What are Conjoined Twins? Symptoms, Causes, & Treatment

Conjoined twins are identical twins who are physically connected at birth, sharing body parts or organs. This rare condition occurs when an embryo begins to split into identical twins but the process stops partway through, leaving the twins joined together.

This happens in about 1 in every 50,000 to 1 in 200,000 births worldwide. While the condition presents unique challenges, many conjoined twins live full, meaningful lives with proper medical care and family support.

What are conjoined twins?

Conjoined twins develop when a single fertilized egg starts to divide into two separate babies but doesn't complete the process. Instead of forming two distinct individuals, the developing embryo remains connected at various points on the body.

The connection can happen anywhere on the body, from the head and chest to the abdomen, pelvis, or back. Some twins share only skin and muscle tissue, while others may share vital organs like the heart, liver, or brain.

Most conjoined twins are female, and they're always identical since they come from the same original embryo. The condition is completely random and not caused by anything parents do before or during pregnancy.

What are the types of conjoined twins?

Doctors classify conjoined twins based on where they're connected on the body. The location of connection helps determine what organs or body systems the twins might share.

Here are the main types you might encounter:

• Thoracopagus twins - Connected at the chest and upper abdomen, often sharing the heart, liver, or other organs in this area
• Omphalopagus twins - Joined at the lower chest and abdomen, typically sharing the liver and sometimes the intestines
• Pygopagus twins - Connected at the buttocks and lower spine, usually sharing the lower spine and rectum
• Ischiopagus twins - Joined at the pelvis, often sharing reproductive organs, bladder, and parts of the digestive system
• Craniopagus twins - Connected at the head, which is quite rare and may involve shared brain tissue or blood vessels
• Parapagus twins - Joined side by side at the pelvis and sometimes the abdomen

Each type presents different challenges and possibilities for separation, depending on which organs and body systems are shared between the twins.

What causes conjoined twins?

The exact cause of conjoined twins remains a mystery to medical science. What we do know is that it happens during the very early stages of pregnancy when identical twins are forming.

Normally, when identical twins develop, a single embryo completely splits into two separate embryos between days 13-15 after conception. With conjoined twins, this splitting process begins but doesn't finish completely, leaving the twins physically connected.

This incomplete separation is completely random and natural. It's not caused by anything the parents did, didn't do, ate, or were exposed to during pregnancy. No genetic factors, medications, or environmental influences have been proven to increase the risk.

Some researchers believe the timing of when the embryo attempts to split plays a role in where the twins end up connected, but this is still being studied.

What are the symptoms and signs during pregnancy?

Most cases of conjoined twins are detected during routine prenatal ultrasounds, usually between 18-20 weeks of pregnancy. Your doctor might notice that the babies appear unusually close together or seem to be sharing body parts.

Early signs that might indicate conjoined twins include seeing two heads but only one body on the ultrasound, or noticing that the babies don't move independently from each other. The twins might also appear to be facing each other in an unusual way.

Sometimes the condition isn't detected until later in pregnancy when more detailed imaging is done. Advanced ultrasounds, MRI scans, or CT scans can help doctors understand exactly where the twins are connected and what organs they might be sharing.

If conjoined twins are suspected, your medical team will likely recommend additional testing and consultations with specialists to better understand your specific situation.

When should you see a doctor?

If you're pregnant and routine ultrasounds suggest conjoined twins, your doctor will immediately refer you to specialists who have experience with this condition. This typically includes maternal-fetal medicine specialists and pediatric surgeons.

You'll want to seek care at a major medical center that has experience with conjoined twins. These facilities have the specialized teams and equipment needed to provide the best care throughout pregnancy and after birth.

Don't hesitate to ask for second opinions or additional consultations. This is a complex situation, and having multiple expert perspectives can help you make informed decisions about your care and your babies' future.

What are the risk factors for conjoined twins?

There are no known risk factors that increase your chances of having conjoined twins. This condition appears to happen completely by chance, regardless of your age, health, family history, or anything you do during pregnancy.

Unlike some other pregnancy conditions, conjoined twins don't run in families and aren't more common in any particular ethnic group or geographic region. Having conjoined twins in one pregnancy doesn't increase your chances of having them in future pregnancies either.

The condition occurs equally across all populations worldwide, which supports the understanding that it's a random developmental event rather than something influenced by external factors.

What are the possible complications?

Conjoined twins face several potential challenges, both during pregnancy and after birth. The specific complications depend heavily on where the twins are connected and which organs or body systems they share.

During pregnancy, complications might include:

• Premature birth, which happens in most cases of conjoined twins
• Excess amniotic fluid (polyhydramnios) around the babies
• Difficulty with the baby's positioning for delivery
• Increased risk of miscarriage, particularly in early pregnancy

After birth, potential complications can include breathing difficulties if the twins share chest space, heart problems if they share cardiac structures, and digestive issues if they share intestines or other abdominal organs.

Some twins may have developmental delays or disabilities, while others develop normally. The outlook varies greatly depending on the individual situation and which body parts are shared.

How are conjoined twins diagnosed?

Diagnosis usually begins with routine prenatal ultrasounds that show something unusual about how the twins are positioned or connected. Your doctor might notice they don't move independently or appear to share body parts.

Once conjoined twins are suspected, more detailed imaging tests help create a complete picture. These might include high-resolution ultrasounds, MRI scans, or specialized 3D imaging that can show exactly where the connection occurs.

Your medical team will also use these tests to understand which organs, blood vessels, or other structures the twins share. This information is crucial for planning their care both before and after birth.

Sometimes additional tests like echocardiograms (heart ultrasounds) or other specialized scans help evaluate specific organ systems that might be affected.

What is the treatment for conjoined twins?

Treatment for conjoined twins is highly individualized and depends on where they're connected and what they share. The approach involves a team of specialists working together to provide the best possible care.

Some conjoined twins can be successfully separated through surgery, while others live full lives remaining connected. The decision about separation depends on many factors, including which organs are shared and whether separation would be safe for both twins.

For twins who can be separated, the process often requires multiple surgeries over time. The surgical team might include pediatric surgeons, plastic surgeons, neurologists, cardiologists, and other specialists depending on what needs to be reconstructed.

For twins who remain connected, treatment focuses on helping them live as independently and comfortably as possible. This might include physical therapy, occupational therapy, and modifications to help with daily activities.

Throughout their lives, many conjoined twins need ongoing medical care to monitor shared organs and address any health issues that arise.

How to prepare for delivery and early care?

Delivery planning for conjoined twins requires careful coordination between multiple medical teams. Most conjoined twins are delivered by cesarean section at a hospital with specialized pediatric facilities.

Your medical team will plan the delivery timing based on the twins' development and any complications. Many conjoined twins are born prematurely, so the neonatal intensive care unit (NICU) team will be prepared to provide immediate specialized care.

After birth, the twins will likely need time in the NICU while doctors evaluate their condition and plan their ongoing care. This period allows the medical team to understand exactly what the twins share and what their specific needs will be.

During this time, you'll work with social workers, counselors, and other support staff who can help you navigate the emotional and practical aspects of caring for conjoined twins.

How should you prepare for medical appointments?

Come prepared with a list of questions about your specific situation. Every case of conjoined twins is unique, so focus on understanding what applies to your babies specifically rather than general information.

Bring a support person to appointments when possible. Having someone else listen and take notes can be helpful when processing complex medical information during an emotional time.

Ask about connecting with other families who have experience with conjoined twins. Many hospitals can put you in touch with support groups or other families who can share their experiences.

Don't hesitate to ask your medical team to repeat or clarify information. This is a lot to process, and it's completely normal to need things explained multiple times or in different ways.

What's the key takeaway about conjoined twins?

Conjoined twins represent a rare but naturally occurring variation in human development. While the condition presents unique challenges, many conjoined twins live fulfilling lives with appropriate medical care and family support.

The most important thing to remember is that every situation is different. What applies to one set of conjoined twins may not apply to another, so focus on understanding your specific circumstances rather than comparing to other cases.

Modern medicine has made tremendous advances in caring for conjoined twins, whether through separation surgery or helping twins live well while remaining connected. With the right medical team and support system, families can navigate this journey successfully.