Objectives: To investigate the effect of anhydramnios on the lung development of 1 twin in the presence of a normal amniotic fluid volume in its diamniotic co-twin.
Methods: Three sets of diamniotic twins, discordant for complete urinary tract obstruction and anhydramnios, were followed prospectively with regular ultrasound scans and after delivery.
Results: All 3 twins with complete urinary tract obstruction and anhydramnios died within 2 days after birth, with confirmed severe pulmonary hypoplasia. In every case the twin with a normal amount of surrounding amniotic fluid had a normal postnatal outcome.
Conclusions: The observation that a normal amniotic fluid volume in one sac does not protect the anhydramniotic twin from pulmonary hypoplasia has important implications for the aetiology of the condition and for the possibility of therapeutic septostomy. These results are discussed in relation to previous human and animal studies.