This is a very rare result.

Campbell, in his celebrated monograph, in a total of 51 operations had only seen recorded the accounts of two children saved, and one of these was too marvelous to believe.

Lawson Tait reports a case in which he saved the child, but lost the mother on the fourth day.

Parvin describes a case in which death occurred on the third day.

Browne quotes Parry as saying that there is one twin pregnancy in 23 extrauterine conceptions.