**Core Concept:** Enuresis refers to the involuntary leakage of urine during sleep in children who are still not fully toilet-trained. The age at which enuresis is diagnosed varies based on the child's developmental stage.

**Why the Correct Answer is Right:** Enuresis is typically diagnosed when a child experiences nighttime urinary accidents after the age of 5 years. This age is considered the normal age at which most children become fully toilet-trained. Delayed toilet training could imply a problem such as sleep-related urine leakage disorder (SRUD), which is classified into primary and secondary enuresis.

**Why Each Wrong Option is Incorrect:**

A. 4 years: This is too early, as most children achieve toilet control before the age of 4 years.
B. 7 years: Although some children may become toilet-trained by this age, 5 years is considered more appropriate for diagnosing enuresis.
C. 9 years: This is still too early, as many children may not reach complete toilet control by this age.
D. 12 years: This is too late and not specific for enuresis diagnosis, as some children may remain enuretic beyond this age.

**Why the child is diagnosed after 5 years:** Diagnosing enuresis after the age of 5 years helps differentiate between normal developmental delays and a potential underlying issue, such as sleep-related urine leakage disorder.

**Clinical Pearl:** Enuresis is a common condition that affects approximately 10-15% of children globally. Understanding the normal toilet training milestones and recognizing the age at which enuresis should be diagnosed is crucial for accurate diagnosis and appropriate management.

**Correct Answer:** . 5 years