Sunday, January 4, 2015

Blighted Ovum Diagnosis? Ask About the Size of the Gestational Sac.

I know, I've said it before but I just have to say it again.

If your doctor is diagnosing a blighted ovum (empty gestational sac), the most important question you need to ask is:

What are the measurements of the gestational sac?


  • It doesn't matter how many weeks you are.
  • It doesn't matter how high your hCG numbers are.
  • It doesn't matter that your doctor has the latest and greatest ultrasound equipment.
What matters most is the size of the gestational sac and whether it is growing.  If that gestational sac is under 25mm, one ultrasound cannot diagnose a blighted ovum.

I've blogged about the UK's new guidelines. If the gestational sac is growing and, if there are no complications, you should wait until the gestational sac is 25mm and then wait one week to verify.

Taken from the  National Institute for Health and Care Excellence's page:

Ectopic pregnancy and miscarriage: Diagnosis and initial management in early pregnancy of ectopic pregnancy and miscarriage

1.4.9 If the mean gestational sac diameter is less than 25.0 mm with a transvaginal ultrasound scan and there is no visible fetal pole, perform a second scan a minimum of 7 days after the first before making a diagnosis. Further scans may be needed before a diagnosis can be made.
1.4.10 If the mean gestational sac diameter is 25.0 mm or more using a transvaginal ultrasound scan and there is no visible fetal pole:
  • seek a second opinion on the viability of the pregnancy and/or
  • perform a second scan a minimum of 7 days after the first before making a diagnosis.
1.4.11 If there is no visible fetal pole and the mean gestational sac diameter is measured using a transabdominal ultrasound scan:
  • record the size of the mean gestational sac diameter and
  • perform a second scan a minimum of 14 days after the first before making a diagnosis.
1.4.12 Do not use gestational age from the last menstrual period alone to determine whether a fetal heartbeat should be visible.
1.4.13 Inform women that the date of their last menstrual period may not give an accurate representation of gestational age because of variability in the menstrual cycle.

Without a doubt, these are the best guidelines I've seen.  If doctors around the world would adopt these guidelines, the number of misdiagnosed miscarriages would plummet.

Generally speaking, the gestational sac will measure at least 25mm by about nine weeks or so for the vast majority of women.


Too many women have shared stories of being misdiagnosed because their hCG levels were really high with no baby seen or their doctor didn't believe there was hope because they were eight weeks.  Don't focus on these things.  Focus on the size of the gestational sac and whether it is growing.  Yes, it still may end up as a blighted ovum but, if you end your pregnancy before the sac reaches 25mm and it is still growing, you may be ending a viable pregnancy.



2 comments:

  1. Does the ges. sac decrease in size overtime, if indeed a blighted ovum has occurred?

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    Replies
    1. Not necessarily. Often, if a natural miscarriage has not occurred by ten weeks, a D&C becomes necessary.

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