Turnaround times
The quoted turnaround time is from sample receipt in the laboratory, to results authorisation in the Laboratory Information Management system. The times do not include transport of specimen to the laboratory or the administrative process to print and post/email reports. Service users must allow for transport and reporting time when ordering tests.
Clinical background:
In pregnancy human chorionic gonadotrophin (hCG) is produced by the placenta shortly after fertilisation. In normal pregnancy urine hCG levels rise rapidly to 50 to 250 IU/L by the day of the expected menstrual period and peaks to 100,000 to 200,000 during the first trimester. In a normal pregnancy hCG may be detected in urine 7 to 10 days following conception.
Specimen container paediatric:
Plain universal container (random urine sample)
Specimen container adult:
Plain universal container (random urine sample)
Minimum volume paediatric:
1 mL aliquot
Minimum volume adult:
1 mL aliquot
Special requirements:
First morning urine is the preferred specimen
Sample stability:
at +2° to +8°C 48 hours
at -20°C 3 months
Interpretation:
hCG can be detected in urine at concentrations of 25 mIU/mL or greater
Reference ranges:
Detection limit 25 IU/L (HCG)
Weak positives should be resampled and retested after 48h
Factors affecting result:
Drugs containing hCG may interfere and produce misleading results.
False positive pregnancy tests have been observed in patients with enterocystoplasties. Confirmation of the result must be made with a serum hCG analysis.
Inconsistent results may be found in urine samples containing excessive amounts of bacteria.