Conjoined Twins

Conjoined twins are two babies born connected to each other. This happens because a single embryo doesn't completely split into two separate individuals during early development. Instead, the babies remain joined, usually at the chest, tummy, or hips. Sometimes, they share internal organs like their hearts, lungs, or other parts of their bodies.

One common type of conjoined twin is called thoracopagus, where they are joined at the chest. Even though they might share organs, they often have separate hearts.

Unfortunately, many conjoined twins are stillborn or die soon after birth. However, medical advancements in surgery and technology have made it possible for some to survive. Doctors can sometimes surgically separate them. The chance of successful separation depends on many factors. These include where they are joined, how many organs they share, and the skills of the surgical team.

Conjoined twins, also called Siamese twins, are a rare occurrence where two babies are born joined together. There aren't specific symptoms that always signal a conjoined twin pregnancy. Like other twin pregnancies, the mother's uterus might grow faster, and she might experience more tiredness, nausea, and vomiting during the early stages. However, these aren't unique to conjoined twins.

Doctors can often diagnose conjoined twins early in the pregnancy using an ultrasound scan. The exact way the twins are joined varies greatly, and each pair is unique. The joining points are usually categorized by the body part where they connect.

Here are some common types of conjoined twins, categorized by the area of connection:

• Chest (Thoracopagus): These twins are joined at the chest, often face-to-face. They frequently share a heart, liver, and part of their intestines. This is one of the more frequent types of conjoined twins.

• Belly Button Area (Omphalopagus): These twins are joined near their belly buttons. Often, they share the liver and parts of the intestines, but not always the heart. Sometimes, they share parts of the small and large intestines.

• Base of Spine (Pygopagus): These twins are joined back-to-back at the base of the spine and buttocks. They may share parts of the intestines or even the genital and urinary systems.

• Along the Spine (Rachipagus/Rachiopagus): Joined back-to-back along a segment of the spine. This type is very rare.

• Pelvis (Ischiopagus): These twins are joined at the pelvis, either face-to-face or end-to-end. They often share the lower intestines, liver, and genital/urinary organs. They may each have two legs or, less commonly, share two or three legs.

• Side-by-Side Trunk (Parapagus): Joined side-by-side at the pelvis and torso, but with separate heads. They might have a variety of arm and leg configurations, such as two, three, or four arms and two or three legs.

• Head (Craniopagus): Joined at the back, top, or side of the head, but not the face. They usually share part of the skull, but their brains are usually separate, though they might share some brain tissue.

• Head and Chest (Cephalopagus): Joined at the head and upper body. Their faces are on opposite sides of a shared head, and they often share a brain. These twins rarely survive.

In some cases, one twin is smaller and less developed than the other (asymmetric conjoined twins). Extremely rarely, one twin might be partially developed inside the other (fetus in fetu).

Understanding these different types of conjoined twins helps medical professionals plan for the best possible care during pregnancy, delivery, and after birth. The outcomes vary greatly depending on the level of shared organs and the overall health of the twins.

Identical twins, also called monozygotic twins, happen when a single fertilized egg divides into two separate babies. This division typically happens within the first 8 to 12 days after the egg is fertilized. At this early stage, the developing embryo is just a collection of cells that are starting to form different parts of the body, like the heart, brain, and limbs. If the division happens during this crucial period, the two embryos develop normally, resulting in two healthy, separate babies.

However, if the division occurs a bit later, between 13 and 15 days after fertilization, the process might not be complete. The two embryos might not fully separate, leading to conjoined twins. This means the twins will be physically connected in some way, like sharing parts of their bodies.

Another idea is that sometimes, two separate fertilized eggs might somehow join together very early in development. This would create a single embryo with two sets of genetic material. Scientists don't know exactly why this happens in some cases and not others.

The precise cause of both types of twinning, whether complete separation or the formation of conjoined twins, or the merging of two separate embryos, remains a mystery.

Conjoined twins are very uncommon. Scientists don't fully understand why they happen, so it's unclear what might increase the chances of a couple having them. There's no known connection between specific factors in a couple's lives or genetics that would make them more prone to having conjoined twins.

Having conjoined twins during pregnancy is a very challenging situation. It significantly raises the chances of problems for both the babies and the mother.

Conjoined twins are often born prematurely, just like regular twins. This means they may arrive too early, and unfortunately, one or both babies might not survive the birth or might die soon after. Immediately after birth, they could have serious health issues like trouble breathing or heart problems. These problems can also show up later in life, such as spinal curvature (scoliosis), cerebral palsy, or learning difficulties.

The specific difficulties depend on exactly how the twins are joined—where their bodies are connected—which organs they share, and the skills and experience of the medical team caring for them. If a family knows they are expecting conjoined twins, they need to have a thorough discussion with their medical team about all the potential problems and how to prepare for them. This includes discussing the options and risks of different types of care.

Doctors can often find out if twins are conjoined (joined together) as early as 7 to 12 weeks into a pregnancy using a standard ultrasound scan. This scan uses sound waves to create pictures of the developing babies.

Later in the pregnancy, around halfway through, more detailed ultrasounds and echocardiograms (sound wave tests of the heart) can be used. These more detailed scans help doctors understand how closely the twins are connected and how well their organs are working. For example, they can see if the twins share a heart, lungs, or other organs.

If the ultrasound suggests conjoined twins, a doctor might order a magnetic resonance imaging (MRI) scan. An MRI uses powerful magnets to create detailed pictures of the inside of the body. This helps doctors see exactly where the twins are joined and which organs they share. This information is crucial for planning the best possible care during and after pregnancy.

After the babies are born, further tests will be needed to get a complete picture of each twin's body and organ function, and to understand what parts of their bodies are shared. This allows doctors to develop a personalized treatment plan that addresses the specific needs of each child.