Twin-to-twin transfusion syndrome (TTTS) is a rare condition that occurs in some pregnancies in which identical twins are sharing the same placenta (monochorionic pregnancies). Normally each fetus has its own separate placenta. Monochorionic twin pregnancies occur when identical twins end up sharing a single placenta. When this occurs the blood vessels attaching each twin's umbilical cord to the placenta may become abnormally connected resulting in TTTS.
TTTS causes abnormal disparity in blood circulation between the twins. The abnormal blood vessel connections inside the shared placenta cause blood to be diverted away from one twin (the "donor") and circulated to the other twin (the "recipient"). The end result is that the donor twin ends up not getting enough blood supply from the placenta while the recipient twin is getting too much blood from the placenta. This can be very serious because blood circulation from the placenta is the key to fetal life and development. All of the oxygen and nutrients the fetus needs to survive and grown comes from maternal blood exchange through the placenta.Dangers of TTTS
TTTS is a very uncommon condition. It can only occur in identical twin pregnancies with a shared placenta. Identical twins are relatively uncommon to begin with and not all identical twins end up sharing a placenta. Even with identical twins and a shared placenta, TTTS still only occurs when the umbilical cords attach close enough together on the placenta for the blood vessels to connect abnormally. This only happens in about 15% of monochorionic pregnancies. When twin-to-twin transfusion syndrome does occur, however, it can be very serious. Until recently, in fact, TTTS was almost always fatal for one if not both twins.
When TTTS occurs the donor twin is deprived of blood supply from the placenta and the condition progressively gets worse. The donor baby's system responds to the lack of blood by circulating all available blood supply to the brain and the heart. Meanwhile, blood is diverted away from secondary organs. If not corrected, the donor twin will eventually die from organ failure. If the donor twin dies it immediately puts the recipient twin at high risk of death or injury.Diagnosis of TTTS
TTTS is diagnosed clinically based on a various symptoms, most of which are apparent from ultrasound images. These include disparities in amniotic fluid levels (one twin has too little while the other twin has too much amniotic fluid). TTTS is a progressive condition meaning it gets worse over time. This means that early diagnosis and intervention is critically important.
Accurate diagnosis of TTTS can be difficult because there is no easy way for doctors to look inside the placenta and see if abnormal blood vessel connections have formed. However, since TTTS is a condition that can only occur in monochorionic pregnancies, the starting point for any TTTS diagnosis is identifying whether identical twins are sharing a single placenta. Making this determination can and should occur fairly early on in the pregnancy. Once the pregnancy is classified as monochorionic, doctors will carefully monitor for clinical symptoms of TTTS.
The primary clinical symptoms used to make a diagnosis of TTTS in monochorionic pregnancies are:
- Amniotic Fluid Levels: when TTTS occurs the donor twin will have a smaller bladder and low levels of amniotic fluid in the amniotic sac (oligohydramnios, defined as the deepest pocket of amniotic fluid of fewer than 2 centimeters). The recipient twin will have excess amniotic fluid levels (polyhydramnios, defined as the deepest pocket of amniotic fluid greater than 8 centimeters).
- Fetal Size: another key indicator of TTTS is where one twin is significantly undersized for its fetal age while the other is over-size.
- Umbilical Cord Differences: with TTTS the umbilical cord of the recipient twin will often appear larger compared to the donor twin, due to the excess blood levels being circulated.
The Quintero staging system is the best path to diagnose twin-twin transfusion syndrome. This includes measurement of bladder sizes, polyhydramnios/oligohydramnios, Doppler findings, and the presence of hydrops fetalis which suggests the most advanced and precarious stage of TTTS.
In malpractice cases, doctors will sometimes push back on the victims' lawyer's contention that there ever was twin-twin diagnosis. One argument defense lawyer's reply upon in this vein is that the fetal echocardiography test was negative. But that test is not adequate to diagnose or stage twin-twin transfusion.
Another common defense argument is that it was not twin-twin transfer but instead was an infection. Usually, this argument can be solved with a placental pathologist who can look at the placenta and see if there are any findings consistent with infection.Treatment Options
There are basically 2 treatment options for TTTS. The first option involves the use of amniocentesis to drain excess amniotic fluid from the recipient twin. Reducing amniotic fluid levels in this situation has been shown to help improve blood circulation. The other treatment option is laser surgery. Doctors can actually use a fiber-optic camera to go into the womb and look at the blood vessel connections inside the placenta. This allows them to use a laser tool to cut and seal the abnormal connections that are causing the disparity in blood circulation between the twins.TTTS and Medical Malpractice
Prompt diagnosis of twin-to-twin transfusion syndrome is absolutely critical. In order to effectively treat and manage TTTS it must be diagnosed very early on. TTTS is a highly progressive condition so a delay in diagnosis can quickly have disastrous results. A delay of just a few weeks in the diagnosis of TTTS can potentially be fatal for both twins. As a result, most TTTS malpractice claims involve allegations that doctors were negligent in failing to timely diagnosis the condition.TTTS Verdicts and Settlements
Summarized below are verdicts and reported settlements from a few cases involving allegations that TTTS was misdiagnosed or otherwise mishandled by doctors.
- J.A.S. v Cambridge Pediatrics (Pennsylvania 2016) $8.4 million: defendants hospital and pediatric practice were sued for negligently mishandling pregnancy and premature delivery of identical twins suffering from twin transfer syndrome. One of the twins was stillborn and the surviving twin was extremely premature with a birth weight of only 2 lbs. and an APGAR score of 5. Hours after birth he suffers severe intracranial hemorrhage (brain bleed) causing extensive brain damage and leaving him severely disabled. Negligence was actually admitted by defendants and the case went to trial solely on the issue of damages. Jury awarded over $8 million.
- Plaintiff v Defendant (Iowa 2007) $2.3 million: Plaintiff sued OB/GYNs and radiologists alleging that they failed to timely diagnose and treat her twin-to-twin transfusion syndrome resulting in one twin dying and the other being born with severe brain injuries. Specifically, plaintiff claimed that doctors failed to identify that twins were sharing a single placenta and other signs of TTTS when ultrasound was performed at 18-weeks. By the time the next ultrasound was done at 29-weeks the donor twin had already died and the recipient twin had suffered hypoxic brain injury. The case settled days before trial for $2.6 million.
- Pardini v Allegheny General (Pennsylvania 2007) $125,000: father filed his own separate claim for emotional distress based on the death of his twins. He alleged that the defendant hospital and doctors failed to properly diagnose and manage twin transfusion syndrome which ultimately led to the stillbirths. Mother had already brought claim on behalf of deceased twins and received separate settlements. Case settled for $125k.
Twin-to-twin transfusion syndrome is a rare complication that can occur in a pregnancy where identical twins share the same placenta and one of the twins dominates the blood flow from the placenta creating an imbalance that can be dangerous for both twins.
Twin-to-twin transfusion syndrome can put both babies at potentially fatal risk. The twin receiving less blood flow will have slowed development and decreased amniotic fluid levels that can potentially cause death. The twin dominating the blood flow is at risk of hypervolemia and an abnormal increase in amniotic fluid which can also be potentially fatal.
If TTTS is left undiagnosed and untreated, the survival rate is only around 15%. However, when timely diagnosed and properly managed the survival rate for TTTS is over 90%.
Laser fetal surgery is the only effective treatment for TTTS. This involves using a laparoscopic laser to separate the blood vessels on the placenta.
If you think you may have a malpractice claim involving TTTS or a birth injury, contact the birth injury lawyers at Miller & Zois for a free consultation. Call us at 800-553-8082 or contact us online.Key TTTS Studies
- Faden, M, et. al: Characteristic ultrasound findings of resolving twin-twin transfusion syndrome after Solomon laser treatment. ACOG Jan, 220(1):S161.
- Bolch, et. al: Twin-to-twin transfusion syndrome neurodevelopmental follow-up. BMC Pediatr. 2018; 18:256.
- Argoti PS, et.al: Fetoscopic laser ablation outcomes for twin-to-twin transfusion syndrome in dichorionic triamniotic triplets compared to monochorionic diamniotic twins. Ultrasound Obstet Gynecol 2014 Nov;44(5):545-9.
- Molina S, et al: Management of stage I twin twin transfusion syndrome' An international survey. Ultrasound Obstet Gynecol. 2010 Jul;36(1):42-7.