Indications:
β-hCG of the assay allows early diagnosis of pregnancy, but mostly ectopic pregnancies.
It also can diagnose secreting tumors, and early detection of trisomy 21 (in this case, the rates are unusually high compared with gestational age).
Principle:
The hormone choriogonadotrope is a glycoprotein secreted by the syncytiotrophobalste, which maintains during the first trimester of pregnancy the activity of the corpus luteum, until the relay is made by the placenta.
Technique:
Sampling 5 mL of blood in a dry tube.
Dosing is done by radioimmunoassay or enzyme immunoassay.
Results:
They depend on the thresholds established by the laboratory.
Normal values:
– Before menopause: less than 10 IU / L;
– After menopause: greater than 20 IU / L;
– If fertilization: greater than 10 IU / L at the 10th day; (10 000 to 100 000 IU / L); it then descends in the last quarter (<1 000 to 50 000).
Pathological changes:
the results are to confront the clinical and especially the ultrasound:
– If the uterine cavity is empty and the β-hCG level is above 10, there is a significant risk of ectopic pregnancy;
– After molar abortion rates higher than 40,000 IU / L are in favor of a choriocarcinoma;
– In case of suspicion of trisomy: hCG levels, especially the β fraction remain high longer during pregnancy; serious doubts exist then; doubt reinforced by the presence of associated signs such as ultrasound (13th week nuchal translucency), alpha-fetal protein, plasma estriol; the result is definitively established with amniocentesis and karyotype.
Cost:
B70.
Practical advice:
Specify the clinical context in which conducted this review.
