Obturer and obstruer
Here are two verbs that should not be confused. "Obturer" (to obturate) means "to plug a hole/close an opening" while "obstruer" (to obstruct) means "to prevent passage, to block/barricade".
The similar pronunciation of obstructing and obturating verbs, and the fact that they have a common meaning, can lead to confusion. In linguistic terms, this is called a paronym.
Lorsque le prélèvement de sang est terminé, le flacon doit être obturé.
Un éboulement a obstrué le tunnel.