mr-said warsame nur

1. HUMAN
CHORIONIC
GONADOTROPIN
HORMON (HCG)

2. Learning Objective
At the end of this lecture, the learner will be
able to:
specimen collection for pregnancy test
Practice the different tests for pregnancy
Explain factors that affect pregnancy tests

3. HCG and Pregnancy
 Human chorionic gonadotropin (HCG) is a
hormone secreted by placenta during pregnancy.
 Its production stimulates secretion of
progesterone by the ovary.
 the HCG level will double every 2-3 days in
early pregnancy

4. HCG and Pregnancy
 It appears in urine, blood and amniotic fluid.
The serum and urine level rise rapidly during
gestation.
 Levels can first be detected by a blood
test about 11 days after conception and
about 12-14 days after conception by
a urine test.

5. Pregnancy Tests
 Pregnancy tests are designed to tell if your
urine or blood contains a hormone called
human chorionic gonadotropin (hCG).
 Laboratory tests for pregnancy are based on
the detection of human chorionic
gonadotrophin hormone in serum or urine;
mainly there are two types of test.

6. Pregnancy Tests
 Pregnancy tests detect the amount of HCG in the
blood or urine and a pregnancy test becomes positive
when there are sufficient levels of HCG.
 Blood HCG testing is much more sensitive than urine
HCG testing, therefore a blood HCG test can detect
pregnancy several days before a urine pregnancy test

7. Biologic animal Bioassay (A-Z
test)
 This test is performed in laboratory animal
(female mouse).
 i.e. Patient’s urine is injected in to a female
mouse after certain period, the mouse will be
killed and the ovary will be examined for sign
of pregnancy.

8. Immunologic test
 Immunologic test could be qualitative and
quantitative.
 Qualitative estimation of HCG in urine is used
for early detection and confirmation of
pregnancy
 Quantitative estimation of HCG in serum has
of value in case of preeclamptic toxemia,

9. Specimen Collection
 An early morning urine specimen is preferable
because this is the most concentrated and contains
the highest level of HCG.
 Urine must be collected in a clean detergent free
container.
 If it cannot be tested immediately, it should be
refrigerated at 4C0 for not longer than 48 hours.
 Specimen preserved with boric acid is also suitable
for testing.

10. Types
immunologic test
Rapid latex slide
test
Indirect latex slide
test
Direct latex slide
test
Tube test
(haemagglutination
inhibition technique)

11. Indirect latex slide test
 Principle
 Urine specimen is first treated with anti-HCG and
then reacted with the latex suspension.
 If the urine contains HCG, the anti HCG will be
neutralized and then the latter will not be available
to the HCG coated latex particles for bringing
about agglutination.

12. Indirect latex slide test
 Reagents and materials
 Antiserum that contain HCG antibody
 Latex reagent coated with HCG
 Positive and negative controls
 Mixing sticks and slides

13. Indirect latex slide test
 Procedure
 Place one drop of urine sample on the ring of the slide provided by the
manufacture.
 Add one drop of anti-HCG reagent to the urine specimen placed on
the slide
 Rock the slide gently for about 30 seconds.
 Gently shake the vial with latex antigen and then add one drop.
 Mix again with applicator stick and observe the appearance of
agglutination at 2 minutes under a bright light.

14. Indirect latex slide test
Reporting
 Latex particle agglutinated _______ Negative
(non-reactive)
 Homogenous suspension of latex particles with
out any sign of agglutination _______ Positive
(Reactive)

15. Direct latex slide test
 Principle
 The reaction is based on the reaction
between HCG in urine and the latex particles
coated with anti HCG.
 In positive result agglutination will be
observed.

16. Haemagglutination inhibition
test (tube test)
 It is more sensitive than slide test
 Principle: similar with latex slide test except the HCG
is coated on red cells, not on polystyrene particles.

17. Haemagglutination inhibition
test (tube test)
 Procedure
 Add a drop of urine and drop of anti-HCG
antiserum in a small tube.
 Add red cell coated with HCG
 Mix the contents of the tube and leave at
room temperature (20-28C0) for 1-2 hrs to
allow time for the red cells to settle down.

18. Haemagglutination inhibition
test (tube test)
 Procedure
 If the urine contains HCG it will combine with
the antibody.
 If the urine contains no HCG, the anti HCG
antibody will react with the HCG on the red
cells and cause their agglutination.

19. Haemagglutination inhibition
test (tube test)
 Reporting
 Reactive __________Non-agglutinated cells
settle in the bottom of the tube
 Non-reactive _______Agglutinated cells settle
and covers the bottom of the tube.

22. Factors
Affecting
Pregnancy
Tests
False Negative
may occur in
conditions
False positive
may occur in
conditions