The document discusses the development of the anal canal and the surgical anatomy of the anal canal. It describes different types of imperforate anus including low and high anomalies. Low anomalies include covered anus, ectopic anus, and stenosed anus. High anomalies include anorectal agenesis, rectal atresia, and cloaca. Initial management involves assessing whether temporary colostomy is needed. Treatment of low anomalies involves dilatations or procedures like V-Y anoplasty or cutback procedure. Treatment of high anomalies includes initial colostomy followed by posterior sagittal anorectoplasty to reconstruct the anal canal. Surgical outcomes vary depending on the type of anomaly repaired.

1. Imperforate anus
Dr. Dinesh. M.G
Professor of Surgery
J.J.M.M.C.
Davangere

2. Development of anal canal
 Cloaca: Early in embryonic life allantois(urinary) and
hindgut(rectum and upper part of anus) open into a
common chamber called cloaca
 The cloaca becomes separated into the bladder and
postallantoic gut(rectum) by the downgrowth of
urogenital septum.
 At this time an epiblastic bud , the proctodaeum, grows in
towards the rectum
 The proctodaeum fuses with rectum in 3rd month of
intrauterine life and forms the anal canal

3. Urogenital septum dividing the cloaca

4. Surgical anatomy-Anal canal

5. Surgical anatomy-Anal canal
 Anal canal starts where rectum passes through the pelvic
diaphragm and ends at the anal verge
 The muscular junction between the rectum and anal canal
is felt as a anorectal bundle or ring
 The internal sphincter is a thickened continuation of
circular muscle coat of rectum. It is pearly white in colour
and involuntary muscle
 The longitudinal muscle is a continuation of longitudinal
muscle coat of rectum
 The external sphincter is pink in colour and composed of
voluntary muscle

6. Surgical anatomy-Anal canal
 Intersphincteric space exists between external and
internal sphincter
 The puborectalis maintains the anorectal angle and is
essential for preservation of continence

7. Surgical anatomy-Anal canal
 Pink columnar epithelium rectal mucosa changes into red
cubical epithelium in anal canal
 Mucosa is thrown into 8- 12 anal columns of Morgagni
which are joined at their lower ends by anal valves. This
wavy junction is called dentate line
 The dentate line separates
Above Below
• Cubical epithelium from squamous epithelium
• Autonomic nerve supply from somatic nerve supply
• Portal venous system from systemic venous system

8. Surgical anatomy-Anal canal
 Anal valves of Ball are series of transversely placed
semilunar folds linking the columns of Morgagni
 The crypts of Morgagni are small pockets between lower
ends of columns of Morgagni. Anal glands open into these
anal crypts by a narrow ducts
 The anorectal ring marks the junction between the rectum
and the anal canal. It is formed by the joining of
 puborectalis muscle
 deep external sphincter
 conjoined longitudinal muscle
 highest part of the internal sphincter

9. Surgical anatomy-Anal canal
 Arterial supply by branches of superior, middle and
inferior haemorrhoidal arteries
 Venous drainage : the superior and middle haemorrhoidal
veins drain via the inferior mesenteric vein into portal
system. The inferior haemorrhoidal veins drain the lower
half of the anal canal to the external iliac vein
 Lymphatic drainage: upper half of anal canal drain into
postrectal lymph nodes. Lower half drains to superficial
and deep inguinal nodes

10. Imperforate anus
 One in 4500 are born with an imperforate anus
 The VATER or VACTERL syndrome (vertebral, anal,
cardiac, tracheoesophageal, renal, and radial limb
anomalies) occurs in approximately 15% of patients.
 A tethered cord and other types of spinal cord
abnormalities are observed in half of patients
 Approximately 60% of patients with high or intermediate
forms of imperforate anus have some form of associated
genitourinary (GU) malformation or vesicoureteral reflux

11. Imperforate anus
 Two main types: Low and High depending on whether
termination of bowel is below or above the pelvic floor
 Low abnormalities
 Covered anus: anal canal is covered by a bar of skin with a
track running forward to the perineal raphe
 Ectopic anus: anus is situated anteriorly and may open in
the perineum in boys or more commonly in the vulva in
girls
 Stenosed anus: the anus is microscopic
 Membranous stenosis: anus is covered with a thin bulging
membrane

12. Imperforate anus(low)
1.Covered anus 2.Vulval ectopic anus
3.Stenosed anus 4.Membranous stenosis

13. Imperforate anus(low)
perineal fistula in boys

14. Imperforate anus(low) in girls
Rectoperineal Fistula Rectovestibular Fistula

15. Imperforate anus
 High abnormalities
 Anorectal agenesis
 Rectal atresia
 cloaca

16. Anorectal agenesis
Recto urethral(bulbar) fistula Rectoprostatic fistula

17. Anorectal agenesis
Imperforate anus without fistulaHigh anomaly –rectovesical fistula

18. Rectal atresia

19. Cloaca

20. Initial Management of the Newborn
 It is best to wait 24 hours prior to any surgery to allow
progression of gas or meconium through the bowel
 To decide whether temporary colostomy is needed

21. Initial assessment
Imperforate Anus in Boys
 Features of low anomaly are:
 If an external opening is visible in the perineum
 Presence of meconium just below the skin of the perineum.
 A skin formation called a “bucket handle”
 An apparently well-formed anal dimple and gluteal crease
 Features of high anomaly needing colostomy are:
 Associated cleft scrotum or significant hypospadias
 Complete absence of the gluteal fold (the crease between the
buttocks)
 Absence of anal dimple
 Presence of abnormalities of the sacrum .

22. Imperforate anus-low in boys
‘bucket handle’ deformity Well formed anal dimple

23. Imperforate anus-high in boys
Flat perineum and absence of anal dimple

24. Imperforate anus in girls
 If only two openings are seen in the perineum, including
the urethra and vagina, and meconium is seen coming
from the vagina, an anomaly called a rectovaginal fistula
or cloacal variant is present.
 If neither a fistula nor meconium is noted on or just
beneath the perineum, ultrasound or an x-
ray(Invertogram) may be done to see if the rectum is near
the skin where the anus was supposed to be. If it appears
to be less than 1 cm away from the skin it is a low variety
 If only one opening is seen, it must be assumed that there
is a problem called a cloaca

25. Management-Investigations
Invertogram
High anomaly

26. Treatment of low anomalies
 Initially by dilatations
After 3-4 weeks
 V-Y anoplasty for stenosed anus
 Anal transposition for ectopic stenosed anus
 Cutback procedure for ectopic stenosed anus
 Regular dilatation of anoplasty by the parents after 3
weeks to prevent stenosis

27. Treatment
 V-Y anoplasty for anal stenosis

28. Treatment
 Plastic cutback operation for anovestibular fistula

29. Treatment of high anomalies
 Initial sigmoid colostomy
 Distal colostogram to define the lower limit of rectum and
fistula
 Currently the posterior sagittal anorectoplasty (PSARP)
procedure described by de Vries and Pena is the preferred
technique
 Laparotomy /laparoscopic rectal pull through operation
after division of abnormal fistula into urinary tract
 Regular dilatation of new anus after 3 weeks
 Colostomy closure after 3 months

30. Management -treatment
 Colostomy

31. Anorectal agenesis
Imperforate anus without fistulaHigh anomaly –rectovesical fistula

32. Posterior sagittal anorectoplasty
(PSARP)

33. Posterior sagittal anorectoplasty
(PSARP)

34. Posterior sagittal anorectoplasty
(PSARP)

35. Posterior sagittal anorectoplasty
(PSARP)

36. Posterior sagittal anorectoplasty
(PSARP)

37. Posterior sagittal anorectoplasty
(PSARP)

38. Posterior sagittal anorectoplasty
(PSARP)
Rectoperineal Fistula Rectovestibular Fistula

39. Posterior sagittal anorectoplasty
(PSARP)

40. Conclusions
 Clinical results are different for each type of the
malformations.
 Faecal continence is good in low anomalies
 Constipation is a common sequelae seen after the repair of
an anorectal malformation.
 Urinary control can be expected in the overwhelming
majority of male patients after repair of imperforate anus
provided a good surgical technique was performed

41. Thank you