[Natural history of monochorionic diamniotic twin pregnancies with and without twin-twin transfusion syndrome].

PURPOSE: to evaluate the evolution of monochorionic-diamniotic twin pregnancies with and without the twin-twin transfusion syndrome (TTTS), followed up in an expectant way.

METHODS: retrospective study in which the pregnancies with and without TTTS and with mild (Quintero's stage I) and severe (Quintero's stages II, III, IV and V) disease manifestations were compared according to extreme preterm delivery, neurological impairment and the twins' nursery discharge. The extreme preterm twins who had had TTTS, or not, were compared whether they had or not neurological impairment. The chi2 or Fisher's exact test were used.

RESULTS: among 149 monochorionic-diamniotic twin pregnancies, 15 presented TTTS, 11 (11/15 - 73.3%) in the severe form and 4 (4/15 - 26.7%) at stage I. The extreme preterm delivery was more frequent (p<0.001) in the cases with the disease (11/15 - 73.3%) than in the cases without it (25/134 - 18.7%), and more common (p=0.033) in severe (10/11 - 91.1%) than in mild cases (1/4 - 25.0%). Neurological impairment in at least one twin was more frequent in cases with (5/8 - 62.5%) than in cases without (9/134 - 6.7%) the disease (p<0.001). Nursery discharge of at least one twin was more common (p<0.001) in cases without (132/134 - 98.5%) than in cases with the disease (8/15 - 53.0%). Neurological impairment in at least one of the twins was more frequent (p=0.04) in the severe (5/5 - 100%) than in the mild (1/4 - 25%) form of the disease. Nursery discharge of both twins was more common (p=0.004) at stage I (4/4 - 100%), than in the severe form of the disease (1/11 - 9.0%). Among the 47 extreme preterm twins, the neurological impairment was more frequent (p=0.001) among the ones who had (6/6 - 100%), than among those who did not have TTTS (11/41 - 26.8%).

CONCLUSIONS: cases with twin-twin transfusion syndrome, followed up in an expectant way have bad perinatal prognosis, with high neonatal mortality and high rates of neurological arrest among the survivors.