Order Guide: Pregnancy Testing
Please note: blood pregnancy testing is an uninsured test, and the lab will charge you an additional fee at the time of testing, as it not covered even if you have an Ontario Health Card.
Standard urine pregnancy tests detect pregnancy at a threshold of 20 to 50mIU/ml B-HCG. Urine concentrations are much lower than blood concentrations, so blood testing is useful to detect a pregnancy earlier than urine testing. Most blood tests detect B-HCG at a threshold of 1-2 mIU/ml and report a negative result at < 5 mIU/ml.
Urine tests are adequate to diagnose pregnancy and are what all family doctors' offices use to confirm a diagnosis of pregnancy in their office. Blood tests are not required.
Blood pregnancy tests are only useful in the 1st 1-3 weeks of pregnancy. A more reliable indicator of the age of the baby is the 1st day of your last menstrual cycle. In fact, doctors can reliably estimate the age of a baby, more accurately than ultrasound, based on the 1st of your last menstrual cycle.
As a general rule of thumb, B-HCG doubles every 48 hours in the first 30 days after a viable embryo has implanted into the uterus. Measurement of B-HCG is NOT a useful measurement of gestation age (i.e. how many weeks old the baby is, or ‘how far along you are’) outside of the first 1-3 weeks of age. B-HCG hormones peak between 8-10 weeks, then decline as part of a normal pregnancy.
- Access to Abortion - For many women who have an unplanned pregnancy, who are seeking a pregnancy termination (abortion), a blood pregnancy test can confirm the diagnosis objectively which is a requirement for many abortion programs. If you require counseling before having an abortion, please arrange an appointment with one of our physicians or speak to a local health care provider before ordering a blood pregnancy test. TeleTest does not currently offer abortion medication. It’s something many of our patients have requested and an area we are exploring. A copy of the laboratory measurement of B-HCG is sufficient proof of pregnancy for your local abortion program, and a doctor’s letter is not required as ‘proof’.
- Confirmation of a viable pregnancy - When an HCG level is repeated in 48 hours, if it shows a doubling (in the 1st 30 days after conception), it helps to establish a viable pregnancy. This ‘serial test’ is not routinely recommended for women in pregnancy.
- Comfort - many women might purchase 3 or 4 pregnancy tests from a pharmacy to confirm a diagnosis of a new pregnancy. Ordering a blood test can provide confidence and confirm pregnancy without having to visit a doctor’s office, as many women do.
- Having a late period
- Nausea and/or vomiting
- Feeling tired
- Food cravings and food aversions
- Breast Tenderness
Having one of these symptoms does not mean you should order a pregnancy test unless you suspect you are pregnant, as there are many other medical conditions that can produce similar symptoms.
What is the earliest stage an ultrasound can help confirm pregnancy?
- 4.5-5 weeks - gestational sack
- 5-6 weeks - yolk sack
- 5.5-6 weeks - cardiac activity
- You have abdominal pain, fevers, or vaginal bleeding.
- You are concerned about having an ectopic pregnancy.
- You are concerned about a miscarriage.
We suggest testing for pregnancy by bloodwork as early as when your next period comes due. If you have a negative pregnancy test, and suspect pregnancy we suggest a repeat test 7 days after your prior test.
Can I have a false negative test?
The most common reason for a false negative test is testing too early. If you have a negative blood pregnancy test and suspect pregnancy, we suggest a repeat test 7 days after your prior test.
Yes - rarely, a urine test can be a false negative result while a blood test would accurately show a positive result. There is based on a process called the ‘variant hook effect’ and can occur between 7-12 weeks, with some studies estimating a false negative rate of 0.34%. In this scenario, a woman is pregnant but tests negative on urine testing, while a blood test would confirm pregnancy.
If you have a positive urine result and are interested in continuing the pregnancy, we suggest reaching out to a primary care provider (family doctor, nurse practitioner, midwife, etc) to discuss the next steps.