At the age of 62, the world sadly bids farewell to the oldest conjoined twins, Lori and George Schappell. Doctors initially predicted that these remarkable twins, joined at the skull and sharing 30% of their brain, would not surpass the age of 30. Yet, Lori and George defied the odds, leading long and successful lives.
The twins garnered media attention in 2007 when George revealed her transgender identity, a testament to their extraordinary and inspiring journey.
Conjoined twins are an exceptionally rare phenomenon, occurring in about one or two out of every 100,000 births. Tragically, approximately 60% of conjoined twins are stillborn or pass away shortly after birth. Interestingly, female conjoined twins have a three times greater chance of survival compared to their male counterparts.
Despite all conjoined twins being identical—or monozygotic—modern genetic studies have unveiled variances in their genes, including those associated with growth and development. The rarity of conjoined twins makes it challenging to comprehend entirely how they develop. However, two main theories have been posited.
The first theory is known as “fission,” where the fertilized egg does not completely divide during the formation of identical twins. The second is “fusion,” involving two fertilized eggs merging shortly after fertilization. Both hold a degree of evidence, yet neither fully explains all the diverse presentations among conjoined twins.
Variations of Conjoined Twins
Conjoined twins come in 15 recognized types, categorized by the specific areas where their bodies are joined. The most common site of fusion is the chest and abdomen, termed thoraco-omphalopagus. Other prevalent fusion locations include the chest (thoracopagus), abdomen (omphalopagus), and skull (craniopagus).
These terms incorporate a combination of body part names followed by “pagus,” the Greek term for “fixed.” Numbers such as bi, tri, or tetra denote two, three, or four respectively, offering further specificity. For instance, a “dicephalic parapagus” would refer to conjoined twins with one trunk and two heads.
Typically, routine ultrasound scans during pregnancy alert health care providers to the presence of conjoined twins. These initial findings are often followed by MRI scans to better understand the fusion type and shared organs. This crucial information facilitates managing complications during delivery and aids decisions on potential surgical separation. Unfortunately, it can also indicate whether termination might be required.
When identified via imaging, conjoined twins are generally delivered through caesarean section.
The Delicate Art of Separating Twins
The surgery to separate conjoined twins is a complex undertaking, performed by specialized surgical teams at select hospitals around the world, including Great Ormond Street Hospital in London, Children’s Hospital of Philadelphia, and Red Cross Children’s Hospital in Cape Town. In Saudi Arabia, a renowned Royal Court surgeon has led more than 60 such operations as well.
Medical advancements are gradually enabling more hospitals to attempt these intricate surgeries, which can exceed 24 hours in duration. One notable operation to separate twins conjoined at the cranium extended beyond 100 hours, illustrating the challenges involved.
Historical records indicate that the earliest attempt to surgically separate conjoined twins dates back to AD945 in Armenia, involving brothers who lived until middle age. After one passed away, surgeons endeavored to separate the surviving brother, but he succumbed a few days later. The first documented success in separating conjoined twins occurred in 1689, involving xiphophagus twins joined at the bottom of their sternums. More recent history tells of an 1860 case where a surgeon separated his omphalopagus daughters, with only one surviving.
Twins conjoined at the abdomen, or those with the omphalopagus variation, see the highest success rates in separation surgeries, with over a hundred instances of both twins surviving. Separating conjoined twins necessitates thorough preparation, including comprehensive imaging such as ultrasound, CT, and MRI.
Although imaging provides insight into shared organs and their connectivity, it lacks information about whether these organs can independently sustain life post-separation. Additional assessments utilizing advanced imaging technologies like fMRI, contrast-enhanced CT, and vascular imaging are essential. These tools help ascertain whether each twin possesses independent vascular systems for organs like the liver, gut, and urinary systems, ensuring functionality post-separation.
The progression from a singular operation to two separate ones, following the twins’ division, requires two complete teams of surgeons, anesthetists, and theater staff for each child.
When conjoined twins share or have fused vital organs, the likelihood of a successful separation diminishes. For instance, Canadian twins Krista and Tatiana Hogan share a thalamus, an egg-shaped structure within the brain, raising intriguing questions about their interconnected yet distinct experiences.
The decision to separate conjoined twins carries profound ethical considerations, as potential harm or even the loss of one twin to benefit the other is a critical aspect challenging surgical interventions.
