Anorectal

SPINAL, SACRAL, AND VERTEBRAL

ANOMALIES

Malformations 1.
2.
Hemivertebrae,
Scoliosis,
3. Butterfly vertebrae,
4. Hemisacrum
Incidence 5. Tethered cord
6. Spinal lipomas,
The average incidence worldwide is 1 in 5000 7. Syringomyelia, and
live births 8. Myelomeningocele
The most common defect in females is
rectovestibular fistula, whereas the most The sacral ratio is a valuable prognostic tool.
common defect in males is rectourethral Patients with ratios less than 0.4 are
fistula. universally incontinent.
Imperforate anus without fistula occurs in 5% Ratios that approach 1.0 usually predict a good
of patients, but interestingly, half of them also prognosis.
have Down syndrome.

Embryology
The cloaca in the embryo is a cavity into
which opens the hindgut, tailgut, allantois, and
later, the mesonephric ducts.
The cloaca is first formed at around 21 days’
gestation; it is U shaped, with the allantois
lying anteriorly and the hindgut posteriorly.
The septum in the middle grows downward
and fuses with lateral folds (Rathke plicae)
until it joins the cloacal membrane.
The cloacal membrane breaks down at 7 GENITOURINARY ANOMALIES
weeks’ gestation, thereby creating two
openings: the urogenital and anal openings. 1. Vesicoureteric reflux
2. Renal agenesis and dysplasia
3. Cryptorchidism
Associated Malformations 4. Hypospadias

Higher abnormalities are associated with more GYNECOLOGIC ANOMALIES

malformations.
Hydrocolpos can lead to urinary obstruction or
CARDIOVASCULAR ANOMALIES can cause pyocolpos.
Cardiovascular anomalies in approximately Mullerian anomalies may become manifest
1/3rd of patients. later when teenagers have obstruction of
The most common lesions are ASD and PDA, menstrual flow.
followed by tetralogy of Fallot and VSD. Obstruction of the tube, atresia of the cervix,
Transposition of the great vessels and or a blind hemivagina.
hypoplastic left heart syndrome are rare. Uterine malformations (predominantly
bicornuate uterus and uterus didelphys),
GASTROINTESTINAL ANOMALIES vaginal abnormalities (particularly a vaginal
1. Tracheoesophageal septum), and associated vaginal atresia.
2. Duodenal obstruction
3. Hirschsprung disease
Anorectal Anatomy and point that if left untreated, megasigmoid
develops.
Pathophysiology In extreme cases, fecal impaction and
SPHINCTER MECHANISM encopresis, or overflow pseudoincontinence,
may develop.
The muscle groups of the sphincter Children with anorectal malformations who
mechanism form a funnel like structure in the have lost their rectosigmoid suffer from the
pelvis. These muscles are innervated by the opposite problem (i.e., tendency to have
pudendal nerve, both motor to the voluntary diarrhea).
muscles and sensory to the skin around the Classification
anus and anal canal. They are derived from the
sacral plexus roots S2 to S4, as well as the
autonomic nervous system via the nervi
erigentes, from the same segments of the
spinal cord.
Electrical stimulation of the upper end of the
levator group pulls the rectum forward.
Stimulation of the muscle complex (vertical
fibers) elevates the anus, and stimulation of
the parasagittal fibers closes the anus. Clinical Findings and Initial
SENSATION AND PROPRIOCEPTION Management
Under normal circumstances, the anal canal is
an exquisitely sensitive area. It allows the
individual to discriminate solids, liquids, and
gas.
Children with ARM lack this anal canal
sensation.
There is, however, proprioception, which is
described as a vague feeling that is perceived
when the rectum is distended, simultaneous
with stretching of the voluntary muscle that
surrounds the rectum.
Must perform a thorough perineal inspection.
COLONIC AND RECTOSIGMOID It is important to not make a decision before
MOTILITY 20 to 24 hours of age.
Significant intraluminal pressure is required
Normally it takes between 3 and 6 hours for for meconium to be forced through a fistula,
the gastric contents to reach the small bowel. which is the most valuable sign of the location
The intestinal contents reach the cecum in a of distal rectum.
liquid state. It then takes about 20 to 24 hours During the first 24 hours, the newborn should
for that fecal material to reach the rectum and receive intravenous fluids, antibiotics, and
become formed stool with the absorption of nasogastric decompression to prevent
water that occurs in the colon. aspiration
The anal canal (below the pectinate line) is An echocardiogram can be performed and
usually empty because of the action of the baby should be checked for the presence of
surrounding sphincteric mechanism. esophageal atresia.
Children with anorectal malformations have a A plain radiograph of the lumbar spine and
spectrum of rectosigmoid motility disorders. sacrum should be taken to evaluate for
Constipation, one of the most important hemivertebrae and sacral anomalies.
functional sequelae, is probably the result of A spinal ultrasound helps screen for tethered
hypomotility of the rectosigmoid, which is cord and other spinal problems.
self-perpetuating and self-aggravating to the
Ultrasonography of the abdomen evaluates
for the presence of hydronephrosis.
After 24 hours, if no meconium is seen on the
perineum or in the urine, a cross-table lateral
x-ray film with the baby in prone position
should be obtained.

Endoscopy is best done outside of the newborn

period when the baby is larger and the
perineum is less swollen, to determine the
anatomy, particularly the length of the
common channel, which helps with surgical
planning.
Keep patients of primary repair with nothing
by mouth, on parenteral nutrition, for 7 days to
decrease the passage of stool.
An ultrasound is an excellent screening
examination to evaluate for associated spinal
anomalies such as myelomeningocele or a
tethered cord but it must be performed before
sacral ossification, which occurs at 3 months
If the gas in the rectum is located below the of age.
coccyx, a posterior sagittal operation without a
protective colostomy can be considered. MANAGEMENT AFTER COLOSTOMY
If rectal gas is seen above the coccyx, a
colostomy is recommended. Before proceeding with definitive
Performing the definitive repair at 2 to 3 reconstruction, the anatomy of the anorectal
months of age has important advantages for malformation is delineated by high-pressure
the patient including; distal colostography.
1. Less time with an abdominal stoma,
2. Less size discrepancy between the
proximal and distal bowel at the time Anorectal Reconstruction
of colostomy closure,
3. Easier anal dilation, and All defects can be repaired using a posterior
4. No recognizable psychologic sequelae sagittal approach.
from painful perineal maneuvers. Approximately 10% of male patients (those
with a rectum bladder neck fistula) and about
In Colostomy, enough redundant, distal 40% of female patients with a cloaca may, in
rectosigmoid must be left to allow for the pull- addition, require an abdominal approach for
through and even a vaginal replacement if that mobilization of a high rectum or vagina.
is necessary. Cloaca
Before undertaking repair of a cloaca, the
Rarely, some patients with cloaca are unable surgeon should perform an endoscopy with the
to empty their bladder because the common specific purpose of determining the length of
channel is almost atretic. In such rare the common channel. A contrast study of each
circumstances, the baby may require a of the three systems is valuable and can be
vesicostomy. done in three dimensions.
There are two well-characterized groups of
patients with a cloaca.
Cloacas with a Common Channel Shorter
than 3 cm
A maneuver called total urogenital
mobilization is used.
Cloacas with a Common Channel Longer
than 3 cm
Vaginal Switch Maneuver

A specific group of patients are born with Colon:

hydrocolpos and two hemivaginas. The
hemivaginas are large and the two hemiuteri Ideal substitute to replace the vagina.
are separated, the distance between them being The left colon or sigmoid work well because
longer than the vertical length of both their arcades reach the perineum nicely.
hemivaginas. In these cases it is ideal to However, sometimes the location of the
perform a maneuver called a “vaginal switch” colostomy interferes with this type of
reconstruction.

Vaginal Replacement

In a patient with a small vagina(s) or in the Small Bowel

rare case of an absent vagina, a vaginal
replacement is required. When the colon is not available.
When the patient has internal genitalia or an The mesentery of the small bowel is longest in
upper blind vagina, the upper part of the bowel an area located approximately 15 cm proximal
used for replacement should be sutured to the to the ileocecal valve, which is the best portion
vaginal cuff. When the patient has no internal of the small bowel for vaginal replacement.
genitalia (no vagina and no uterus), a vagina is
created and left with its upper portion blind
and used only for sexual purposes. GENERAL PRINCIPLES OF
Rectum: POSTOPERATIVE
This form of vaginal replacement is feasible CARE
only in patients who have a good size rectum
that is large enough to be able to divide it In the absence of a laparotomy, oral feedings
transversely or longitudinally into a portion may begin when the child is awake.
with its own blood supply that will form a new Antibiotics are given for 48 hours. In males
vagina and another portion with enough who had a rectourethral fistula, the urinary
circumference to reconstruct an adequately catheter should be left in place for 7 days. In
sized rectum. patients who have undergone cloaca repair, the
urethral catheter is left in place for 2 to 3 An anal dilatation program is recommended to
weeks until the urethral orifice is visible. avoid strictures.
A dilatation program is begun 2 weeks after Difficult anal dilatations usually reflect a
surgery. The anus is calibrated, and a dilator major problem related to ischemia or tension
that fits snugly is initially used to dilate the that will result in a long narrow stricture or
anus twice a day. Every week, the size of the even acquired atresia.
dilator is increased by one unit until the Rectal mucosal prolapse
desired size is reached. 1. tacking of the posterior rectal wall to
the posterior edge of the muscle
complex,
2. tapering a dilated rectum if necessary,
and
3. performing the anoplasty under slight
tension so that after the sutures of the
anoplasty are cut, the rectum retracts
Dilatations must continue after closure. Once slightly with no mucosa being visible.
the dilator can be inserted easily, the schedule Mucosal prolapse is managed by full-thickness
is reduced to once a day for 1 month, twice a trimming and is performed when prolapse
week for 1 month, once a week for 1 month, causes excess mucus production or ulceration
and then once a week for 3 months. or interferes with anal sensation.
After the colostomy is closed, the patient may Urethral, ureteral, vas deferens, and seminal
have multiple bowel movements and perineal vesicle injuries can occur.
excoriation may develop. Postoperative neurogenic bladder in male.
A constipating diet may be helpful in the
treatment of this problem. Constipation is the most common sequela.
After 3 to 6 months, a more regular bowel The lower the malformation, the more likely
movement pattern develops patient who has the development of constipation.
one to three bowel movements per day A vicious cycle ensues with megarectosigmoid
remains clean between bowel movements and leading to more constipation. Constipation that
shows evidence of a feeling of pushing during is not properly managed will lead to more
bowel movements. This type of patient has a megarectosigmoid, resulting in overflow
good bowel movement pattern, generally has a pseudoincontinence.
good prognosis, and is trainable. Patients appear to be incontinent, but if their
constipation is managed appropriately, they
become continent. Such patients sometimes
Outcomes benefit from sigmoid resection to reduce their
COMPLICATIONS laxative requirement.

Wound infection and retraction are known to CONTINENCE

occur.
If not accompanied by dehiscence of the Long-term follow-up of our series suggests
structures pulled through, and is promptly that good bowel control is achieved in about
treated, it is likely that no functional sequelae 75% of patients.
will result. Patients with low anomalies have done
Infection accompanied by dehiscence may extremely well; those with high lesions and
reach catastrophic proportions and leave those with associated spinal or sacral problems
sequelae that include incontinence, strictures, have done less well.
acquired atresias, recurrent fistulas, and severe The majority can have voluntary bowel
pelvic fibrosis. movements, sometimes with the help of
Infections and dehiscence have occurred laxatives.
mainly in patients operated on primarily, For the others, we implement a bowel
without a colostomy. management program that uses enemas to
Main contributing factors are fecal ensure adequate emptying for a 24-hour period
contamination, ischemia, and suture line of cleanliness. With the rational administration
tension.
of bowel irrigation, diet, and drugs, most
patients, including those with inherent fecal
incontinence, are able to remain clean for 24
hours.
Patients suffering from fecal incontinence are
evaluated and classified into those with
constipation or those with increased motility
(tendency to have diarrhea).
In the first group the saline enema must be of
large volume, with additives (e.g., glycerin,
soap, phosphate) to help empty the colon. This
program takes advantage of the decreased
bowel motility in constipated patients; they
remain clean for the next 24 hours. No
laxatives or diets are given as part of this
protocol.
The second group (patients who suffer from
increased bowel motility because of loss of the
rectal reservoir) require a constipating diet
medication to decrease bowel motility, and a
smaller daily saline enema.
The treatment is adjusted by trial and error
over a period of 1 week, with 95% of patients
remaining clean.
When the patient reaches the age of 7 to 12
years or sometimes younger, more
independence is usually desirable.
At that point, creation of a continent
appendicostomy (Malone procedure) is
beneficial.

Some patients benefit from an enema program

early on, but if they have potential for bowel
control, when they are a little older, a laxative
trial can be used to help their colon empty,
with careful radiologic monitoring. This may
allow them to demonstrate the capacity for
voluntary bowel movement and thus eliminate
the need for enemas.