Book of Medical Disorders in Pregnancy - Tintash

y the maternal kidney in urine or by the
maternal liver in the bile.
The measurement of serial estriol levels
in the third trimester will give an
indication of general well-being of the
fetus. If the estriol level drops, then the
fetus is threatened and delivery may be
ne-cessary emergently. Estriol tends to
be lower when Down syndrome is
present and when there is adrenal
hypoplasia with anencephaly.
In general estriol excretion is increased
progressively from a level of 0.1 mg/ml
at the 6th week of gestation to value of
12 to 15 mg/ml at term. Estriol levels are
useful only after the 20th week of
gestation, as regards monitoring of fetal
well being.
When there is a progressive and dramatic
fall in estriol level, fetal death
becomes very likely. Low values are
found in cases of anencephaly. Serum
estriol is much easier to determine in the
laboratory. The test is available in most
advanced obstetrical units. The problem
of 24 hours urine collection is also
avoidable, where serum estriol is used
for fetal monitoring.
A number of drugs interfere in
determination of the estriol level in the
urine by chemical competition. When
acid hydrolysis is employed, methenamine,
mandelate, ampicillin and sugar
in the urine all interfere with estimation
of estriol. Low levels of maternal urinary
estriol may in some cases, be due to
renal problems where inadequate clearance
of estriol occurs from maternal plasma.
False low urinary estriol level may also
be noted in patients who are on cortisol
191
therapy. High levels are often present in
urine of patients with severe erythroblastosis:
Progesterone - Although it is produced
in increasing amount by the placenta,
measurement of its metabolites, such as
pregnanediol has very poor correlation
with the fetal well being, therefore, it is
useless test for clinical purposes.
Fig15.4: Shows stained vaginal cells
used to determine KP index.
Cytology - Maternal cells which have
desquamated from vagina during pregnancy
have been employed to assess the
hormonal status of the pregnancy. An
inverse relationship between number of
cells with pyknotic nuclei and estriol
level has been reported. Risk of abortion
increases with rising level of K P index.
The value of hormone cytology has not
been fully established.
Enzymes:
Alkaline phosphatase:
Heat stable alkaline phosphatase is
produced by the placenta and has been
used for assessment of placental function.
There is considerable increase in
alkaline phosphatase production in
pregnancy the non gestational enzyme is
destroyed by heat, while the placental
alkaline phosphatase when heated at
600C for 30 minutes remains stable. If
there is a progressive increase in the heat
stable enzyme level the fetal prognosis is