Which duct is blocked in a child with chronic dacryocystitis undergoing a dacryocystorhinostomy?

Chronic dacryocystitis in children is often due to obstruction of the nasolacrimal duct, which is the pathway that allows tears to drain from the eye into the nasal cavity. In cases where this duct is blocked, tears accumulate in the lacrimal sac, leading to infection and inflammation, known as dacryocystitis.

During a dacryocystorhinostomy, a surgical procedure is performed to create an alternative drainage pathway for tears by connecting the lacrimal sac directly to the nasal cavity. The objective of this surgery is to bypass the obstructed nasolacrimal duct and relieve the symptoms associated with chronic dacryocystitis.

Given this context, the correct answer identifies the blocked duct as the lacrimal duct, specifically the nasolacrimal duct, which is critical to the development of the condition in question. Other ducts listed, such as salivary duct, common bile duct, and ureter, are not involved in the lacrimal drainage system and do not relate to the pathophysiology of chronic dacryocystitis.