Alternative names 
Syndactyly; Webbing of the fingers or toes


Webbing (syndactyly) refers to the union of two or more fingers or toes, which usually only involves a skin connection between the two, but may rarely also include fusion of bones in the affected digits.

Webbing may extend partially up between the digits, frequently just to the first joint, or may extend the entire length of the digits. “Polysyndactyly” describes both webbing and the presence of an extra number of fingers or toes.


Syndactyly may be discovered during an examination of an infant or child. In its most common form, it is seen as webbing between the 2nd and 3rd toes. This form is often inherited and is not unusual. Syndactyly can also occur as part of a pattern of other congenital (present from birth) defects involving the skull, face, and bones.

Common Causes

Relatively common causes:

Extremely rare causes:

  • Apert’s syndrome  
  • Fetal hydantoin effect (mother took hydantoin during pregnancy)  
  • Carpenter’s syndrome  
  • Smith-Lemli-Opitz syndrome  
  • Pfeiffer syndrome  
  • Cornelia de Lange syndrome

Call your health care provider if
This condition is normally discovered at birth and evaluated during the newborn hospital stay.

What to expect at your health care provider’s office

The medical history will be obtained and a physical examination performed.

Medical history questions documenting your symptom in detail may include:

  • Which fingers (toes) are involved?  
  • Have any other family members had this problem?  
  • What other symptoms or abnormalities are also present?

An infant with webbing may have other symptoms and signs that, when taken together, define a specific syndrome or condition. Diagnosis of that condition is based on a family history, medical history, and thorough physical evaluation.

Laboratory studies (such as chromosome studies, enzyme assays, X-rays, and metabolic studies) may be ordered to confirm the presence of a suspected disorder.

If a diagnosis was made by your health care provider associated with the webbing, you may want to note that diagnosis in your child’s personal medical record.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.