Syndactyly (Webbed Digits)

What is Syndactyly?

Syndactyly is the medical definition for having webbed fingers or toes (digits). It’s one of the most common birth defects that affect babies’ hands and feet.

Syndactyly in fingers is a form of congenital hand difference.

Your healthcare provider will probably diagnose your baby with syndactyly right after they’re born. How it’s treated depends on which of your baby’s fingers or toes are affected and how they’re fused together.

Syndactyly vs polydactyly

Syndactyly and polydactyly are both birth defects that affect babies’ hands and feet.

Syndactyly causes two (or more) of your child’s fingers or toes to fuse together — to have webbing that connects them. Polydactyly causes extra fingers or toes to grow on your baby’s hand or foot.

Polysyndactyly is the combination of both conditions and causes babies to have both webbed and extra digits.

All of these conditions are usually diagnosed at birth and are treated as soon as it’s safe. They usually don’t have any lifelong impacts on babies after they’re treated.

Who does syndactyly affect?

Syndactyly can affect any newborn baby.

Babies who are assigned male at birth are twice as likely to have syndactyly than babies assigned female at birth. White babies are more likely to be born with syndactyly than other ethnicities.

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

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

How common is syndactyly?

Around 1 in 2,000 babies born each year has some form of syndactyly. It’s more common in toes than fingers.

Half of syndactyly cases occur bilaterally, which means it affects digits on both hands or both feet.

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

How does syndactyly affect my baby’s body?

If your baby’s digits aren’t treated by separating them, there's a chance your child will have a harder time using them as they grow. This is especially true for fingers that are fused together.

Because most cases of syndactyly are treated while your child is very young (around a year old), they might never experience any effects or even know they were born with it.

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

What are the symptoms of syndactyly?

The only symptom of syndactyly is your child having two (or more) fingers or toes fused together. The fused digits will be visible at their birth.

How your baby’s digits are fused depends on which type of syndactyly they have.

Types of syndactyly

Your provider might use a few terms to describe the syndactyly in your baby’s fingers or toes. Which type they have depends on which of their fingers or toes are affected — and how much of their digit is part of the fusion.

Simple syndactyly is the term for fingers or toes that are fused together by only skin. Complex syndactyly means your child’s bones, nerves and blood vessels are fused together too. Complex syndactyly is rarer than simple syndactyly.

Additionally, your child can have either complete or incomplete syndactyly. Complete syndactyly means the whole length of their digits are fused together, from the base to the nailbed. Incomplete syndactyly means the fusion only runs along part of their digit.

These terms are usually more for your provider to use to describe the syndactyly. No matter which type your baby is diagnosed with, your provider will explain how they can treat it.

What causes syndactyly?

Syndactyly 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 syndactyly and other birth defects.

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 syndactyly. Genetic disorders can interfere with these genes, but so can environmental factors (things that happen to or around a pregnant person).

Genetic disorders that frequently cause syndactyly include:

• Down syndrome.
• Apert syndrome.
• Poland syndrome.

Is syndactyly dominant or recessive?

Studies have found that syndactyly is a dominant trait, which means that if one parent carries the genetic code for it, their babies are much more likely to be born with it.

How is syndactyly diagnosed?

Your provider will diagnose syndactyly when your baby is born. They’ll identify any webbed digits on your child’s hands or feet, and will diagnose a type of syndactyly.

What tests will be done to diagnose syndactyly?

Syndactyly doesn’t usually need any tests to diagnose it. You should be able to see any webbed digits on your baby’s hands or feet. In fact, your provider might be able to diagnose syndactyly before your baby is born with an ultrasound test.

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

Genetic testing

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 syndactyly.

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 syndactyly treated?

Syndactyly is treated by surgically separating the fused digits. Most babies are treated for syndactyly when they’re around a year old.

A surgeon will separate your child’s fingers or toes (including any fused bones and other tissue). They’ll usually also perform a skin graft to cover the separated digits.

Your child might need to wear a splint or cast on their surgically repaired hand or foot after surgery to support their separated fingers or toes. They might also need some physical therapy to make sure their hand or foot regains its strength and can fully function after surgery.

Your provider or surgeon will tell you which kind of surgery your child will need, and what you’ll need to do after their fused digits are separated.

Nonsurgical syndactyly treatment

Some children with mild cases of syndactyly may never need surgery. This is usually only for syndactyly affecting toes. Your provider will tell you whether or not your child needs surgery to separate their digits.

It’s rare for kids not to need syndactyly surgery on their fingers because anything that restricts their ability to move can affect the overall function of your child’s hand.

How long does it take to recover from syndactyly treatment?

It depends on which type of surgery your child needs. In general, syndactyly surgery has a quick recovery time. Your provider or surgeon will tell you how to care for your baby’s hand or foot after their fingers or toes are separated.

How can I prevent syndactyly?

You can’t prevent genetic conditions like syndactyly from developing during your pregnancy. But syndactyly and other genetic conditions are linked to certain environmental factors, including:

• Drinking alcohol.
• Smoking or using tobacco products.
• Using recreational 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 syndactyly?

You should expect your baby to make a full recovery from having their fused digits separated. No matter which type of syndactyly your baby is diagnosed with, the surgery to correct it won’t impact their future growth or development.

If their syndactyly was caused by (or diagnosed alongside) another birth defect 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 your child’s separated digits have any of the following symptoms:

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

What questions should I ask my doctor?

• What type of syndactyly does my baby have?
• Do they have any genetic conditions?
• When will you separate their digits?
• How should I care for their hand or foot after surgery?

A note from Cleveland Clinic

Hearing your baby has a birth defect can be shocking. But syndactyly is very treatable, even in complex cases. The surgery to separate your baby’s fingers or toes has a quick recovery and won’t impact their ability to use their hand or foot in the future. In fact, it will help them grow and develop without any lasting effects from being born with webbed fingers or toes.

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.