Indication of prenatal diagnosis in pregnancies complicated by undetectable second-trimester maternal serum estriol levels.

OBJECTIVES Undetectable maternal serum unconjugated estriol levels in the second-trimester screening test have been associated with congenital pathology and an adverse pregnancy outcome. We reviewed outcomes of pregnancies with undetectable levels of estriol (<0.25 ng/ml) in the triple-marker screening test and assessed the clinical value of this finding. METHODS We studied estriol values in 6,018 pregnant patients who underwent a triple-marker screening test during a seven-year period. RESULTS 26 women had estriol levels at or below the sensitivity of the assay. The most common explanations were dating errors, prematurity, growth restriction and X-linked ichthyosis. We also observed one fetal death at 16 weeks, one severe threatened fetal abortion, one case of multiple congenital anomalies and one case of isolated adrenocorticotropin hormone deficiency. There were 6 women remaining with unexplained undetectable estriol. CONCLUSION Undetectable maternal estriol values may indicate a severe fetal pathology and should lead to further investigations.