It is a question that sounds like the plot of a gothic horror novel, but for the roughly one in 200,000 live births involving conjoined siblings, it is a looming medical reality. We don't like to talk about it. Death is uncomfortable enough, but when two lives are physically interlaced, the passing of one becomes a ticking clock for the other. Honestly, the internet is full of misconceptions about this. People think it’s an instant "lights out" for both parties, but biology is way more complicated and, frankly, more harrowing than that.
When we look at what happens when a conjoined twin dies, we aren't just looking at a single event. We are looking at a physiological chain reaction.
The Immediate Physiological Crisis
The moment one twin’s heart stops, the clock starts. This isn't just about grief. It is about hemodynamics. In almost all cases of conjoined twins, especially those who have survived into adulthood like the famous Daisy and Violet Hilton or Ronnie and Donnie Galyon, there is some level of shared circulatory system. Even if they have two hearts, their blood vessels often bridge the gap between their bodies.
Once Twin A passes away, their heart stops pumping. Their blood pressure drops to zero. But Twin B’s heart is still beating. It’s still trying to push blood through a system that has now become a massive, open-ended sinkhole.
Basically, the living twin begins to pump their own blood into the deceased twin’s body. This leads to a rapid drop in blood pressure for the survivor. They can go into hypovolemic shock. It’s like trying to keep a pool filled while a massive pipe is draining it into an empty reservoir next door.
The Toxic Threat of Sepsis
If the survivor doesn't die from the immediate drop in blood pressure, the next threat is much more insidious. It’s rot.
It sounds cold, but a deceased body begins the process of necrosis almost immediately. Without blood flow, cells break down. They release toxins. They attract bacteria. In a conjoined setup, the living twin’s circulatory system eventually picks up these necrotic byproducts and carries them back into their own healthy organs.
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Sepsis is the real killer here.
Historically, this was the fate of many conjoined twins. Take the Hilton sisters, the famous vaudeville performers. In 1969, Daisy Hilton died of the Hong Kong flu. Violet was still alive. She reportedly called for help but couldn't reach the phone. According to the forensic reports, Violet lived for somewhere between two to four days after her sister passed. She eventually succumbed to the same flu and the mounting toxicity of her sister's body. It is a haunting thought. Two days of knowing what is coming.
Can Surgery Save the Survivor?
You’ve probably wondered why they don't just rush them to the OR. In the modern era, that is exactly what would happen, but the "emergency separation" is one of the most dangerous procedures in medical history.
Dr. James O’Neill, a pioneer in pediatric surgery at Vanderbilt, has noted in various medical journals that the success rate of emergency separations is significantly lower than planned ones. When one twin is already dead, the survivor is usually already in "consumptive coagulopathy"—their blood isn't clotting right because it's exhausted all its resources trying to fix the systemic failure.
The logistics are a nightmare:
- Anesthetizing a patient who is already in septic shock.
- The risk of "clamping off" shared organs like the liver or large intestines.
- The psychological trauma of the survivor waking up without the person who was literally their other half.
It isn't just a matter of "cutting them apart." If they share a heart (thoracopagus) or a brain (craniopagus), surgery is often impossible. In those cases, when one dies, the other follows shortly—usually within hours.
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The Case of Chang and Eng Bunker
We have to talk about the Bunkers. They are the reason we use the term "Siamese Twins." They lived to be 62, which was incredible for the 1800s. They were connected at the torso by a band of flesh and a shared liver.
On a cold January night in 1874, Chang died of a cerebral hemorrhage. Eng woke up to find his brother dead. He panicked. The family doctor was summoned to perform an emergency separation, but he didn't make it in time. Eng died just three hours later.
For a long time, people thought Eng died of fright. Literally. But a later autopsy performed at the College of Physicians of Philadelphia suggested that while the shared liver played a part, Eng likely died of the aforementioned blood loss—pumping his life force into Chang’s lifeless body.
Why Some Twins Choose Not to Separate
Despite the risks, many adult conjoined twins—like Lori and George Schappell or Abby and Brittany Hensel—have historically expressed a lack of interest in separation. For them, the risk of the surgery outweighs the "what if" of death.
Lori and George, who were joined at the head, lived into their 60s (they recently passed in 2024). They spent their lives navigating a world not built for them. For twins like them, separation isn't "fixing" something; it's an amputation of their identity.
But when that choice is made, the medical reality of what happens when a conjoined twin dies becomes a settled pact. They know that they will likely go together. There is a strange, heavy beauty in that, even if it’s hard for the rest of us to wrap our heads around.
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The Ethical Minefield for Doctors
What happens if one twin wants to be separated to save their life and the other is too ill to consent? Or what if the surgery will definitely kill one to save the other?
Courts have had to get involved. In a famous UK case in 2000 involving twins known as "Jodie and Mary," doctors knew that Mary (the weaker twin) was only alive because Jodie’s heart and lungs were doing all the work. If they stayed joined, both would die within months. If they separated, Mary would die instantly, but Jodie would live.
The parents refused on religious grounds. The court overruled them. The judges argued that Mary’s life was already "forfeit" by nature and that Jodie had a right to life. Mary died during the surgery. Jodie survived and grew up.
It’s an impossible choice. Doctors have to play God in a way that most of us will never understand.
Summary of the Medical Timeline
If you are looking for the "tl;dr" of the biological process, it usually follows this trajectory:
- Cardiac Arrest: Twin A’s heart stops.
- Pressure Shift: Twin B’s blood pressure drops as blood migrates to Twin A.
- Metabolic Acidosis: The survivor’s blood chemistry begins to turn acidic as the dead twin’s cells break down.
- Sepsis: Bacteria and necrotic toxins flood the survivor's organs.
- Multi-organ Failure: Without surgical intervention, the survivor usually passes within 3 to 72 hours, depending on the extent of their shared circulation.
Actionable Reality for the Modern Era
While this topic is macabre, it highlights the incredible importance of specialized medical centers. If you are ever following a news story or looking into this for research, look toward institutions like Great Ormond Street Hospital or Children's Hospital of Philadelphia (CHOP). They are the ones actually writing the protocols on how to handle these crises.
For those interested in the ethics or the science, the next step is to look into the Glasgow Coma Scale and Sepsis protocols specifically tailored for pediatric anomalies. Understanding how "shunting" works in the circulatory system is the key to understanding why separation is so difficult.
Ultimately, the death of a conjoined twin is a rare event, but it serves as a profound reminder of how deeply our lives—and our deaths—are tied to our physical bodies. It's not just a medical curiosity. It's a testament to the resilience of the human spirit in the face of an inevitable, shared ending.