Conjoined at Birth: When One Becomes Two

Conjoined twins occur once in every 60,000 births, and approximately 70 percent of conjoined twins are female. Conjoined twins they’re normally diagnosed within the first 18 weeks of pregnancy with prenatal ultrasound. As an uncommon scenario, conjoined twins require significant, special attention and care during the mother’s trimester, as additional testing is needed to help provide the decision on whether the twins can be separated. At Rosenberg Maternal-Fetal Medicine, this article will briefly discuss conjoined twins, imaging tests for diagnosing and evaluating conjoined twins, and what mothers can expect from their care. 

The Types of Conjoined Twins at Birth: When One Becomes Two

When it comes to diagnosing the prognosis for conjoined twins, it depends on where the twins are connected. Conjoined twins are typically classified through these connections:

  • Thoracopagus: This is considered the most common type of conjoined twin, representing about 75 percent of cases. When this occurs, the two babies lie face to face and share a common diaphragm, sternum, and upper abdominal wall.
  • Omphalopagus: Considered the least-complicated connection, it occurs when the babies face one another and join along the anterior abdominal wall, often connecting by a bridge of the liver. 
  • Pygopagus: This type represents about 20 percent of cases, where the two babies are joined at the buttocks, facing away from each other.
  • Ischiopagus: This type represents less than 5 percent of cases, and the connection between the two occurs along the bony pelvis, and the intestinal tracts often join into a single colon.
  • Craniopagus: As considered the least common for conjoined twins, it accounts for 2 percent of cases and is represented by the fusion of the skull.

For women faced with a conjoined pregnancy, your team of obstetrics, surgeons, and maternal-fetal medicine specialists will work with you through comprehensive prenatal monitoring and help you manage your pregnancy and prepare for delivery. 

When working with your pregnancy care team, you can expect the following imaging tests used to diagnose and evaluate conjoined twins:

  • Fetal ultrasound: A safe, noninvasive procedure that uses high-frequency sound waves to provide detailed high-resolution images. 
  • Fetal echocardiogram: A noninvasive ultrasound that assesses the fetal heart’s structure and function. These tests are considered vital for evaluating conjoined twins, as they determine whether the twins share a heart. 
  • Ultrasound and MRI: An imaging technique that combines both MRI and ultrasound to produce a 3D MRI reconstruction to obtain images, creating additional levels of detail that don’t require sedation or muscle relaxants. 

Visit Rosenberg Maternal Fetal Medicine Today for a Consultation

At the end of the day, expecting parents will need to meet with their multidisciplinary team to discuss the results of their tests and outline their options for prenatal management and delivery. If you are seeking further advice for your pregnancy, our team can help you by referring you to our recommended physicians and helping you make an informed decision about how to move forward. For more information, please get in touch with us at either one of our locations by calling Hewlett: (516) 501-9840 or Suffern: (845) 764-9880.