by Soraya Azari, MD
I am an extremely fortunate person - not only am I awaiting the arrival of my first child, but I've had a relatively uncomplicated pregnancy. I say "relatively" because there has been one unpleasant aspect: having to do extra, unnecessary testing. To explain, a bit of background: during pregnancy it is common to measure a fundal height, which represents the distance from the pubic bone to the top of where the uterus is felt. This numerical height should roughly equal the number of weeks that have elapsed in the pregnancy. For example, at 20 weeks gestation, the height from the pubic bone to the top of the uterus should be 20 centimeters.
At 29 weeks, my obstetrics provider measured this distance for the first time and deemed that I was "measuring small" - 26 weeks when I was dated at 29 weeks gestation, where anything 3cm off is considered abnormal. Though right on the border, my provider recommended we perform an ultrasound to check the size of the fetus. I was immediately concerned. As a doctor, I was aware of the condition "SGA" or small for gestational age, wherein the baby doesn't grow properly because of some defect. Prior to this, several people had commented that I "looked small." Had I been doing something wrong? Was my baby healthy? The worst-possible outcomes entered my mind: will I need to deliver early because the placenta isn't functioning properly? Will my child spend the beginning of its life in the neonatal intensive care unit? Will my child be normal?
Even though I was reassured that this was "probably nothing" and we just want to "be on the safe side," I couldn't suppress my worried thoughts. Fortunately, I only had to wait 5 days for the ultrasound that would measure the baby's size. And then I received the result: concern for fetal macrosomia, or an abnormally large fetus. I couldn't help but laugh at the irony, but following that, I felt frustrated by what had happened to me, which was 5 days of extremely unpleasant worry and anxiety.
As a primary care provider, I discuss testing and screening with patients frequently. For example, routine screening for prostate cancer is not recommended by the United States Preventive Services Task Force, a body of independent, volunteer experts that make recommendations about screening tests in the United States. When I explain to them this isn't recommended, they may ask "Well don't you think it's better just to know?" I then try to explain the effect of false positive tests and unnecessary testing. I explain that an "abnormal" result can be falsely positive - meaning that the test is abnormal, but it does not indicate that the person actually has the disease. In other words, it is an imperfect test. Every test is imperfect, and therefore associated with the chance of giving an inaccurate result that requires more testing. More testing can sometimes lead to adverse events - for example, a prostate biopsy that may lead to incontinence - and more testing almost always leads to anxiety. This harm from excess testing should be weighed into the decision to do the test in the first place, but this is often something that is difficult for patients to imagine.
Now that I have had my own experience now with a falsely positive result - my abnormal fundal height measurement - I feel like I have better insight into the harms of excess testing. Once I got the ultrasound, which showed a baby that was oddly too big, it was then recommended that I be re-tested for diabetes. I had a one-hour glucose tolerance test that returned abnormal, even though it was normal before. I then had to have a 3-hour glucose tolerance test which involved four separate blood samples (read: sticks). Before and during this test, I again felt anxiety and worry - what if I have diabetes? Will I need to take insulin? Will my child be normal?
Fortunately, this test also returned normal. I did some research on my own and learned that 1) measurement of the fundal height is prone to error, 2) baby size measurements from ultrasound are less accurate the further you progress in pregnancy, and 3) insulin resistance increases with length of pregnancy and the one-hour glucose tolerance test has a high false-positive rate also. So while everything "turned out ok" the whole process has made me reflect about indiscriminate ordering of tests and the risk of false positive results with my own patients. I should know why I want to order a test, how it will change what I do for the patient, and what the risk is of a false positive (or false negative) result and how that will affect my patient. I should be able to explain this to her/him in a way that is understandable, and we should participate in shared decision making about whether to do the test in the first place. This is not easy to do, but here are a couple of "pearls" I have learned:
1. Set expectations early. For example, before I have a patient do a stool screening test for colon cancer, I explain, "Sometimes this can return positive. This does NOT mean you have colon cancer, but it does mean we would have to do a colonoscopy. What do you know about colonoscopy and might you be ok with that?"
2. Be honest with your patient. Recently a patient asked me to do a blood test to screen for "metal levels" even though he had no symptoms. I explained to him that while there are tests for metal levels, because he is asymptomatic, we would do nothing different as a result of the findings, so there is no need to do it. He said "Ok...that makes sense."
3. Learn from your patients. When a patient wonders about a new test or procedure, this is an opportunity to learn about what is important to his/her health. In the aforementioned example, I then asked him "Tell me about why you're interested in knowing your metal levels?" I then learned about his belief of the importance of metal levels for good digestion.
These tips may seem self-evident, but for me, they are a helpful reminder. Again, while not easy, talking about unnecessary testing is important for both for the patient and our health care system: less unnecessary testing, less worry, less potential for adverse effects from testing, and less wasteful spending of health care dollars.