Microtia and atresia

Microtia happens more often in boys than in girls. It usually affects one side (unilateral microtia) and more often affects the right ear than the left. About 1 in 10 children with microtia are affected on both sides (bilateral microtia).

There are 3 types of microtia.

Lobular type microtia

The outer ear (pinna) is present but small and underdeveloped (peanut shaped). This is the most common type of microtia.

The ear canal is usually absent or underdeveloped (atresia).

Conchal type microtia

The outer ear is present and has a conchal bowl (middle part of the ear cartilage), but it is much smaller than normal. The upper part is often underdeveloped.

The ear canal is present but may be very narrow (canal stenosis) or have a blind ending with no eardrum (atresia).

Small conchal type

The ear is smaller than usual but the key features of the outer ear are present. They may have small differences in shape or form, such as a small conchal bowl.

The ear canal is either missing (atresia) or has a narrow and blind ending.

Microtia or atresia happens when the outer part of the ear doesn’t develop fully during the early stages of pregnancy. It is not caused by anything the mother did or didn’t do before or during the pregnancy.

Medical research has suggested that microtia or atresia may sometimes be caused by:

• certain prescribed medications taken during pregnancy
• genetic factors (1 in 10 children with microtia or atresia have another family member with the same condition)
• environmental factors.

However, it’s usually a random, one-off event. One baby in every 6,000 births is affected by microtia.

If your child is affected by microtia and atresia, you should be referred to a specialist multidisciplinary team (a team of professionals with specialised skills and expertise). This team will include doctors, nurses and surgeons who can work with you to support your child. The specialist multidisciplinary team will explore the possible causes of your child’s microtia or atresia.

In some cases, microtia and atresia can be part of a syndrome (a collection of signs or symptoms that doctors recognise as being related). Your doctor may offer you a range of medical tests to rule out any medical conditions. These tests are optional, so you don’t have to take them if you don’t want to.

If you have any concerns about your child’s treatment, you can check the UK Standards for the Management of Patients with Microtia and Atresia (Microtia UK).

Microtia and atresia can cause different types and levels of deafness. The most common type is conductive deafness, caused by differences in the structure of the middle ear.

Most children with unilateral microtia or atresia have typical hearing in their unaffected ear. However, they may be affected by glue ear, a common childhood condition which causes temporary deafness. If a child with unilateral microtia or atresia develops glue ear in their fully developed ear, this may need to be managed by the specialist multidisciplinary team.

Children with microtia and atresia should have regular hearing tests to make sure any changes to their hearing are picked up early.