OBJECTIVE: We sought to identify clinical factors at diagnosis that predict
outcome in twin-twin transfusion syndrome.
STUDY DESIGN: In this retrospective series 23 patients with twin-twin trans
fusion syndrome were seen in a tertiary referral fetal medicine center over
a 3-year period. Ten antenatal factors were assessed to determine their ab
ility to predict outcome by use of ordered logistic regression. These facto
rs were the following: (1) absent or reversed end-diastolic flow in the umb
ilical artery, nonvisible bladder, anhydramnios, and estimated fetal weight
of <3rd percentile in the donor; (2) pulsatile umbilical vein, either abse
nt or reversed end-diastolic flow in the ductus venosus, or both, and tricu
spid-mitral valve regurgitation in the recipient; and (3) gestational age a
t presentation, estimated fetal weight discordancy. absent arterioarterial
anastomosis, and spontaneous rupture of the membranes or cervical change as
pregnancy factors. Management comprised serial amnioreduction (n = 10), se
lective feticide (n = 5; 4 also had amnioreduction), septostomy (n = 4; 1 a
lso had amnioreduction), and delivery (n = 2). Two patients miscarried befo
re treatment.
RESULTS: The chance of survival of both twins fell and double deaths increa
sed linearly with increasing number of adverse factors (P = .026). A low ch
ance of survival was independently associated with absent or reversed end-d
iastolic flow in the donor umbilical artery (P = .02) and with a pulsatile
umbilical vein or absent or reversed end-diastolic flow in the ductus venos
us (P =.03) of the recipient. The probability of at least one twin survivin
g was only 33% ii there was absent or reversed end-diastolic flow in the do
nor umbilical artery or 37% when abnormal venous recordings were seen in th
e recipient. An arterioarterial anastomosis detected at diagnosis also infl
uenced prognosis. with all twins surviving when an arterioarterial anastomo
sis was identified (P = .04),
CONCLUSIONS: Three factors identified at diagnosis independently predict po
or survival in twin-twin transfusion syndrome-absent or reversed end-diasto
lic flow in the donor umbilical artery, abnormal pulsatility of the venous
system in the recipient, and absence of an arterioarterial anastomosis. The
se may have a role in the counseling of parents and in selecting the approp
riate treatment strategy.