Latex agglutination inhibition test (LAI)
The latex agglutination inhibition test means that if the HCG content in the urine of the subject is increased, a corresponding amount of antiserum (HCG antibody) is added, and after fully acting, the antibody binds to HCG in the urine, and then the HCG latex antigen is added, and the agglutination reaction should be performed. Inhibited, indicating that the urine contains HCG, which is positive for pregnancy reaction. The LAI test is generally positive 35 to 40 days after pregnancy. The positive rate was as high as 98% in 60-70 days, and the positive rate gradually decreased after 120 days.Basic Information
Specialist classification: maternity check check classification: urine / kidney function test
Applicable gender: whether women are fasting: not fastingAnalysis results:
If the HCG content in the urine of the subject is increased, the corresponding amount of antiserum (HCG antibody) is added. After sufficient action, the antibody binds to HCG in the urine, and then the HCG latex antigen is added. The agglutination reaction is inhibited, indicating that the urine is in the urine. Containing HCG, it is positive for pregnancy reaction.Clinical significance
The LAI test is generally positive 35 to 40 days after pregnancy. The positive rate was as high as 98% in 60-70 days, and the positive rate gradually decreased after 120 days. The LAI test not only produces a positive reaction in normal gestational urine; in some pathological conditions, such as ectopic pregnancy, hydatidiform mole, choriocarcinoma, testicular teratoma, it also has a positive reaction due to the presence of HCG in the urine.
In addition to normal pregnancy, expired abortion or incomplete abortion and placenta still exist, can also be positive, after the abortion curettage without placenta residue, can be negative reaction; in twin pregnancy or combined with pregnancy poisoning, the original After the urine is diluted, the LAI test is still positive, but the dilution (except for a few) is generally not high.
In the urine of patients with hydatidiform mole, choriocarcinoma and testicular teratoma, the HCG content is significantly higher than that of normal pregnant women. The urine can be highly diluted and then tested for LAI, which is still positive and can be used as a differential diagnosis.
When the patient's urine HCG content is low, the LAI test is not enough to produce a positive reaction, and the urine HCG is concentrated 30 times and 60 times, which can improve the sensitivity. Clinically used for the observation of postoperative hysterectomy or choriocarcinoma, such as concentrating the patient's urine 30 times, 60 times, the LAI test is negative, indicating complete or no recurrence. Conversely, if it is positive, it means that the treatment is not complete or the disease progresses.
In the case of LAI-negative, the pregnancy and pregnancy-related diseases cannot be negated, and should be analyzed in combination with clinical analysis. If necessary, the examination may be repeated at intervals. Negative reactions can occur in the following cases; when the diagnosis is early pregnancy, but a small number of pregnant women have less hormone secretion or very early pregnancy, urine samples contain lower HCG; when abortion or ectopic pregnancy, placental tissue is no longer present; Or when the urine specimen is not fresh.
Pregnant women in need of testing, abortion women.Precautions
Before the test: pay attention to the diet, normal work schedule, adjust the body.
When checking: Relax and unwind, and carefully cooperate with the doctor's examination.Inspection process
1. Take a black glass plate with a paint circle of 2.5~3cm size, mark it with special pencil, circle 1 as experiment, 2 as positive control, 3 negative control.
2. Add 3 drops of urine, pregnant urine, normal human urine (or normal saline) in circle 1, circle 2 and circle 3 with 3 clean capillary drops, and then lower in the above three circles. A drop of the immune serum is mixed with a toothpick (or matchstick) and shaken continuously for 1 to 2 minutes on the table.
3. One drop of each latex antigen in the above three circles, mix well, and then shake continuously for 2~5 minutes to observe the result.Not suitable for the crowd
There are no taboos.Adverse reactions and risks
There are no related complications and hazards.