssynergy. An example of iatrogenic diverticula is herniation of the bladder mucosa through the ureteral hiatus after antireflux surgery because of inadequate closure of the ureteral hiatus.

Many diverticula that are related to obstruction spontaneously resolve after relief or correction of the obstruction. In some cases, the diverticula that occur in response to obstruction serve a beneficial function by acting as pressure pop-off mechanism, protecting the kidney and ureters from high pressures.

Some children with diverticula have voiding dysfunction on urodynamic testing. Whether the voiding dysfunction leads to the formation of diverticula or the presence of diverticula leads to voiding dysfunction is unclear.[13]

Urachal anomalies

A urachal sinus derives from a persistently patent urachus. The sinus drains to the umbilicus, and this drainage often is the result of episodic infections of the sinus, resulting in the appearance of purulent drainage at the umbilicus. Children may present with periumbilical tenderness, a wet umbilicus, or granulation tissue at the level of the umbilicus. In many cases, these children have undergone multiple silver nitrate cauterizations under the mistaken notion that this is simply granulation tissue after severance of the remnant umbilical cord.

A urachal cyst is a fluid-filled structure occurring in between the two obliterated ends of the urachus (ie, the umbilicus and bladder dome). Most occur in the distal third of the urachus. In infancy, such cysts are rarely symptomatic, but they are detected with increasing frequency as an incidental finding during bladder ultrasonography (US) in children undergoing evaluation for other reasons (eg, antenatal hydronephrosis or urinary tract infections [UTIs]). More commonly, the urachal cyst is detected in early childhood or adolescence.

Symptoms of a urachal cyst are generally related to infection and the resultant inflammation and include suprapubic mass, fever, pain, and bladder or irritative voiding symptoms. Staphylococcus aureus is the most common bacterial organism. The peritoneum alone separates the cyst from the intra-abdominal cavity; thus, the inflammatory process may involve the adjacent intra-abdominal contents, resulting in abdominal pain. Death from intra-abdominal rupture has been reported.

A patent urachus is a communication from the umbilicus to the bladder. Infants present with continuous or intermittent drainage from the umbilicus. Crying, straining, voiding, or the prone position may accentuate intermittent drainage. The tract may become inflamed, resulting in tenderness, periumbilical swelling, and serosanguineous or purulent discharge.

A patent urachus may also be associated with bladder outlet obstruction, such as PUVs. Correction of the obstruction may result in the spontaneous resolution of the patent urachus. However, if the patent urachus persists beyond several months after relief of the obstruction, it should be surgically corrected.

A vesicourachal diverticulum is an outpouching at the apex of the bladder that results from incomplete closure of the proximal urachus. Most patients are asymptomatic because the diverticula drain well with bladder emptying. Often, vesicourachal diverticula are incidentally discovered during evaluation for other reasons. Rarely, they become large and empty poorly, resulting in recurrent UTI or stone formation.[14]

Bladder ears

Bladder ears are lateral protrusions of the bladder through the internal inguinal ring and into the inguinal canal. In infants, the bladder assumes a more abdominal position, which places it in close proximity to the internal inguinal ring. With growth, the pelvis becomes more developed, and the bladder assumes a more pelvic position. Therefore, this anomaly is rarely observed in adults.

Bladder ears are often observed during voiding cystourethrography (VCUG) or intravenous pyelography (IVP), when the bladder is filled to capacity. Bladder ears have also been seen on computed tomography (CT) body imaging. Knowledge of this entity is important to surgeons during inguinal herniorrhaphy because occasional reports have been made of partial or near-total cystectomy performed under the mistaken notion that this was a large hernia sac.

Bladder agenesis

Bladder agenesis is rare and generally incompatible with life. Fewer than 20 cases have been reported in live births, all of them in females, presumably because females have less outlet resistance than males do and thus have preservation of renal function. Ureters may enter into the urethra, vagina, Gartner duct cyst (female), prostatic urethra, rectum, or the patent urachus.

Most often, associated hydroureteronephrosis and renal dysplasia (variable) are present. Other associated anomalies include neurologic, orthopedic, hindgut, and other urogenital anomalies, such as renal agenesis and absence of the prostate, vagina, seminal vesicles, epididymis, or penis.

Megacystis

Megacystis is an enlarged bladder, believed to be secondary to overfilling of the fetal bladder during development. It is often discovered postnatally as the evaluation of antenatal hydronephrosis is completed. Febrile UTI is the other common presentation.

This condition is associated with massive high-grade VUR, which may also be the etiology of megacystis. In the presence of massive reflux, a large percentage of the voiding bladder volume is refluxed into the upper tracts. This causes constant recycling of the urine between the bladder and ureters, resulting in progressive dilation of both.[15]

Megacystis can be observed in other conditions, such as PUVs, Ehlers-Danlos syndrome,[16] urethral diverticulum, microcolon hypoperistalsis syndrome,[17] sacral meningomyelocele, sacrococcygeal teratoma, and pelvic neuroblastoma.

Bladder duplication

Bladder duplication is rare.[2, 3] It can be complete or partial, with complete duplication more common than incomplete duplication.[18, 19] The two halves of the bladder are on either side of the midline, with the corresponding ipsilateral ureter draining each bladder half.

Associated anomalies occur with much greater frequency in complete bladder duplication, including duplication of the penis, vagina, uterus, lumbar vertebrae, and hindgut. In addition, fistulas may be present between the rectum, vagina, and urethra. With complete bladder duplication, two urethras exist; with incomplete bladder duplication, the bladder joins distally into a single common urethra.

Bladder septation

Bladder septation anomalies are rare. Fibromuscular or mucosa septations divide the bladder into equal or unequal portions. Septations may be complete or incomplete. The functioning of the associated renal units depends on the adequacy of upper-tract drainage.

For many of the bladder anomalies, no overt physical findings are observed. They are elucidated after radiologic imaging for such things as a history of antenatal hydronephrosis or UTI. The usual physical findings relative to each of the anomalies are as follows:

• Bladder diverticula - None
• Urachal sinus - Intermittent drainage from umbilicus (may be serous or serosanguineous)
• Urachal cyst - None (with an infected cyst, physical findings include infraumbilical or suprapubic mass with tenderness or erythema of overlying skin)
• Patent urachus - Intermittent umbilical drainage (may be serum or urine)
• Vesicourachal diverticulum - None
• Bladder ears - None
• Bladder agenesis - None (most of the physical findings pertain to various associated anomalies)
• Megacystis - None
• Bladder duplication - None (in complete bladder duplication, two urethral openings may be identified)
• Bladder septation - None

Laboratory studies that should be considered for the various pediatric bladder anomalies are as follows:

• Bladder diverticula - None
• Urachal sinus - None
• Urachal cyst - None
• Patent urachus - Analysis of the umbilical drainage for creatinine or urea to determine if the values are consistent with urine may help differentiate the patent urachus from other entities listed in the differential diagnosis
• Vesicourachal diverticulum - None
• Bladder ears - None
• Bladder agenesis - Serum electrolytes, creatinine
• Megacystis - Urine culture, serum creatinine
• Bladder duplication - Urine culture, serum creatinine
• Bladder septation - Urine culture, serum creatinine

For bladder diverticula, voiding cystourethrography (VCUG) is the best imaging modality (see the first and second images below). Bladder ultrasonography (US) may also be used to detect bladder diverticula (see the third image below), but it does not provide the same anatomic definition that VCUG does. Intravenous pyelography (IVP) may detect bladder diverticula, particularly those that protrude laterally. Anteriorly or posteriorly placed diverticula may be obscured from view because they are overshadowed by the contrast within the bladder.

Sinography is the best test for detecting a urachal sinus. Other modalities include US, computed tomography (CT), and magnetic resonance imaging (MRI).[20, 5]

US is the best test for detecting a urachal cyst (see the images below). CT or MRI can help delineate the size and location of the cyst. In addition, with infected urachal cysts, CT is used to determine the involvement of adjacent structures secondary to the inflammatory mass.[20]

VCUG may demonstrate a patent urachus, in addition to identifying any evidence of bladder outlet obstruction or vesicoureteral reflux (VUR). It is also the most useful test for detecting a vesicourachal diverticulum.

Bladder ears can be incidentally discovered with VCUG or IVP.

For bladder agenesis, full evaluation is best performed with IVP and VCUG. These two tests delineate both upper-tract and lower-tract anatomy.

In patients with megacystis, VCUG is the best test for demonstrating the enlarged bladder and massive refluxing megaureters (see the image below). Additional studies, such as nuclear medicine renal scanning, are helpful in determining renal function. Cystography and urodynamic studies may be necessary in those children with voiding dysfunction (eg, incomplete bladder emptying, frequent cystitis, or incontinence).

Full evaluation of bladder duplication is best performed with IVP and VCUG (see the images below). These two tests delineate both upper-tract and lower-tract anatomy.

In cases of bladder septation, the use of several imaging modalities, including VCUG, IVP, and bladder US, is often required for full delineation of the anatomy.

In some instances, percutaneous drainage of an infected urachal cyst is necessary as a temporary measure. After percutaneous decompression and adequate antibiotic therapy, complete surgical excision of the urachus is necessary.

With bladder diverticula, bladder outlet obstruction should be corrected if present because many bladder diverticula resolve spontaneously after relief of obstruction. Congenital diverticula are usually removed surgically.

Urachal sinus can be observed in the first 4-8 weeks of life. For small asymptomatic urachal cysts discovered incidentally, observation with serial ultrasonography (US) may be appropriate. A patent urachus can generally be observed in the first few months of life because some cases may resolve spontaneously.[21] Persistence after 2 months warrants surgical correction. If bladder outlet obstruction is present, it should be corrected first because it may be the cause of the persistent urachal patency. Most patients with a vericourachal diverticulum do not require treatment.

No treatment is necessary for bladder ears, because nearly all cases resolve spontaneously.

Bladder agenesis must be treated by means of urinary diversion and subsequent reconstruction (eg, continent urinary reservoir).

With megacystis, clean intermittent catheterization (CIC) may be considered in patients who have incomplete bladder emptying or frequent urinary tract infections (UTIs). In children in whom CIC is instituted, urodynamic studies should be obtained. (See Surgical Care.)

Incomplete bladder duplication often need not be treated when the upper urinary tracts are normal and the bladder empties completely. If other associated anomalies are present, they should be addressed individually. (See Surgical Care.)

For bladder septation, depending on the anatomy, no treatment may be appropriate; an example would be a small incomplete septation with normal upper tracts and complete bladder emptying.

Patients with bladder diverticula generally require surgery when the diverticula are causing obstruction, recurrent UTIs, vesicoureteral reflux (VUR), or stone formation.[22, 23] If diverticula have arisen secondary to obstruction, the outlet obstruction should be corrected first because some of these diverticula spontaneously resolve with relief of the obstruction.

Surgical diverticulectomy for congenital diverticula may be approached extravesically or intravesically. The surgical approach varies, depending on lesion size and location, associated anomalies (eg, VUR), and individual surgeon preferences. In very large paraureteral diverticula, care must be taken to avoid injuring adjacent structures (eg, ureter or vas deferens).

A robot-assisted laparoscopic approach to bladder diverticulectomy has been described.[24, 8]  Marte et al, in a series of 16 male children (age range, 4-12 years) with symptomatic bladder diverticula, found vesicoscopic diverticulectomy to be safe and effective.[25]

In the presence of ureteral obstruction, renal function dictates management. If the associated kidney has little or no function, a nephrectomy with bladder diverticulectomy is performed. If kidney function is adequate, diverticulectomy and ureteral reimplantation are indicated.

Surgical correction of a urachal sinus involves complete removal of the urachus, from the umbilicus to the dome of the bladder. In an infant or child, this can be approached easily via a Pfannenstiel incision. In an infant, the distance from the dome of the bladder to the base of the umbilicus is very short. Complete removal eliminates any further problems. Surgical removal should be planned after adequate treatment of the infection because intraperitoneal structures may adhere to the urachus in the inflammatory process.[26]

After adequate treatment of an infected urachal cyst, surgical removal of the entire urachus is warranted. A Pfannenstiel incision can be used in an infant or child. Again, in an infant, the distance from the dome of the bladder to the base of the umbilicus is very short. Complete removal eliminates any further problems.[27, 28]

As is the case with a urachal cyst, complete removal of a patent urachus using the described technique eliminates any further problems.

Surgical removal of a vesicourachal diverticulum is reserved for large symptomatic diverticula causing recurrent UTIs, stones, or poor emptying.

Patients with bladder ears do not require surgical treatment, because nearly all cases resolve spontaneously.

Initial treatment of bladder agenesis consists of urinary diversion. Complex urinary reconstruction (eg, creation of a continent urinary reservoir) may be undertaken later in life.

In patients with megacystis, the massive VUR is corrected by ureteral reimplantation, which usually involves tapering the ureters at the time of reimplantation. Correction of megacystis by means of reduction cystoplasty often is not necessary; correction of the reflux alone may suffice. If recurrent UTIs or incomplete bladder emptying occur after reimplantation, reduction cystoplasty may be considered. In rare cases, vesicostomy can be performed as a temporary measure in children with megacystis and severe VUR until a more formal reconstruction can be performed.

Complete bladder duplication has a much higher incidence of associated anomalies necessitating surgical correction, such as fistulas between the urethra and adjacent structures. The variable anatomy of each case dictates the surgical approach. A combined robotic-open approach was described by Bowen et al in a patient with bladder duplication and urethral triplication.[29]

Surgical treatment of bladder septation is dictated by the individual patient's anatomy. The goals are to relieve bladder and upper-tract obstruction.

Complications are related to persistent obstruction or recurrent UTIs—namely, renal insufficiency or failure. If the obstruction is corrected and urinary drainage is unimpeded, long-term complications are minimal.

In the case of bladder agenesis, the long-term complications are related to those specific to urinary diversion, continent reservoir, or both. These include ureteral stricture at the junction of the ureter and reservoir, reservoir stones, recurrent UTI, stomal stenosis of the catheterizable segment, and metabolic disturbances relative to the intestinal segment used.

Generally, no dietary restrictions are needed for the various bladder anomalies. In cases of significant renal insufficiency, the nephrologist may impose certain dietary restrictions, such as limited protein intake.

For all of the bladder anomalies, consultation with other professionals is dictated primarily by the presence of the associated anomalies. In situations of renal insufficiency with the various obstructive entities (eg, posterior urethral valves [PUVs], neurogenic bladder), consultation with a nephrologist is advisable.

For bladder diverticula, no follow-up care is required after surgical removal. Small diverticula that are treated by observation alone may be annually monitored with renal and bladder US.

No follow-up care is required after surgical removal of a urachal sinus, a urachal cyst, or a patent urachus. If a small urachal cyst is to be monitored, yearly US studies are indicated. No follow-up care is necessary for a vesicourachal diverticulum.

No follow-up care is necessary for bladder ears.

For bladder agenesis, frequent outpatient follow-up visits are necessary after urinary diversion. Initially, outpatient follow-up care may occur as often as monthly. Once stability has been achieved, follow-up visits usually are annual. Evaluation with serial renal US is performed to assess renal growth and the presence or absence of hydronephrosis. Conduit US can detect the presence of stones. Serum electrolyte and creatinine determinations help detect metabolic disturbances and renal insufficiency.

For megacystis, yearly evaluation with renal and bladder US may be appropriate until just after the toilet training period to monitor the upper tracts and ensure adequate bladder emptying. Similar evaluation is also appropriate for bladder duplication and bladder septation.