Anorectal Malformations(ARM)�(Imperforate anus)

Dr.Haidar Mohammad Muhssein Alathari

MBChB,FAAP FACS

Consultant Pediatric Surgeon

Medical Education Unit

University of Kufa,College Of Medicine

Objectives:

1. Identify the type of ARM.
2. Classify a patient born with ARM.
3. Understand the most common associated defects.
4. Manage the patient preoperatively in the neonatal period.
5. Decide whether the patient need colostomy vs primary repair.
6. Choose the right type of colostomy.
7. Show the importance of high pressure distal colostogram in male with ARM.
8. Follow up the patient postoperatively.
9. List the possible complication after definitive surgery.

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Incidence & Terminology

• ARM occur in ONE of every 4000-5000 newborns.
• Slightly more common in males.
• Most frequent defect in male is rectourethral fistula while in female is rectovestibular fistula.
• Rectovaginal fistula is a rare defect , present in < 1% of all cases .
• Rectobladderneck fistula in male is the only true supralevator malformation occur in about 10%.

Classification

Male

1. Rectoperineal fistula
2. Rectourethral bulbar fistula
3. Rectourethral prostatic fistula
4. Rectolabberneck fistula
5. Imperforate anus without fistula
6. Rectal atresia/ stenosis

Female

1. Rectoperineal fistula
2. Rectovestibular fistula
3. Cloaca
4. Complex malformations
5. Imperforate anus without fistula
6. Rectal atresia/ stenosis

Rectoperineal fistula

• The lowest defect
• The rectum is located within most of the sphincter mechanism ,only the lowest part is anteriorly mislocated.

Meconium on perineum

Rectoperineal fistula “Anterior displaced anus”

Rectourethral fistula

• The most common defect in males.
• The fistula is located at the lower (bulbar) or higher ( prostatic) part of the urethra.
• Immediately above the fistula, the rectum and the urethra share a common wall.
• Lower urethral fistulas are usually associated with good quality muscles, well- developed sacrum and a prominent midline groove and anal dimple.
• Higher fistulas are more frequently associated with poor quality muscles, an abnormally developed sacrum,a flat perineum, a poor midline groove and barely visible anal dimple.

If the infant passes meconium through the urethra, this is an unequivocal sign of a rectourinary fistula

Meconium stained urine

Rectourethral fistula

Rectobladderneck fistula

• The rectum opens into the bladderneck.
• Poor Prognosis for bowel control/ poorly developed muscles
• Deformed and short sacrum
• Flat perineum

Imperforate anus without fistula

• Well-developed sacrum and good muscles
• Good prognosis for bowel control
• The rectum terminates about 2cm from perineal skin
• 50 % have Down`s syndrome

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Rectal atresia/stenosis

• < 1% of patients
• The lumen of the rectum is totally( atresia) or partially ( stenosis ) interrupted.
• Excellent functional prognosis.

Rectoperineal fistula in females

• Equivalent to the defect in males.
• The key anatomic issues are the anal opening in relation to the sphincter mechanism and the length of the perineal body.

Rectovestibular fistula

• Most common defect
• Excellent functional prognosis
• Diagnosis by clinical examination by finding a third hole in the vestibule.
• This defect can be repaired without a protective colostomy by experienced surgeons.

Female with the most common clinical finding

Rectovestibular fistula

Imperforate anus without fistula

• The same therapeutic and prognostic implications as described for male patients.

Persistent Cloaca

• It represents the extreme in the spectrum of complexity of female malformations.
• It’s a defect in which the distal portion of the rectum, vagina and urinary tract fuse and create a single common perineal channel.
• Diagnosis is clinical.
• The length of the common channel varies from 1-7 cm.
• A common channel < 3cm means that it can be repaired posterior sagittal approach only.
• Common channels longer than 3cm are more complex.

Female with a single perineal opening

Cloacal Malformation

• Hydrocolpos
• Pyocolpos
• Hydronephrosis
• Cervical and uterine separation
• Rarely cervical atresia
• Short common channel < 3cm usually have a good functional prognosis.

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Associated Defects

• Sacrum and Spine.
• Tethered Cord
• VACTERL ( vertebral, anal, cardiac,tracheoesophageal renal and limb).
• Associated GU defects varies from 20-54%.
• The higher the malformation, the more frequent are the associated urologic anomalies.
• Sacral ratio range from 0.0 to 1.0
• Normal ratio is 0.77

Sacral Ratio: BC over AB

Newborn Management

• Thorough perineal inspection .
• No decision whether colostomy or primary repair before 24 hours of life.
• I.V fluid, AB, NG decompression and evaluation for associated defects ( cardiac ECHO, Renal and spinal US ).

Continue …

• If there is signs of rectoperineal fistula 🡺 Anoplasty.
• No meconium in the perineum, we recommend obtain cross-table lateral radiograph in prone position.
• If air in the rectum is seen distal to the coccyx, consider PSARP without protective colostomy.
• If the rectal gas does not extend beyond the coccyx or the patient pass meconium in urine, do colostomy which allows future high pressure distal colostogrm to delineate distal rectal anatomy. Then do Posterior sagittal anorectoplasty (PSARP)2-3 months later.

Proceeding with the posterior sagittal approach looking blindly for the rectum has resulted in a spectrum of serious complications including damage to the urethra, complete division of the urethra,pullthrough of the urethra,pullthrough of the bladderneck,injury to the ureters and division of the vas deferens or seminal vesicles.

colostomy

• Perform divided descending colostomy in such a manner as to leave enough redundant, distal rectosigmoid colon to allow for the subsequent pull-through.

Continue….

• Drain Hydrocolpos if present ( for cloaca).
• Endoscopic evaluation of the cloaca to delineate the anatomy few months later.

High-pressure distal colostogram

• The most important study in diagnosis of

ARM prior to definitive repair in males .

• Vital in planning definitive repair.

Rectourethral Bulbar Fistula

Rectourethral prostatic fistula

Rectobladderneck Fistula

Definitive Repair �Posterior Sagittal Anorectoplasty ( PSARP)�For Cloaca, Posterior Sagittal Anorectovaginourethroplasty(PSARVUP)

Postoperative Management &�Colostomy closure

• Urinary catheter left for 7 days in male with rectourethral fistula and 10-14 days in case of cloaca.
• If dislodged, NO catheter replacement.
• I.V antibiotics for 24-48 hr and antibiotic ointment applied for perineal sutures for 7 days.
• Anal dilatation schedule started 14 days postop. by using Hegar`s dilators.
• Once reach the desired size, colostomy can be closed.

After colostomy closure

• The patient may have multiple bowel movements and may develop perineal excoriation.
• After several weeks, the number of bowel movement decreases and most patients will develop constipation and need laxatives.
• After 1-3 months, the patient develops a more regular bowel movement pattern.
• A good prognosis can be predicted in a patient who has one to three bowel movements per day, remains clean between bowel movements and shows evidence of feeling or pushing during bowel movements

Complications after PSARP

• Wound infection
• Wound separation
• Anal strictures
• Constipation
• Rectal prolapse
• Transient femoral nerve palsy.
• Urologic injuries

Specific to the cloacal repair

• Urethrovaginal fistula
• Fibrosis of the vagina

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FOR MORE INFORMATIONS &VIDEOS VISIT :

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www.expertsinsurgery.com: Marc Levitt

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Thanks for listening