system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
The antrochoanal polyp is?
assistant
The correct answer is  Antrochoanal polyp is usually single and unilateral. More tendency to grow posteriorly and do not bleed. Unilateral nasal obstruction is the presenting symptom. Obstruction may become bilateral when polyp grows posteriorly into the nasopharynx and stas obstructing the opposite choana. (Ref - PL DHINGRA diseases of ear nose and throat, 7th edition, page no 193)