Parasitic twin

Parasitic twin is a medical condition where one twin is not fully formed, and is dependent on the body of the other twin. This condition is a type of conjoined twins, but unlike conjoined twins, one twin is less formed, or undeveloped, and is wholly dependent on the other twin.

JohannSchenk Twins

Definition

A parasitic twin is not a complete organism, but a part of a twin pair. The less developed twin is termed as the parasite, as it relies on the body functions of the complete twin, known as the autosite, to survive. The parasitic twin can be attached to any part of the autosite's body.

Causes

The exact cause of parasitic twinning is unknown. However, it is believed to occur when a twin embryo begins developing in utero, but the pair does not fully separate, and one embryo maintains dominant development at the expense of the other.

Diagnosis

Diagnosis of a parasitic twin is usually made through ultrasound during pregnancy. The ultrasound can reveal the presence of extra limbs or organs, which are not part of the normal development of the fetus.

Treatment

Treatment for parasitic twins involves surgery to remove the parasitic twin from the autosite. The complexity of the surgery depends on the point of attachment and the extent of shared organs and tissues.

Prognosis

The prognosis for the autosite after surgery is generally good. However, the prognosis for the parasitic twin is poor, as it is not a viable organism on its own.

See also

• Twin
• Conjoined twins
• Vanishing twin

Parasitic twin Resources
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