Polydactyly (Extra Digits)

What is Polydactyly?

Polydactyly is the medical term for having extra fingers or toes (digits). You might also see it referred to as hyperdactyly. It’s one of the most common birth defects that affects babies’ hands and feet.

Polydactyly that causes extra fingers to form on your child’s hand is a form of congenital hand difference.

Your healthcare provider will diagnose your baby with polydactyly using an ultrasound before they’re born or with a physical exam right after they’re born. How it’s treated depends on where your child’s extra digits are located.

Polydactyly types

Your provider will classify the polydactyly your baby is born with depending on where they have extra fingers or toes. The types of polydactyly include:

• Preaxial (radial/tibial) polydactyly: An extra thumb or big toe.
• Central polydactyly: An extra finger or toe near the middle digits — between the index, middle or ring fingers or any of the toes that aren’t the big or pinkie toe.
• Postaxial (ulnar/fibular) polydactyly: An extra pinkie finger or toe

Your provider might refer to your baby’s polydactyly with different terms.

Providers sometimes refer to extra big toes as tibial polydactyly and extra pinkie toes as fibular polydactyly. Extra thumbs are sometimes called radial polydactyly and extra pinkie fingers are ulnar polydactyly.

No matter which type of polydactyly your child has, your provider will usually diagnose it right after your baby is born.

Who does polydactyly affect?

Polydactyly can affect any newborn baby.

African American babies are 10 times more likely than white babies to be born with polydactyly. Babies assigned male at birth (AMAB) are more likely to be born with polydactyly than those assigned female at birth (AFAB).

Your child might be more likely to develop it if you have a family history of genetic disorders — especially if any of your immediate relatives (like your biological grandparents, parents or siblings) were born with extra fingers or toes.

Being born with extra digits doesn’t guarantee your child will have developmental disorders or any other conditions.

How common is polydactyly?

Around 1 in 1,000 babies born each year has some form of polydactyly.

Even if it’s one of the most common congenital conditions (conditions present from birth), these issues as a whole are still relatively rare. Talk to your provider if you’re concerned about your baby’s likelihood of being born with a congenital condition.

How does polydactyly affect my baby’s body?

Polydactyly itself might have little or no effect on your child’s body. Having an extra finger or toe isn’t dangerous. The extra digits themselves won’t cause your baby any symptoms or discomfort.

If your baby is diagnosed with a genetic disorder or other birth irregularities at the same time as polydactyly, those other conditions might have a lifelong impact on their growth and development.

What are the symptoms of polydactyly?

The only symptom of polydactyly is your child having more than five fingers or toes on their hand or foot. The extra digits will be visible at their birth.

Depending on which type of polydactyly your baby has, their extra fingers or toes might be fully developed and look like the rest of their digits. However, the additional digits are usually less developed than typical fingers or toes and might be attached by only skin or nerves.

What causes polydactyly?

Polydactyly is caused by disruptions to your baby’s genes while they’re developing. Genes are the biological building blocks that parents pass down to their children. They contain instructions for the growth and function of each cell in your body.

Anything that interrupts or changes a gene while your baby is developing can cause changes in their body. Sometimes these changes are things we never notice, and other times they cause issues like polydactyly and other congenital conditions.

If something affects the genes that are responsible for developing your baby’s limbs, hands and feet, there’s a chance they might be born with polydactyly. Genetic disorders can interfere with these genes, but so can environmental factors (things that happen to or around a pregnant person).

Is polydactyly dominant or recessive?

Studies have found that some forms of polydactyly are dominant traits. This means that if one biological parent carries the genetic code for it, their babies have a 50% chance of being born with polydactyly.

How is polydactyly diagnosed?

Your provider will diagnose polydactyly either before your baby is born with an ultrasound test or when your baby is born. They’ll identify any extra digits on your child’s hands or feet, and will diagnose a type of polydactyly.

Your baby might need an X-ray of their hand or foot before your provider treats the polydactyly.

Genetic testing for polydactyly

If you have a family history of a genetic disorder, genetic counseling can help you decide if genetic testing is appropriate for you. This can screen for any issues, including the genetic mutations that cause polydactyly.

In many cases, carrying mutations doesn’t mean your children are certain to develop a genetic disorder. Genetic counselors can explain your risk, and if there are steps you can take to protect your health or lower your risks of passing certain genetic issues on to your children.

How is polydactyly treated?

Polydactyly is usually treated by removing the extra digit from your child’s hand or foot. How it’s removed depends on where the extra digit is.

Surgical ligature

If your child has an extra finger on their hand, they might only need what’s called a surgical ligature. Your provider will tie a tight string or band around the base of the extra finger that cuts off its blood supply. A week or two later, the extra finger will fall off.

This process won’t hurt your baby or endanger blood flow to their other fingers or the rest of their body. Your provider will give you specific instructions to protect your baby’s hand during and after this process.

Surgical ligature is usually only used if your baby’s extra finger doesn’t have any bones or other connective tissues developed in it.

In-office excision

Your provider might remove your baby’s extra digit during an office visit. This is called an in-office excision. Your provider will numb the skin around your child’s extra digit with an injection. Then they’ll use a cautery device to remove the extra finger or toe. This technique uses a handheld device (probe) similar to a pen. An electric current heats the tip. This lets your provider seal off the skin around the extra digit while they’re removing it.

Your baby won’t feel anything while the extra digit is removed. The numbing injection might make them slightly uncomfortable, but they won’t feel any pain during the excision.

In-office excision is only an option if the extra digit isn’t connected to the rest of your baby’s hand or foot by bones.

Polydactyly surgery

If your baby’s polydactyly is on their feet — or if they’re not a good candidate for surgical ligature or in-office excision — they’ll need their extra digit surgically removed.

What type of surgery your child will need depends on which type of polydactyly they have and how developed the extra digit is.

Your provider might not recommend surgery to remove an extra digit until your baby is around a year old. They’ll explain which type of surgery your child will need and what to expect.

How long does it take to recover from polydactyly treatment?

It depends on which type of treatment your child needs. However, both surgical ligature and polydactyly surgery have quick recovery times. Your provider or surgeon will tell you how to care for your baby’s hand or foot after their extra digit is removed.

How can I prevent polydactyly?

You can’t prevent genetic conditions like polydactyly from developing during your pregnancy.

Polydactyly — and other genetic conditions — are linked to certain environmental factors, including:

• Drinking alcohol.
• Smoking or using tobacco products.
• Using recreation drugs.

Talk to your provider about what you should avoid eating, drinking or doing while you’re pregnant.

What can I expect if my baby has polydactyly?

You should expect your baby to make a full recovery from having an extra digit removed. No matter which type of polydactyly your baby is diagnosed with, removing their extra finger or toe will have no impact on their future growth or development.

If their polydactyly was caused by (or diagnosed alongside) another birth irregularity or genetic condition, your child might need other kinds of treatment or care. Talk to your provider about what to expect.

When should I see my healthcare provider?

Talk to your provider if you notice any changes in your baby’s hands or feet. Visit your provider if the site the extra digit was removed from has any of the following symptoms:

• Bleeding.
• Discoloration.
• Swelling.
• Discharge or leaking fluid.
• Your baby is in pain or seems unusually agitated.

What questions should I ask my doctor?

• What type of polydactyly does my baby have?
• Do they have any genetic conditions?
• How will you remove the extra digits?
• How old will they be when you remove the extra digit?
• How should I care for their hand or foot after the digit is removed?

A note from Cleveland Clinic

It might be surprising to see an extra finger or toe after your baby is born, but polydactyly is extremely treatable. Your child will have no long-term impacts from having the extra digit removed, and polydactyly doesn’t mean they’ll have any other developmental complications.

Talk to your healthcare provider about genetic conditions, and ask them if you should get screened. They’ll help you understand what you need to know before your baby is born.