CHILD WARNING Conjoined Twins AKA Siamese Twins

Definition

Oxford Languages:

Twins that are physically joined at birth, sometimes sharing organs, and in some cases separable by surgery (depending on the degree of fusion).

Medical Definition:

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

Causes

Conjoined twins develope when an early embryo only partially seperates to form two children. That means, two children develope but they stay physically connected. It is believed that this only occurs when an embryo of identical twins (monozygotic twins) splits later than usual, causing the seperation to stop before the process is complete. There is also a theory that the bodies fuse together after their development, however this hasn't been proven yet.

Cases of Conjoined Twins

Chest: These twins are called Thoracopagus twins. They are joined at their chest, facing each other. They may share a heart and liver.

Abdomen: Omphalopagus twins are joined near the bellybutton. They often share a liver and the upper digestive tract. Some twins share the lower part of the small intestine (ileum) and the longest part of the large intestine (colon). They never share a heart.

Base of the Spine: Pygopagus twins are commonly joined back to back at the base of the spine and the buttocks. Some pygopagus twins share the lower gastrointestinal tract, some even their genitals and urinary organs.

Length of the Spine: Rachipagus, also called rachiopagus, twins are joined back to back along the length of the spine. Often only one of the twins is fully developed. The other one is seen as a Parasitic Rachipagus Twin. This type is very rare.

Pelvis: Ischiopagus twins are joined at the pelvis, they can be face to face or end to end. They often share the gastrointestinal tract, as well as liver, genitals and urinary organs. Some even share a leg or two, but that is very rare.

Trunk: Parapagus twins are joined side to side at the pelvis and part or all of the belly (abdomen) and chest, but with separate heads. The twins can have two, three or four arms and two or three legs.

Head: Craniopagus twins are joined at the back, top or side of the head, but not the face. Craniopagus twins share a portion of the skull. But their brains are usually separate, though they may share some brain tissue.

Head and chest: Cephalopagus twins are joined at the head and upper body. The faces are on opposite sides of a single shared head, and they share a brain. These twins rarely survive.

Diagnosis

Conjoined twins are often diagnosed in the early stages of pregnancy with a prenatal ultrasound. A thorough prenatal evaluation is particularly important for conjoined twins, as the location and extent of where the twins are joined and what organs are shared plays a crucial role in deciding whether the twins will be separable. To thouroughly diagnose conjoined twins, a fetal ultrasound, a fetal echocardiogram and an Ultrafast fetal MRI are used.

Seperation Surgery

If the conjoined twins are candidates for separation surgery, CHOP's pediatric surgical team (which may include general surgeons, plastic and reconstructive surgeons, neurosurgeons and other surgical specialties) will work with a multidisciplinary team to monitor the babies and determine the timeline and approach for the surgical procedure. Specialists involved in your care will likely include neonatologists, cardiologists, advanced practice nurses and maternal-fetal medicine specialists, among others.

One of the many procedures required to prepare twins for separation is the insertion of tissue expanders to increase the skin surface available to cover exposed tissue after surgery.

As separated twins recover after surgery, they are closely followed by nutritionists, developmental pediatricians and other specialists to ensure their ability to thrive and grow.

When the conjoined twins share a heart, successful surgical division is usually not possible.

Notes: I couldn't find video material of a seperation surgery, so if you have some, it would be greatly appretiate it if I can add them to my post!