 | Precautions For in-vitro diagnostic use. Do not use the reaction units after the expiry date. All patient samples should be handled as if they were capable of transmitting disease Quality Control A built-in control is included in the test. In addition, in accordance with good laboratory practice, negative and positive controls should be used with each assay. Such controls are available commercially. Specimen Collection For optimal results it is best to test the first urine voided in the morning because it contains the greatest concentration of HCG. However, specimen urine collected anytime during the day can be used. Specimens can be stored at 2 o C to 8 o C for up to 48 hours, or below -20 o C for at least 3 months. Specimens should not be frozen and thawed repeatedly. Thawed specimens should be inverted several times just prior to testing. Urine samples containing excessive bacterial contamination should not be used. | | Limitations As in the case of any other diagnostic procedures, the results obtained from this kit must be used only as an adjunct to other information available to the physician. A normal pregnancy cannot be distinguished from an ectopic pregnancy based on HCG levels alone. Positive results from very early pregnancy may later prove negative due to natural termination of pregnancy. This is estimated to occur in 50% of all conceptions. It is recommended that weak positive results be re-tested with a fresh urine sample 48 hours later. Patients with trophoblastic and non-trophoblastic disease, or specimens with a high Rheumatoid Factor ( RF ), may have elevated HCG levels, therefore the possibility of HCG secreting neoplasms should be eliminated prior to the diagnosis of pregnancy. A negative result obtained with a urine specimen collected from a very early pregnancy may be due to an extremely low concentration of HCG. If pregnancy is still suspected, a test should be repeated on a fresh specimen obtained about 2 days later. If a urine specimen is too dilute (i.e., low specific gravity), it may not contain a representative urinary HCG concentration. If a negative result is obtained with a low specific gravity specimen and pregnancy is still suspected, a first morning specimen should be obtained and re-tested. After an extended period of time, negative results obtained with the recommended timing may become weakly positive. This may be due to a level of HCG less than 25 mlU/ml. If pregnancy is still suspected, a repeat test is suggested in after 48 hours. In rare cases one pink line may appear 1 cm from the edge of the solid blue tape indicating a positive result with a very high concentration of HCG. |
