Adenoids are glands, just like tonsils in the throat, or the glands in the neck. They sit just behind the back of the nose, and can contribute to nasal blockage. If large they can also contribute to upper airway obstruction when asleep with snoring, disturbed sleep and even sleep apnoea.
It is not possible to see the adenoids looking at the front of the nose as they actually sit right at the back, behind the nose itself. The nose on each side has a front nostril, then there is the nasal cavity, which can be thought of as a pipe on each side, and then there is a back nostril, with the adenoids sitting just behind the back nostril. If the adenoids are large then they can block this back nostril.
It is also not possible to see the adenoids by looking in the mouth as they are on the back wall above the uvula (often called “the dangly bit) which sits in the middle at the back of the mouth.
In some children it is possible to assess the size of the adenoids by looking at them directly with a thin telescope passed through the nose.
If nasal blockage with nasal discharge (i.e. infection coming constantly out of the nose), is present, and thought to be due to enlarged adenoids then they can be removed by adenoidectomy surgery. (“ectomy” means “out”, so the word adenoidectomy just means removal of them). Removal is done going via the mouth, using electricity to effectively vaporise them. It takes about 20 minutes surgical time, although children are gone from the parents eyes for about an hour as safety checks and preparation in theatre add to the total time.