Grommets are most commonly used in the treatment of glue ear in which
(They are also used very occasionally in recurrent ear infection and the occasional patient with symptoms from a poorly functioning eustachian tube in which glue ear is not a persistent problem.)
In most cases however, a conservative, non surgical approach is the most appropriate as glue ear usually resolves without treatment by 6-7 years and non-treatment is associated with few medical complications. Surgery is recommended for a small proportion of patients with significant and persistent symptoms.
A grommet is a tiny plastic tube shaped like a cotton reel which is inserted into a small slit in the eardrum (called a myringotomy) in order to allow air into the middle ear. It does not act as a drain but ventilates the middle ear (i.e. the part behind the eardrum) because the normal route for ventilation, which is the eustachian tube, is blocked.
Grommets are designed as a temporary measure to overcome a blocked eustchian tube while growth takes place and the child "outgrows" the blocked eustachian tube.
The type of grommet most commonly used in first time surgery (the Shepherd or Shah pattern) is designed to only stay in the ear for about a year, though this time is very variable. There are tubes designed to stay longer which have a larger diameter or a larger flange which probably have a slightly higher chance of leaving a hole (perforation) when the tube comes out. There are also tubes designed to stay for 2-5 years that have a different shape with a "T" piece behind the eardrum. These have a significantly higher chance of leaving a perforation, but are still appropriate in some children.
This is a misunderstanding as they are designed to come out at about a year. If the eustachian tube remains blocked, fluid re-accumulates and the child is once again symptomatic it may be advisable to replace the grommets. The majority of children will only require one set of tubes.
The evidence is rather contradictory in that studies looking at children swimming have not shown any increase in ear infections. However when grommets are placed in models of the human ear canal, water will pass through with a pressure of water equivalent to only a couple of feet. These studies also show that soapy water may get through the grommet.
Initially I would suggest allowing your child to swim, bath and hair-wash without protection. If your child does have a number of episodes of discharge then it is probably sensible to take additional precautions. A swim hat does not stop water from getting into the ear canal but may reduce the pressure. Most preformed over-the-counter ear plugs are poor and I recommend silicone malleable ear plugs. Individually moulded plugs are effective but need to be replaced as the ear grows and are expensive to lose. A neoprene head band is added security for either type of plug.