How to Diagnose

In many cases, it is possible to diagnose spina bifida before birth. Up to 90% of cases of spina bifida can be detected by fetal ultrasound between 16 and 24 weeks of the pregnancy. Ultrasound may also be helpful in identifying other abnormal formations of the brain and spinal cord, as well as other organ systems. Other tests can be performed on the mother’s blood or amniotic fluid checking for alpha-fetoprotein (AFP) and acetylcholinesterase. AFP can leak from an open spina bifida defect into the amniotic fluid resulting in the highest levels by the 13th to 15th week after conception. The first test is typically measuring AFP levels in the mother’s blood between 16 and 18 weeks after conception.

AFP levels can be elevated in certain other conditions, such as fetal death or an abdominal wall defect, so other testing may be required. Testing of the amniotic fluid by amniocentesis is more specific than testing of the maternal blood. Elevated levels of acetylcholinesterase in the amniotic fluid will confirm the diagnosis. This is usually performed 15-18 weeks after conception. These tests will only detect open spina bifida lesions, not spina bifida occulta.

If spina bifida has not been diagnosed prior to birth, the child often looks healthy and normal, with the exception of a sac protruding from the back typically at the base of the spine. The severity and level of the spinal defect will determine the neurologic function of the child. The spine is divided, from top to bottom, into the cervical (neck), thoracic (upper back), lumbar (lower back), and sacral (the triangular bone at the base of your back) regions. The higher the level and the larger the lesion, the more leg muscles are involved. The legs may be flaccid or floppy. In some cases, there can be spasticity with high muscle tone and strong reflexes. This is usually the case if the lesion is in the thoracic region or higher. It is not unusual to find varying degrees of weakness from side to side, mixtures of high and low muscle tone, or patchy areas of muscle control. Bowel and bladder function are almost always abnormal.