Friday, April 12, 2013

Conjoined twins, Omphalopagus, joined twins , Siamese twins, Parasitic twins

Conjoined twins

As we read and understood, "conjoined" , yeah particularly "joined". This be in news and documentaries a lot nowadays. 

What it means ?
Why this happens?
What happens next?

loads of question in our mind,
Answers will be given soon enough, keep reading

What it means ?

Conjoined twins are two babies that are born physically connected to each other. 

When and How this happens ?  

Conjoined twins develop when an early embryo partially separates to form two individuals. Although two fetuses will develop from this embryo, they will remain physically connected — most often at the chest, pelvis or buttocks. Conjoined twins may also share one or more internal organs. 

What Causes this ?

Two contradicting theories exist to explain the origins of conjoined twins.

 The older theory is fission, in which the fertilized egg splits partially. Identical twins (mono-zygotic twins) occur when a single fertilized egg splits and develops into two individuals. Eight to 12 days after conception, the embryonic layers that will split to form mono-zygotic twins begin to develop into specific organs and structures. It's believed that when the embryo splits later than this — usually between 13 and 15 days after conception — separation stops before the process is complete, and the resulting twins are conjoined.

The second and more generally accepted theory is fusion, in which a fertilized egg completely separates, but stem cells (which search for similar cells) find like-stem cells on the other twin and fuse the twins together. Which means two separate embryos may somehow fuse together in early development.

What might cause either scenario to occur is unknown.

What happens next?

"Harsh truth"
Most conjoined twins die in the womb (stillborn) or soon after birth.
Conjoined twins must be delivered by cesarean section. About 40 to 60 percent of conjoined twins are stillborn. Of conjoined twins born alive, less than half survive long enough to be candidates for separation surgery.

Ancient fame 

The most famous pair of conjoined twins was Chang and Eng Bunker (Thai: อิน-จัน, In-Chan) (1811–1874), Thai brothers born in Siam, now Thailand. They traveled with P.T. Barnum circus for many years and were billed as the Siamese Twins. Chang and Eng were joined by a band of flesh, cartilage, and their fused livers at the torso. In modern times, they could have been easily separated.[5] Due to the brothers' fame and the rarity of the condition, the term "Siamese twins" came to be used as a synonym for conjoined twins.


Yes they do have types!
Conjoined twins are typically classified by the point at which their bodies are joined. The most common types of conjoined twins are:

Thoraco-omphalopagus (28% of cases): 

Two bodies fused from the upper chest to the lower chest. These twins usually share a heart, and may also share the liver or part of the digestive system. 

Thoracopagus (18.5%):

Two bodies fused from the upper thorax to lower belly. The heart is always involved in these cases.

Omphalopagus (10%):

Two bodies fused at the lower chest. Unlike thoracopagus, the heart is never involved in these cases; however, the twins often share a liver, digestive system, diaphragm and other organs.


Parasitic twins (10%):

Twins that are asymmetrically conjoined, resulting in one twin that is small, less formed, and dependent on the larger twin for survival.

Craniopagus (6%):

Fused skulls, but separate bodies. These twins can be conjoined at the back of the head, the front of the head, or the side of the head, but not on the face or the base of the skull.

Other less-common types of conjoined twins include:


Two faces on opposite sides of a single, conjoined head; the upper portion of the body is fused while the bottom portions are separate. These twins generally cannot survive due to severe malformations of the brain. Also known as janiceps (after the two-faced god Janus) or syncephalus.


One head with a single face but four ears, and two bodies.



Bodies fused in the head and thorax. In this type of twins, there are two faces facing in opposite directions, or sometimes a single face and an enlarged skull.

Two bodies fused in the xiphoid cartilage, which is approximately from the navel to the lower breastbone. These twins almost never share any vital organs, with the exception of the liver. A famous example is Chang and Eng Bunker.



Fused lower half of the two bodies, with spines conjoined end-to-end at a 180° angle. These twins have four arms; two, three or four legs; and typically one external set of genitalia and anus.


 Fused in a similar fashion as ischiopagus twins, but facing each other with a joined abdomen akin to omphalopagus. These twins have four arms, and two, three, or four legs.


Parapagus :

 Fused side-by-side with a shared pelvis. Twins that are dithoracic parapagus are fused at the abdomen and pelvis, but not the thorax. Twins that are diprosopic parapagus have one trunk and dicephalic. Twins that are dicephalic parapagus are dicephalic, and have two (dibrachius), three (tribrachius), or four (tetrabrachius) arms.

Craniopagus parasiticus:

 Like craniopagus, but with a second bodiless head attached to the dominant head.

Pygopagus (Iliopagus)

Two bodies joined at the pelvis.


Twins joined along the dorsal aspect (back) of their bodies, with fusion of the vertebral arches and the soft tissue from the head to the buttocks

Hope you all got all the information ,
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1 comment:

  1. Good information, I'm doing a study on children malformations, and the causes. It doesn't look like this is related to the agent orange tragedy. It seems like this sort of birth is increasing. Thanks