ANORECTAL MALFORMATION

ANORECTAL MALFORMATION

Anorectal malformation

Introduction :

It is a Congenital defect.Anorectal malformations occur in approximately 1 per 5000 live births. It comprises several forms of imperforate anus , which are often associated with the anomalies of the genitourinary and pelvic organs.In most cases, anorectal malformations present as an absence of an anus in its normal position.

It may occur in isolation or as a part of the VACTERL or VATER syndrome:

V - Vertebral anomalies

A - Anal atresia

C - Cardiovascular anomalies

T - Tracheoesophageal fistula

E - Esophageal atresia

R - Renal (Kidney) and/or radial anomalies

L - Limb defects

Types of Anorectal malformation

A persistant cloaca

Is a complex anorectal malformation in which the rectum , vagina and urethra drain into a common channel that opens into the perineum via usual perineal site

In patients with persistent cloaca, abdominal examination may reveal a mass that likely represents a distended vagina (hydrocolpos),

Cloacal extrophy

Is a rare , severe defect in which there is externalization of the bladder and bowel through the abdominal wall.

I Classification(Wong’s)

        

Level	Male	Female
High	•      Anorectal agenesis •      with rectoprostatic     urethral  fistula •      without fistula •      Rectal atresia	•      Anorectal agenesis  •      with rectovaginal fistula •      without fistula •      Rectal atresia
Intermediate	•       Rectobulbar uretral fistula •      Agenesis without fistula	•       Recto vestibular fistula •      Agenesis without fistula
Low	•  Anocutaneous fistula •  Anal stenosis •  Rare malformation	•      Anocutaneous fistula •      Anal stenosis cloacha •      Rare malformation

II classification (Marlow)

•      Stenosis of the anus : in which there is a stricture may be at the anus , at levels 1to 4 cm above from the anus, or extend the entire length of the anus

•      Anal membrane atresia : in which a persistant anal membrane produce the obstruction, behind which meconium can be seen

•      Anal agenesis : in which there is imperforate anus, possibly seen as dimple, with a rectal pouch end blindly  some distance above the anus. This accounts for 80 % of anorectal malformation

•      Rectal atresia: in which there is normal anus and anal pouch, with the rectal pouch ending blindly  in the hollow of the sacrum

Dignosis

•      Check the patency of  the anus & rectum: routine

•      Check for the passage of the meconium

•      Inspection of the perineal area

•      Presence of meconium in the perineum may not exclude the disease

•      If meconium in the urine suspect rectourethral fistula

•      Anal stenosis may not be evident till the child grow old with h/o difficult defecation, abd . Distension and ribbon like stool 

•      Abd  ultra sound

•      IVP

•      Voiding cysto - urethrogram- high defect

•      If a syndrome is suspected cardiac evaluation, spinal fims
 Early treatment

•      For neonates born with an ano-rectal anomaly, early treatment is crucial.

•      During the first 24-48 hours of life in a newborn with an ano-rectal malformation, the following 2 questions should be answered:

•      Does the newborn have any associated life-threatening anomalies that need to be addressed immediately?

•      Should the neonate undergo a primary procedure without a protective colostomy, or should he or she undergo a protective colostomy with definitive repair at a later date?

•      The surgeon must also determine whether female neonates have a dilated vagina, if it should be drained, and whether urinary diversion is required. These maneuvers are intended to prevent sepsis and metabolic acidosis

Treatment

•      Rectal stenosis : manual dilatation later imperforate membrane can be excised

•      Reconstruction of anus in proper position is the goal of surgical treatment

•      Malformations of the lower rectum often can be corrected by simple dilatation or a minor perineal procedure

•      Infants with high malformation may need temp. colostomy in neonatal period

The indications for colostomy compared with anoplasty based on sex

Newborn boys

           Anoplasty - Rectoperineal fistula

           Colostomy - Rectobulbar urethral fistula, rectoprostatic urethral fistula, rectovesical           fistula, imperforate anus without fistula, rectal atresia

Newborn girls

         Anoplasty - Rectoperineal fistula

         Colostomy - Rectovestibular fistula, imperforate anus without fistula, persistent cloaca,       rectal atresia, rectovaginal fistula

Postoperative management

•      The posterior sagittal incision is relatively painless.

•      In patients with a rectourethral fistula, the Foley catheter usually stays in place for approximately 5-7 days. Occasionally, a longer period is required.

•      If a laparotomy was necessary, the patient may require a period of fasting and nasogastric decompression.

•      At 2 weeks' postsurgery, anal calibration is performed, followed by a program of anal dilatations. The anus must be dilated twice daily, and the size of the dilator is increased every week. The final size to be reached depends on the patient’s age.

•      Once the desired size is reached, the colostomy may be closed.

•      Dilatations are continued afterward according to a prescribed protocol.

•      Dilatations are a vital part of postoperative treatment to avoid an anoplasty stricture.

•      After colostomy closure, severe diaper rash is common, because the perineal skin has never before been exposed to stool.

Nursing consideration

•      Identification of undetected anorectal malformations

•      A poorly developed anal dimple , a genitourinary fistula  or  vertibral anomalies suggest a high lesion

•      If meconium not passed within 24 hour care should be taken

Preoperative  care

•      Diagnostic evaluation

•      Decompression

•      I/V fluids

Post operative care

 Goal

•      Prevent healing without any infection or complication

Post. op

•      Keep the anal area clean – perineal care

•      Temporary dressing and drain to manage continuous passage of stool

•      Protective ointment such as zinc oxide and occlusive dressing such as hydrocolloids to decrease skin irritation from frequent

•      Position ; side lying prone position with hips elevated or a supine position with legs suspended at a 90º angle to the trunk to prevent pressuse on the perineal sutures

•      Infant is given formula when  normal peristalsis observed

•      In the meantime NG tube for abd. Decompression and IVF

Family support , discharge planning and home care

•      Prevent constipation

•      Encourage breast feed

•      If cows milk is given laxatives should be given

•      Bowel habit training, diet modification, and administration of stool softners or fibre are important

•      Support and reassurance

•      Perineal and wound care& colostomy care

•      Observe stool pattern