Syndactyly (Webbed Toes or Fingers)

Syndactyly (pronounced “sin-dak-tuh-lee”) is the medical definition for having webbed fingers or webbed toes (digits). Syndactyly in your baby’s fingers is a form of congenital hand difference.

Syndactyly and the related condition polydactyly are both birth defects (congenital conditions) 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.

Your baby’s healthcare provider will probably diagnose your baby with syndactyly right after they’re born. Treatment will depend on the type of syndactyly, but will most likely involve surgery to separate your baby’s digits.

While the idea of surgery on your baby may sound scary, it’s important to listen to your provider’s recommendation. Without separating your child’s digits, there’s a chance they’ll have a harder time using them as they grow. This is especially true for fingers that are fused together.

Types of syndactyly

Your baby’s healthcare provider may use a few terms to describe the syndactyly of their toes or fingers. These are:

• Simple syndactyly: Simple syndactyly is the term for fingers or toes that are fused together by skin and soft tissues only.
• Complex syndactyly: Complex syndactyly means that your child’s bones, nerves and blood vessels are fused together in addition to their skin and soft tissues.
• Complete syndactyly: Complete syndactyly means the whole length of your child’s digits is fused together, from the base to the nailbed.
• Incomplete syndactyly: Incomplete syndactyly means the fusion only runs along part of their digits.

Symptoms of syndactyly

The only symptom of syndactyly is your child having two (or more) fingers or toes fused together. This difference in the anatomy of your child’s hands or feet will be visible at birth. Half of syndactyly cases occur bilaterally, which means it affects digits on both hands or both feet.

Syndactyly causes

A disruption to your baby’s genes during development causes syndactyly. 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 the 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 congenital conditions.

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

Genetic disorders that may cause syndactyly include:

• Apert syndrome
• Carpenter syndrome
• Down syndrome

Risk factors for syndactyly

Syndactyly can affect any newborn baby, but some are more likely than others to develop the condition. Risk factors for developing webbed fingers or toes include:

• Sex: Male babies are twice as likely to develop syndactyly as female babies.
• Ethnicity: White babies are more likely to be born with syndactyly than babies of other ethnicities.
• Family history: Your baby may be more likely to have syndactyly if you have a biological family history of genetic disorders, especially if any relatives were born with webbed fingers or toes.

How doctors diagnose syndactyly

Your baby’s healthcare provider will diagnose syndactyly when they’re born. The provider will identify any webbed fingers on your baby’s hands or webbed toes on their feet.

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

Your baby may need an X-ray of their hand or foot to determine the type of syndactyly before their provider treats it.

Genetic testing for syndactyly

If you have a biological family history of webbed fingers or webbed toes, you may want to consider genetic counseling. A genetic counselor 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. They can also tell you 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?

Treatment for syndactyly depends on the type of condition your baby has. Some children with mild cases of webbed fingers or toes may never need surgery. This is usually only for syndactyly affecting toes. 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 their hands.

Most babies are treated for syndactyly when they’re about a year old. A surgeon will surgically separate your child’s webbed toes or fingers (including any fused bones and other tissue). They’ll usually also perform a skin graft to cover the separated digits.

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

When should my baby see their healthcare provider?

Talk to your baby’s healthcare provider if you notice any changes in your baby’s hands or feet. Visit the provider if your child is in pain or their separated digits have any of the following symptoms:

• Bleeding
• Discharge or leaking fluid
• Discoloration
• Swelling

What can I expect if my baby has syndactyly?

You should expect your baby to make a full recovery from having their webbed toes or fingers 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 the syndactyly was caused by (or diagnosed alongside) another congenital or genetic condition, your child may need other kinds of treatment or care. Talk to your baby’s healthcare provider about what to expect.