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Webbing of the fingers or toes

Webbing of the fingers or toes is called syndactyly. It refers to the connection of 2 or more fingers or toes. Most of the time, the areas are connected only by skin. In rare cases, the bones may fuse together.


Syndactyly is often found during a child's health exam. In its most common form, webbing occurs between the 2nd and 3rd 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 finger or toe.

"Polysyndactyly" describes both webbing and the presence of an extra number of fingers or toes.


More common causes include:

  • Down syndrome
  • Hereditary syndactyly

Very rare causes include:

  • Apert syndrome
  • Carpenter syndrome
  • Cornelia de Lange syndrome
  • Pfeiffer syndrome
  • Smith-Lemli-Opitz syndrome
  • Use of the medicine 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 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 present?

An infant with webbing may have other symptoms that together may be signs of 1 syndrome or condition. That condition is diagnosed based on a family history, medical history, and physical exam.

The following tests may be done:

  • Chromosome studies
  • Lab tests to check for certain proteins (enzymes) and metabolic problems
  • X-rays

Surgery may be done to separate the fingers or toes.

Alternative Names

Syndactyly; Polysyndactyly


Carrigan RB. The upper limb. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 681.

Jones KL, Jones MC, Del Campo M. Craniosynostosis syndromes. In: Jones KL, Jones MC, Del Campo M, eds. Smith's Recognizable Patterns of Human Malformation. 7th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap M.

Review Date 11/19/2015

Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.