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Estetrol Amniotic Fluid Test

Last updated May 20, 2019

Approved by: Krish Tangella MD, MBA, FCAP

The Estetrol Amniotic Fluid Test helps determine the levels of estetrol in the amniotic fluid.

What are other Names for this Test? (Equivalent Terms)

  • E4 Amniotic Fluid Test

What is the Estetrol Amniotic Fluid Test? (Background Information)

  • Estetrol is a hormone produced by a developing fetus during pregnancy. It appears in the mother’s bloodstream, where it may serve as an indicator for the health of the growing, unborn child
  • Estetrol is a type of estrogen hormone. It is made from estradiol (E2) and estriol (E3) by the actions of two enzymes, which are 15a-hydroxylase and 16a-hydroxylase. The reactions are carried out in the developing baby’s liver
  • Estetrol crosses the placenta and enters the mother’s blood circulation. Levels of estetrol are detectable after week 20 of pregnancy (in the second trimester)
  • During the third trimester of pregnancy, estetrol levels may be used to indicate problems with pregnancy. Specifically, if levels of estetrol in the mother’s blood decrease, there may be a health condition pertaining to the placenta or the fetus
  • By the time the baby is born, estetrol makes up 0.05% to 2% of its total estrogen content. Estetrol is no longer made after birth, because the two enzymes responsible for estetrol production ceases to be produced
  • The Estetrol Amniotic Fluid Test helps determine the levels of estetrol in the amniotic fluid. It is used to help diagnose any associated problems with pregnancy

What are the Clinical Indications for performing the Estetrol Amniotic Fluid Test?

Following are the clinical indications for performing the Estetrol Amniotic Fluid Test:

  • Following up to ultrasound imaging indicating problems with fetal development
  • Miscarriage
  • Vaginal bleeding
  • Cramping
  • High blood pressure
  • Abnormal weight gain (less than 20 lbs or more than 40 lbs)

How is the Specimen Collected for the Estetrol Amniotic Fluid Test?

Following is the specimen collection process for Estetrol Amniotic Fluid Test:

Sample required: Amniotic fluid

Process of obtaining an amniotic fluid sample in adults (amniocentesis):

  • A local anesthetic is applied to the site of amniocentesis
  • A needle is inserted into the mother’s abdominal wall, through the uterus and into the amniotic sac
  • Ultrasound imaging is used to guide the needle as it punctures the sac, at a location away from where the baby is
  • Approximately 20 mL of amniotic fluid is obtained, and the needle is withdrawn

Preparation required: No special preparation is needed prior to the test.

What is the Significance of the Estetrol Amniotic Fluid Test Result?

Interpretations of the Estetrol Amniotic Fluid Test value depend on how far the pregnancy progressed.

A low value is indicated as follows:

  • Weeks 32+: 0.8 ng/mL
  • Weeks 40+: 13.0 ng/mL

A low value for the test may indicate:

  • Fetal distress
  • Intrauterine fetal death
  • Anencephalic fetus
  • Fetal malformations

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and Relevant Useful Information:

  • Currently, there is no one single test that helps determine fetal distress. The Estetrol Amniotic Fluid Test is just one of several tests, including the amniotic fluid index, used for this purpose

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

The following DoveMed website link is a useful resource for additional information:


Please visit our Laboratory Procedures Center for more physician-approved health information:


References and Information Sources used for the Article:

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: Jan. 31, 2016
Last updated: May 20, 2019