Handbook of Genetic Counseling/Spina Bifida

Spina Bifida

Quote Risks

  • Spina bifida is usually an isolated birth defect.

Level II Ultrasound

  • At 18-20 weeks, a high resolution, targeted ultrasound examination can be done to carefully and specifically examine the baby's spine.
  • This is noninvasive and may provide reassurance but cannot be used as a diagnostic tool.
    • If no evidence of a NTD is seen, it cannot be guaranteed that the baby does not have a NTD.


  • If the triple screen results indicate an increased risk for a NTD, one may choose to have an amniocentesis, which is a more invasive, but more diagnostic test.
  • What is it?
    • Procedure used to obtain a small sample of fluid from the fluid-filled sac that surrounds the fetus
    • Performed at 15 weeks gestation or later
      • 15-18 weeks is optimal because it leaves the patient with options
      • 22 weeks is probably the latest it can be done leaving the option of elective abortion
    • Amniotic fluid contains the fetus's urine as well as other cells from the skin, throat, and digestive tract
    • Fluid is studied in the lab for abnormalities
  • What can it tell me?
    • Amnio can detect certain abnormalities in the fetus.
      • Chromosome abnormalities
      • NTDs (Spina Bifida)
    • It can determine the sex of the baby.
  • What can it NOT tell me?
    • Amnio cannot detect all birth defects or mental retardation.
      • For example, congenital heart defects, cleft lip & palate cannot be seen.
      • Also the severity of the defect cannot be known from amnio.
  • Exactly what does the procedure involve?
    • Show figure of amniocentesis.
    • You will lie down on your back with hands behind your head.
    • Your abdomen will be cleaned with alcohol or iodine.
    • A local anesthetic may be applied to your stomach.
    • Ultrasound will be used to locate the position of the baby and the placenta and to find a safe spot for the needle.
    • A long, thin needle will be inserted through the skin, into the uterus.
    • The first few cc's of fluid will be discarded because they probably contain contamination from your cells.
    • Then a small amount (about 1-2 tablespoons) of fluid is removed and the needle is withdrawn.
    • The procedure itself usually takes ~5 minutes.
    • The baby will quickly replace the fluid that is removed.
    • The baby's heartbeat will be monitored by ultrasound.
    • Fluid will be sent to the lab and results are available in 1-2 weeks.
    • There is a small possibility of lab error or lack of cell growth
      • In this case, the procedure would have to be done again.
  • What will it feel like?
    • If an anesthetic is used, you may not feel the needle enter the skin, but you will still feel it enter the uterus.
    • This is described as a sharp pain, like a menstrual cramp that usually lasts a few seconds.
    • You may also feel some cramping after the procedure.
    • You should avoid strenuous activity for 24 hours after the procedure.
    • Call your doctor immediately if you experience abdominal pain or cramps, vaginal bleeding, leakage of clear fluid from the vagina, fever, or anything else unusual.
      • Approximately 2% of women experience light bleeding or spotting.
  • What are the risks?
    • The risk of miscarriage is between 1/400 and 1/200.
    • This means that the added risk for pregnancy loss attributable to the procedure is 0.5% or less.
    • There is a risk of uterine infection but this is less than 1 in 1,000
    • There is a remote chance that birth defects can be caused by the amnio (0.1%).
    • There are special considerations for mothers who are Rh negative. They need to take RhoGam after the amnio procedure.

Other Resources

  • Spina Bifida Association of America

Review and summarize major points


www.sbhac.ca spina bifida association of Canada

Elicit final questions and concerns


Reporting of the Results

  • If they are having a procedure, discuss how they would like to receive the results
    • Appointment, phone call, etc.
    • Who will contact them?
  • Discuss the options: elective abortion, adoption, etc.