top of page
  • MIRAI 3D

Separation of thoracopagus siamese twins with 3D planning

Dra. Celia Britto + Multidisciplinary team

Hospital Ana Nery - Salvador de Bahía, Brasil


Understand in detail the shared vasculature

Identify congenital cardiac anomalies in each infant

Define the surgical approach

Plan the intervention

Improve communication between the professionals involved

Improve communication with the family

Provide greater safety for surgeons and patients

Guide the approach in real time

Clinical case

In this report, we will present how 3D technology assisted the medical team in charge of the separation of 3-month-old thoracopagus siamese twins.

Currently, the worldwide incidence of siamese twin births is 1:50,000 to 1:100,000 pregnancies. Their separation is a very challenging procedure not only because of the surgery itself but also because of the postoperative period for both babies.

The twins, Nathan and Nathanael, were born prematurely in December 2020, at the Maternidade de Referência Professor José Maria de Magalhães Netto, interconnected through the thorax and abdomen.

The following table summarizes the main pathologies they presented:

For more details on the pre-surgical diagnosis, see the Appendix at the end of this publication.

3D Biomodels

Given the great complexity of the case, Dr. Celia Britto contacted MIRAI 3D in order to have an anatomical 3D model of the patients. In this way, the entire surgical team was able to understand in greater detail the anatomy of the patients and perform a thorough planning of the surgery.

Multiple virtual 3D models were made with different anatomical views, specially created to observe in detail each region of interest.

Subsequently, one of these models was 3D printed, in alliance with the company SKA (Brazil) who donated the manufacture of the model:

◾ Technology: HP MultiJet Fusion

◾ Material: Nylon Powder

◾ Resolution: 0.01 mm

◾ Finishing: Multiple colors

Surgical planning and results in the operating room

The multidisciplinary team of about 50 health professionals from the Netto Maternity Hospital and Ana Nery Hospital spent 4 months studying the case to prepare the procedure. The preparation included more than one simulation of the entire procedure to contemplate every possible situation.

In planning the surgery, the virtual 3D models and the physical biomodel were used to explore the anatomy accurately, especially the hepatic connection (the biggest challenge of the separation) and the cardiovascular system that had several congenital anomalies.

The 3D planning "was very important to know the vasculature of each baby and the communication of the vascular circuit. It was very valuable for us to have a more realistic image of the case", explained Dr. Celia Britto.

The 3D anatomical models were also very useful for improving communication with the professionals involved.

"This is a surgery that requires a multidisciplinary team. Sharing the knowledge and experience of a team with these characteristics for the benefit of medical treatment is very gratifying", says Dr. Celia Britto.

The operation took place at Ana Nery Hospital. The operation began with the opening of the thoracic area, where they tried to identify the mammary artery and the brachiocephalic communication. As a first instance, they tried to clamp the artery of a single baby, but separate vascular treatment created hemodynamic and respiratory decompensation. They then had to treat the vascular restructuring of the area in parallel in both babies. They then separated the outer thorax, the shared pericardial ligaments and separated the diaphragm.

In the second part of the surgery, they treated the hepatic connection. Again, the individual treatment generated decompensation, so they had to clamp the vessels of both babies in one go. In that way, they remained stable, and were able to divide the liver parenchyma and its vasculature.

The biomodels were taken to surgery and served as support for the surgical team in real time during the approach.

The tireless work together allowed for a successful surgery, and ended with both twins stabilized.

Despite the joint efforts, unfortunately the second baby (G2), who had a more complicated diagnosis, suffered a cardiorespiratory arrest hours later and was unable to survive.

Currently, the first twin, Nathan, continues with his treatments, evolving satisfactorily in a gradual manner. With more attention to wound closure and respiratory assistance.

From MIRAI 3D we congratulate the great work of the great team behind this case and we are proud to have done our bit in such a special case ❤️


More on pediatric surgery: "Biomodel of pancreatic tumor for pediatric surgery" At the Garrahan Foundation, Dr. Horacio Questa used a three-dimensional model to plan the resection of a Frantz tumor in a 9-year-old patient.


Annex - Detail of pre-surgical diagnosis


At the cardiovascular level, each baby had its own heart. The free wall of the right ventricle of one of the twins (G1) was in intimate contact with the cardiac apex of the sibling's heart (G2).

Twin 1 (G1): located on the right side in the tomography.

Particularly, G1 had ventricular septal defect and atrial septal defect. In addition, it had persistent truncus arteriosus. The cardiac chambers, the pulmonary arterial trunk and pulmonary arteries, the aortic root and its ascending portion were dilated. The ventricles were also hypertrophied.

The brachiocephalic trunk of G1 is long and tortuous, giving origin, in its distal portion, to a subbranch of medium caliber (5.7mm), long and tortuous that crosses the anatomy and makes connection with the pulmonary trunk of the other twin (G2). The predominant direction of flow was from G1 to G2.

Finally, the inferior vena cava of G1 was found receiving hepato-abdominal venous tributaries from G2.

Twin 2 (G2): located on the left side in the CT scan.

The second twin had dextrocardia (inverted heart) and mesopposition of the cardiac apex. It also had a wide interatrial communication and ventricular septal defect. The atria, pulmonary arterial trunk and pulmonary arteries were dilated and the ventricles were dilated and hypertrophied.

The aortic root emerges riding the ventricular septal defect and is dilated. The aortic valve is stenosed and the proximal ascending portion has aneurysmal dilatation. The aorta of this twin also has an interruption. The descending aorta originates from a large ductus arteriosus, which emerges from the pulmonary trunk.

The left subclavian and left vertebral arteries emerge from the brachiocephalic trunk subbranch of G1 and the inferior vena cava shares hepato-abdominal circulation with the other G1 twin.

Liver, pancreas and biliary tract

At the hepatic level, both twins share part of their livers (fusion of the parenchyma), including the hepatic vasculature.

Twin 1 (G1)

The portal vein and hepatic artery were preserved and the gallbladder of usual appearance without dilatation of the bile ducts. The pancreas and spleen present anatomical morphology, size and density.

Twin 2 (G2)

The second baby had a preserved portal vein, although with a single origin from the celiac trunk and the superior mesenteric artery.

The gallbladder was small, but there was no dilatation of the intra or extra hepatic bile ducts. The pancreas and spleen had normal anatomical morphology, size and density.

Lungs and airway

The twins did not share any airway or lung parenchyma and both babies had patent trachea.

Twin 1 (G1)

The first twin had left lung hypoplasia and atelectasis in the same lung. In contrast, the right lung was hyperexpanded.

Twin 2 (G2)

On the other hand, the second twin had right pulmonary hypoplasia and atelectasis in the same lung.

bottom of page