Circulating free soluble fms-like tyrosine kinase-1 during late first trimester in relation with placental volume as a surrogate for trophoblastic production: a physiology study in low-risk cohort.
BACKGROUND
Data on first-trimester circulating soluble fms-like tyrosine kinase-1 (sFlt-1) and ischemic placental disease is limited and conflicting. This study aimed to study its physiology in relation to trophoblastic mass as the source of production.


METHODS
Low-risk (representing normal placentation) women from 11 0/7 to 13 6/7 weeks' gestation were prospectively enrolled. Selective measurement of serum free sFlt-1 using a new automated assay from 100 eligible subjects was analyzed with gestational age, maternal weight, fetal crown-rump length (CRL), and mean uterine artery Doppler pulsatility index (PI). Placental volume (surrogate for trophoblastic mass) was estimated using 3-dimensional ultrasound and was assessed for its association with serum free sFlt-1.


RESULTS
There was no significant association between serum free sFlt-1 and placental volume in either arithmetic (r = 0.053, p = 0.600), logarithmic (r = 0.005, p = 0.963), or quartile (p = 0.703) scale. There was a significant negative correlation between free sFlt-1 level and maternal weight (r=-0.213, p = 0.033). No significant correlation was found between free sFlt-1 level and gestational age (r = 0.007, p = 0.947), CRL (r = 0.027, p = 0.788), and uterine artery Doppler mean PI (r = 0.020, p = 0.828).


CONCLUSIONS
Lack of correlation between circulating free sFlt-1 level and placental volume suggests that trophoblasts are not its major source during first trimester with presumably physiologic placentation.
a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Faculty of Medicine, Siriraj Hospital , Bangkok , Thailand.
Sudtawin
S
Manthati
b Department of Clinical Pathology, Siriraj Hospital , Bangkok , Thailand , and.
Busadee
B
Pratumvinit
b Department of Clinical Pathology, Siriraj Hospital , Bangkok , Thailand , and.
Ratchaneekorn
R
Hanyongyuth
c Department of Clinical Epidemiology, Faculty of Medicine, Siriraj Hospital , Bangkok , Thailand.
Suthipol
S
Udompunthurak
a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Faculty of Medicine, Siriraj Hospital , Bangkok , Thailand.
Amprapha
A
Phaophan
a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Faculty of Medicine, Siriraj Hospital , Bangkok , Thailand.
Tuangsit
T
Wataganara
D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D009929:Organ Size; D010920:Placenta / Q000000981:diagnostic imaging / Q000378:metabolism*; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000096:biosynthesis / Q000097:blood*; D055815:Young Adult
C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1
Free sFlt-1; placental volume; preeclampsia; serum biomarker