Donor twin with marked oligohydramnios

Donor twin with marked oligohydramnios at 24+2 weeks of gestation. Arrow denotes the membrane, which can be seen extending between the lower fetal abdomen and the fetal thigh of the donor twin. The difficulty in finding this membrane can often lead to the erroneous diagnosis of monoamniotic twins. The sac of the recipient twin has polyhydramnios.