Conjoined twins

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Conjoined twins
File:Conjoined X-ray.jpg
Synonyms	Siamese twins
Pronounce	N/A
Specialty	N/A
Symptoms	Physical connection of two bodies
Complications	Organ sharing, surgical separation
Onset	Congenital
Duration	Lifelong
Types	N/A
Causes	Monozygotic twinning
Risks	Premature birth, Stillbirth
Diagnosis	Ultrasound, MRI
Differential diagnosis	Parasitic twin, Teratoma
Prevention	N/A
Treatment	Surgical separation
Medication	N/A
Prognosis	Varies depending on type of conjoining and organ sharing
Frequency	1 in 49,000 to 1 in 189,000 births
Deaths	N/A

A monoamniotic twin gestation in which the twins share one or more organs.

File:Infans bicorporeus xyphopagus.jpg

Infans bicorporeus xyphopagus

File:Kind met twee hoofden, RP-P-OB-10.106.jpg

Kind met twee hoofden, RP-P-OB-10.106

Conjoined twins are also known as siamese twins, and are a rare phenomenon in which two individuals are born physically connected to each other. This condition results from a monoamniotic twin gestation, where the twins share the same amniotic sac during development and can share one or more organs.

Development and Causes

Monoamniotic twins develop from a single fertilized egg, or zygote, that fails to separate completely after around 8 to 12 days following fertilization. If the separation occurs later than this, the twins can become conjoined. The exact cause of the incomplete separation is unknown.

Types of Conjoined Twins

There are several types of conjoined twins, categorized based on the point of attachment:

• Thoracopagus: Attached at the upper portion of the torso, sharing a heart.
• Omphalopagus: Attached at the lower chest and upper abdomen, may share liver but usually have separate hearts.
• Pygopagus: Attached back to back at the buttocks, may share a lower gastrointestinal tract.
• Craniopagus: Attached at the head, the rarest type.

Diagnosis

Prenatal ultrasound is the primary method for diagnosing conjoined twins during pregnancy. More detailed imaging, like MRI or CT scan, may be used to understand the extent of organ sharing and plan for possible separation surgery.

Treatment and Prognosis

Treatment for conjoined twins varies greatly depending on the degree of organ sharing and overall health of the twins. If feasible, surgical separation may be considered, but carries significant risks. The prognosis for conjoined twins varies widely, with survival rates higher for those who share fewer organs.

See Also

• Monozygotic twins
• Twin
• Prenatal Diagnosis