What symptom is commonly associated with pinworms?

Itching at the rectum is the symptom most commonly associated with pinworms. This uncomfortable sensation occurs primarily during the night as female pinworms migrate to the anal area to lay their eggs. This nocturnal activity can lead to significant itching, prompting individuals, particularly children, to scratch the area, which may further contribute to irritation or secondary infections.

The other options represent symptoms more associated with different conditions or more severe gastrointestinal issues. Severe abdominal cramps are typical of various intestinal disorders but are not specifically indicative of pinworm infection. Heavy bleeding is not a symptom of pinworm infection and would warrant investigation for other causes. Painful urination usually relates to urinary tract issues rather than an infection like pinworms, which predominantly affects the gastrointestinal tract.