Surgery MCQs Q46

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PAEDIATRIC SURGERY • ANOMALIES

A newborn fails to pass meconium and is noted to have an absent anal opening on perineal examination. Further evaluation is planned to classify the anomaly and guide management.

Which of the following statements regarding imperforate anus (anorectal malformations) is true?

A Affects males more frequently than females

B Results in passage of meconium only in first 24 hours

C The rectum usually ends in a blind pouch

D Is divided into high and low variety for the purpose of treatment

E Is always associated with absent sacrum

The correct answer is Is divided into high and low variety for the purpose of treatment.

Decoding the Stem

1

CLUE "Congenital absence of anal opening"

TRANSLATION Anorectal malformation (ARM) spectrum.

Detailed Explanation

✅ Correct Option (Classification): Anorectal malformations are traditionally divided into high, intermediate, and low varieties based on where the rectum ends relative to the levator ani (puborectalis muscle). This classification is vital for surgical planning: low lesions are often repaired via a simple anoplasty, whereas high lesions typically require a staged approach (diverting colostomy followed by pull-through).

❌ Why other options are incorrect:

→ Males vs Females: ARM affects both sexes roughly equally, though the specific types of associated fistulas differ significantly between them.

→ Meconium passage: Infants usually fail to pass meconium altogether, or meconium may appear at an abnormal site (urethra in males, vestibule in females) via a fistula.

→ Blind pouch: While the rectum ends "blindly" in terms of a normal anus, it most commonly connects to a neighboring structure via a fistula rather than being a completely isolated pouch.

→ Sacrum: While sacral agenesis or anomalies are common (part of VACTERL), the sacrum is not always absent.

🧠 High-Yield Pearls

✔ Key Concept: Level of the lesion (High vs. Low) determines the surgical strategy.

✔ Association: VACTERL is found in up to 50% of patients with ARM.

✔ Physical Exam: Perineal inspections and urinalysis (for meconium/fistula) are the first steps.

Integrated Clinical Questions

1. What is VACTERL association?

→ Vertebral, Anal, Cardiac, Tracheo-Esophageal, Renal, and Limb anomalies.

2. Most common fistula in males?

→ Rectourethral fistula (specifically bulbar or prostatic urethra).

3. Most common fistula in females?

→ Rectovestibular fistula.

4. Initial investigation?

→ Invertogram (or Wangensteen-Rice view) or a cross-table lateral X-ray in the prone position after 24 hours of life.

5. Definitive treatment?

→ Posterior Sagittal Anorectoplasty (PSARP), also known as the Pena procedure.

⚡ Exam Pearls

• • High vs Low classification = fundamental concept for management.
• • Always look for associated VACTERL anomalies.
• • Meconium in urine = Rectourethral fistula (High/Intermediate lesion).
• • Surgical planning relies on the distance of the rectal pouch from the perineal skin.

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