Anorectal malformations (ARMs) are congenital anomalies involving the anus and rectum. They vary in severity and type, affecting the position and presence of the anal opening. The Wing Spread Classification is one of the clinical methods used to categorize ARMs based on the physical examination of the perineal area, especially the distance between the ischial tuberosities (the “wings”) and the position of the anal dimple or fistula.
Overview of Wing Spread Classification
The Wing Spread Classification divides anorectal malformations into types according to the anatomical location of the rectal pouch relative to the perineum, and the presence or absence of fistulas. It helps in planning surgical repair and predicting prognosis.
Classification Types
1. Low (Perineal) Anorectal Malformation
- The rectal pouch ends near the skin surface at the perineum.
- Usually, a thin membrane or a small fistula is present.
- The anal dimple is shallow or slightly displaced.
- The distance between the “wings” (ischial tuberosities) is normal.
- These cases are easier to repair and have better prognosis.
- Common in both males and females.
2. Intermediate Anorectal Malformation
- The rectal pouch ends higher than the perineum but below the levator ani muscle.
- The anal dimple is absent or displaced.
- The “wing spread” (distance between ischial tuberosities) may be slightly increased.
- Fistulas may communicate with the urinary tract (males) or vagina (females).
- Requires more complex surgical correction.
3. High (Supralevator) Anorectal Malformation
- The rectal pouch ends above the levator ani muscle.
- The anal dimple is absent.
- The distance between the “wings” is widened due to muscle and bone malformation.
- Often associated with fistulas to the urinary tract in males or urogenital tract in females.
- Surgical repair is more complicated with guarded prognosis.
Clinical Examination Using Wing Spread
- The neonate is placed in a prone position with hips flexed and abducted to expose the perineum.
- The examiner assesses the inter-ischial distance (“wing spread”) using fingers or calipers.
- The perineum is inspected for an anal dimple or fistulous openings.
- Palpation may be done to feel for a rectal pouch or muscle tone.
Significance of Wing Spread Classification
- Helps in identifying the level of malformation.
- Guides the choice of surgical approach (e.g., posterior sagittal anorectoplasty for low and intermediate types).
- Predicts continence outcome depending on muscle development.
- Assists in counseling parents regarding prognosis and postoperative care.
Summary Table
| Type | Location of Rectal Pouch | Wing Spread Distance | Fistula Presence | Surgical Implication |
|---|---|---|---|---|
| Low (Perineal) | Near skin surface at perineum | Normal | Small perineal fistula | Simple repair; good prognosis |
| Intermediate | Below levator ani muscle | Slightly increased | Urogenital fistulas possible | Complex surgery needed |
| High (Supralevator) | Above levator ani muscle | Widely increased | Urinary or urogenital fistulas | Difficult repair; guarded outcome |
Conclusion
The Wing Spread Classification is a practical tool for assessing anorectal malformations based on perineal anatomy and muscle development. It provides valuable information for diagnosis, surgical planning, and prognosis in neonates with ARM.