Unlock
the mystery of pregancy hormone
Q.1:
What are the limitations of Urine for preg tests ?
Most of the
pregnancy tests kits available in the
market are intended to test for the presence
of a pregnancy by looking for the presence of the beta
subunit of hCG or
human chorionic gonadotropin in
the blood or urine.
Q.2:-
What is the chemical nature of hCG?? Ans: We know that human chorionic
gonadotropin is a glycoprotein
hormone secreted by the developing
placenta shortly after implantation
. hCG can be
detected in the urine and serum of pregnant women as early as 6-15 days after conception. Q. 12 : Why Quantitative serum beta hCG levels estimation is superior to UPT .(Pregnancy hCG
measurement Tests) : Advantages of Quantitative Tests :-
Qualitative
blood tests
generally have a threshold
of 25 mIU/mL and are less sensitive. However quantitative blood
tests can detect hCG levels
as low as 1 mIU/mL, while urine
tests have published detection thresholds
between 20 and 100 mIU/ml .
Quantitative beta hCG readings
are also used in evaluation of
trophoblastic and other germ cell
tumors.
Quantitative
serum beta hCG levels are measured in mIU/mL and a level above 25 mIU/mL
usually indicates the presence of a pregnancy .Two tests are usually
necessary to verify a normal
increase usually 2-3 days
apart. The increase in serum hCG
can be interactively monitored .
Q. 13: What do we mean by Doubling time of
hCG?? Doubling time varies:--Below an hCG
level of 1,200 mIU/mL the hCG
usually doubles every 48-72 hours, though a rise
of 50-60 % is still considered
normal . Between 1,200 and 6,000
mIU/mL serum , The hCG usually takes 72 -96 hours to double and above 6,000 mIU/mL
the hCG often takes more than
four days to double. Failure to
increase normally may indicate that the pregnancy is not developing well and
can be an early sign for a
possible miscarriage or an ectopic pregnancy . After a miscarriage.
HCG
levels fall steadily back to the non pregnancy range
. Also an ectopic pregnancy
may be suspected when hCG
levels fall to double particularly if the HCG level rises, fails and rises again .
Tips for performing hCG : if testing is entrusted then
each your clinic the “Need for
patience in Pregnancy tests”
Since pregnancy tests look for the hCG hormone
which is produced once the
fertilized egg has implanted in the uterine wall in most
cases, this happens about 6 days after
conception. This has been duly mentioned couple of times. But
studies show that in up to
10 percent of women
, the embryo doesn’t implant until much
later , after the first day
of the missed period.
Hence home pregnancy tests will be accurate as soon as one day after a
missed period for some women but
not for others. And because the
amount of hCG in the urine at different points in early pregnancy is different
for every woman Some woman will
have accurate results on the day of the missed period while others will need to wait longer. But
whatever may be time period a
positive pregnancy test further confirmed to be healthy by ultrasound techniques
makes all the hard work and effort
of planning pregnancy worthwhile
Role of
ultrasound in pregnancy detection
Once a pregnancy has advanced past the first 6-8
weeks the pregnancy is usually
easier to follow by
ultrasound as more
information is obtained in real
time. In general a pregancy is detectable 25 days after ovulation by transvaginal sonography
usually corresponding to an hCG
level of >1,500 miu/mL
Q.
3: Can there be false +ve hCG?? Ans:-However, in rare cases, it may be produced by a) choriocarcinoma or some other b)
germ cell tumours , or even other
forms of cancer, e.g. c) lung cancer.
If there is amenorrhoea and pt is in repro age group then one should
keep these very rare possibilities in mind. Needless to mention that H mole
also gelid +ve preg tests.
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