Webbing of the fingers and toes is called syndactyly. It refers to the connection of two or more fingers or toes. Most of the time, the areas are connected only by skin. In rare cases, the bones may fused together.
Syndactyly is often found during a child’s health exam. In its most common form, webbing occurs between the second and third toes. This form is often inherited and is not unusual. Syndactyly can also occur along with other birth defects involving the skull, face, and bones.
The web connections most often go up to the first joint of the finger or toe. However, they can run the length of the digit.
"Polysyndactyly" describes both webbing and the presence of an extra number of fingers or toes.
More common causes include:
Very rare causes include:
Cornelia de Lange syndrome
Use of the medication hydantoin during pregnancy (fetal hydantoin effect)
When to Contact a Medical Professional
This condition is normally discovered at birth while the baby is in the hospital.
What to Expect at Your Office Visit
The health care provider will perform a physical exam and ask questions about the child's medical history. Questions 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 that together may be signs of one syndrome or condition. That condition is diagnosed based on a family history, medical history, and physical exam.
The following tests may be done:
Lab tests to check for certain proteins (enzymes) and metabolic problems
Surgery may be done to separate the fingers or toes.
Carrigan RB. The upper limb. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 673.
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.