Irregular Gestational Sac

Definition - What does Irregular Gestational Sac mean?

An irregular gestational sac is the sac of fluid in which an embryo develops that has irregular or ill-defined borders in comparison to a normal gestational sac.

Gestational sacs can vary in shape to a certain degree, but an irregular gestational sac is usually a cause for concern as they are predictors of poor pregnancy outcomes.

Ultrasounds that show irregular gestational sacs are normally followed up by further ultrasounds or other imaging to confirm the diagnosis and determine the risk of miscarriage.

FertilitySmarts explains Irregular Gestational Sac

Gestational sacs are visible on ultrasound imaging and are the only structures used to establish the existence of a pregnancy before an embryo can be detected. Measurements can also be used to estimate the age of the embryo at the early stages (5-6 weeks).

A normal gestational sac:

  • Is round or elliptical
  • Is located in the main body of the uterus
  • Contains the amniotic sac (which will eventually take up the entire sac)

An irregular gestational sac:

  • Is generally larger than usual
  • Has no embryo or yolk sac inside (at an age where they should be seen)
  • Has a distorted shape
  • Has a position low in the uterus
  • Has thin walls

A gestational sac with one or more of these features can indicate a non-viable pregnancy that will end in spontaneous miscarriage.

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