What is a pilonidal cyst, as seen in Call the Midwife?

One such patient is 17-year-old Michael Leeks (Jack Archer), a hotel employee who asks Turner to check out a painful area at the bottom of his spine, which Turner subsequently diagnoses as a pilonidal cyst.

But what is a pilonidal cyst? And how are they treated? Here's everything you need to know about the condition as seen in Call the Midwife.

What is a pilonidal cyst?

A pilonidal cyst is a pocket in the skin, usually located around the tailbone area, usually containing hair and skin – with pilonidal meaning nest of hair.

They're typically caused when a hair punctures the skin and becomes embedded within it, and commonly occur in people who sit down for long periods of time with young men more likely to develop them. Excessive sitting can increase pressure on the coccyx area which can inflame an existing cyst in the area.

Pilonidal cysts are related to pilonidal sinuses – a small hole or tunnel in the skin that occurs at the top of the buttocks which can turn into a pilonidal cyst.

Most people with a pilonidal cysts tend to be asymptomatic and won't need treatment, but if the cyst becomes infected, it can become painful and uncomfortable.

What are the symptoms of a pilonidal cyst?

While many with pilonidal cysts won't notice them, they definitely will if the cyst becomes infected. The cyst becomes a painful, swollen abscess, surrounded by reddening skin and usually leaking with foul-smelling pus or blood.

If someone notices any of these symptoms, they must visit their doctor for treatment.

How are pilonidal cysts diagnosed?

In Call the Midwife, 17-year-old Michael visits Dr Turner with something that's troubling him at the bottom of his spine and Dr Turner diagnoses it as a pilonidal cyst.

This is similar to how a modern-day doctor who diagnose a pilonidal cyst – they would take a look at the affected area and prescribe treatment depending on the symptoms and the size of the cyst.

Can pilonidal cysts be treated?

Yes – infected pilonidal cysts are treatable with antibiotics. Your doctor may also drain the cyst if it's filled with pus, which may require a minor surgery under either general or local anaesthetic.

If a pilonidal cyst keeps returning and covers a large area, it may require surgery to cut the sinus out and a procedure to clean it.

Call the Midwife continues on Sundays at 8pm on BBC One. While you’re waiting, take a look at the rest of our Drama coverage, or check out our TV guide.