Soluble FMS-like Tyrosine Kinase-1 (sFlt-1) and Serum Placental Growth Factor (PlGF) As Biomarkers for Ectopic Pregnancy and Missed Abortion

Context: Diagnosis of early pregnancy failure is hampered by the lack of reliable serological markers.

Objective: We assessed whether a single serum measurement of placental growth factor (PlGF) and the soluble Flt-1 (sFlt-1) receptor of vascular endothelial growth factor at 6-8 wk gestation could differentiate failed pregnancies, whether ectopic pregnancies (EP) or missed abortions (MA), from healthy intrauterine pregnancies (IUP).

Design And Setting: We conducted a prospective clinical study at a tertiary university hospital between January 2009 and February 2011.

Patients: A total of 78 consecutive patients (38 EP, 40 MA) with failed early pregnancy and 50 IUP (control group) participated in the study.

Intervention(s): Determination of serum PlGF and sFlt-1 has been carried out by ELISA. Gene expression of PlGF and Flt-1 in trophoblasts was performed by RT-PCR.

Main Outcome Measure(s): We investigated whether a single, combined serum measurement of the above markers could contribute to the differential diagnosis.

Results: PlGF and sFlt-1 concentration was lower in both EP (mean, 14.60 ± 3.42/178.16 ± 76.03 pg/ml) and MA (mean, 16.25 ± 4.73/399.42 ± 337.54 pg/ml) compared to IUP (mean, 21.64 ± 5.68/1390.32 ± 655.37 pg/ml). sFlt-1 (P = 0.033) and sFlt-1/PlGF ratio (P = 0.029) but not PlGF had the ability to discriminate MA from EP. Compared to women with viable IUP, mRNA gene expression levels of PlGF and Flt-1 were considerably lower in women with MA and in women with EP.

Conclusions: Combined measurement of sFlt-1 and PlGF levels can differentiate normal from failed pregnancies, whereas sFlt-1 as well as sFlt-1/PlGF ratio can also discriminate EP from MA. PlGF and Flt-1 gene expression in trophoblasts from women with EP and MA appears impaired.