Clinitest hCG

Principles of hCG testing

What is hCG?

Human Chorionic GonadotropinA hormone released early in pregnancy. Detected in the urine as early as 14 days after conception.

Test results: Qualitative. Qualitative tests provide a straightforward positive/ negative answer

Value of test: Rapid and reliable marker for early detection of pregnancy.

hCG / Pregnancy testing

• hCG helps maintain the early stages of pregnancy.

• Initially the level of hCG rises very rapidly, approximately doubling in quantity every 2 days until a peak is reached between the sixth and eighth week.

• Over the next ten or more weeks, the level of hCG decreases.

• Detectable levels of hCG may be present a month or two after delivery.

• The first catch of urine in the morning will contain the highest level of hCG.

Urine or Serum?

• In normal pregnancy, hCG can be detected in serum as early as seven days following conception.

• Urine hCG concentrations are approximately one half (or less than one half) of serum concentrations.

• Therefore hCG can be detected in urine as early as 14 days from the date of conception.

Performing a test

Select ‘Cassette Test’ on the

Clinitek Status

Adjust the test table for a cassette test (turn the table insert)

Insert the cassette into the table

Performing a test

Input operator and patient identification details

Performing a test

Draw up sufficient urine sample into the pipette.

Any excess sample will go into the overflow chamber.

Use one pipette measurement ONLY (this is equal to 200μL)

Performing a test

Press “start” and put the sample into the sample well. Press and release the pipette to ensure that the full sample volume is applied (DO NOT EMPTY THE OVERFLOW CHAMBER).

The instrument will now automatically time and record the result

Performing a test

Clinitest hCG takes up to 5 minutes to perform the test (strongly positive samples may be detected more quickly)

Once complete, remove the cassette and record the results into the patient notes

Instrument maintenance

Clean the test table at least once a week to remove any build up. The test table can be soaked in 5% hydrochloride and rinsed thoroughly.

Check that the calibration strip on the instrument is clean EVERY day. If not, clean with a soft cloth ensuring that you do not scratch it.

Avoiding Errors

Each test includes two Quality Control lines (a Reference line and a Control line).

If the instrument does not detect these within 2 minutes,an error is reported

Key reasons for this include:– Short samples– Incorrect storage of cassettes

Clinitest hCG is ONLY licensed to be read using the Clinitek Status Analyser

Interpretation of resultsPOSITIVE- If the hCG intensity is more than 25mIU/ml and both the control and reference regions meets the minimum intensity (Note: hCG levels of 100 mIU/mL can be reached on the day of the first missed menstrual period.)

BORDERLINE, REPEAT IN 48-72 HOURS- If the hCG intensity is less than 25mIU/ml, but more than 5 mIU/ml and both the control and reference regions meets the minimum intensity

NEGATIVE- If the hCG intensity is less than 5mIU/ml

INVALID- The instrument will automatically determine if a procedural error or a test reagent deterioration has occurred. The user will be advised to repeat the test and contact support if the problem persists.

Interpretation of results

• Results must be recorded in the POCT log sheet and printouts attached to the patient notes. If you use Sellotape make sure it is not over any of the printing.

 • Due to the fact that false positives can occur, any

positive result for a child under 16 years should be confirmed by sending a blood sample for serum hCH to the

Conditions which may produce a positive or borderline hCG result

In Ectopic pregnancies, the levels of hCG rise at a significantly slower rate than in normal pregnancy.

Trophoblastic diseases (e.g. an ovarian tumour or hydatidiform mole)

It has also been reported that hCG levels in healthy, non-pregnant post-menopausal women increase with age.

Passively acquired hCG from a blood transfusion

Low levels of hCG in women of childbearing age are sometimes observed due to a recent pregnancy that has spontaneously aborted (about 22% of pregnancies abort spontaneously, without being detected).

hCG levels may remain detectable for up to several weeks following delivery, miscarriage or hCG injections (IVF)

Discussing hCG testing inevitably raises some queries.

The following slides are some of the most frequently asked questions…

hCG Frequently asked questions

Interfering Substances

The presence of interfering substances in the urine:

• Preservatives• Micro-organisms• Erythrocytes and/or leucocytes

Are there any interfering substances that should not be used to clean the urine collection container?

Detergents, disinfectants, preservatives or other contaminants in a urine collection container may interfere with the hCG test results.

The urine sample should always be collected in a clean, dry container as stated in the package insert.

False Positives…

All qualitative pregnancy tests will produce a small number of false positive results (<1%).

Siemens Healthcare Diagnostics aim to minimise this, however, you should always evaluate not only the diagnostic test result, but also all other clinical signs and symptoms.

What actions should I take with a positive hCG result that is not in line with other clinical signs?

As is true with any diagnostic test, clinical diagnosis should not be based solely on a single test result.

Clinical Diagnosis should incorporate all clinical and laboratory data & look at “the bigger picture”

If in doubt…

If a positive test result is obtained and non-pregnancy is suspected, it is standard laboratory and clinical practice to have the test repeated with another urine sample obtained 48 hours later (bear in mind that hCG levels in pregnant women approximately double every 2 days).

In acute situations, it is recommended that the result is confirmed with a quantitative laboratory test.

?????

• Name two of the essential points to remember when collecting a specimen.

• At what level does Clinitest hCG report a positive result?

• Name some scenarios where you may get a positive hCG in a non-pregnant woman.

• What is the Trust policy for pregnancy testing?

• What is the recommended cleaning of the Clinitek Status?