anorectal malformation

 Anorectal Malformation

Anorectal malformation indicates defects involving in distal anus and rectum and urogenital tract. Anorectal malformation resulting in absence of anal opening which occurs during 4th -16th week of gestation.

Types of Anorectal Malformation

There are 4 types of Anorectal anomalies;

1. Anal Stenosis

Stricture present 1-4cm above the anus or stricture extends through entire length of anus.

2. Anal membrane atresia

An membrane produces obstruction, behind membrane meconium can seen.

3. Rectal atresia

Normal anus present but rectum ends has blind poch.

4. Anal agenesis or imperforated anus

Seen as dimple with rectum ending as blind pouch above the anus.

Fistula or abnormal opening may present between rectum and urogenital tract.

1. Low imperforated anus

Distance between blind pouch of rectum and anal dimple is less than 1.5cm. Rectum descended below the level of ischial spine.

2. Intermediate imperforated anus

Rectal pouch lies below the joining pubis and coccyx (pubococcygeal line). 

Rectal pouch lies between pubococcygeal line and ischial line.

3. High imperforated anus

Distance between blind pouch of rectum and anal dimple is more than 1.5cm. 

Rectal pouch ends blindly above pubococcygeal line.

Diagnostic Evaluation

Detection of imperforated anus done at birth;

1. No anal opening

2. Into the infant's rectum gloved finger or thermometer cannot inserted.

3. No history of passage of meconium

4. Abdominal distension presence

5. Rectovaginal fistula; if presence of meconium in urine

6. Find out distance between blind end of rectum and anal dimple 

1. Invertogram

Invertogram is a radiograph taken with infant in inverted position.

Infant held upside down, Infant cries, air is swallowed, swallowed air forced through bowel.

Air reaches upto blind rectal pouch.

Radiograph is obtained with baby in inverted position.

Radiograph shows presence of air upto level of rectal pouch.

Distance between rectal pouch and anus ascertained.

2. Abdominal ultrasound

Detect Associated urinary tract anomalies.

3. Intravenous pyelogram

4. Micturating cystourethrogram

5. Vesicoureteral reflux

Management

Surgical procedure

1. For Anal Stenosis

Manual dilatation by using Hegar's dilators done by doctor. Repeated regular dilatation.

2. In presence of Anal Membrane Atresia

Incision the membrane with blunt instrument.

3. In presence of low Imperforated anus

Abdominal pull through and anoplasty is done followed by anal dilatation to prevent stenosis.

4. In presence of intermediate or high imperforated anus

(Where distance between anal dimple and blind end of rectum is greater than 1.5cm).

First stage involves;

Creation of Temporary colostomy

Second stage;

Intestinal repair and Colostomy closure performed.

Rectal pouch brought down through abdomino- perineal procedure and sutured over anal dimple.

If any fistula present; fistula repair with posterior sagittal anorectoplasty and pena's procedure done; in which rectum pulled down and opened at normal anatomic site.

Nursing Management

Pre operatiive nursing care

1. Child kept on NPO, oral feed stop

2. Administer IV fluids to meet nutritional requirements of baby

3. Observe Abdominal girth to detect abdominal distension

4. Gastric decompression done by nasogastric aspiration

5. Monitored vital sign

Post operative nursing care

1. Post anaesthesia care given

2. Nasogastric suction done to prevent Abdominal distension

3. Intravenous fluids administerd

4. When peristalsis returns, start oral feeding

1. Care of colostomy

Keep stroma clean and dry

Observe color of stoma

Change colostomy dressings frequently

Zinc oxide ointment or Vaseline applied around stoma to prevent excoriation of skin due to fecal matter coming out from stoma.

2. Care after pull through and Anoplasty

Anal site should kept clean and dry

Diaper not used

Anal area protected by covering with sterile Vaseline gauze.

Not any foreign object such as rectal thermometer inserted in baby's rectum.

Place baby in side lying position with hip raised, helps to prevent tension on suture line.

Observed baby for abdominal distension, bleeding or any discharge

Administration of IV fluids to meet nutritional requirements and fluid and electrolytes balance.

Outcome/Prognosis

1. Fecal incontinence

2. Urinary incontinence