Anorectal abscess

A 45-year-old male presents with severe, throbbing perianal pain and fever, but physical examination does not reveal any obvious signs of inflammation or infection around the anus. Which of the following scenarios most warrants the use of imaging to identify an anorectal abscess?

1: When there is visible erythema and fluctuance
2: When the abscess has spontaneously drained
3: When the abscess is not apparent on external exam
4: When there is a history of pilonidal cyst