The incidence of ARM 2-2.5/10,000 live births. It varies across the world. About 3.8-6.13/10,000 live births (Europe & North America). 5.5/10,000 live births in South Africa. Occurs in both boys and girls. High anomalies are more common in boys. Generally, boys are more affected than girls. Our experience in Nigeria/Africa 1988 – 2013 indicate that most common cause of neonatal intestinal obstruction (49% - 69%). ARM indicate frequent indication for operative emergency neonatal surgery (44%).

Pathogenesis of ARM in Humans

This remains controversial and commonly misunderstood. Several theories based on normal development (Not confirmed by studies). Abnormal development of urorectal septum resulting in incomplete separation of cloaca into urogenital & anorectal portions. Current evidence (animal models/study of foetuses with severe malformations) indicate:

• Deficiency in dorsal component of cloacal membrane & adjacent dorsal cloaca.

• Extent of deficiency determines the severity of anomaly.

Genetic Considerations

ARM is reported to occur in families, suggesting possible genetic aetiology. Consanguinity may play a role. In 8%, genetic factors play a clear role. Chromosomal & multiple congenital anomaly syndromes like Trisomy, Kaufman-McKusick, Lowe, Currarino etc.

Categorizations

• Non-syndromic: Only pathological finding.

• Sporadic: Only one individual in family affected.

• Syndromic: As part of more complex phenotypes.

• Familial: More than one individual in same family.

There are three classifications currently in use:

1. Wingspread Classification: This classification is based on embryologic understanding & anatomy. 2.5cm (PC line) from expected anal position used as cut off mark.

2. Pena Classification (widely used): It is based on therapeutic decision making. 1cm (level of Coccyx) from expected anal position used as cut off mark (Figure 1).

3. International (Krickenbeck) Classification: Is based on consensus around the world. This classification helps in diagnostic evaluation, follow up and evaluation of outcome, and comparison of results.

Figure 1: Pena Classification

Associated anomalies are not unusual findings in addition to diagnosis of Anorectal malformations in about 58% - 60% of affected children. These associated anomalies include cardiovascular anomalies, gastrointestinal, vertebral and genitourinary defects.

In another study, it was reported that the most frequent malformations associated with ARMs are the urogenital anomalies. Other common associated anomalies are the VACTERL associations (V- Vertebral, A-Anorectal, C-Cardiac, TE-Tracheo-Esophageal, R-Renal, L-Limbs)

It was also shown by Amit et.al that associated anomalies with ARMs were seen more with high types (78.08%) than in patients with low types of ARMs (37.31%). About 58.5% of all the patients had associated anomalies which include those of urinary system (37.14%), vertebral system (34.28%), skeletal system and other vertebral (15.17%), genital system (14.29%), cardiovascular system (12.14%), gastrointestinal system (10.70%) and spinal cord (10.00%).

Goals of Treatment ARMs

These are to achieve intestinal decompression, create normally sited anus, achieve normal defaecation, preserve normal voiding and renal function and to preserve sexual and reproductive function).

Objectives at Initial Presentation

• Resuscitate.

• Identify associated anomalies (some may be life threatening).

• Define the nature/type of anorectal anomaly.

• Determine correct initial operation: Colostomy or anoplasty or posterior sagittal anorectoplasty (PSARP).

Modes of presentation

• Neonatal period: They usually present with intestinal obstruction, absent anal opening, abnormal opening in the perineum, passage of meconium from vulva or passage of meconium or gas in urine.

• Older child: This is common among girls

• Other History worthy of asking are antenatal history, family and consanguinity.

General condition includes dehydration, hypothermia, anaemia, jaundice and cyanosis.

Abdominal & Perineal Examination

• The abdomen is often distended, there is a suprapubic mass (hydrometrocolpos) and other masses could be seen too.

• Perineum: Examination should be done meticulously and carefully with good lighting. Is the anus present or not? Where is the anal opening? Vestibule? Perineum? Is the meconium in in the subepithelial tract+ with a ridge of tissue? (Bucket-Handle deformity). Check for skin tags/bridges and flat bottom

Exclude Associated Anomalies VACTERL-H

Initial

1. Plain abdominal X-rays exclude bowel perforation in those presenting late. Identifies the level of anomaly.

2. Cross-table lateral X-ray: This is only done if there is no clinical evidence of fistula. The bowel gas to skin distance is ≤1cm or >1cm. This shows the level of blind ending bowel whether below or above the coccyx.

3. Sacral X-ray: This shows if the sacrum is absent or hemi-sacrum. >2 missing pieces indicate poor prognosis.

4. Distal colostogram (Pressure augmented)

5. Renal ultrasonography

6. Echocardiography

7. Spinal US/MRI can show tethered cord.

8. Blood tests: It is also crucial to ascertain the patient is fit for surgery. Electrolytes and complete blood count.

▫ Resuscitation & Initial Management.

▫ Definitive treatment.

▫ Follow up & Evaluation of Outcome.

▫ Continuing & further treatments.

Resuscitation & initial treatment

• Correct fluid, electrolyte depletion and anaemia.

• Decompress intestines.

Colostomy (Divided or Loop) is recommended with AMR with high anomalies, >1cm, boys with urinary fistula and in girls with vestibular or vaginal fistula.

Perineal procedure done with those with low anomalies, ≤1cm (Primary PSARP ± no stoma), boys and girls with perineal fistula (Anoplasty) and ectopic anus boys and girls (Anoplasty)

Definitive Treatment

Factors Necessary for Faecal Continence

• Normal rectal sensation.

• Normal colonic motility (rectosigmoid normally quiet for 24-48hrs).

• Good voluntary muscles/sphincteric function.

Timing of surgery: It is important to ensure normal growth and development. Optimal timing is 3-6 months but this can be done earlier or later.

Preparation: A requirement is bowel preparation, thorough cleansing of distal loop. The options are either 3-day and 1-day.

Surgical options

International Grouping of Surgical Procedures (Krickenbeck).

All accepted but: Do what works for you and you must be able to defend it.

1. Perineal procedures (anal transplant, anoplasty etc).

2. Anterior Saggital Approach (Mollard’s technique: ASARP).

3. Sacroperineal Procedure.

4. Posterior Sagittal AnoRectoPlasty (PSARP) – My preferred technique.

5. Abdominosacroperineal pull through (Stephen’s operation).

6. Abdominoperineal pull through.

7. Laparoscopic-assisted pull through.

This is the most widely practiced and accepted that gives best results. All types of anomalies can be treated this way. The entire anatomy is visualized. Anomaly can then be corrected under direct vision

Postoperative care

• Analgesia: A combination of parental and caudal

• Antibiotics

• Wound care

Dilatation regime: Implement a carefully planned regime. Use a dilator that snugly fits. This is started 10-14 days postoperative and done twice daily until the desired size for age is reached. Then dilate according to the following table (Figures 2 & 3).

Figure 2: Dilatation Regime

*Total duration: 7 months

Figure 3: *Target dilator size

*Other types of dilators available and can be used. Can improvise depending on local circumstances.

**Caliber of anus (mm) = 1.34 x body weight(kg) + 6.8

Postoperative complications

Early postoperative complications include surgical site infection and wound dehiscence

Late postoperative complications are: anal stenosis, anal stricture, mucosal prolapse, constipation and soiling/incontinence.

Bowel management: Normal continence is expected within 2½-3years. Before this age, however, there are indicators that point to good prognosis and poor prognosis

• Good prognosis: put on TOILET TRAINING

• Poor prognosis: put on BOWEL MANAGEMENT programme

Indicators for Good Prognosis

√ Good bowel movement pattern (1-3 motions per day, no soiling between).

√ Evidence of rectal sensation at defaecation (pushes).

√ Good urinary control.

Indicators for Poor Prognosis

√ Constant soiling or passing stool

√ No sensation (no pushing)

√ Urinary incontinence/dribbling of urine

Bowel (Toilet) training programme.

√ Remember: child has never passed stool that way.

√ Critical to normal bowel function.

       • Parental education & motivation.

       • Simulate normal bowel movements.

       • Sit on potty: morning & evening.

√ Start at 2 years.

√ Sit child on potty after every meal and encourage to defaecate.

√ Parents should show excitement/enthusiasm when stool is passed.

√ Reward child when stool is passed.

√ Make a game out of it so the child looks forward to it/enjoys it.

√ Avoid making it look like punishment (this will put child off).

Prognostic factors are dependent on 

• Type of anomaly: high anomalies.

• Sacral anomalies: >2 missing pieces.

• Shape of buttocks: Flat buttock.

• Postoperative complications.

The coexistence of VACTERL anomalies negatively affects not only the surgical outcome but also the bowel functioning.

In the treatment of patients born with anorectal malformations, the ultimate goal has moved from mere survival to alleviating symptoms and improving quality of life after surgical reconstruction. In spite of the technical advances in the surgical repair of anorectal malformations that have occurred over the recent years, complications that require a secondary procedure are still common. The patient’s best chance for a good functional result is when the proper operation is performed during the first definitive procedure and complications are avoided. This is especially true in those patients born with a defect that has a good prognosis. The introduction of posterior sagittal anorectoplasty has reduced significantly the number of patients requiring a reoperation for complications such as fecal incontinence over the years. This procedure provides superior exposure of the sphincter muscle complex and prevents the complete mislocation of the rectum that was seen with other techniques.