5. Although, depending on the concentration of hCG

in the specimen, positive results may start appearing

as early as 30 seconds, negative results must be

confirmed only at the end of 5 minutes.

Limitation of Tests

1. A number of conditions other than pregnancy including trophoblastic and non-trophoblastic neoplasms

such as hydatidiform mole, choriocarcinoma, etc.

cause elevated levels of hCG. Such clinical conditions

must be ruled out before a diagnosis of pregnancy can

be made.

2. Highly dilute urine specimens and specimens

from very early pregnancy may not contain

representative levels of hCG. If pregnancy is still

suspected, repeat the test with first morning urine

after 48–72 hours.

3. As with all diagnostic tests, the results must be

correlated with clinical findings.

ICT Techniques for Urine/Serum Sample

For routine pregnancy testing, urine is the most preferred

specimen, requiring no specialized skills for collection,

processing and storage. However, during problem

pregnancies and bad obstetrics cases, levels of hCG in

urine are very low. Due to factors such as fluid intake,

time of collection of specimen, urine may not contain

representable amounts of hCG, thereby affecting the

sensitivity of membrane based one step assays.

Advantages of Serum Testing

¾ During normal pregnancies, hCG is present as an intact

molecule in maternal serum.

¾ Serum hCG levels can be detected within 24 hours

post-implantation.

¾ Serum specimens facilitate early pregnancy detection.

¾ hCG is uniformly distributed in serum and is not

affected by fluid intake and can be collected at any time

of the day.

¾ hCG is a very stable molecule when stored in serum.

DIPSTICK ICT, URINE/SERUM PREGNANCY TEST

(Gravi check from Orchid Biomedical Systems)

Specimen Collection and Preparation

Urine as Sample

Though random urine specimens can be used, first morning

urine specimen is preferable as it contains the highest

concentration of hCG. Specimens should be collected in

clean glass or plastic containers. If testing is not immediate,

the urine specimens may be stored at 2–8°C for up to 72 hours.

Turbid specimens should be centrifuged or allowed to settle

and only the clear supernatant should be used for testing.

Serum as Sample

No special preparation of the patient is necessary prior

to specimen collection by approved techniques. Though

fresh serum is preferable, serum specimens may be stored

at 2–8°C for up to 24 hours, in case of delay in testing. Do

not use hemolyzed or contaminated specimens. Turbid

specimens should be centrifuged or allowed to settle and

only the clear supernatant should be used for testing.

Test Procedure and Interpretation of Results

1. Collect urine/serum specimen in a clean test tube.

Ensure that only sufficient quantity of the specimen is

collected to allow submerging the orange area of the

dipstick (About 1 cm high).

2. Bring the sealed pouch to room temperature, open

the pouch and remove the dipstick. Once opened, the

dipstick must be used immediately.

3. Dip the orange area of the dipstick in the urine/serum

specimen submerging only the orange area.

4. For urine samples: Dip the dipstick in the urine

sample for 10–15 seconds and place horizontally on

a flat surface. Alternatively, the dipstick may be left to

stand in the specimen for the entire duration of the test

ensuring only the orange area is left submerged in the

specimen. At the end of 5 minutes, read the results as

described below.

 For serum samples: Leave the dipstick in the specimen

for entire duration of the test ensuring only the orange

Pregnancy Tests 419

area is submerged in the specimen. Read the results

at the end of 15 minutes as follows:

 Negative: Only one coloredband appears on the dipstick.

 Positive: Two distinct colored

bands appear on the dipstick.

5. The test should be considered invalid if neither the

test band nor the control band appears. Repeat the

test with a new dipstick ensuring sufficient dip time.

Limitations of the Test

1. A number of conditions other than pregnancy including

trophoblastic and non-trophoblastic neoplasms such

as hydatidiform mole, choriocarcinoma, etc. cause

elevated levels of hCG. Such clinical conditions must be

ruled out before a diagnosis of pregnancy can be made.

2. Highly dilute urine specimens and specimens from very

early pregnancy may not contain representative levels of

hCG. If pregnancy is still suspected, repeat the test with

first morning urine after 48–72 hours after the initial test.

3. As with any assay employing animal antibodies,

presence of cross-reacting heterophilic antibodies may

yield discrepant results.

4. As with all diagnostic tests, the results must be

correlated with clinical findings.

DEVICE ICT URINE/SERUM PREGNANCY TEST

(Gravi check from Orchid Biomedical Systems)

Specimen Collection and Preparation

Urine as Sample

Though random urine specimens can be used, first

morning urine specimen is preferable as it contains the

highest concentration of hCG. Specimens should be

collected in clean glass or plastic containers. If testing is not

immediate, the urine specimens may be stored at 2–8°C for

up to 72 hours. Turbid specimens should be centrifuged or

allowed to settle and only the clear supernatant should be

used for testing.

Serum as Sample

No special preparation of the patient is necessary

prior to specimen collection by approved techniques.

Though fresh serum is preferable, serum specimens

may be stored at 2–8°C for up to 24 hours, in case of

delay in testing. Do not use hemolyzed or contaminated

specimens. Turbid specimens should be centrifuged or

allowed to settle and only the clear supernatant should

be used for testing.

Altered Laboratory Results in Normal Pregnancy

Test Alteration Demonstrated or possible reason

Hematology

Hb Falls but not lower than 11 g% Plasma volume expands more than RBC mass

WBC Mild neutrophilia; no lymphocytosis Similar response seen in stress, strenuous exercise

Platelets Slight decrease or no change Plasma volume expansion

Reticulocytes Rise to 2–5% Need to increase RBC mass

Blood volume Rises by 40–50% Increase in plasma and red cells

Serum iron Falls modestly, even if stores are adequate Loss to fetal blood supply; increased plasma volume;

supplementation is desirable

Iron binding capacity Increases Estrogen-induced increase in protein synthesis

Folate levels Serum concentration falls; RBC concentration

should be constant

Fetal use; estrogen associated folate block

Supplementation desirable

ESR Increases markedly Elevated fibrinogen levels

Contd...

420 Concise Book of Medical Laboratory Technology: Methods and Interpretations Test Alteration Demonstrated or possible reason

Coagulation

Fibrinogen Rises about 50% ? Acute phase reaction

PT and PTT Normal or slightly shortened Increased factor levels affect tests relatively little

Plasminogen Increases ?

Antithrombin III Decreases moderately Comparable effect seen with therapy

Fibrin degradation

products

Increased slightly ? Effect of increased plasminogen and decreased

antithrombin III ? Effect of fibrin deposition in placenta

Chemistry

Serum albumin Decreases by as much as 1 g% Increased degradation, hemodilution

Immunoglobulins Ig G, Ig A drop ? Degradation

? Altered immunologic responsiveness

Serum alkaline phosphatase

↑ by 200–300% Placental alkaline phosphatase in serum

Serum cholesterol ↑ 30–40% ? Effect of placental hormones

Serum free fatty acids ↑ 50–60% ? Effects of placental hormones, altered insulin reactivity

Serum creatinine ↑ Hemodilution; ↑ Glomerular filtration rate (GFR)