Webbing of the fingers or toes

Syndactyly; Polysyndactyly

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.

Considerations

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.

Causes

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 (phenytoin) 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

Your child's 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 one syndrome or condition. That condition is diagnosed based on a family history, medical history, and physical exam.

The following tests may be done:

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

Surgery may be done to separate the fingers or toes.

References

Carrigan RB. The upper limb. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 722.

Mauck BM. Congenital anomalies of the hand. In: Azar FM, Beaty JH, eds. Campbell's Operative Orthopaedics. 14th ed. Philadelphia, PA: Elsevier; 2021:chap 80.

Son-Hing JP, Hardesty CK. Congenital abnormalities of the upper and lower extremities and spine. In: Martin RJ, Fanaroff AA, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine. 12th ed. Philadelphia, PA: Elsevier; 2025:chap 103.

Review Date: 10/1/2025

Reviewed By: Charles I. Schwartz, MD, FAAP, Clinical Assistant Professor of Pediatrics, Regional Medical Director of Penn Medicine Primary and Specialty Care, Perelman School of Medicine at the University of Pennsylvania, General Pediatrician at PennCare for Kids, Phoenixville, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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06/01/2028

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