Exstrophy and Epispadias—Modern Staged Approach



Exstrophy and Epispadias—Modern Staged Approach


EZEKIEL E. YOUNG

JOHN P. GEARHART

BRIAN M. INOYUYE



Bladder exstrophy is a rare, severe congenital defect that affects the lower urinary tract, genitalia, abdominal wall, and pelvis. The reported incidence ranges from 1:10,000 to 1:50,000 live births, with boys being affected 5 to 6 times more frequently than girls (1). Bladder exstrophy is usually an isolated defect, and in its classic form, associated chromosomal abnormalities or defects of the central nervous system, heart, and digestive tract are extremely uncommon.

Until the middle of the 19th century, bladder exstrophy was treated primarily nonsurgically. Early forms of repair focused on abdominal wall closure using skin flaps for partial reconstruction, leaving a fistula to attach a urinal for dryness. Trendelenburg recognized that pubic reapproximation would not only prevent prolapse of the reconstructed bladder but also be crucial to achieve continence. Although his theoretical assumptions were correct, his surgical efforts were not successful (2). Early failures led to an abandonment of interest in primary closure with a shift toward urinary diversion. In 1942, Hugh Hampton Young performed the first successful primary closure of a female exstrophy patient (3). Although similar reports about continent, primary closures were published in the same era, the numbers were small and most surgeons were not able to reproduce these favorable results. Both Jeffs (4) and Cendron (5) published their descriptions of successful staged anatomic reconstruction in the mid-1970s, and their pioneering work set the standard for the modern staged repair of exstrophy (MSRE). Grady and Mitchell (6) subsequently developed the complete primary repair of exstrophy (CPRE), in which the primary closure is combined with epispadias repair by complete penile disassembly, often resulting in a hypospadias position of the urethral meatus (7).

While older techniques have evolved and alternative approaches have been developed, the primary objectives of modern exstrophy management remain consistent:



  • Secure closure of the abdominal wall, pelvis, bladder, and urethra.


  • Reconstruction of a functional and cosmetically acceptable penis in the male and external genitalia in the female.


  • Urinary continence, preferably via urethral voiding, with preservation of renal function.

The complex embryology and genetics of exstrophy are not well understood. A number of theories have been proposed, which include premature rupture of the cloacal membrane, arrested mesenchymal ingrowth, and failure of cranial yolk sac progression during development (1). In its classic form, bladder exstrophy describes the condition in which an exteriorized bladder template develops in association with a diastasis of the pubic symphysis. This pubic separation results in characteristic genital and pelvic abnormalities. The pubic diastasis is found in association with foreshortened, externally rotated anterior pubic rami and a wide pelvic inlet. The perineum is short and broad and there is anterior displacement of the anus. The appearance of the genitalia varies by gender. In boys, the urethra lies in an epispadiac position, splayed open on the dorsal surface of the corporal bodies. The pubic diastasis results in corporal shortening and severe dorsal chordee. The testes are usually descended, but inguinal hernias are extremely common, especially in boys. In girls, the pubic diastasis results in an absence of a mons pubis, with a bifid clitoris and lateral displacement of the labia. Girls usually present with a bifid clitoris and a shortened vagina, often with a stenotic orifice. In isolated epispadias, which can be viewed as the least severe form of exstrophy, the bladder is closed and covered by a normal abdominal wall, but the pubic separation and genital abnormalities persist. Degrees of epispadias vary in a manner analogous to hypospadias from the very proximal “complete” epispadias in which the urethra is open through the bladder neck, to minor distal variants. A number of other exstrophy variants have been described (8).




INDICATIONS FOR SURGERY

Historically, some children with bladder exstrophy have survived without surgical reconstruction. As mentioned previously, the earliest attempts at treatment focused on providing
a suitable drainage apparatus that would help to manage chronic wetness and odor. The importance of treating this condition, however, can be inferred from several studies that have investigated the profound negative impact of urinary incontinence and sexual dysfunction on quality of life and social and psychological well-being (10,11). Furthermore, it is known that chronic exposure of the exposed bladder mucosa to the environment results in painful ulceration and metaplastic and ultimately neoplastic changes (12). It seems reasonable to conclude that all children with exstrophy should receive appropriate surgical reconstruction, regardless of their economic circumstances.


ALTERNATIVE THERAPY


Urinary Diversion

Historically, a number of different urinary diversion techniques have been successfully used in the management of exstrophy (13). Although incontinent conduits are rarely indicated in contemporary pediatric practice, reconstructive urologists should be comfortable employing them in very select circumstances. Ureterosigmoidostomy was the first successful continent diversion performed for exstrophy, and such patients have demonstrated very good rates of continence without the need for intermittent catheterization (14). The role of ureterosigmoidostomy has decreased with the application of anatomic reconstructions, but it is still used in some centers today. The Mainz II pouch is a modification of the ureterosigmoidostomy that reconfigures the sigmoid into a theoretically lower pressure reservoir, thereby promoting continence and renal preservation (13). Long-term concerns for malignancy at the ureterocolonic anastomosis and renal deterioration necessitate ongoing postoperative surveillance. Urinary diversion remains an important salvage approach in children who fail anatomic reconstruction.


Anatomic Reconstruction

MSRE will be described in detail as performed at Johns Hopkins. Alternate anatomic reconstructions have been proposed and are used in some centers. As is fully described in a separate chapter, Grady and Mitchell (6) developed the one-stage closure in the newborn period, combining primary closure of the bladder, urethra, abdomen, and pelvis with epispadias repair by penile disassembly. Proponents of CPRE believe that this approach will promote bladder growth and better continence outcomes by initiation of bladder cycling early on (6). Schrott (15) describes bladder closure, ureteral reimplantation, epispadias repair, and bladder neck reconstruction in the newborn period, applying the same technique to even older children without osteotomies. Primary newborn exstrophy closure followed by subsequent combined bladder neck reconstruction and epispadias repair has been described by Baka-Jakubiak (16). The combination of bladder closure with modified Cantwell-Ransley epispadias repair has been reported in a series of delayed and secondary exstrophy closures (17).


SURGICAL TECHNIQUE


Preoperative Considerations

A type and screen with baseline complete blood count and coagulation studies should be obtained. A plain film of the pelvis allows for precise measurement of the pubic diastasis. A baseline renal/bladder ultrasound is recommended to establish the presence of both units and for purposes of later comparison. Three-dimensional magnetic resonance imaging is obtained in all of our patients preoperatively but remains investigational. The umbilical cord should be ligated with a heavy silk suture. If a plastic cord clamp was used initially, this should be changed in order to prevent it from irritating the bladder mucosa. Likewise, the bladder template should be kept moist with periodic saline irrigation and covered with either a hydrated gel or Saran-type dressing. Petroleum-based gauze dressings are discouraged as they may dry and denude the mucosa when removed. Latex precautions are recommended, as many of these children will develop latex sensitivity or allergy later in life.


Timing and Staging

Modern staged closure has defined strict criteria for the selection of patients suitable for this approach. The technique includes early bladder, posterior urethral, and abdominal wall closure, usually with pelvic osteotomy in the newborn period, subsequently followed by an early epispadias repair at 6 months of age after intramuscular testosterone stimulation. Around age 4 to 5 years, a competent bladder neck is reconstructed along with bilateral ureteral reimplantation, when adequate bladder capacity is reached and the child demonstrates the maturity necessary to participate in a postoperative voiding program (18).

Successful initial bladder and posterior urethral closure is the most important factor for achieving eventual urinary continence and sufficient bladder capacity. The primary objective in initial, functional closure is to convert the bladder exstrophy into an incontinent penile shaft epispadias, balancing posterior outlet resistance in order to preserve renal function while stimulating bladder growth. The size and the functional capacity of the detrusor muscle are ultimately the most important determinants of success (19). In the presence of a small, fibrotic bladder template without elasticity or contractility, the operation should be deferred until adequate template growth has taken place. If sufficient size is not reached 4 to 6 months after birth, alternative options should be considered. Inguinal hernia repairs should be considered early if the closure is delayed in order to guard against incarceration during this time interval.

The role of pelvic osteotomy performed at time of initial closure ensures a tension-free approximation of the bladder, posterior urethra, and abdominal wall, and placement of the urethra deep within the pelvic ring, enhancing bladder outlet resistance, and aligning the large pelvic floor muscles to support the bladder neck. Usually, osteotomies are not needed in the patient <72 hours old with malleable pubic bones that are easily brought together in the midline by medial rotation of the greater trochanters. However, if the pubic bones are
>4 cm apart or unable to be reapproximated without tension under anesthesia, osteotomies are mandated to ensure a secure closure.


Osteotomy

The bilateral anterior innominate and vertical iliac osteotomy has been used in our institution because it has numerous advantages over the posterior approach. The patient is placed in a supine position, preparing and draping the lower body below the costal margins and placing soft absorbent gauze over the exposed bladder. The pelvis is exposed from the inferior wings inferiorly and the pectineal tubercle posteriorly to the sacroiliac joints. The periosteum and sciatic notch are carefully elevated and a Gigli saw is used to create a transverse innominate osteotomy exiting anteriorly at a point halfway between the anterosuperior and the anteroinferior spines (Fig. 100.1). This osteotomy is created at a slightly more cranial level than that described for a Salter osteotomy to allow placement of external fixator pins in the distal segments. Also, the posterior ileum may be incised from the anterior approach in an effort to correct the deformity more completely. This is important because anatomic studies have shown that the posterior portion of the pelvis is also externally rotated in patients with exstrophy, and as patients age, they lose the elasticity of their sacroiliac ligaments. An osteotome is used to create a closing wedge osteotomy vertically and just lateral to the sacroiliac joint. The posterior iliac cortex is kept intact and used as a hinge. Two fixator pins are placed in the inferior osteotomized segment and two pins are placed in the wing of the ilium superiorly. Radiographs are obtained to confirm pin placement, soft tissues are closed, and the urologic procedure is performed. At the conclusion of the exstrophy closure, external fixators are applied between the pins to hold the pelvis in a correct position.

Radiographs are taken 7 to 10 days postoperatively. If the diastasis has not been completely reduced, the right and left sides can be gradually approximated using the fixator bars over several days. Light longitudinal Buck skin traction is used to keep the legs still. The patient remains supine in traction for approximately 4 weeks to prevent dislodgement of tubes and destabilization of the pelvis. The external fixator is kept on for approximately 6 weeks, until adequate callus is seen at the site of osteotomy. The pins are removed under light sedation at the bedside. Postoperatively, newborns undergoing closure without osteotomy are immobilized in modified Bryant traction for 4 weeks with the hips in 90 degrees of flexion.






FIGURE 100.1 Combined transverse anterior innominate and anterior vertical iliac osteotomies with pin placement and preservation of the posterior periosteum and cortex. (Drawings by Timothy Phelps after Leon Schlossberg. Copyright © 2013 Brady Urological Institute, with permission.)

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Apr 24, 2020 | Posted by in UROLOGY | Comments Off on Exstrophy and Epispadias—Modern Staged Approach
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