When 32-year-old Shelley Roberts of Sacramento, California was contacted by a nurse from her obstetrician's office calling to reveal the results of her recent blood test she immediately handed the phone off to her husband. Roberts, the mother of a three-year-old son, could not bear to hear that her blood test had come back abnormal, suggesting her unborn child had a risk for possible birth defects.
Anayat Durrani

"I was completely devastated. My test had come back 1/78 for Down Syndrome and they couldn't get me an appointment with the genetic counselor for two weeks," says Roberts. "Those two weeks were the hardest. I didn't sleep, eat or live."

Thirty-three-year-old Angela Williams of San Antonio, Texas, got the call at work. "I was told by the nurse 'Your baby tested positive for Downs.' I was speechless, and in total shock," she says. "Needless to say, I left work early that day in tears, calling my husband with the sad news."

What is the AFP test?
The Alpha-fetoprotein test (AFP) is a blood test given to women in their second trimester of pregnancy, usually between weeks 15 and 20. When a woman is pregnant, alpha-fetoprotein is produced by the fetus and mixes with the mother's blood. Alpha-fetoprotein can be detected in a blood sample taken from the arm, according to the Division of Research at Kaiser Permanente, a healthcare system in Northern California.

A high level of AFP can be an indication of a neural tube defect such as spina bifida. However, high levels of AFP can also indicate that the mother is further along in her pregnancy than realized and her due date needs to be recalculated. A high AFP could also mean the mother is carrying twins, according to Kaiser Permanente.

A low level of AFP can be an indication of genetic defects such as a higher risk of Down Syndrome (Trisomy 21) or Trisomy 18, a more severe and less common chromosomal anomaly.

Most AFP tests now also include testing of two or three more markers, says Dr Harold N. Bass of the Department of Genetics at Kaiser Permanente Medical Center in Panorama City, California. The triple marker test, also known as the multiple marker, measures levels of AFP, hCG and estriol. The quad screen measures the same as the triple, as well as another marker called Inhibin.

"In California, triple marker screening, with a screen-positive rate of 5.6 percent, has an overall Down Syndrome detection rate of 66 percent. The detection rate for Trisomy 18 is 60 percent and for open neural tube and abdominal wall defects, 80 to 97 percent," says Dr Bass, clinical professor of human genetics and pediatrics at the David Geffen School of Medicine at the University of California, Los Angeles.

Dr Bass says the expanded AFP screening, as it is called in California, is required by law to be offered to all pregnant women in the state. Patients in California are given the option to refuse the test and the follow up services. Most other states do not require that AFP/multiple marker screening be offered.

Positive/abnormal AFP
Once a patient receives an abnormal or positive AFP result they are then advised to schedule an appointment to see a genetic counselor, a health professional with a specialized graduate degree and experience in medical genetics and counseling.

"When I see a patient who had a positive screen for one of these conditions, I explain the difference between a screening test and a diagnostic test. A positive screening test does not mean that there is a problem, it only means that further testing is warranted," says Diane Masser-Frye, a certified genetic counselor at the University of California, San Diego Center for Fetal Diagnosis. "Traditionally, about 5 percent of women who take the AFP test will get a positive result, but more than 90 percent of those will go on to have normal babies."

When a patient meets with a genetic counselor a family history is plotted to determine if further testing is needed. The genetic counselor also explains the option of having a level II ultrasound which uses sound waves to give a detailed examination of the fetus and an amniocentesis, which is a test of the fluid that surrounds the fetus in the womb.

"Genetic counseling is helpful for patients so they can understand their testing choices, the risks they involve and other options they have," says Masser-Frye.

False positives
Williams, whose ultrasound and amnio results came back normal, says her only complaint has been that she wished her doctor had given her more information about the AFP test and the option of not taking it in advance. "We have tried to just put the bad experience behind us and focus on [the birth of] our healthy girl."

AFP tests can sometimes be wrong. This is called a false positive. One of the major complaints about the AFP test has been what is perceived as a high rate of false positives. "The screen-positive rate is not unacceptably high for a screening test," says Dr Bass. "Without such a rate, the screening test would pick up far fewer fetuses with Down Syndrome, Trisomy 18 or neural tube or abdominal wall defects."

When an ultrasound and amniocentesis returns normal, there are other explanations as to why a patient could have received an abnormal AFP test.

"An 'unexplained' elevated maternal serum AFP level might signify potential pregnancy complications down the line, such as maternal hypertension, preterm birth and poor fetal growth," says Dr Bass.

Roberts' case proved to be a false positive. She gave birth to a healthy baby girl by C-section. After having gone through months of stress and constant worrying, Roberts says it was all worth it. But would she take the AFP test again? "I myself would take the test again. Just to know if there is the possibility of a problem."

Genetic counselor Masser-Frye believes the AFP test should be available to all women should they chose to take the test. "I do recommend the AFP test for women who feel like they want to know about Down Syndrome, Trisomy 18 or spina bifida prior to delivery," she said. "For women who would prefer not to have any kind of prenatal diagnosis, taking the AFP is not necessarily helpful."PregnancyAndBaby.com

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Elise July 15, 2014
25 years ago, my husband and I went though the same agonizing experience when results came back with a low AFP indicating downs syndrome. My life was on hold until we got the results back from genetic testing. We did some research and found that false positives are frequent and may be because the due date was miscalculated or the baby is a girl. Further testing concluded that everything was normal and we were having a girl! Our precious daughter is normal and healthy and incredibly intelligent. Over the years, I have known other women who have gone through the same horrible experience and it turns out they, too, had normal baby GIRLS. I now know of another young mom is living this nightmare. After all this time, you would think these tests would have improved. The two extremely emotional and terrifying weeks it took to determine that my daughter was perfectly fine were totally unnecessary. I refused the test when I was pregnant with my second child. I had a stress free pregnancy and a healthy baby boy!
Stallion April 23, 2013
Thank you. Very informative article.
We got the results for AFP test for my wife and those came to be positive for Neural Tube Defect. The doctor then decided to play around a little more to see the spine and found out we were having twins!!.
We are just hoping that is what gave a positive result as explained in this article and our doctor seconds that. The detailed Ultrasound will reveal all probably in 10 days time. Cannot wait for the detailed ultrasound to confirm it, anxious days ahead.
Christine March 30, 2013
We had the test taken at week 18 at the next appointment the doctor notified us that the test levels came back low. Once I was at the desk I had asked to take a look at the test results wondering how low the level was. Upon noticing they did not enter the weight correctly, in fact they were off by nearly 33% of my body weight. With the body weight being incorrect could the whole test results be obscured. I asked the doctor she told us that it had no implication, but after looking into this a little further weight and age are two of the most important factors to give them the readings. Now they want to send us to a specialist 100 miles away. What do we do and this makes me nervous about our baby doctors ability to correctly order and read test? This test is nothing but problems wish it was never done
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yessica February 06, 2013
i had a afp blood test and came back ubnormal im so scared i dont know what to do my dr. send me to take an ultrasound and a amniocentesis i dont know what to do i feel like if my live is over i have 2 boys and when i finally get pregnant with a baby girl my dr said she has a chance of birth defects
Colleen January 15, 2013
I'm sorry you all had to go through this. I am a mother of a Trisomy 18 child. She is such a blessing despite many challenges. Please visit Trisomy 18 Mommies on Facebook and join to get the support you need (For all Trisomy conditions, including Down Syndrome. They helped me in my journey in being the best advocate for my daughter. God bless you all!
amy November 30, 2012
I went to the doctor today and my APF test came back positive and a 1:2 chance of having something wrong with the spine. The doctor also said that it could also just be a chance that the bowels are on the outside of the baby ( the intestines) which is a quick fix after the baby is born . He also said it could be because the dates of the tests were taken at the wrong time . I am 22 yrs old and so scared and stressed out . I pray for my baby to be healthy. If anyone has any stories close to mine I would really appreciate you sharing them. I now have to wait to get the ultrasound from the specailist to find more reasoning for what is going on .
Amanda July 10, 2012
Mine came back abnormal, with a chance of spina bifida. Im hoping it will be a false, its scary. I have one very healthy child already and didnt see this coming at all. I go to the specialist on thursday. :/
lj March 14, 2012
Mines came bk abnormal But i hope Its false