RESULTS AND RECOMMENDATIONS: TTTS is a serious condition that can complicate
8-10% of twin pregnancies with monochorionic diamniotic (MCDA) placentation. The
diagnosis of TTTS requires 2 criteria: (1) the presence of a MCDA pregnancy; and (2) the
presence of oligohydramnios (defined as a maximal vertical pocket of2 cm) in one sac,
and of polyhydramnios (a maximal vertical pocket of8 cm) in the other sac. The Quintero
staging system appears to be a useful tool for describing the severity of TTTS in a
standardized fashion. Serial sonographic evaluation should be considered for all twins with
MCDA placentation, usually beginning at around 16 weeks and continuing about every 2
weeks until delivery. Screening for congenital heart disease is warranted in all monochorionic
twins, in particular those complicated by TTTS. Extensive counseling should be
provided to patients with pregnancies complicated by TTTS including natural history of the
disease, as well as management options and their risks and benefits. The natural history
of stage I TTTS is that more than three-fourths of cases remain stable or regress without
invasive intervention, with perinatal survival of about 86%. Therefore, many patients with
stage I TTTS may often be managed expectantly. The natural history of advanced (eg, stage
III) TTTS is bleak, with a reported perinatal loss rate of 70-100%, particularly when it
presents 26 weeks. Fetoscopic laser photocoagulation of placental anastomoses is
considered by most experts to be the best available approach for stages II, III, and IV TTTS
in continuing pregnancies at 26 weeks, but the metaanalysis data show no significant
survival benefit, and the long-term neurologic outcomes in the Eurofetus trial were not
different than in nonlaser-treated controls. Even laser-treated TTTS is associated with a
perinatal mortality rate of 30-50%, and a 5-20% chance of long-term neurologic handicap.
Steroids for fetal maturation should be considered at 24 0/7 to 33 6/7 weeks,
particularly in pregnancies complicated by stageIII TTTS, and those undergoing invasive
interventions.