Bladder exstrophy: A surgically correctable condition

Please note this article contains graphic medical images.

By Michael E. Mitchell, MD

Exstrophy of the bladder represents a spectrum disease and is quite unusual in two regards. The most frequent form of the disease (1 in 30,000 live births) is complete classic exstrophy (See Figure 1.), where the bladder, urethra and genitalia all are exposed on the lower abdominal wall. The most severe form, cloacal exstrophy (See Figure 2.), includes malform-ations of the primitive hindgut, cecum, bladder (completely open  and divided into two parts), small bowel (significant potential for malabsorption), spine and lower extremities. Fortunately, this form is uncommon (1 in 300,000-500,000 births). What makes the exstrophy complex unique is that the least severe form, epispadias (See Figure 3.), is also rather uncommon (1 in 300,000-500,000). This form primarily involves the genitalia, although we now realize there is significant involvement of the bladder neck and, except for the most insignificant epispadias in males, there is a high potential for urinary incontinence. The other significant and unique aspect of exstrophy is that the malformation does not represent a step in normal development, unlike cloacal malformations, cleft lip and palate, hypospadias, etc. There is no "exstrophic" stage in normal development.

Figure 1	Figure 2	Figure 3
Boy with classic bladder exstrophy. The bladder plate is just caudal to the stump of the umbilical cord. The epispadic phallus is caudal to the bladder plate. Note the separation of the epispadic phallus and the scrotum. Often, the rectum is anterior. There can be moderate to significant symphyseal diastasis in this, the most common form of bladder exstrophy.	Classic cloacal exstrophy of the bladder, which demonstrates an oomphalocele (most cephalad). The bulging central area is the cecum, which is opened. The terminal small bowel is seen to the right of the cecal plate. The hindgut cannot be seen, but usually is located in the midline and caudal to the cecum. The bladder plates are two in number, and they are noted as superior to the cecal plate and on each side of the large oomphalocele. In this case, a male, the genetalia are completely bifid and cannot be visualized because of the overlying herniated bowel. This is the most severe form of exstrophy and is associated with a severe diastasis of the symphysis and flattening of the pelvis.	Female epispadias demonstrating a bifid clitoris and severely shortened urethra. This malformation is almost always associated with urinary incontinence.

These unique characteristics have led us to believe that the condition is not necessarily of genetic origin and may in fact represent an environmental or "single hit" phenomenon during development. This is supported by the fact that the overall frequency of exstrophy has not changed and cases seem to be clustered.

Another clinically interesting aspect of exstrophy is that, until very recently, most cases were diagnosed after birth and were a surprise to the parents and their physician. This created significant problems for all parties concerned. Physicians, who because of the rarity of the condition, often were unprepared and uncertain as to the diagnosis and acute management. Parents were very confused and anxious. Now with improved in utero ultrasound techniques, the detection of exstrophy antenatally is possible (occurs 50 to 75 percent of the time). The findings on ultrasound include no imaging of bladder filling on repeat attempts, observation of epispadias and a lower abdominal wall defect. Often there is difficulty with appropriate genital identification. Upon receiving such information, families often will go online for more information. Access to advanced information can help take away much of the emotional trauma at birth.

Definition

Exstrophy is a hernia. There is failure of anterior closure of the abdominal wall because of anterior migration of posterior structures. The major variable that results in the spectrum of the disorder is the timing of the "causative episode." If the episode occurs early, in the first four weeks of gestation, the cloaca of the developing embryo herniates anteriorly, resulting in classic cloacal exstrophy. If the herniation occurs in five to 10 weeks after fertilization, only bladder and urethra herniate, and genitalia fail to fuse, resulting in classic bladder exstrophy. If the episode occurs later, nine to 10 weeks' gestation, the result is epispadias, often with failure of the bladder neck to close anteriorly, but the bladder is intact. All patients with classic bladder exstrophy have an open bladder neck and an open urethra, seen open on the abdominal wall. (See Figure 1.) A potential explanation for the spinal and lower extremity malformation observed in cloacal exstrophy would be that the herniation occurs before the tail bud curls appropriately, resulting in abnormality of the spine (lipomeningocele and potential tethering of the cord) and limb bud deformation. In some series the potential for cord tethering is as high as 90 percent. It is interesting that although exstrophy patients can have significant anatomic problems, these patients seem to have superior intellect and tend to be high achievers.

Treatment history

Exstrophy has been recognized since early Roman times. Attempts at treatment 150 years ago resulted in one of the earliest urinary diversions, uretero-sigmoidostomy. This was performed in a young exstrophy patient and was used as the primary treatment for exstrophy for almost a century. Uretero-sigmoidostomy achieved reasonable urinary continence, but many patients had difficulty with chronic watery diarrhea and electrolyte resorption-acidosis. However, the significant increased risk of cancer in the sigmoid bowel led to the extinction of this form of diversion. Other forms of diversion, primarily ideal or colon conduits, became popular.

It was not until the 1960s that primary reconstruction of the bladder was attempted. However, these early attempts failed because of obstruction resulting in hydronephrosis and even renal failure in some patients. As a solution to this, a staged closure of exstrophy was championed by Dr. Robert Jeff, who did his early work at The Hospital for Sick Children in Toronto and then at The Johns Hopkins Hospital in Baltimore. With staging closure he was able to preserve renal function and achieve reasonable urinary continence. This repair achieved unparalleled results, but it required a minimum of three operations. It was the standard of care until recently. 

Current treatment

Over the past 20 years, techniques have been developed for complete primary repair of exstrophy (CPRE) in one procedure at birth. The basic concept is no different than applied in the 1960s except our technique focuses on achieving normal anatomy. In CPRE, not only is the bladder closed, but the bladder neck and proximal urethra and genitalia are reconstructed in one operation, and the urethra is moved posterior to    the pelvic diaphragm. The rationale behind the complete repair is that a better anatomic closure is accomplished because the bladder, bladder neck and urethra are treated as related anatomic structures (common blood supply, innervation and development). Repair of one aspect can be achieved successfully only with involvement of the other components of the lower urinary tract.

Why did the early attempts of primary complete repair fail? There was failure to completely resolve a pathologic anatomic defect. In the exstrophic patient the pelvic diaphragm is posterior to the urethral plate (which has migrated anteriorly). The urethra must be tabularized and moved posteriorly with deep incision into the pelvic diaphragm. This maneuver facilitates placement of the urethra within the diaphragm structure, which results in restoration of normal anatomy and permits proximal urethral function without obstruction.

The most significant factor, however, of a primary anatomic closure of the bladder is that we can achieve normal bladder emptying and filling. This is rarely possible with the staged approach and never with urinary diversion. Filling and emptying of the bladder (cycling) becomes the stimulus for bladder growth and development and, in fact, seems to facilitate a normalization of bladder structure. The exstrophic bladder is abnormal at birth because there is no cycling of the bladder, which is triggered by the production of urine, in utero. For example, with complete renal dysplasias (no urine production), the bladder and ureters remain anatomically present but are severely abnormal (hypoplastic). Studies have shown that the developing bladder undergoes significant histologic change during fetal development. This change seems to continue after birth. Many physicians suspect that this reflects the different physiologic needs of the in utero and postnatal environments. Throughout this process it seems that without the stimulus of filling and emptying, the natural progression of the develop-mental process stops. Hence, if the urine is diverted by surgery at birth, there is no potential for the bladder to change and ultimately function appropriately. Similarly, if the bladder is not closed in a manner that will permit regular filling and emptying, the potential for normal bladder development is significantly reduced. Therefore, present efforts focus on achieving anatomic reconstruction of the bladder as early as possible in an effort to achieve normal cycling. This voiding ultimately is the stimulus for normal bladder development and bladder healing. In our series of primary complete repairs, the fact that only 1 in 36 patients to this point has required bladder augmentation lends credence to this hypothesis (versus 23 to 70 percent in staged regions).

Future outlook

Prior to aggressive complete repairs at birth, a child born with classic bladder exstrophy would anticipate at least three major surgeries and usually many more. Continence rates of 40 to 80 percent are reported, but many of these children achieve dryness through augmentation of the bladder (23 percent) and use of intermittent catherization (50 to 70 percent).

Our recent complete repairs are showing about 80 percent complete continence with voiding without the need for catherization and without the need for bladder augmentation. Many of these children require only one major operation.

Unfortunately, long-term follow-up data used for present decisions in management of patients with exstrophy are based on treatments that now clearly are antiquated. For example, there are many centers that recommend termination of the exstrophic fetus based on these data. We emphatically disagree with this practice because the condition is surgically correctable. Exstrophy is a severe deformity, however, it is surgically very correctable and, furthermore, patients with exstrophy often are exceptional in every way–intelligent, motivated and attractive.

Michael Ernst Mitchell, MD, is a pediatric urologist and medical director of Urology at Children's Hospital  of Wisconsin. He also is a professor and chief of Pediatric Urology at the Medical College of Wisconsin and a member of Children's Specialty Group.

For more information Urology Clinic (414) 266-6420

To make an appointment Central Scheduling (414) 607-5280 local or (877) 607-5280 toll-free

 

To earn CME credit click here to open the quiz online or to download as a .pdf click here.

You may need Adobe Acrobat Reader to view an item on this page. Click here to download the reader for free.