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Background

Anorectal malformations include a wide spectrum of defects in the development of the lowest portion of the

intestinal and urogenital tracts. Many children with these malformations are said to have an imperforate anus

because they have no opening where the anus should be. Although the term may accurately describe a child's

outward appearance, it often belies the true complexity of the malformation beneath. When a malformation of

the anus is present, the muscles and nerves associated with the anus often have a similar degree of

malformation. The spine and urogenital tract may also be involved.

The position and nature of these malformations made repair difficult for early surgeons. The affected organs are

located deep in the pelvis and are not well visualized through abdominal incisions. Traditional surgical dictum

did not allow for division of the posterior midline because this division of the muscle was believed, somewhat

erroneously, to cause incontinence in the child. Therefore, surgeons approached these malformations using a

combined abdominal, sacral, and perineal approach, with limited visibility. Such approaches have put

continence, and surrounding genitourinary structures, at greater risk than simply cutting sphincter muscles

because of the difficulty of adequately visualizing the malformation through limited incisions. This principle

was central to the development of the surgical techniques currently used to repair these malformations.

In 1982, Peña et al reported the results of the use of a posterior sagittal surgical repair approach. [1] Peña et al

used the traditional approach with a sacral incision and made the incisions progressively larger in an attempt to

adequately visualize the anatomy. Eventually, the entire posterior sagittal plane was opened, affording a full

view of the complete malformation. This technique, referred to as posterior sagittal anorectoplasty (PSARP) or

posterior sagittal anorectovaginourethroplasty (PSARVUP), has led to a more complete understanding of the

anatomy of these children and of what is required to repair the malformations with optimal results.

After reconstructive surgery for the malformation, many children still experience effects in the form of urinary

or fecal incontinence. Despite optimal surgical management, no adequate repair for poorly developed muscles

or nerves has been developed. Bowel-management regimens can provide an excellent quality of life for these

children when primary continence is not achievable.

Pathophysiology

The embryogenesis of these malformations remains unclear. The rectum and anus are believed to develop from

the dorsal potion of the hindgut or cloacal cavity when lateral ingrowth of the mesenchyme forms the urorectal

septum in the midline. This septum separates the rectum and anal canal dorsally from the bladder and urethra.

The cloacal duct is a small communication between the 2 portions of the hindgut. Downgrowth of the urorectal

septum is believed to close this duct by 7 weeks' gestation. During this time, the ventral urogenital portion

acquires an external opening; the dorsal anal membrane opens later. The anus develops by a fusion of the anal

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tubercles and an external invagination, known as the proctodeum, which deepens toward the rectum but is

separated from it by the anal membrane. This separating membrane should disintegrate at 8 weeks' gestation.

Interference with anorectal structure development at varying stages leads to various anomalies, ranging from

anal stenosis, incomplete rupture of the anal membrane, or anal agenesis to complete failure of the upper

portion of the cloaca to descend and failure of the proctodeum to invaginate. Continued communication

between the urogenital tract and rectal portions of the cloacal plate causes rectourethral fistulas or

rectovestibular fistulas.

The external anal sphincter, derived from exterior mesoderm, is usually present but has varying degrees of

formation, ranging from robust muscle (perineal or vestibular fistula) to virtually no muscle (complex long–

common-channel cloaca, prostatic or bladder-neck fistula).

Epidemiology

Frequency

United States : Anorectal malformations occur in approximately 1 newborn per 5000 live births.

Mortality/Morbidity

Anorectal and urogenital malformations are rarely fatal, although some associated anomalies (cardiac, renal)

can be life threatening. Intestinal perforation or postoperative septic complications in a newborn with

imperforate anus can result in mortality or severe morbidity.

Morbidity generally arises from the following 2 sources:

Malformation-related morbidity

o Malformation-related morbidity relates to associated malformations of rectal motility, anorectal

innervation, and sphincteric musculature. The most common morbidity in this category is constipation.

Most children have mild malformations that commonly result in constipation for reasons that remain

unclear. If left untreated, chronic constipation results in rectal dilation, which worsens the constipation.

This becomes a vicious cycle, which, if untreated, results in fecal impaction and overflow

pseudoincontinence, also known as encopresis.

o The most severe forms of malformation-associated morbidity are fecal and urinary incontinence. Higher

malformations, such as long–common-channel cloacae and prostatic or bladder-neck fistulas, are

associated with poorer nerve and muscle formation, all of which increase the likelihood of fecal or urinary

incontinence. Malformations that directly involve urinary sphincteric mechanisms, and, specifically, any

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malformation in which the rectum or vagina joins the urinary tract at the bladder neck, often results in

either urinary incontinence or inability to completely void.

Surgery-related morbidity

o This can include standard complications such as line infections and pneumonia.

o Wound infections or anastomotic breakdowns can occur in any intestinal surgery.

o Children with imperforate anus are at greater risk for injury to surrounding pelvic organs because these

organs (such as vagina or urethra and seminal vesicles) are located immediately adjacent to the rectum,

and may also be involved in the malformation in some unsuspected way.

o During blind exploration in the pelvis, a dilated ureter can be mistaken for the rectum. Urethras can be

opened or transected, and prostates or seminal vesicals can be easily injured. Dissection of these delicate

structures can result in ischemia and possible stricture or complete stenosis.

Race : No known racial predilection has been reported.

Sex : No known sex predilection has been reported.

Age

Most children with an anorectal malformation are identified upon routine newborn physical examination.

Delayed presentation is often the result of incomplete initial examination. Newborn anorectal and urogenital

examination can be technically challenging and makes many practitioners uncomfortable.

Subtle malformations, such as those in some children with perineal fistula that may look normal to the casual

glance, may present months or years after birth when the child presents to a primary care provider for

constipation or urinary tract infection and appears to have a small perineal body upon physical examination.

Anorectal malformations in females with a normal-appearing anus who have absent vagina or persistent

urogenital sinus may go undiagnosed for years because of examiner reluctance to separate the labia during

physical examination. These malformations can be discovered upon evaluation for urinary tract infection or

primary amenorrhea.

History

Prenatal ultrasonography examination findings are often normal, although the polyhydramnios or

intraabdominal cysts may suggest imperforate anus with associated hydrocolpos or hydronephrosis.

Newborns with imperforate anus are usually identified upon the first physical examination. Malformations in

newborns that are missed upon initial examination are often discovered within 24 hours when the newborn is

observed to have distention and has failed to pass meconium and a more thorough examination is performed.

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Physical

During a thorough physical examination, attention should be focused on the abdomen, genitals, rectum, and

lower spine.[2] The umbilicus should be examined for the absence of an umbilical artery (2-vessel cord), which

may suggest an absent kidney. The abdomen should be palpated for masses, which may include a dilated

kidney, bladder, hydrocolpos, ectopic kidney, duplication, or other cystic structure.

In males, the testicles must be palpated in the scrotum. The perineum is then examined. Perineal fistulas are

diagnosed upon discovery of openings on the perineum, meconium or mucus in a small strip running up into the

scrotal median raphe, a perineal groove, or a bucket-handle malformation in the anal dimple skin. If no opening

is present, urine is obtained for study, and the child is observed for 24 hours.

In females, a perineal fistula can be directly identified as a small opening on the perineum. If none is present,

the labia are separated to search for a vestibular fistula. A fourchette fistula is a type of vestibular fistula that

straddles the spectrum of malformation between perineal and vestibular; it is characterized by wet mucosa of

the vestibule anteriorly and a dry anoderm posteriorly at the junction of the vestibule and perineum (see the

image below). PIC 1

Fourchette fistula. This malformation is somewhere halfway between perineal fistula and vestibular fistula. The

fistula has a wet vestibular mucosal lining on its anterior half, but the posterior half is dry perineal skin.

If no fistula is visible and only one opening between shortened labia is observed, the child has a cloaca (see

image below). PIC 2

Cloaca. This is the classic appearance of a girl with a cloacal malformation with a single perineal orifice. The

genitals appear quite short, which is a finding consistent with cloaca. If the child has a normal urethra and no

vestibular fistula, she may have imperforate anus without fistula. If she appears to have trisomy 21, the

likelihood increases that she does not have a fistula. Girls with normal urethra and no visible fistula are

observed for 24 hours to allow a perineal fistula to present before operation is required. This waiting period is

beneficial in differentiating between children with perineal fistula who may be effectively treated using only a

minimal anoplasty from those who require colostomy with further evaluation using distal colostography.

Examples of colostography findings are shown in the images below.

PIC 3 Distal colostogram, posteroanterior view. The initial phase of augmented-pressure distal colostography

aims to determine where the colostomy was placed in the colon and how much colon is available for pull-

through, without taking down the colostomy.

PIC 4 Distal colostogram, lateral view. This image shows the second phase of distal colostography, in which

the patient is placed in the lateral position. A radio-opaque marker is clearly visible in the lower right side of

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the image, marking the muscle complex on the skin. This image shows that the rectal pouch joins the urinary

tract at the level of the bulbar urethra, a relatively common malformation in boys.

The remainder of physical examination is focused associated malformations. Cardiovascular malformations

occur in 12-22% of patients. The most common lesions are tetralogy of Fallot and ventricular septal defects.

Transposition of the great arteries and hypoplastic left heart syndrome have been reported but are rare.

Many GI malformations have been described in association with imperforate anus. As many as 10% of patients

have tracheoesophageal abnormalities. Duodenal obstruction due to annular pancreas or duodenal atresia occurs

in a small percentage of patients. Malrotation with Ladd bands that causes obstruction has also been described.

Hirschsprung disease has been well described in association with imperforate anus, although the incidence of

this combined condition is unknown. Constipation is common.

The association of imperforate anus and vertebral anomalies has been recognized for many years. Patients with

high lesions have an increased risk of this association. Lumbosacral anomalies predominate and occur in

approximately one third of patients with imperforate anus.[3]

The frequency of spinal dysraphism (evaluated with ultrasonography or MRI) had been thought to increase with

the severity of the lesion, with higher malformations having greater frequency than lower malformations.

Several studies have disputed this and have even shown higher incidence of spinal malformations in children

with low malformations. The most common type of dysraphism is tethered spinal cord, which is present in as

many as 35% of patients. The normal spinal cord terminates between the first and second lumbar vertebral

bodies. In patients with a tethered spinal cord, the cord ends lower in the lumbar spine. Cord lipomas and

syringohydromyelia are also common. All lumbosacral spinal malformations negatively affect the child's

prognosis with respect to urinary and fecal incontinence.

Currarino described a triad of sacral defect, presacral mass, and imperforate anus. [4] All patients with an

anorectal malformation must be screened for these vertebral abnormalities in the newborn period using sacral

radiography and lumbosacral spinal ultrasonography. As many as one half of patients with anorectal

malformations have urologic abnormalities. Urinary anomalies are more common in patients with more

complex lesions. Improved imaging studies have provided the ability to document an increased range of

abnormalities. Mild hydronephrosis is the most common abnormal ultrasonography finding. Vesicoureteric

reflux is also a frequent finding, followed by renal agenesis and dysplasia. Cryptorchidism reportedly occurs in

3-19% of males.

Vaginal and uterine abnormalities are common. Bicornate uterus and uterus didelphys occur in 35% of female

patients with imperforate anus. A vaginal septum is the most common vaginal abnormality and is seen in as

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many as one half of girls born with a cloacal malformation. Vaginal duplication and agenesis have also been

reported. Vaginal agenesis may be associated with ipsilateral absent ovary and kidney.

Causes

Although the precise embryologic defect that causes anorectal malformations has not been determined, cloacal

membrane formation and subsequent breakdown into urogenital and anal openings should occur by 8 weeks'

gestation. Defects in the formation or shape of the posterior urorectal septum account for many of the described

abnormalities of imperforate anus. Müllerian ducts appear after this critical period; how they are incorporated

into this development is unclear.

No known risk factors predispose a person to have a child with imperforate anus, which should be clearly

emphasized to parents of affected children who may harbor feelings of guilt. A genetic linkage is sometimes

present. Most cases of imperforate anus are sporadic without a family history of the condition, but some

families have several children with malformations. Genetic studies are ongoing.

Laboratory Studies

CBC count, blood typing and screening, and serum electrolyte levels should be measured in all children

with imperforate anus who require operation.

Urinalysis should be performed to determine the presence of a rectourinary fistula in all cases in which

the diagnosis cannot be made based solely on the physical examination findings. If a child has a perineal

fistula, vestibular fistula, or a single perineal orifice, urinalysis is unnecessary. Urinalysis is required in all

other affected children.

Imaging Studies

Sacral radiography: Two views of the sacrum, posteroanterior and lateral, should be obtained to measure

sacral ratios and to look for sacral defects, hemivertebrae, and presacral masses. This should be

performed before surgery.

Abdominal ultrasonography: This study is specifically used to examine the genitourinary tract and to look

for any other masses. Hydronephrosis, hydrocolpos, presacral mass, abdominal mass, or any similar

finding can profoundly affect management. This study should be performed before surgery and must be

repeated after 72 hours because early ultrasonography findings may be insufficient to rule out

hydronephrosis due to vesicoureteral reflux.

Spinal ultrasonography or MRI: All children with any form of anorectal malformation, even those

considered minor, should undergo screening for spinal malformations. These lesions can be diagnosed

using ultrasonography prior to the ossification of the spine. Ultrasonography should be performed as early

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as possible but is not essential prior to a newborn surgical procedure. Due to ossification, the use of

ultrasound diminishes after 3-4 months of age, and by 6 months MRI is usually necessary. MRI may be

required any time an ultrasound is suggestive or nondiagnostic.

Lateral pelvic radiography at 24 hours: Children who could not be diagnosed based solely on physical

examination findings, traditionally underwent invertography, which consisted of holding the baby upside

down and using lateral radiography to observe the level of gas in the distal rectum. A similar, but more

humane, approach is to wait 24 hours after birth to observe for possible maximal pelvic pouch distension

and then to use cross-table lateral pelvic radiography with a radio-opaque marker on the anal dimple with

the child in the prone position and the hips slightly raised. If the pouch is observed within 1 cm of the

marker, some surgeons offer primary repair without colostomy. For pouches farther than 1 cm, colostomy

is performed. This 1-cm guideline has been validated only using radiographic measurements and is not

directly translatable for measurements made using ultrasonography. Currently, perineal ultrasonography

has no role in diagnosis.

Augmented-pressure distal colostography: This is the single most important diagnostic test used to clarify

the anatomy in all children with malformations who require colostomy. It is personally performed by the

colorectal surgeon in many centers. In a fluoroscopy suite, a balloon catheter is placed into the distal

stoma, and the balloon is inflated. The catheter is pulled back, and water-soluble contrast is injected by

hand. This pressure is required to overcome the pressure of the levator muscles and to allow the contrast

to flow into the lowest part of the colon and reveal any fistula. In patients with a fistula to the urinary

tract, the bladder often fills, and the study is continued to obtain as much information as is provided with

voiding cystourethrography. If no fistula is present, the distal pouch has a rounded appearance, and no

urinary extravasation is visible.

Voiding cystourethrography or micturating cystourethrography: These studies are not necessary if

comprehensive distal colostography is performed. They are not recommended for primary evaluation of

children with anorectal malformations because of poor sensitivity compared with that of distal

colostography.

MRI: All children who have sacral defects on plain radiographs should undergo spine ultrasonography to

rule out associated malformations, such as meningocele or meningomyelocele, teratoma, or mixed

lesions. If ultrasonography findings are suggestive or nondiagnostic, MRI should be performed. All

children who have suggestion of tethered cord on ultrasound, a nondiagnostic ultrasound, or have not had

an ultrasound and are older than 6 months should undergo MRI.

CT scanning: CT scanning presently plays no role in the routine evaluation of children with anorectal

malformations.

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Other Tests : Anorectal manometry: Although this study has no role in the newborn period, it may be used in

older children who suffer from varying degrees of incontinence. However, the findings are primarily of

academic interest.

Staging

Imperforate anus was historically classified based on the position of the distal-most aspect of the colon in

relation to the levator ani muscles. Malformations at or above the levator muscle complex were defined as high

anomalies. Infralevator lesions were termed low and were considered simpler and were associated with better

prognosis. This system was based on the now obsolete Wingspread classification.

Information obtained from the posterior sagittal approach has led to an anatomic classification that lists

malformations based on their specific anatomy. The following is a list of the most common malformations:

Perineal fistula

o This malformation is associated with good prognosis, occurs in either sex, and involves a closed anus

with a small connection opening on the perineal body.

o Some babies with this malformation have a small loop of skin at the anal opening that resembles a

bucket-handle. This is pathognomonic for perineal fistula.

o Some boys may have no visible perineal opening but may accumulate mucous or meconium in the fistula,

which can extend up the median raphe of the scrotum and resembles a black cord (meconium) or a string

of pearls (mucous).

o This malformation is amenable to primary neonatal pull-through.

o Healthy girls who have normal-sized anal openings and small-appearing perineal bodies do not have

perineal fistula. This is easily determined by measuring the size of the anus using Hegar dilators. The

anus of an average-term newborn should be approximately 12 mm but varies with the size of the child.

The "correct" size of the perineum is largely a matter of experience.

Vestibular fistula

o This malformation is associated with good prognosis and is easily diagnosed upon physical examination

based on the appearance of a small opening at the posterior aspect of the vestibule. The opening is

external to the hymen and is, therefore, not vaginal.

o The term vaginal fistula was commonly and incorrectly used to describe vestibular fistula. True solitary

congenital rectovaginal fistula is exceedingly rare.

o Vestibular fistula is safely treated with diverting colostomy, although some pediatric colorectal surgeons

repair this malformation primarily in the newborn period without using colostomy.

Cloaca

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o Persistent cloaca is a malformation in females that encompasses a spectrum of defects, including the

presence of a common channel that incorporates the urethra, vagina, and rectum.

o The length of the common channel correlates with complexity and prognosis. Shorter channels (< 3 cm)

have fewer associated malformations and carry a better prognosis. Longer channels have more complex

malformations and poorer prognosis.

o One half of all girls with this malformation have 2 hemivaginas and many have hydrocolpos.

o This malformation is easily diagnosed upon physical examination based on the presence of a solitary

perineal orifice. Females with this malformation often have very small-appearing labia.

o All children with cloacae should undergo colostomy shortly after birth.

Bulbar urethral fistula

o This malformation observed in boys is relatively common.

o No fistula is observed upon physical examination, and urinalysis often shows meconium.

o Colostomy is essential to relieve obstruction, prevent urinary soiling, and to allow for distal

colostography, which clarifies the malformation for definitive surgical repair.

Prostatic urethral fistula

o This malformation observed in boys is rarer than bulbar fistula and carries a poorer prognosis.

o The diagnosis and treatment algorithm are identical to those of bulbar fistula, although the surgical

procedures used differ.

Bladder-neck fistula

o This rare malformation observed in males (10% of all malformations in males) carries a very poor

prognosis.

o Most patients with bladder-neck fistula require bowel-management regimens.

o The diagnosis and treatment algorithm are identical to those of bulbar and prostatic fistulas, although the

surgical procedures used differ.

o This fistula is best approached abdominally.

Absent fistula

o This malformation can occur in either sex, is somewhat rare, and is associated with a good prognosis. It is

commonly associated with trisomy 21.

o Diagnosis is primarily by exclusion.

o Lateral pelvic radiography is performed in babies who have no external evidence of fistula, who pass no

meconium after 24 hours, and who have no meconium in the urine.

o If the pelvic rectal pouch is within 1 cm of the anal dimple, a primary pull-through may be performed. In

these instances, a fistula is unlikely but should be definitely excluded using the proper surgical technique.

o If the surgeon opts for colostomy, the absence of a fistula is confirmed using distal colostography.

Cloacal exstrophy

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o This extremely rare malformation can occur in either sex but is most common in boys. It encompasses a

spectrum that includes variant forms of covered exstrophy. The classic form is devastatingly complex.

o Affected children have an omphalocele and a large extrophied cloacal plate on their lower abdominal

wall. They have 2 hemibladders separated by an intestinal plate, often with prolapsed terminal ileum that

proceeds distally to include an extrophied urethral plate flanked by 2 hemiphallic or hemiclitoral

structures.

o All children with cloacal exstrophy have some degree of pubic symphysis diastasis and may have a spinal

malformation, most commonly myelocystocele.

o Thankfully, this complex malformation is rare but it has devastating implications on quality of life.

Medical Care

Newborns with imperforate anus should not be fed and should receive intravenous hydration. Life-threatening

comorbidities take precedence and must be treated first. If a urinary fistula is suspected, broad-spectrum

antibiotics can be administered, although anaerobic coverage is unnecessary within the first 48 hours of life.

Any cardiac murmurs identified upon physical examination should be evaluated using echocardiography prior

to surgical intervention. The remainder of treatment includes diagnostics and surgical evaluation and

management.

Surgical Care

The decision-making process aims to determine which children should undergo primary repair in the neonatal

period and which children require colostomy and definitive repair in a staged fashion. Children with anorectal

malformations may undergo one or several of the following surgical procedures based on the child's

presentation, physical examination findings, and imaging study findings.

Neonatal colostomy

o A colostomy is performed in children who are not amenable to primary pull-through either because of

malformation complexity (any urinary fistula in boys, vestibular fistula and cloaca in girls, no fistula in

either sex >1 cm from perineal skin) or associated comorbidity.

o The colostomy is usually fashioned through a left lower quadrant incision. The colon is divided at the

point where the descending colon meets the sigmoid colon, and both ends are brought to the abdominal

wall. By fashioning the colostomy at this location, the entire sigmoid colon is kept in place; thus, when

the pull-through is eventually performed, a large portion of the colon is available for the surgeon to bring

down to the perineal skin.

o The mucous fistula (the downstream segment) should be very small, flush with the skin, and far enough

from the proximal end to be outside the colostomy appliance (or under the flange) to avoid continued

urinary soiling with feces.

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o During this operation, the distal segment of the colon must be exhaustively irrigated to clean out the

impacted meconium, which is always significant. This prevents postdiversion urinary sepsis and allows

for effective distal colostography.

Primary neonatal pull-through without colostomy

o Many pediatric surgeons opt for primary pull-through in children with perineal fistulas (or no fistulas) and

close (< 1 cm) rectal pouches on 24-hour lateral pelvic radiography. Some pediatric surgeons who

specialize in colorectal problems often offer the same procedure for girls with vestibular fistulas.

o Cystoscopy is usually performed to rule out associated malformation. This is performed immediately

prior to the pull-through operation. A Foley catheter is inserted following the cystoscopy.

o The preferred surgical approach is the posterior sagittal approach developed by Peña et al.

The child is placed in the prone position with generous padding under the face and chest and a large

bolster under the hips to elevate the area of interest.

A muscle stimulator is used to show the precise position of the rectal muscle complex to enable exact

division at the midline. The midline for this operation is defined by the line that precisely divides the

muscle complex in half.

Dissection proceeds until the rectal pouch is identified. The pouch is then mobilized until adequate length

is obtained and the rectum is fully separated from its attachment to the genitourinary tract. Even if the

structures do not communicate, they remain intimately associated until fully mobilized. This step ensures

that the surgeon does not miss a fistula that was missed on urinalysis findings.

Once the rectum has been mobilized, the muscle stimulator is used to mark the anterior and posterior

limits of the muscle complex. The perineal body is then reconstructed, and the rectum is tacked down in

the middle of the muscle complex. The posterior wound is closed and anoplasty is performed.

Posterior sagittal pull-through with colostomy

o This approach is used in boys with rectourinary fistula (bulbar, prostatic, or bladder-neck fistula), in girls

with cloaca or vestibular fistula, and in patients of either sex who do not have a fistula when the rectal

pouch is further than 1 cm on 24-hour lateral prone abdominal radiography.

o The approach is also used in children who may have malformations that were amenable to primary

neonatal pull-through but were unable to undergo such a procedure because of extreme prematurity or

other comorbidity.

o Colostomy is performed after 24 hours (or immediately if one of the above diagnoses is made based on

either physical examination findings or meconium in the urine).

o Several weeks following colostomy, distal colostography is performed, and the specifics of the

malformation are clarified.

o Cystoscopy is usually performed to clarify anatomy and to rule out associated malformation. This is

performed immediately prior to the pull-through operation. A Foley catheter is inserted following the

cystoscopy, except in girls with cloaca.

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o The reconstructive procedure varies based on the malformation, but the essential concepts include

identifying and separating the rectum from other structures, dividing and ligating any fistulas, and fully

reconstructing the pelvic anatomy with placement of the rectum within the confines of the muscle

complex. Procedures for specific malformations are as follows:

Vestibular fistulas are directly visible but have the longest common wall between the rectum and vagina

and require significant delicate mobilization to avoid holes in either structure.

The posterior sagittal approach is used in boys with bulbar or prostatic urethral fistulas. The rectum is

isolated and opened, and the fistula is identified through progressive distal opening. Once the fistula is

identified, the rectum proximal to it may be mobilized, and the fistula is then ligated. Reconstruction then

proceeds with primary pull-through, as described above.

Abdominal (open or laparoscopic) and posterior sagittal approaches are best in boys with bladder-neck

fistulas because the fistula is best identified in the abdomen.

Cloaca procedures are complex. A short – common-channel cloaca can be repaired using total urogenital

mobilization. The posterior sagittal wound is opened into the cloaca, which is then further proximally

opened until the urethral orifice is identified and catheterized. The rectum is then sought. In girls with 2

hemivaginas (50%), the rectum opens in the vaginal septum, although significant asymmetry may be

present. After identification, the rectum is separated from the urogenital tract and completely mobilized.

The urogenital tract is then mobilized as a solitary structure until the urethral orifice reaches the

perineum. This is then reconstructed, and the muscle is marked to enable creation of an adequate vaginal

opening and perineal body without impinging on rectal space.

A long – common-channel cloaca repair often necessitates formal separation of the bladder and vagina,

which requires laparotomy and ureteral catheterization. Vaginal replacement is sometimes necessary if

the vaginal length is insufficient for reconstruction.

Colostomy closure: Once the wound has completely healed and postoperative dilations have achieved

their goal (ie, the neoanus is at the desired size), the colostomy may be closed in traditional surgical

fashion.

Consultations

Pediatric surgeon: Early consultation with a pediatric surgeon experienced with these anomalies is

essential. Ill-conceived procedures during the newborn period may have lifelong consequences for the

patient.

Neurosurgeon: Consultation with a neurosurgeon is warranted if a tethered spinal cord is present (25% of

all cases).

Urologist: The need for consultation with a urologist depends on the malformation and the individual

pediatric surgeon.

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Diet

After the obstruction is relieved using colostomy, primary pull-through, or dilation, children do not

require special diet.

The most common complication of imperforate anus repair is constipation or anal incontinence; therefore,

diet can be a crucial part of management. Many patients may require laxatives, enemas, or other

medications or irrigations in addition to dietary manipulations.[5] Children should avoid constipating

foods, such as those included in the bananas, rice, applesauce, and toast (BRAT) diet. High-fiber and

laxative foods (whole-grain foods and breads, dairy, fruits, vegetables, greasy foods, spicy foods) should

be encouraged. Unfortunately, dietary manipulation is often of limited effectiveness because of the fussy

nature of most children regarding diets. Fiber supplements and laxatives can be critically important in

avoiding constipation, which can significantly affect prognosis.

Activity

Children with anorectal malformations are often otherwise healthy.

Activity limitations are usually related only to the period around their surgical procedures.

Medication Summary

Many children with anorectal malformations require medications for various reasons. Beyond

perioperative medications, maintenance medications often include urinary antibiotic prophylaxis or

treatment and/or laxatives.

Urinary prophylaxis is used to mitigate the risk of urinary infection and urosepsis in children with risk

factors for urinary infection such as urinary fistula, vesicoureteral reflux, or continent diversion. Common

agents include oral amoxicillin, oral trimethoprim/sulfamethoxazole, and gentamicin bladder irrigations.

Comprehensive information on all these medications and others is available in the eMedicine pediatric

topic Urinary Tract Infection.

Common laxatives include senna products, milk of magnesia, and propylene glycol solutions (eg,

MiraLax, GlycoLax).

Further Inpatient Care

After initial colostomy, the child is able to eat and grow, and any other associated malformations may be

addressed. Most patients are discharged once their ostomy has started to function and they tolerate a

regular diet.

Following definitive repair, inpatient course is dictated by the presence or absence of a colostomy.

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o If a child has been diverted with a colostomy prior to definitive repair and the repair is effectively

completed using a posterior sagittal incision without laparotomy, the postoperative course is usually brief.

The child may eat after the anesthesia wears off and requires a short hospitalization with perioperative

antibiotic administration.

o Complicated repairs that require laparotomy also require more lengthy postoperative courses. These

children usually require several days before intestinal function returns and a diet may be resumed.

o Repairs made without a colostomy may be treated with a "medical colostomy," meaning the child is not

fed (ie, strict nothing-by-mouth [NPO] status) and a central line is placed for total parenteral nutrition.

After an arbitrary period (commonly 5, 7, or 10 d, determined at the discretion of the surgeon in

consideration of a host of factors), a diet is resumed and the total parenteral nutrition is stopped. The

central line is removed, and the child may then be discharged.

Following ostomy closure, the child usually remains in the hospital for 2-3 days until intestinal function

returns. Diet is then resumed, and the child may be discharged.

Further Outpatient Care

Children with an anorectal malformation require close follow-up for life. Continuity of care is essential in

the growing years and into adulthood, as the children deal with issues relating to continence and

constipation.

Following the initial colostomy, further investigations in preparation for definitive operation, such as

distal colostography or repeat renal ultrasonography, are performed in an outpatient setting.

Following definitive operation in either the neonatal period or after colostomy, follow-up is necessary 2

weeks after surgery. Parents are often instructed as to how to obtain a set of Hegar dilators, which they

are to bring to the first postoperative visit. At that visit, the surgeon measures the size of the anus and

instructs the parents how to perform the daily dilations. These dilations continue until the anus has

reached its goal size. At this time, the colostomy may be closed if one was performed.

Patients with cloacal anomalies need specialized follow-up care after puberty to assess sexual function

and to correct genitourinary problems.

o Some girls who have undergone surgical correction for cloaca have incompletely canalized fallopian

tubes and can develop painful cystic collections of menstrual blood following menarche. This condition

sometimes requires surgical intervention. A pediatric gynecologist can be extremely helpful for these girls

and can suppress menstrual blood production through exogenous hormone administration until a clear

treatment strategy is established.

o Only within the past 20-30 years have significant numbers of girls with cloaca undergone definitive

repair. A few have become pregnant. While this is miraculous, the delivery process should include close

involvement of the pediatric surgeon who performed the original repair, if possible. If this is not possible,

15

a surgeon experienced in cloaca repair should be consulted. Caesarean delivery is the only safe way to

avoid damage to tissues that originally required complex reconstruction.

Some children present with prolapse during the toilet-training years. Eliminating constipation as a cause

helps identify children who need surgical trimming of prolapsed mucosa.

Visits for constipation are frequent, and it is best treated with a regular preventative regimen that includes

diet, fiber, and laxatives for as long as they are needed. Dietary water does not influence stool quality in a

healthy child.

Inpatient & Outpatient Medications

Routine pain medications for surgical procedures are warranted. Acetaminophen (15 mg/kg every 4 h) or

morphine sulfate (0.05-0.1 mg/kg intravenously every 2-4 h) usually suffices.

The usual perioperative antibiotics include ampicillin (50 mg/kg every 6 h), gentamicin (2 mg/kg every 8-

12 h), and clindamycin (10 mg/kg every 8 h).

Many laxatives have been used to control constipation in these patients. Senna comes in various forms

and can be highly effective, although dosage must be individualized. The clinician must be personally

engaged and must establish an effective dose response for each patient on a case-by-case basis.

Balanced electrolyte solutions have been used for years as a bowel preparation for surgical procedures.

These solutions have only recently been made available in powdered form for mixing at home and for use

as a laxative (under the name MiraLax or GlycoLax). These nonstimulant laxatives are very palatable to

children because they dissolve in any beverage with minimal impact on taste.

In children who require urinary prophylaxis, standard medications include amoxicillin (first-line

medication in newborns), nitrofurantoin, and trimethoprim/sulfamethoxazole (not used in babies aged < 2

mo). To ascertain a prophylaxis dose for one of these antibiotics, calculate a treatment dose based on the

normal administration interval (2, 3, or 4 times per day) and then administer that same dose once per day.

For example, if the amoxicillin treatment dose is 20-50 mg/kg/d divided every 8 hours and a patient

weighs 10 kg, the normal dose may be 30 mg/kg/d (which falls within the recommended range). Because

the patient weighs 10 kg, the dose is 100 mg every 8 hours. The prophylaxis dose would then be a once-

daily dose of 100 mg.

Transfer

Proper consultation and surgical management are important. Transferring these patients to a facility that

provides pediatric surgical care aids in proper classification, diagnosis, and management. Optimal

resources for the care of these children includes a pediatric surgeon with experience in anorectal

malformations, a pediatric urologist, a pediatric anesthesiologist, a critical care specialist, and a

neonatologist.

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Complications

Pitfalls abound in the diagnosis and treatment of children with anorectal malformations. A logical

approach and an experienced eye are essential for starting the child down the right path from the outset.

Complications, while sometimes unavoidable, can have devastating ramifications with respect to a child's

chances for urinary and fecal continence.

The following are a few of the most common issues encountered at pediatric colorectal centers:

o Primary repair without colostomy: Although certain malformations can be primarily repaired by an

experienced pediatric surgeon in the neonatal period without the protection of colostomy, more complex

malformations should by treated with colostomy at the initial operation. Primary neonatal operations do

not afford the surgeon the benefit of distal colostography to help clarify anatomy. This has resulted in

devastating injuries that could have been avoided with a staged approach (colostomy, followed by

definitive operation, followed by colostomy closure) with appropriate diagnostic studies.

o Colostomy type and position: The ideal colostomy position in children with an anorectal malformation is

at the junction of the descending and sigmoid colon. The colostomy should be completely divided, with

the ends spaced far enough apart to ensure that the mucous fistula is not located within the ostomy

appliance. This prevents continued soiling of the urinary tract by feces, which can result in urinary

infection. Loop colostomies are never completely diverting and put a child at risk for urinary sepsis.

Transverse colostomies seem to be associated with a significant degree of mucous accumulation in the

long defunctionalized segment, resulting in chronic distension and dysmotility similar to that seen in

children with atresias. Desire to perform laparoscopic pull-through should not be a primary factor in the

decision to perform colostomy.[6]

o Intestinal perforation

This complication can arise during any phase of management.

In children diagnosed with imperforate anus at birth, 24 hours is allowed to pass prior to surgical

treatment if perineal fistula (or other visible malformation, eg, vestibular fistula or cloaca) is not evident

and urinalysis findings do not show meconium. This allows the distal colon to distend a bit, and

meconium occasionally leaks out on the perineum from a tiny perineal fistula. This waiting period is

advocated by the most experienced surgeons and should not increase the risk of perforation prior to repair

or colostomy. Although exceedingly rare, some children have perforated during this period.

Perforation has also occurred during anal dilations. Dilations should always be performed first by the

surgical staff. Dilation (performed instead of anoplasty) should be performed only by the surgical staff in

extremely low birthweight premature babies. Parents may be taught how to dilate larger babies but must

be closely supervised.

Perforation is minimized by appropriately positioning the colostomy while avoiding a transverse

colostomy.

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o Operative complications: Correction of malformations, even those that some surgeons may describe as

minor, requires significant experience, a keen eye, and a sensitive hand. Devastating complications (eg,

complete dehiscence, postoperative fistula, missed fistula, urologic injury, ischemia) can render a child

who may have been continent after a successful operation completely incontinent. Thus, these children

should be directed to a subspecialist with a special interest in this area at the earliest possible opportunity.

o Stenosis: This is a narrowing of the new anus. A tight ring of scar tissue forms instead of a soft and

stretchable anus. This is a devastating complication and usually requires complete surgical repair. A

regular schedule of slow progressive dilation of the neoanus prevents stenosis. Weekly dilations increase

risk of stenosis. If the dilations are spaced too far apart, the anus can narrow between the dilations. Large

dilations provoke tears. Tears heal with scar tissue, which causes stenosis.

o Undrained hydrocolpos

Many baby girls born with cloaca have a very large mucous-filled vagina. This may appear as a giant

cystic structure on prenatal ultrasonography. Ultrasonography should be performed at birth to look for

such a cystic mass. If present, it must be drained either from below (through the cloaca) or at the time of

colostomy using a vaginostomy tube. If it is left undrained, complications ensue.

Hydrocolpos can large enough to obstruct the ureters. Some children with undrained hydrocolpos have

undergone vesicostomy and ureterostomy, when simple drainage of the hydrocolpos would have sufficed.

Hydrocolpos can also become infected. If the vagina perforates, it usually scars and becomes unusable,

often necessitating vaginal replacement.

o Constipation

Many children who have undergone anorectal malformation repair develop constipation. This must be

prevented by strong parental counseling and diligence to ensure the child clears the rectum daily.

Constipation on its own is not a complication. The complication is not preventing the constipation

through close follow-up and parental counseling.

Once constipation develops, the distal colon can become dilated, which exacerbates the constipation

because the dilated bowel has poor motility. The end result is termed encopresis. Fecal impaction forms,

and liquid stool leaks around it constantly, leaving the child incontinent. This can be treated but is best

prevented.

Incontinence: Many children who have malformations associated with poor prognosis develop fecal or

urinary incontinence, even after a flawless operation without complication. While "the plumbing" may

seem to be a relatively simple matter of rearranging some tubes, continence is a complex state that

requires a delicate balance of nerves, anorectal and colonic motility, and sphincter muscles. Parents

should be given realistic expectations and should be made aware of all options, including bowel

management or continent diversion and intermittent catheterization, should incontinence occur.

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Prognosis

All patients who have an anorectal malformation with no significant life-threatening comorbidity should

survive. Therefore, prognosis is best determined based on the probability of primary fecal continence.

Continence, defined as voluntary bowel movements with minimal soiling, varies based on primary and

associated malformations. A tethered spinal cord or another spinal malformation, such as hemivertebrae

or spinal dysraphism, may significantly increase the risk of incontinence.

Surgical complications worsen the chances for primary continence, although this effect is difficult to

quantify. Reoperation significantly decreases the opportunity for primarily continence.

All children with a perineal fistula should be continent. Spinal malformations are exceedingly rare in this

group.

Approximately 90% of girls with a vestibular fistula have voluntary bowel movements.[7]

Approximately 80% of boys with a bulbar urethral fistula have voluntary bowel movements, whereas

66% of boys with prostatic urethral fistula have voluntary bowel movements. Only 15% of boys with

bladder-neck fistulas have voluntary bowel movements.[7]

Children with imperforate anus without fistula have a 76% chance of having voluntary bowel movements.[7]

The chance of fecal and urinary continence in girls with cloaca varies based on the length of the common

channel. Girls with a short common channel and no associated urological or spinal malformations can

have excellent results, with as many as 75% of girls developing voluntary bowel movements. Urinary or

fecal continence is very unlikely in girls with long–common-channel cloacae, sacral malformations, and a

tethered spinal cord.[7]

The best determination for future continence is observation of function. A child who constantly leaks

stool or urine constantly will probably not improve by school age and may benefit from early bowel

management or intermittent catheterization. If a child is able to hold urine, stool, or both, the best course

is to observe his or her function.

Regardless of what the child will be capable of in the future, cleanliness of urine and stool must be

established before a child enters a school peer group. No child should be allowed to suffer the stigma of

being the "smelly" child simply because their physician or parents were unable to accept the child's

incontinence or because they were not yet ready to proceed. Even in the worst cases, hope remains.

However, the decisions made must be practical and must allow the child to seamlessly fit in with their

peer groups.