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Conjoined twins

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Conjoined twins, who are also known as Siamese twins, is a rarely occurring phenomenon. In most cases, conjoined twins do not survive birth. However, in some cases, conjoined twins can be separated through surgery, thanks to the advancement in technology and surgical methods.

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What are conjoined twins?

Conjoined twins are identical twins born physically joined together usually at the chest, pelvic region or the abdomen. It happens when an embryo has separated enough to form two individual fetuses but not enough to become physically separate. Sometimes, the twins also end up having a few common internal organs.

Most conjoined twins who do not survive are stillborn while others die within 24 hours after being born.

What causes conjoined Twins?

Conjoined twins are identical twins whose embryos do not split fully. In other words, it is caused when a fertilized egg splits only partially and develops into two individuals with bodies that are joined together. The exact causes or reasons for conjoined twins is not known. However, some theories have been proposed to explain it.

In non-conjoined twins, the embryonic layers will split so that monozygotic twins are formed, and organs are developed. This usually happens between eight and twelve days after the twin is conceived. In conjoined twins, the embryo splits thirteen to fifteen days after being conceived so that they stop separating before completing the process. As a result, the twins become conjoined.

Alternatively, some theories suggest that the two separate embryos may fuse during the early stages of embryonic development and form conjoined twins.

What are the symptoms of conjoined twin pregnancy?

Conjoined twin pregnancies don’t come with any specific symptoms or signs other than the fact that the uterus will grow much faster than in the case for a single pregnancy, which is observed for all twin pregnancies. Hence, if you suspect you are carrying conjoined twins (or twins in general), look for how fast your belly is growing. You may also experience more than usual fatigue, vomiting and nausea during pregnancy’searly stages.. However, you will need to get an ultrasound test to determine whether the twins are conjoined or normal.

What are the diagnosis of conjoined twin pregnancy?

You can diagnose or detect a conjoined twin pregnancy early on by undergoing a standard ultrasound procedure. It can be diagnosed towards the end of the first trimester. Further along in the pregnancy (about halfway through), you can also get echo cardiograms and magnetic resonance imaging (MRI) scans to determine where and at which body parts the twins are conjoined.

When diagnosing, conjoined twins are usually classified based on the part of the joined body, which is typically at matching locations for most conjoined twins. Sometimes they can be joined at more than one location and share internal organs or other body parts.

They can be joined at any of these locations on the body:

  • Chest: They are joined face to face at the chest, and it is the most common joined part in conjoined twins. Such conjoined twins are called thoracopagus twins. They tend to have a common heart and a common liver and upper intestine in some cases.
  • Abdomen: They are joined near the belly button. Such conjoined twins are called thoracopagus twins omphalopagus twins. They tend to have a common liver and common ileum (lower part of the small intestine) in some cases. They have different
  • Base of the spine: They are joined back to back at the spine’s base and the buttocks. Such conjoined twins are called pygopagus twins. Some pygopagus twins have a common lower gastrointestinal tract and common genital and urinary organs in some cases.

What are the treatment of conjoined twin pregnancy?

Your treatment options for conjoined twins will depend on each pair of conjoined twins’ health conditions and unique circumstances. If you have a conjoined pregnancy, you will be closely monitored by specialists to learn about the anatomy of the conjoined fetus, the functionality of their organs, and plan out the best possible treatment plan for you and the babies.

After the twins are delivered, specialists will thoroughly evaluate them to determine whether it is safe for the twins to undergo separation surgery. This will take up to a year or so to allow enough time to make a correct evaluation.

The separation surgery is optional, but sometimes it may become necessary, such as where one twin develops a life-threatening condition. In such instances, the healthier twin will have to be separated surgically to save their life. Some of the other factors that are considered for separation surgery are:

  • ● Whether or not the twins have a common vital organ like the heart
  • ● Whether or not the twins can handle separation surgery
  • ● Challenges the twins may face if they remain conjoined
  • ● What are the odds of a successful separation surgery?

What is the Result and Risks in surgery?

The type of complications that may arise will depend on the location, organ or body part at which the twins are joined. It will also depend on the expertise and experience of the medical team. The parents and the medical team must have a detailed discussion on potential complications and lay plans to solve them in the best possible way.

Conjoined twin pregnancies are complex and can have serious complications. Conjoined twin babies typically need delivery by surgery because of their anatomical features, so you will have to undergo caesarean section (C-section).

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What are Some of the Other Body Parts Which Can be Conjoined in Conjoined Twins?

They can be joined along the length of the spine, via the pelvis, trunk, head and the head and chest. The twins may be facing towards or away from each other in the latter cases.

Can One Twin be Smaller than the Other in Conjoined Twins?

Yes, this can happen in rare cases (called asymmetric Conjoined Twins). Very rarely, some Conjoined Twins can remain underdeveloped inside the other twin (called fetus in fetu).

What Types of Tests are Best for Diagnosing Conjoined Twins?

Fetal MRI and fetal echocardiography are best to determine whether twins are conjoined.

What Types of Specialists should I see for My Conjoined Twin Pregnancy?

You may be referred to several specialists including paediatric surgeons, orthopaedic surgeons, plastic surgeons, paediatric cardiologists and neonatologists, to name a few.

What Happens if My Conjoined Twins Cannot Undergo Separation Surgery?

If your Twins cannot go through separation surgery or if you opt out of it, your medical team will be able to assist you in other ways such as in the proper care and comfort of your twin babies as well as of yourself.


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