Pediatrics

Urachal Anomalies and Congenital Diverticulum

OVERVIEW: What every practitioner needs to know

A rare, but encountered issue in pediatrics is the child with a congenital malformation of the bladder. Both urachal anomalies and congenital bladder diverticulum are outpouchings in an otherwise smoothly contoured bladder. Urachal anomalies tend to be picked up by physical exam, and diverticula are usually noted on radiographic imaging. Both may be an incidental finding; however, in some cases surgical reconstruction may be required.

Are you sure your patient has a urachal anomaly or congenital bladder diverticulum? What are the typical findings for this disease?

Both urachal anomalies and bladder diverticula may appear as outpouchings off of the normally smoothly contoured bladder. The origins of both are quite different, and differentiating them is straightforward.

Oftentimes, a urachal anomaly will be seen on prenatal ultrasound. However, after birth it will present typically with the following signs on physical examination: clear fluid draining from the periumbilical region or a small umbilical mass, possibly with red mucosa protruding outward. Typical symptoms in a patient with a urachal anomaly may be either: 1) a mass in the dome of the bladder, 2) peri-umbilical pain, most often with voiding, 3) dysuria, or 4) urinary tract infection (UTI).

A congenital bladder diverticulum may also be seen on prenatal ultrasound in some cases. Typically, it cannot be detected on physical examination unless it is so large as to produce an abdominal mass. It is usually found radiographically on ultrasound. Potential signs of a patient with a congenital bladder diverticulum are: UTI, bladder outlet obstruction, vesicoureteral reflux, ureteral obstruction, or asymptomatic findings on bladder ultrasound.

Types of urachal anomalies

A urachal sinus is a partial communication between the bladder and umbilicus, with one end of the sinus being obliterated or closed off.

A urachal cyst is a walled-off communication between the bladder and umbilicus.

A patent urachus is a complete communication between umbilicus and bladder, where urine from the bladder can drain freely from the umbilicus.

A vesicourachal diverticulum is typically an asymptomatic outpouching of the bladder in the dome at the site of the urachal insertion.

The difference between a congenital and acquired bladder diverticulum is:

Typically, an acquired bladder diverticulum presents with multiple diverticula. They are associated with a trabeculated bladder and result from bladder outlet obstruction or increased voiding pressures.

A congenital bladder diverticulum presents differently. Typically, congenital diverticula are solitary, the bladder is usually smooth walled, and they are not generally associated with bladder outlet obstruction.

What other disease/condition shares some of these symptoms?

  1. Gastrointestinal malformations such as omphalocele would present with protrusion around the area of the umbilicus, but would include gastrointestinal contents.

  2. Vitelline duct abnormalities may present with inflammation or a persistent umbilical sinus

  3. Meckel's diverticula are associated with inflammation or incarceration or volvulus of a bowel segment in the umbilical area.

  4. Ureteroceles can mimic a congenital diverticula as of the bladder, but generally appear cystic and within the bladder instead of an external outpouching.

What caused this disease to develop at this time?

A urachal anomaly develops from the failure of the urachal communication between the bladder and umbilicus to properly obliterate during fetal development. A major theory is that fetal bladder outlet obstruction may cause urine to escape via a patent urachus like a pop-off valve. Clinically, the presence of a postnatal outlet obstruction in a patent urachus is exceedingly rare.

A congenital bladder diverticulum is typically located in the lateral aspect of the bladder trigone and is thought to occur due to an inherent weakness in the detrusor muscle. It is also postulated that a deficiency of the fascial covering in that area of the bladder may allow for a diverticulum to develop.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

  1. No laboratory studies are required.

  2. Many times, a UTI results in the finding of a congenital anomaly. If a child with a known bladder anomaly is suspected of having a recurrent UTI, catheterized urinalysis and urine culture are the preferred manner to obtain the sample.

Would imaging studies be helpful? If so, which ones?

The work-up for both urachal anomalies and congenital diverticula includes an up-front renal and bladder ultrasound. The renal and bladder ultrasound evaluates for concomitant renal defects, while defining the bladder anatomy more precisely with minimal risk/radiation. Also, ultrasound of the area of the urachus may better define the urachal anatomy.

In both urachal anomalies and diverticula, a voiding cystourethrogram (VCUG) is recommended as part of the work-up. It assesses for bladder anatomy, ureteral reflux and also evaluates the urethra for possible outlet obstruction.

If there is still concern about the urachal anatomy prior to a surgical procedure, a sinogram through the patent urachus may be performed. This involves injection of dye down the urachal tract under fluoroscopy to delineate the anatomy of the defect.

Confirming the diagnosis

The diagnosis of urachal anomaly can usually be made with the physical exam finding of clear fluid draining from a patent umbilicus sinus. A bladder diverticulum may be identified with the above-mentioned radiologic testing.

If you are able to confirm that the patient has a urachal anomaly or congenital diverticulum, what treatment should be initiated?

The treatment for urachal anomalies is surgical excision. Surgical excision should be undertaken if the periumbilical drainage persists or if recurrent UTIs occur. Optimal timing for surgical excision is within the first year of life; however, some cases of conservative management have been reported with drainage ceasing in the first few months of life.

Bladder diverticula require treatment only if they are symptomatic. Symptoms necessitating treatment of diverticula include: 1) recurrent UTIs due to poor emptying of the diverticulum; 2) persistence of vesicoureteral reflux attributed to the diverticulum; and; 3) there is ureteral obstruction being caused by the diverticulum.

What are the adverse effects associated with each treatment option?

Excising a urachal anomaly carries with it the surgical risks inherent to the specific procedure chosen by the patient and the surgeon. Not removing a urachal anomaly can lead to an increased cancer risk or issues with incontinence from the patent urachus.

In the case of a congenital diverticulum, not surgically excising it is an acceptable treatment option, and conservative management may be pursued if it is asymptomatic. If the diverticulum is causing reflux or obstruction, excision is recommended, as that problem may persist and/or worsen over time.

What are the possible outcomes of urachal anomalies or congenital diverticula?

  1. Persistent urachal anomalies can lead to:

    1. Continuous bladder and urine drainage around the umbilicus (42%)

    2. Recurrent urinary tract infections (5-10%)

    3. While extremely rare, urachal carcinoma may develop within these anomalies, occurring in an estimated 0.01% of cases

  2. An untreated bladder diverticulum may:

    1. Have no ill effects on the patient if it is asymptomatic

    2. If the diverticulum is symptomatic, not surgically repairing it may lead to worsening:

      1. Infection (up to 90% in symptomatic patients)

      2. Urinary stasis (80-90% in symptomatic patients)

      3. Vesicoureteral reflux (8-13%)

      4. Ureteral obstruction (5%)

What causes this disease and how frequent is it?

The origin of the urachus in theory is as a low-resistance urinary outlet for drainage of the bladder while the urinary sphincter matures in utero. Abnormal embryological development and failure of the urachus to properly close/obliterate is the proposed etiology of persistent urachus. It is rare, and the incidence and genetic data are not known.

Congenital bladder diverticula are rare, but not uncommon. They occur in up to 1.5% of children with genitourinary abnormalities. Congenital diverticula are seen in association with: Menkes syndrome, Ehlers-Danlos syndrome, Williams syndrome, Williams-Beuren syndrome, and cutis laxa.

How do these pathogens/genes/exposures cause the disease?

This is not known at this time.

Other clinical manifestations that might help with diagnosis and management

There are no additional manifestations than those discussed. The primary decision point with these two congenital birth defects is the presence of symptoms necessitating surgical treatment. Specific symptoms would be: recurrent urinary tract infections, persistent pain, persistent umbilical drainage, or a diverticulum causing reflux or ureteral obstruction.

What complications might you expect from the disease or treatment of the disease?

  1. Urachal anomalies can result in:

    1. Persistent periumbilical urinary leakage (43%)

    2. Umbilical mass (33%)

    3. Abdominal pain (22%)

    4. Dysuria (2%)

    5. Rarely, urachal carcinoma

    6. Surgical resection will carry the implicit surgical risks specifically related to the surgery and a small risk of recurrence.

  2. Bladder diverticulum may cause:

    1. Recurrent UTIs (90% in symptomatic cases)

    2. Urinary stasis (80-90% in symptomatic cases)

    3. Vesicoureteral reflux (8-13%)

    4. Ureteral obstruction (5%)

    5. Surgical repair carries surgical risks that must be weighed based on symptomatology and history

Are additional laboratory studies available; even some that are not widely available?

There are no additional laboratory studies required. A catheterized urine sample is always encouraged when evaluating these patients for a urinary tract infection.

How can urachal anomalies and congenital diverticulum be prevented?

It is not known how to prevent urachal anomalies or congenital diverticula from developing in utero

What is the Evidence?

  1. Urachal anomalies and congenital diverticula are rare birth defects with no randomized controlled trials or longitudinal prospective data.

  2. Almost all evidence is level 3 and 4 coming from retrospective reviews, and expert opinion.

We recommend the following publications for further reading:

Gearhart, JP, Rink, RC, Mouriquand, PDE. Pediatric Urology. Saunders Elsevier. 2010.

Bauer, SB, Retik, AB.. "Urachal anomalies and related umbilical disorders". Urol Clin North Am. vol. 5. 1978. pp. 195-211.

Powell, CR, Kreder, KJ.. "Treatment of bladder diverticula, impaired detrusor contractility, and low bladder compliance". Urol Clin North Am. vol. 36. 2009. pp. vii-25.

Ongoing controversies regarding etiology, diagnosis, treatment

  1. Surgical technique, timing, and methodology of the reconstruction are surgeon- and center-specific, and may be debated.

  2. The diagnosis and imaging studies recommended are standard.

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