unstable lie

Last reviewed 01/2018

When the presentation of the foetus changes from day to day the lie is said to be unstable.

It is not a sinister sign in the grand multip - the uterus is relatively flaccid and able to accommodate a lot of movement of the fetus.

In other women it ought to be investigated as a possible sign of placenta praevia - the low lying placenta preventing engagement of the fetal head.

Other possible causes of an unstable lie include:

  • polyhydramnios
  • prematurity
  • subseptate uterus
  • pelvic tumours such as fibroids and ovarian cysts