TTTS occurs when the blood supply of one twin moves to the other the shared placenta. The twin that loses the blood is called the donor twin. The twin that receives the blood is called the recipient twin.
Both infants may have problems depending on how much blood is passed from one to the other. The donor twin may have too little blood, and the other may have too much blood.
Most of the time, the donor twin is smaller than the other twin at birth. The infant often has anemia, is dehydrated, and looks pale.
The recipient twin is born larger, with redness too the skin, too much blood, and higher blood pressure. The twin that gets too much blood may develop cardiac failure because of the high blood volume. The infant may also need medicine to strengthen heart function.
The unequal size of identical twins is referred to as discordant twins.
Signs and tests
This condition is usually diagnosed by ultrasound during pregnancy.
After birth, the infants will receive the following tests:
Blood clotting studies, including prothrombin time (PT) and partial thromboplastin time (PTT)
Comprehensive metabolic panel to determine electrolyte balance
Complete blood count
Treatment may require repeated amniocentesis during pregnancy. Fetal laser surgery may be done to stop the flow of blood from one twin to the other.
After birth, treatment depends on the infant's symptoms. The donor twin may need a blood transfusion to treat anemia.
The recipient twin may need to have the volume of body fluid reduced. This may involve an exchange transfusion.
The recipient twin may also need to take medicine to prevent heart failure.
If the twin-to-twin transfusion is mild, both babies often recover fully. Severe cases may result in the death of a twin.
Carol WA. The high-risk infant. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 91.
Habli M, Lim FY, Crombleholme T. Twin-to-twin transfusion syndrome: a comprehensive update. Clin Perinatol. 2009 Jun;36(2):391-416, x.
Cunningham FG, Leveno KJ, Bloom SL, et al. Multifetal gestation. In: Cunnigham FG, Leveno KL, Bloom SL, et al, eds. Williams Obstetrics. 23rd ed. New York, NY: McGraw-Hill; 2010:chap 39.
Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.