Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at September 6, 2016

Syndactyly is a condition in which there is webbing of the fingers and toes. It is commonly called webbed fingers or webbed toes. Different studies have different estimates about the incidence of syndactyly, ranging from 1 out of every 1,000 to 3,000 births; it is one of the most common birth defects today.


Definition & Facts

Syndactyly occurs when the skin between the fingers or toes fails to separate and continues to form along the length of the digit, forming what appears to be a web. Twice as many males are born with this condition as females. There are different ways to classify syndactyly, based on the extent of the webbing and the kinds of tissue that is fused. One classification system that is used incorporates the following criteria:

  • Incomplete. This form of syndactyly involves webbing below the fingertips.
  • Complete. A more severe style of the malformation, this fusion includes the entire length of the affected fingers, including the nail bed.
  • Simple. This form involves skin only, no bone or other tissue, partially joining the fingers. 
  • Complex. This form of syndactyly involves the fusion of not only skin and tissue, but bones and cartilage as well.
  • Complicated. This form of syndactyly involves fusion of bones that are not side by side.

Symptoms & Complaints

Symptoms of syndactyly typically do not cause pregnancy complications. There is rarely pain involved with the milder types of webbing but some complications can arise with increased severity. The complete type encompasses the nail bed which can cause irritation or even infections when the nail causes abrasions under the skin. The risk of infection is also present if the nail punctures the skin.

Complex cases of syndactyly can be potentially more painful since the bones are joined. An infant instinctively moves their fingers in stretching and grasping motions. When the bones are joined, it impedes that motion and causes grinding of the joints as they attempt to follow their normal pattern. Given enough time, this can cause lasting damage and hinder dexterity later. To prevent this, the physician will begin treatment as soon as possible. 


Syndactyly is a congenital disorder, occurring in the first trimester. As baby’s hands and feet are developing, they begin as almost fin-shaped growths with the skin steadily retracting and forming individual fingers and toes during a process called apoptosis. The webbing occurs when that portion of the process does not execute fully and the skin does not completely withdraw from the fingers.

The most common cause is genetic mutations. A family with a history of webbing has the highest chance of having a baby with webbing as well. There are more than 300 syndromes associated with syndactyly according to an article published on the National Institutes of Health. Poland syndrome, Apert syndrome, Carpenter syndrome, Down syndrome, and macrocephaly-capillary malformation are several genetic disorders associated with syndactyly.

The health of the mother during pregnancy can also lead to syndactyly. An unhealthy diet during pregnancy, smoking while pregnant, drinking alcohol while pregnant or doing drugs in pregnancy will have a large impact on the infant and can cause birth defects like syndactyly.

Diagnosis & Tests

Syndactyly is difficult to diagnose in utero unless it is complex (bone fusion involvement) and complete. Fetal ultrasounds may be able to detect these abnormalities.

Diagnosis of an infant will involve a physical examination of not only the hands and feet but also the face and torso. The health care professional will take note of how many of the digits are joined, the condition of the nails, and the extent of the webbing.

The doctor will also get a complete medical history and family history. Although syndactyly can initially be diagnosed visually, there are more tests that need to be done to determine the severity of the condition as well as the presence of underlying conditions.

An X-ray is typically ordered to reveal if the bones are involved. Chromosome studies, genetic testing, blood tests, and metabolic studies may all be conducted to detect genetic mutations and abnormalities.

Treatment & Therapy

To correct webbing and prevent permanent deformity and loss of function, surgery is a necessity in severe cases. Ideally, the surgery should occur before age two to minimize complications and promote healing and allow the child to re-learn how to re-use his or her hand again with fully functioning fingers. Surgery can be performed when the child is as young as five months of age.

Typically the surgeon will cut the excess flesh, separate the conjoined digits, and then perform a skin graft with hairless skin from near the groin. The surgery will build the missing portions of the fingers and recreate the nail flaps where needed.

Following surgery, the patient will need a course of antibiotics and will be given a cast. The cast is necessary to prevent any pulling or stretching of the new grafts. The first post-operation visit will be at the two week mark to check on healing and make sure there is no infection developing. After a few more follow-up visits with the surgeon and six weeks of healing, rehabilitation can begin.

Parents should expect subsequent visits through the early years of childhood to ensure that the child’s hands are developing and functioning normally. Complications from surgery that may need to be addressed later in the child's life include the presence of pigment and hair on the skin graft.

Prevention & Prophylaxis

Achieving optimal health while pregnant can help prevent syndactyly as well as other birth defects. Quitting smoking, avoiding secondhand smoke, and abstaining from alcohol and drugs while pregnant are all important measures for ensuring the health of the child.

Genetic counseling may be sought by prospective parents to assess the risk that their future child may have certain genetic disorders associated with syndactyly.