This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'Choanal atresia is due to the persistence of \nSelect and explain. \nA. Bucconasal membrane, B. Oropharyngeal membrane, C. Laryngotracheal fold, D. Tracheoesophageal fold', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Choanal atresia \nChoana, also called posterior nares, is an opening in the posterior part of each nasal cavity,\xa0through which the nasal cavity communicates with nasopharynx.\nChoanal atresia is a congenital anomaly characterized by closure of one or both posterior nasal cavies (i.e., choana). It is due to the persistence of bucconasal membrane.\nApproximately 60- 70% of cases are unilateral and are more common on the right side.\nBilateral cases occur in 20-30% of patients and 50% of these patients are associated with other congenital anomaly, i.e.,\nCHARGE syndrome\n→ Coloboma, Heart defects,\xa0Choanal atresia,\xa0Retarded growth,\xa0Genitourinary abnormalies and Ear defects.\nDiagnosis - Unilateral lesions go unnoticed until the child presents with persistent unilateral nasal discharge.\nThere is the absence of air bubbles in nasal discharge.\nA simple test for unilateral choanal atresia is to have the child attempt nose blowing with opposite nostril occluded by external pressure.\nFailure to detect any air movement is suspicious for complete obstruction.\nBilateral choanal atresia presents as respiratory distress in newborn and requires support immediately after birth.', 'role': 'assistant'}]