Twin-to-twin transfusion syndrome

Twin-to-twin transfusion syndrome (TTTS, also known as Feto-Fetal Transfusion Syndrome (FFTS) and Twin Oligohydramnios-Polyhydramnios Sequence (TOPS)) is a complication of disproportionate blood supply, resulting in high morbidity and mortality. It can affect monochorionic multiples, that is, multiple pregnancies where two or more fetuses share a chorion and hence a single placenta. Severe TTTS has a 60–100% mortality rate.[

Imbalance in development
Some doctors recommend complete bed-rest for the mother coupled with massive intakes of protein (generally in the form of "protein shakes" such as Boost or Ensure) as a therapy to try to counteract the syndrome. Research completed shows these nutritional supplements do work. Diet supplementation was associated with lower overall incidence of TTTS (20/52 versus 8/51, P = 0.02) and with lower prevalence of TTTS at delivery (18/52 versus 6/51, P = 0.012) when compared with no supplementation. Nutritional intervention also significantly prolonged the time between the diagnosis of TTTS and delivery (9.4 +/- 3.7 weeks versus 4.6 +/- 6.5 weeks; P = 0.014). The earlier nutritional regimen was introduced, the lesser chance of detecting TTTS ( P = 0.001). Although not statistically significant, dietary intervention was also associated with lower Quintero stage, fewer invasive treatments, and lower twin birth weight discordance. Diet supplementation appears to counter maternal metabolic abnormalities in DiMo twin pregnancies and improve perinatal outcomes in TTTS when combined with the standard therapeutic options.

Stages
A staging system proposed by fetal surgeon Dr. Ruben Quintero is commonly used to classify the severity of TTTS.


Stage I: A small amount of amniotic fluid (oligohydramnios) is found around the donor twin and a large amount of amniotic fluid (polyhydramnios) is found around the recipient twin.

Stage II: In addition to the description above, the ultrasound is not able to identify the bladder in the donor twin.

Stage III: In addition to the characteristics of Stages I and II, there is abnormal blood flow in the umbilical cords of the twins.

Stage IV: In addition to all of the above findings, the recipient twin has swelling under the skin and appears to be experiencing heart failure (fetal hydrops).

Stage V: In addition to all of the above findings, one of the twins has died. Usually the donor twin is the twin to die first, but it can happen to either.

The Quintero staging does not provide information about prognosis, and other staging systems have been proposed.

Treatment
Various treatments for TTTS include:

Non-Treatment
Expectant Management

This is equivalent of zero intervention. It has been associated with almost 100% mortality rate of one or all fetuses. Exceptions to this include patients that are still in Stage 1 TTTS and are past 22 weeks gestation.

Treatment through adjustment of amniotic fluid
Serial Amniocentesis

This procedure involves removal of amniotic fluid periodically throughout the pregnancy under the assumption that the extra fluid in the recipient twin can cause preterm labor, perinatal mortality, or tissue damage. In the case that the fluid does not reaccumulate, the reduction of amniotic fluid stabilizes the pregnancy. Otherwise the treatment is repeated as necessary. There is no standard procedure for how much fluid is removed each time. There is a danger that if too much fluid is removed, the recipient twin could die. This procedure is associated with a 66% survival rate of at least one fetus, with a 15% chance of cerebral palsy and average delivery occurring at 29 weeks gestation.

Septostomy, or Iatrogenic Disruption of the Dividing Membrane

This procedure involves the tearing of the dividing membrane between fetuses such that the amniotic fluid of both twins mixes under the assumption that pressure is different in either amniotic sac and that its equilibration will ameliorate progression of the disease. It has not been proven that pressures are different in either amniotic sac. Use of this procedure can preclude use of other procedures as well as make difficult the monitoring of disease progression. In addition, tearing the dividing membrane has contributed to cord entanglement and demise of fetuses through physical complications.

Treatment through adjustment of blood supply
Laser Therapy

This procedure involves endoscopic surgery using laser to interrupt the vessels that allow exchange of blood between fetuses under the assumption that the unequal sharing of blood through these vascular communications leads to unequal levels of amniotic fluid. Each fetus remains connected to its primary source of blood and nutrition, the placenta, through the umbilical cord. This procedure is conducted once, with the exception of all vessels not having been found. The use of endoscopic instruments allows for short recovery time. This procedure has been associated with 85% survival rate of at least one fetus, with a 5% risk of cerebral palsy and average delivery occurring at 33–39 weeks' gestation.

Umbilical Cord Occlusion

This procedure involves the ligation or otherwise occlusion of the umbilical cord to interrupt the exchange of blood between the fetuses. The procedure is typically offered in cases where one of the fetuses is presumed moribund and endangering the life or health of the other twin through resultant hypotension. Use of this treatment has decreased as TTTS is identified and treated in earlier stages and with better outcomes. When used, it is associated with an 85% survival rate of the remaining fetus(es) with 5% risk of cerebral palsy and a 33–39 weeks of gestation at delivery.

A recent review found that laser coagulation resulted in less fetal and perinatal deaths than aminoreduction and septostomy, and recommended its use for all states of TTTS.

Source:

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