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Symptoms
By Mayo Clinic staffThere aren't any specific signs and symptoms that indicate a woman is carrying conjoined twins. As with other twin pregnancies, the uterus may grow more rapidly than expected, and mothers of twins may also have more fatigue, nausea and vomiting early in the pregnancy.
How twins are joined
Conjoined twins are usually classified according to where they're joined, and there are many ways that conjoined twins may be connected. Some of the more common include:
- Joined at the chest. One of the most common of conjoined twins, thoracopagus twins are joined at the chest. They have a shared heart and may also share one liver and upper intestine.
- Joined near the bellybutton. Omphalopagus twins are joined near the bellybutton. Many omphalopagus twins share the liver, and some share the lower part of the small intestine (ileum) and colon. They do not, however, share a heart.
- Joined at the base of the spine. Pygopagus twins are joined at the base of the spine. Some pygopagus twins share the lower gastrointestinal tract, and a few share the genital and urinary organs.
- Joined at the pelvis. Ischiopagus twins are joined at the pelvis. Many ischiopagus twins share the lower gastrointestinal tract, as well as the genital and urinary tract organs.
- Joined at the head. Craniopagus twins are joined at the head. Craniopagus twins share the skull, and possibly brain tissue. Some also share the cerebral cortex — the part of the brain that plays a central role in memory, language and perception.
Many conjoined twins have separate arms and legs, but in some cases, limbs are shared. In rare cases, twins may be asymmetrically conjoined, with one twin smaller and less fully formed than the other (parasitic twins).
- Cunningham FG, et al. Multifetal gestation. In: Cunningham FG, et al. Williams Obstetrics. 23rd ed. New York, N.Y.: McGraw Hill; 2010. http://www.accessmedicine.com/content.aspx?aID=6037146. Accessed Sept. 24, 2010.
- Winkler N, et al. The imaging spectrum of conjoined twins. Ultrasound Quarterly. 2008;24:249.
- Spitz L. First trimester diagnosis of conjoined twins. Prenatal Diagnosis. 2005;25:820.
- Amin S, et al. Live conjoined twins: A rare first trimester diagnosis during emergency department sonography. Emergency Medicine. 2010;39:e105.
- Roque H, et al. Monoamniotic twin pregnancy. http://www.uptodate.com/home/index.html. Accessed Sept. 24, 2010.
- Martinez-Frias ML, et al. Epidemiological and clinical analysis of a consecutive series of conjoined twins in Spain. Journal of Pediatric Surgery. 2009;44:811.
- Kokcu A, et al. Conjoined twins: Historical perspective and report of a case. Journal of Maternal Fetal Neonatal Medicine. 2007;20:349.
- Pajkrt E, et al. First-trimester diagnosis of conjoined twins. Prenatal Diagnosis. 2005;25:820.
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