Parasitic twin

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Parasitic twin
Synonyms	Asymmetrical conjoined twins, heteropagus twins
Pronounce	N/A
Specialty	N/A
Symptoms	Presence of extra limbs or body parts
Complications	Infection, organ dysfunction
Onset	Congenital
Duration	Lifelong unless surgically treated
Types	N/A
Causes	Abnormal twinning process
Risks	Pregnancy complications, premature birth
Diagnosis	Ultrasound, MRI, CT scan
Differential diagnosis	Teratoma, conjoined twins
Prevention	N/A
Treatment	Surgical removal of parasitic tissue
Medication	N/A
Prognosis	Generally good with treatment
Frequency	Rare
Deaths	Can be fatal if untreated

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.

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