- Anorectal malformations range from simple anal stenosis to the more severe persistence of a cloaca. The most common defect is an imperforate anus with a fistula between the distal colon and urethra in boys or vagina in girls. - During embryonic development, failure of the urorectal septum to divide the cloaca can result in fistulas. Incomplete resorption of the anal membrane can also cause anomalies. - Anorectal malformations are classified based on fistula location and level of the defect, which can predict appropriate treatment. Higher lesions generally require initial colostomy before corrective surgery. - Treatment involves evaluating associated anomalies, classifying the defect,

1. Anorectal Malformation
Hakim J. Jamba
Surgery Resident
lokadae@gmail.com

2. o Introduction
o Definition
o History
o Incidence
o Embryology
o Anatomy
o Classification
o Associated anomalies
o Clinical presentation
o Management
o Prognosis
o Complications
o Referrences
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3. Introduction
o1: 4000/5000 live births
oBoys more commonly affected 58%
oRanging from simple anal stenosis to the persistence of a cloaca
oImperforate anus with a fistula between the distal colon and urethra
in boys or the vestibule of the vagina in girls
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4. oEmbryoloy:
oUrorectal septum moves caudally
to divide the cloaca into anterior
urogenital sinus and a posterior
anorectl canal
oFailure results in fistula
oComplete or partial failure of anal
membrane to resorb results in an
anal membrane or stenosis
oAnterior displaced anus
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5. Classification
oAnatomical or therapeutic & prognostic oriented
oFistula location can predict pouch level
oLow lesion
oHigh lesions
oRectal atresia; partial or complete
oPersistent cloaca;
o Single orifice in female
o Two orifices:
o Vagina & urethra high imperforate anus
o Anus & urogenital sinus Persistent urogenital sinus
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9. Associated anomalies
oVACTERL must be considered
during evaluation
o1/3 sacral anomalies
oAbsence of > 2 vv is associated
with poor prognosis for bowel and
bladder continence
• Genitourinary
• Cardiovascular
• MSS
• GI
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10. Treatment
oPreoperative evaluation:
oPhysical
oPlain radiograph
oU/S scan
oVCUG
oEcho
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11. Decision algorithm
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12. Surgical management
oLow lesions:
oPrimary single-stage repair
without colostomy
oAnal dilatation
oCutback anoplasty or transposition
anoplasty
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13. oHigh lesions:
o1*; divided colostomy with a distal
mucous fistula that is evaluated
later for rectourinary fistula
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14. o2nd ; 3-6 months later dividing the
fistula and a pull through into the
normal anal position
(Pena/deVries-PSARP)
o Locating the centre of the anal
sphincter
o Midline incision from the coccyx to
the anterior perineum
o Through the sphincter & levator
musculature till the rectum
o Fistula divided
o Mobilization of the rectum and
perineal musculature closure
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15. o3rd ; colostomy closure several
weeks later
oAnal dilatation begins 2 weeks
after ARP and continues several
months thereafter
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16. oRecently minimal invasive approach;
o Intraabdominal for high lesions
oTheoretical benefit of placing the neorectum within the central position of
the sphincter and the musculature
oAvoids cutting across muscles
oStill to be evaluated
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17. Out come
oAssociated anomalies affect the outcome
oPrognostic factors include;
oLevel of pouch
oNormal sacrum
oFaecal continence is a main goal
o75% have voluntary bowel movements
o50% soil underwears occasionally while the rest are completely continent
oConstipation is the most common sequel
oPostop enema reduces frequency of soiling and improve life quality
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18. Complications
Early
Infection
Dehiscence
Neurogenic bladder
Transient femoral nerve palsy
Intraoperative injury to urethra, vas deferens
Complete necrosis of the mobilized vagina
Late
Anastomotic stricture
Neoanus
Vagina
Narrow introitus
Urethrovaginal fistula
Persistent rectourethral fistula
Prolapse of bowel
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19. References
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22. • The spectrum of anorectal malformations ranges from simple anal
stenosis to the persistence of a cloaca; incidence ranges from 1 in
4000 to 5000 live births and is slightly more common in boys. The
most common defect is an imperforate anus with a fistula between
the distal colon and the urethra in boys or the vestibule of the
vagina in girls.
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23. • Anorectal Embryology
• By 6 weeks of gestation, the urorectal septum moves caudally to divide the cloaca
into the anterior urogenital sinus and posterior anorectal canal.
• Failure of this septum to form results in a fistula between the bowel and urinary
tract (in boys) or the vagina (in girls).
• Complete or partial failure of the anal membrane to resorb results in an anal
membrane or stenosis.
• The perineum also contributes to development of the external anal opening and
genitalia by formation of cloacal folds, which extend from the anterior genital
tubercle to the anus.
• The perineal body is formed by fusion of the cloacal folds between the anal and
urogenital membranes.
• Breakdown of the cloacal membrane anywhere along its course results in the
external anal opening being anterior to the external sphincter (i.e., anteriorly
displaced anus).
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24. Classification of Anorectal Anomalies
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26. Summary
• 1. Anorectal malformations (ARMs) occur commonly and are a
• cause of significant morbidity for African children.
• 2. The most common ARM in males is a fistula of the rectum into
• the urinary tract (usually urethra); in females, it is a fistula into
• the vestibule of the vagina.
• 3. ARMs are one component of the VACTERL complex, and
• diagnostic techniques appropriate for a particular locale
• should be used to look for the other components of this
• complex.
• 4. The specific type of ARM is diagnosed on the basis of the
• newborn physical examination and a few technologically easy
• techniques.
• 5. Low lesions, which unfortunately constitute the minority of
• lesions, can be treated by a primary anoplasty without a
• colostomy.
• 6. Most ARMs are high lesions and should be treated initially with
• a sigmoid colostomy.
• 7. Improperly constructed colostomies can be a source of great
• morbidity for children.
• 8. The recommended definitive treatment for ARMs is a posterior
• sagittal anorectoplasty.
• 9. Even after the best of operations, children with ARMs can
• suffer from bowel management problems. A proper bowel
• management program can make a significant positive
• change in the life of a previously miserable child with faecal
• incontinence.
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