Anorectal malformations.pptx

Anorectal malformations
Pushpa Lal
Bhadel

Introduction
 Birth defects in which the anus and rectum don’t develop properly.
 More frequent congenital anomalies encountered in pediatric
surgery.
 Incidence : 1 in 4000 live births
 Male > female

Introduction
 In female: Rectovestibular fistula is the most common
 In male: Rectourethral fistula is the most common
 Imperforate anus without fistula: 5%
 Estimated risk of 2nd child being affected is 1.4%
 Risk increases to 3% if first child is born with perineal or vestibular
fistula

Introduction
 Most female have low or intermediate anorectal malformations
while the reverse is true for males.
 Female babies usually have a fistula from the terminal end of the
bowel opening externally
 While in male this fistula is usually well hidden.

Embryology
The hindgut gives rise to:
distal third of transverse
colon, the descending colon,
the sigmoid, the rectum and
upper part of anal canal

Embryology
 Hindgut enters the posterior
portion of cloaca, the future
anorectal canal; the allantois
enters the anterior portion, the
future urogenital sinus.
 The urorectal septum is formed
by merging of the mesoderm
covering the allantois and the
yolk sac.

Embryology
 As caudal folding of the embryo
continues, the urorectal septum
moves closer to the cloacal
membrane.

Embryology
 Breakdown of the cloacal
membrane creates an opening for
the hindgut and one for the
urogenital sinus.
 The tip of the urorectal septum
forms the perineal body.

Embryology
 Anorectal malformations may be caused by abnormalities in
formation of cloaca and/or urorectal septum.
 For example, if the cloaca is too small or urorectal septum does not
extend far enough caudally, the opening of hindgut shifts to
anteriorly leading to the opening in urethra or vagina.
 Imperforate anus occurs when cloacal membrane fails to breakdown.

Classification
 Wingspread classification
 Pena’s classification
 Krickenbeck classification
 Anatomical classification

Classification
Wingspread classification (1984)

Classification
Pena’s classification

Classification
Krickenbeck classification

Classification
Anatomical classification

Rectoperineal fistula
 Traditionally was known as a “low
defect.”
 The rectum is located within most
of the sphincter mechanism.
 Only the lowest part of the rectum
is anteriorly mislocated .

Sometimes, the fistula does not open into the perineum but
rather follows a subepithelial midline tract, opening
somewhere along the midline perineal raphe, scrotum, or
even at the base of the penis.
Diagnosis established by perineal inspection
No further investigations required.

 The terms covered anus, anal membrane, anteriorly mislocated anus,
and bucket-handle malformations all refer to perineal fistulas.

Rectourethral fistula
 Imperforate anus with a rectourethral fistula is most common defect in boys.
 The fistula may be located at
o The lower (bulbar) part of the urethra
• Lower urethral fistulas are usually associated with good-quality
muscles, a well-developed sacrum, a prominent midline groove, and a
prominent anal dimple.
o The higher (prostatic) part of the urethra
• Higher urethral fistulas are more frequently associated with poor-quality
muscles, an abnormally developed sacrum, a flat perineum.

Recto-bladder neck fistula
 Rectum opens into the bladder neck
 Levator muscle, muscle complex, and parasagittal fibers are poorly
developed
 Sacrum is often deformed or absent
 Entire pelvis is underdeveloped
 Prognosis for bowel function is poor

Recto-bladder neck fistula
 The perineum is often flat,
which is evidence of poor
muscle development.
 About 10% of males with
anorectal atresia fall into this
category.

Imperforate anus without fistula
 Have a well-developed sacrum and good muscles and have
a good prognosis in terms of bowel function.
 The rectum usually terminates approximately 2 cm from the
perineal skin.
 Common in patients with Down syndrome.

Rectal atresia
 Occur in 1 % of case
 Born with normal appearing anal canal
 Often discovered during an attempt to take rectal temperature
 ~2 cm from the anal verge, there is an atretic or stenotic area
 The sacrum is normal, the sphincter mechanism is excellent
 Prognosis is good.

Rectal atresia
 These two structures may be
separated by a thin membrane or
by dense fibrous tissue.

 From the therapeutic and prognostic viewpoint, this common defect
is equivalent to the perineal fistula described in the male patient.
 The rectum is well positioned within the sphincter mechanism, except
for its lower portion, which is anteriorly located
 The rectum and vagina are well separated.

Rectovestibular fistula
 Rectovestibular fistula is the most common defect in girls and has
an excellent functional prognosis.
 The diagnosis is based on clinical examination.
 Meticulous examination of neonatal genitalia allows clinician to
observe normal urethral meatus and a normal vagina, with a third
hole in the vestibule which is the recto vestibular fistula

Imperforate anus without fistula
 This defect in female patients
carries the same therapeutic and
prognostic implications as
described for male patients.

Persistent cloaca
 A cloaca is defined as a defect in which the rectum, vagina,
and urinary tract meet and fuse, creating a single common
channel.
 This group of defects represents the extreme in the
spectrum of complexity of female malformations.

Persistent cloaca
 The diagnosis of persistent cloaca is a clinical one.
 This defect should be suspected in a female born with
imperforate anus and small-looking genitalia.
 Careful separation of the labia discloses a single perineal
orifice.

Persistent cloaca
 The length of the common channel varies from 1 to 7 cm.
 This distance has technical and prognostic implications.
1. Short common channel less than 3 cm
2. Long common channel more than 3 cm

Examination
 Pelvic floor
 Absence or presence of anal opening
 Position of anus – normal or anteposed
 Bulge in perineum on crying or straining
 Anal dimple
 Anal reflex
 Perineal groove
 Bucket handle deformity
 Meconium or mucus running up the median scrotal raphe

Examination
 Genitalia
Boy Girl

Examination
Abdomen
 Large visible loop occupying more than half of
abdomen
 Hydrocolpos(in girl) – palpable lump in lower
abdomen

Examination
Lumbo-sacral spine
 Occult or obvious spinal dysraphism
 Absent sacral vertebrae of variable levels

Approach to case of ARM
 History of neonate
 Clinical examination
 Investigation

Investigations
 Invertogram
 Cross table lateral radiography
 USG abdomen & pelvis(to rule out genitourinary anomalies)
 Ultrasonography
o a)transperineal
o b)infracoccygeal
 MCU,IVP
 CT Scan, MRI
 High-pressure distal colostography

Invertogram
Above PC line – High type ARM
Between PC line and I point – Intermediate type ARM
Below I point – Low type ARM

Investigations
Cross table lateral radiograph of a patient

Transverse infracoccygeal sonogram shows the distal rectal pouch (R), which
passes through the puborectalis muscle (arrows), indicating low-type imperforate
anus. U = urethra

Investigations
CT scan
 Mainly required before surgery.
 Clearly shows the anatomy of sphincter muscles,
 Levator ani, muscle complex.
 Delineates the rectal pouch and fistula.
 Clearly shows the relationship between intestine
 Surrounding muscles.

Investigations
MRI
 Provides better soft tissue imaging.
 No radiation hazard.
 Scan is expanded to include pelvis, kidneys and spinal
cord in case of associated anomalies.
 Post operatively it clearly shows whether the pulled through
intestine is within Levator ani sling or not

Investigations
High pressure distal colostography
 Before the definitive repair, distal colostography
is performed.
 It is the most valuable and accurate diagnostic study to
define the anatomy of the anorectal malformation.

Investigations
 Water-soluble contrast medium is instilled into the distal stoma,
which fills the distal intestine and enables demonstration of the
location of the blind rectum and the precise site of a rectourinary
fistula.
 The contrast medium must be injected with considerable
hydrostatic pressure under fluoroscopic control.

Investigations
 The use of a Foley catheter is recommended; it is passed through
the distal stoma, the balloon is inflated (2–5 mL), and it is pulled
back as far as possible to occlude the stoma during the injection
of the contrast medium.
 This maneuver permits to overcome the muscle tone of the
striated muscle mechanism, fill the rectum, and demonstrate the
urinary fistula when present.

Operative procedures
 Colostomy
 Posterior sagittal anorectoplasty
 Pull through procedures
 Laparoscopic assisted procedures

Colostomy
 Descending colostomy is preferred.
 The colostomy is constructed through a left lower quadrant
oblique or transverse incision.
 The proximal stoma is exteriorized through the upper and
lateral part of the wound and the mucous fistula is placed
in the medial or lower part of the wound.

Colostomy
 The colostomy should be made in the mobile portion of
the colon, immediately distal to the descending colon
taking advantage of its retroperitoneal attachments, and
the mucous fistula is made very small to avoid prolapse.
 During the opening of the colostomy, the distal intestine
must be irrigated to remove all the meconium, preventing
the formation of a mega-sigmoid.

Colostomy
 Advantages of descending colostomy
o Mechanical preparation of the distal colon before the definitive
repair is easy due small length of remaining segment.
o Due to shorter distal segment in patient with recto-urethral or
recto-vesical fistula urine is not accumulate in distal segment of
colon.(which leads to development of metabolic acidosis)
o Less chance of development of megarectosigmoid.
o The incidence of prolapse in the proximal limb of descending
colostomies is almost zero.

Posterior sagittal anorectoplasty (PSARP)
 All anorectal malformations benefit from the use of the
posterior sagittal approach.
 The length of the incision depends on the specific
defect.
 The patient is placed in the prone position with the
pelvis elevated.

Position

An incision that starts in the lower portion of the
sacrum and extends anteriorly to the anal sphincter.
Recto vestibular and recto perineal fistula requires
smaller incision so, called limited posterior sagittal ano
rectoplasty and minimal posterior sagittal ano
rectoplasty respectively.

Repair in Boys
Recto perineal fistula
 The repair of these defects consists of a small anoplasty
with minimal mobilization of the rectum, sufficient for it
to be transposed and placed within the limits of the
sphincter.
 It is done during the neonatal period without a
colostomy.

Repair in Boys
 These patients have an excellent prognosis.
 If they have significant associated spinal or sacral
problems an alternative approach, a Pott’s transplant
anoplasty, whereby the majority of the perineal
body is preserved, the mobilized fistula is brought
through a separate incision which is confined to the
size of the future neoanal canal.

Repair in Boys
Rectourethral fistula
 Most important thing in these cases are to put per
urethral catheter.
 Toavoid the catheter to be entered in rectum, the
catheter must be intentionally directed anteriorly by the
use of a lacrimal probe inserted in the distal tip of the
catheter to find its correct path.

Repair in Boys
Rectobladder neck fistula
As it is very high defect both approach (through perineum
and through abdomen) is needed.
 A plasty of the distal dilated portion of the rectum is
necessary in some cases to reach the perineal skin.
 It is also called as abdomino perineal pull through
operation.

Repair in Boys
Imperforate anus without fistula
 About 5 percent of patients have imperforate anus without a fistula.
 In both boys and girls, the rectum lies about 2 cm from the perineal
skin.
 The rectum must be carefully separated from the urethra because the
two structures have a common wall.
 The rest of the repair must be performed as described for the
rectourethral fistula type of defect

Repair in Boys
Rectal atresia and stenosis
 These defects are repaired through a posterior sagittal
approach.
 The entire sphincteric mechanism is divided in the
midline.
 The narrowed area of the distal rectum is opened
posteriorly.

Repair in Boys
Rectal atresia and stenosis
 The posterior rectum is mobilized to reach the anal skin.
No anterior dissection is needed.
 The sphincter mechanism posterior to the rectum is
reconstructed.
 Any presacral mass is dealt simultaneously in the
same operation.

Repair in Girls
Recto perineal fistula
 The treatment of rectoperineal fistula in girls is the same
as that discussed for boys, except of course that the
anterior rectal wall is mobilized off the area behind the
vagina.

Repair in Girls
Rectovestibular fistula
 Incision in this defect is usually shorter as compare to
recto urethral fistula in boys.
 Starting from posteriorly sphincter mechanism is
divided till reach rectal fascia which is helpful in
indenting the plane of dissection.
 Then we go laterally and then anteriorly using this
plane.

Repair in Girls
 Because the rectum and vagina have single wall it is
divided using needle cautery.
 The most common error in performing this operation is
incomplete separation of the vagina and rectum.
 This may create a tense anastomosis between the
rectum and the skin, which may provoke dehiscence
and recurrence of the fistula

Repair in Girls
The anterior limit of the external sphincter is identified
using electrical stimulation and the anterior edge of the
muscle complex are reapproximated as previously
described, creating the perineal body.

Repair in Girls
Rectovaginal fistula
 Imperforate anus with a true rectovaginal fistula is extremely
rare.
 A true rectovaginal fistula requires a full posterior sagittal
incision.
 The operation is essentially the same as that described for
a rectovestibular fistula, except that it is necessary to
dissect much more of the rectum to gain enough length to
pull it down to the perineum.

PSARP in female
 Involves a midline incision from the fistula to the putative
site of the anus.
 Division of the muscles in the midline, separation of the
rectum from the vagina under vision
 Placement of the rectum within sphincteric complex and
reconstruction of the perineal body.
 Indications:
o All low and intermediate type of abnormality in females
o Revision surgery following cutback operations

Abdomino perineal pull through
operation
 Lower bowel is mobilized
 New passage is created through the pelvic floor keeping
close to the urethra
 Fistulous tract is divided and ligated
 Bowel can be pulled down and its mucosa stitched to the
skin of the newly formed anus.
 Daily dilatation will be required for at least 3 months

Laparoscopically assisted anorectal pull
through (LAARP) for highARM
 Advantages:
 LAARP allows the surgeon to treat a high lesion like a low lesion.
 No need to divide the muscle complex from below.
 Immediately after the procedure strong and symmetric contraction of the
sphincter around the neo anus can be seen.
 It also avoids the complication and multiple procedures associated with
colostomy.
 More rapid return of bowel function
 Improved cosmetic appearance
 Shorter postoperative recovery
 Decreased postoperative complications

Post operative care
 In cases of rectourethral fistula in boys, the urethral
catheter is left in place for 7 days.
 If the urethral catheter is accidentally dislodged, the patient
can be observed for spontaneous voiding, which usually
occurs.
 Attempts to reintroduce a urethral catheter is avoided.

Post operative care
 Intravenous antibiotics are administered for 24 hours. An antibiotic ointment
is applied to the anoplasty for 5 days.
 The patient is discharged after 2 days in cases of a posterior approach without a
laparotomy or laparoscopy, and after 3–5 days in cases of an abdominal
approach.
 The parents are instructed to keep the incision clean, not to wipe, and to apply
antibiotic ointment for 1 week.
 Two weeks after the operations, anal dilatations are started. On the first
occasion, a dilator that fits loosely into the anus is used to instruct the parents,
who must carry out dilatation twice daily.

Post operative care
 Every week, the size of the dilator is increased until the rectum
reaches the desired size, which depends on the patient’s age.
 Once the desired size is reached, the colostomy can be closed.
 Frequency of dilatation should be reduced in following
schedule:
o At least once a day for one month; every third day for one month;
twice a week for one month; once a week for one month; and every
2 weeks for three months.

Post operative care
Initially patient may have diaper rash due to multiple bowel
movement which is converted to 2 or 3 bowel movement per
day in 6 months.
Patient with 2 to 3 bowel movement in day, with some feeling
on having bowel movement have good prognosis and
responds to toilet training.

Complication
 Wound infection
 Anal strictures
 Constipation
 Transient femoral nerve pressure
 Neurogenic bladder
 Fecal incontinence

Anorectal malformations.pptx

More Related Content

What's hot (20)

Similar to Anorectal malformations.pptx (20)

More from Pushpa Lal Bhadel (15)

Recently uploaded (20)

Anorectal malformations.pptx

Editor's Notes