Estriol, pregnancy

Alphabetical Test listing

Estriol, pregnancy-994

Estriol, pregnancy
Pregnancy, estriol
Unconjugated estriol
  • This test is only appropriate for pregnant patients to evaluate fetal distress and placental function in the management of patients facing complications such as preëclampsia, fetal growth retardation, diabetes, Rh immunization, choriocarcinoma, and hydatidiform mole.
  • May be elevated in hydrops fetalis in the presence of a dying fetus.
  • May be low in the presence of a living anencephalic fetus.

Patient usually in third trimester of pregnancy

1.0 mL
0.3 mL

Immediately following collection, thoroughly mix sample by gently inverting 5 times

  1. Allow sample to clot for a minimum of 30 minutes
  2. Spin within two (2) hours of sample collection

Gold serum separator (SST) tube

  1. Allow sample to clot
  2. Spin within two (2) hours of sample collection
  3. Transfer serum to a Transfer vial/tube with cap - 12mL (LabCorp), labelled as serum

Refrigerated (preferred) – 14 days

Ambient – 14 days

Frozen – 14 days

Freeze/thaw cycles - stable x3

LabCorp Burlington (004614): R-NX
Mo - Fr
4 days

Immunochemiluminometric assay (ICMA)


See report


Estriol, E3, is synthesized in the placenta from 16-α-hydroxydehydroepiandrosterone of fetal origin. Thus, normal production can serve as a measure of the integrity of the fetoplacental unit. Sequential monitoring of estriol in high-risk pregnancy has made possible early intervention and fetal salvage. Chronically low estriol values are found in intrauterine growth retardation but also are sometimes seen in normal pregnancy. A decreasing trend is indicative of fetal distress. The sensitivity and specificity of this test for detecting fetal distress are very poor; thus its use for this purpose has been largely abandoned.

Combined evaluation of unconjugated serum estriol, maternal serum hCG, maternal serum AFP, and maternal age has value in predicting risk for fetal chromosomal abnormalities during pregnancy. The use of maternal serum AFP, hCG, and estriol predicts 65% of Down syndrome, as opposed to 28% if only serum AFP is used.