When people wonder what it is like to live as a conjoined twin, they are usually thinking about the physicality of existing as two separate people connected, potentially sharing organs and sensations. Naturally, a lot of people have borderline-invasive questions concerning the intimate and romantic lives of conjoined twins. Many folks also have a morbid curiosity surrounding the question of what happens if one conjoined twin perishes.
It's a tricky question with complicated answers that are dependent on the way the twins are connected. Often, once one conjoined twin passes, be it from natural causes or an unintentional incident, their twin follows in their ghostly footsteps rather quickly. Sometimes it takes mere hours, other times a few days, but the unfortunate reality is once one conjoined twin is gone, the other has a limited amount of time left on this earth.
The most common type of conjoined twins shares a connection in the upper part of their ribcage: thoracopagus twins. These twins share a heart and circulatory system, making it highly likely the living twin would quickly succumb to sepsis - a complication of an infection that can lead to organ failure and septic shock - if their sibling passed.
The next most common conjoined twins are omphalopagus, which is a connection that occurs from the breastbones to the waists. These twins usually share a gastrointestinal system, a liver, and possibly one reproductive system.
In only 2% of conjoined twins, the siblings share a cranium: craniopagus. In these cases, survival without medical intervention for the living twin would depend on how large the connection is and whether medical attention and separation could be performed before infection sets in.
Medical Daily reports that one of every 200,000 births is conjoined twins, or .000005%. Of this small percentage, 40 to 60% are stillborn and 35% perish within a day of their birth. Female conjoined twins are more likely to survive birth, making them 70% of living conjoined twins in the world.
There are only about 12 sets of conjoined twins in the world today. Since the advent of the separation procedure in 1950, doctors are only able to save one of the twins in 75% of cases.
According to Dr. Eric Stauch, when the heart of one of the twins stops, they will lose blood into the living twin. There are only hours to save the living twin with surgery, meaning they would need to be in the hospital prior to the loss with a team of surgeons ready to go. Separation surgeries usually take more than 10 hours, so even that would likely not save the living twin.
Sepsis occurs when the infection from the deceased twin overwhelms the living twin's system, causing inflammation that leads to organ failure.
When doctors attempt to separate conjoined twins, it is usually before one of them passes; they know one twin will likely expire in order to save the other. In lucky cases, like Erin and Abby Delaney, both twins survived the separation and had healthy lives. In other situations, the shared systems may leave one twin without all of the organs necessary for survival.
Separating the twins can mean life or death for the more viable of the two, forcing parents to make complicated decisions with their children - or forcing the twins to make the decision.