Anorectal malformation

Classification:

Wingspread (1984):

·         High

·         Intermediate

·         Low

·         Rare anomalies

Functional significance?

Wingspread classification

·         Low

o   Primary reconstruction possible

o   No colostomy required

·         High

o   Primary reconstruction not advisable

o   Initial colostomy required

o   Reconstruction at 4-6 weeks

Functional classification (Pena):-

Distance between the skin and termination of the rectum decides management

·         <1cm: primary anoplasty / minimal PSARP at birth, no colostomy

·         >1cm: colostomy at birth, PSARP at 4 weeks

Krickenbeck classification 2005

·         Major clinical groups

o   Perineal cutaneous fistula

o   Recto urethral fistula

§  Bulbar, prostatic

o   Recto vesical fistula

o   Vestibular fistula

o   Cloaca

o   No fistula

o   Anal stenosis

·         Rare regional variants

o   Pouch colon

o   Rectal atresia/ stenosis

o   Recto vaginal fistula and others

 

Female anomalies:

·         Anovestibular fistula

·         Rectovaginal fistula

·         Cloaca

Cloaca:

·         90% have associated malformation

·         Need emergency evaluation of urinary tract

·         Obstructed ureters because of distended vagina

·         May require vaginostomy/ vesicostomy

Female defects
Common: ·         Anovestibular fistula ·         Perineal fistula ·         cloaca	Uncommon: ·         rectovaginal fistula ·         no fistula

Ano rectal agenesis with no fistula:

• ·         unique and rare defects in males and females
• ·         5% of all ano rectal malformation
• ·         Rectum ends 2cm from skin
• ·         Rather thin common wall between rectum and urethra/ vagina
• ·         50% have Down syndrome; the rest have other syndromes
• ·         90% of Downs  with ARM have this defect

Rectal atresia:

·         Rare (1% of all ARM)

·         Normal anal canal- normal perineum

·         Pass thermometer- fails to go

·         Rectum and anal canal separated by thin membrane or fibrous tissue

·         Normal muscles- good prognosis

Associated malformations in ARM:

·         Incidence: 50-60%

·         60% genitourinary

·         25% vertebral

·         20% cardiac

·         15% VACTERAL association

·         5% have Down’s (typically no fistula)

Higher the anomaly, higher the incidence of associated malformation

GU abnormalities

·         50% have neurovesical dysfunction

·         40-50% have VUR

·         Low anomaly- 10%

·         Cloaca- 90% (may have obstructive uropathy)

o   Implications-

§  Investigate – emergency evaluation in cloaca before opening a colostomy, may require vesicostomy

§  Prognosticate

§  Source of morbidity

Skeletal associated malformations:

·         Sacrum most affected

·         Less number

·         Hypoplasia

·         Hemisacrum – always have pre sacral mass

·         Hemivertebrae

·         Translate into poor outcome for continence

Sacral ratio

·         BC/AB= 0.77

·         Low sacral ratio

·         Sacral hypoplasia

·         Poor outcome of continence

Other associations-

·         TEF

·         Triple atresia- duodenal atresia, oesophageal atresia and anal atresia

·         Chromosomal disorders

·         Syndromic associations-

o   Downs, Apert, Cat eye others

Examinations:

1.       Perineum

2.       Natal cleft

3.       Anal dimple

4.       Contractions

5.       Sacrum and spine

6.       Midline epithelial aggregations

Management:

·         NPO

·         Nasogastric tube

·         IV maintenance fluid

·         Plain abdominal film

·         Urinalysis

·         Wait 24 hours for the anomaly to reveal itself

·         Do not jump at conclusions at birth

Answers these questions within 24 hours:

·         Is the case suitable for primary repair without colostomy?

·         Does the case need a colostomy now and delayed PSARP later?

·         Is there a life threatening associated problem that needs more urgent attention? TOF, cardiac etc?

·         Is urgent urological evaluation needed?

Decision making:

·         Clinical examination at 24 hours

·         AXR/ Prone cross table lateral film

·         USS renal

Prone cross table lateral shoot film:

·         At 24 hours

·         Marker at anal site

·         Knee elbow position

·         Pelvis elevated

·         Wait for 10 min

·         Dead lateral

·         Centre over greater trochanter

Invertogram now no longer done

Gas from marker:-

·         <1cm = anoplasty

·         >1cm = colostomy

Colostomy (Indication):-

·         Meconuria

·         Flat bottom

·         Good perineum but no meconium on perineum in 24 hours and gas >1cm from marker on cross table prone lateral film

·         Vestibular opening, cloaca, no meconium on perineum

·         If in doubt- better open colostomy

Primary repair (Indication):-

·         Meconium on perineum (perineal fistula)

·         Good perineum, no meconium on perineum, gas<1cm from marker on cross table prone lateral film

·         Vestibular fistula?

·         Primary repair in boys with bulbar fistula?

Colostomy:

·         Divided sigmoid colostomy

o   Easy to manage effluent

o   Less electrolyte disturbance

o   Easy to clean distal bowel

o   Colostogram easy

Post colostomy:

·         Distal washout

·         Distal cologram

·         Investigate for associated malformations

·         Prophylaxis until VUR excluded

·         Weight gain, immunisations

·         Colostomy care

Further investigations:

·         Cardiac echo

·         Chromosomes

·         Renal Ultrasound

·         Spine film: sacrum, Pena ratio

·         Spine US- tethered cord

·         Distal cologram

·         MCUG

Dista cologram:

·         Single most important investigation

·         Level of fistula

·         Length of available colon

·         Dilatation

·         Feculoma

How to do distal cologram:

·         Distal washout to clean distal colon

·         Cover with antibiotics

·         Marker at skin dimple

·         Foley catheter- inflate baloon and pull

·         Water soluble dye

·         Inject with pressure (40mm Hg)

·         Lateral film

·         May require simultaneous RGU

·         Give washout after study

Definitive management:

·         PSARP

·         PSARVP

·         PSARVUP

PSARP Position:

·         Pelvis elevated

·         Prone jack knife position

·         Chest supported by cotton roll

·         Abdomen should be kept free  (helpful in ventilation)

·         Cautery plate strapped to leg

·         Foley’s catheter placed before putting patient into this position

·         Cover the colostomy

·         Retract gluteal fold (with the help of Elastoplast)

·         Take care of pressure points

Urinary catheter:

v  Infant feeding tube or Foley

v  Confirm position in bladder

v  Fix with a stitch to glans

v  Problem?- catheter in rectum through this fistula

v  Try these-

o   Infant feeding tube with curved packing- memory negotiates the curve

o   Leave catheter in the rectum and manipulate during posterior dissection

o   Endoscopic placement over guide wire

o   Supra pubic cystostomy

Post op:

·         IV antibiotics- Ceftriaxone & Metronidazole

·         Feed when recovered from GA (few hrs)

·         Catheter for 5-6 days

·         Remove early if malfunctions

·         Do not reinsert if comes out accidently

·         Follow dilatation schedule

·         Close colostomy when adequately dilated (8-12 weeks)

Dilatation programme – Hegar’s Dilator:-

·         Start at 3 weeks

·         Size 12 for a week

·         Increase by one size every week

·         Size 16-18 every week

·         Finger massage

·         Use mild steroid cream to prevent fibrosis

·         Do not cause bleeding while dilating

Functional outcomes:-

·         Patients for life

·         No one is normal

·         Continence is the only outcome measure

·         Many factors play role

·         Normal bowel movements are ideal but not truly realistic

Is continence possible:-

·         Requirements

o   Sensation

o   Muscles

o   Rectum

§  Storage

§  sensation

o   normal bowel motility

continence:-

·         sensory receptors found in

o   rectum

o   anal canal

o   striated muscle around rectum

·         rectal ES is the only striated muscle in the body which is active 24*7

complications –

·         urethral injury, left over fistulous tract

·         prolapse, stenosis, dehiscence, infection

·         recurrent fistula

·         urethral diverticulum

·         constipation

·         incontinence/ incopresis

·         malposition of rectum in relation to the muscle complex

Other problems in the long term-

·         urinary tract

o   incontinence

§  relation to sacral dysplasia, neurovascular dysfunction, urethral and bladder anomalies

§  minority secondary to operative damage to bladder neck or urethra

§  increased risk with ‘high’ lesions

§  ?true incidence (10-33%)- depends on how hard it is looked for

o   Death from renal failure

§  6.4% of ‘high’,  1.1% of low (McLorie 1987)

·         Vaginal problem

o   Dyspareunia

o   Increased risk of 3^rd degree tear with vaginal delivery

·         Male problem

o   Ejaculatory duct obstruction

o   Weak or absent erections

o   Retrograde ejaculations

·         Vertebral

o   Chronic back pain

o   Progressive scoliosis

o   Tethered cord

·         Psychological

Constipation:

·         Inherent for low malformations

o   Has to be managed

o   Cannot be cured

o   Diet changes help

·         Secondary to anal stenosis

o   Megarectum

o   Encopresis

Bowel management-

·         Normal bowel movements are ideal

·         Not achievable in all

·         Inherent motility disorder

·         Type of defect dictates outcome

·         Ensure adequate calibre of anus

·         Bowel washouts- retrograde/ ACE

·         Diet changes

Current issues-

·         Primary neonatal PSARP in males

·         ASARP or PSARP

·         Laparoscopic pull through

o   Indications

o   Judicious use

o   Training

Primary PSARP in boys with rectourethral fistula
Advantages: ·         Easy planes ·         Better sensory input ·         Better continence ·         Avoids colostomy and its complications	Disadvantages: ·         Colostogram not available, therefore anatomy uncertain ·         Requires experience ·         Requires patient selection ·         Urethral injury possible

Laparoscopic repair of anorectal malformation
·         Role limited to boys who would require abdominal exploration such as recto vesical fistula ·         No role in female anorectal malformations
Advantages: ·         Better visualization of pelvic floor ·         Accurate placement of anus in the centre of muscle complex ·         Supine/ lithotomy position ·         Smaller incision in the perineum	Disadvantages: ·         Dissection of common wall difficult ·         Remnant fistula ·         Urethral diverticulum may form ·         Unsuitable for bulbar fistula ·         Requires experience

ASARP or PSARP

·         In girls ASARP is a valid alternative

·         Same operation but different approach

·         Supine position

·         Choice depends on surgeons preference