Prenatal Flashcards
How does the neural tube form?
Step one the neural tube begins to form when microtubules elongate and become columnar forming the neural plate
Step two apical microfilaments change the cells shape, forming two parallel ridges, which bend towards the midline
Step three after the neural tube forms, there is an interior and posterior neuropore region, which promotes brain growth/expansion and spinal cord regrowth, respectively
Step four interior neuropore closes. If not, and anencephaly , results and is fatal.
Step five the posterior neuropore closes. If not, spina bifida occurs which can range in severity, but can be corrected by surgery.
When does the neural tube close?
It closes at four weeks post fertilization, or six weeks gestational age
Spina bifida occulta
Failure of caudal or posterior neuropore to close. Spinal cord, meninges and overlying skin remain intact.
Spina bifida cystica
Meningocele (herniation of the meninges only); and myelomeningocele (herniation of the meninges and neural tissue)
Myeloschisis
Exposed neural tissue without skin or meninges covering
Anencephaly
Failure of the rostral anterior neuropore to close. Therefore the brain and cranial vault are grossly malformed with normal high brain development.
Most common and severe form of spina bifida
Myelomeningocele is the most severe and most common form of spina bifida. It involves a spinal cord, unlike meningocele
What is the incident of all neural tube defects?
One in 3000
What is the incident of anencephaly?
About one and 1000
What is the incidence of spina bifida?
One and 1500 births
What are the implications of folate in a pregnancy?
0.4 mg of folate prevents 75% of pregnancies from being affected with a neural tube defect. If there is a previous pregnancy with a neural tube defect, the carrier of the pregnancy should take 4 mg in the next pregnancy since they have a 2 to 3% increased risk of having another child with a neural tube defect.
Fate is another word for vitamin B9
What is the cut off for abnormal AFP?
Greater than 2.5 MOM is a screen positive. Anything under is a screen negative. This is done between 15 to 22 weeks.
What are other causes of neural tube defects?
Folate deficiency, family, history of neural tube defects, maternal diabetes, or obesity, maternal fever in early pregnancy and anti-seizure medicine, such as valproate or carbamazepine
What is microchimerism?
Presence of two genetically distinct and separately, derived population population of cells (one population being at a low concentration) in the same individual
Example: during pregnancy, fetal cells are present in maternal circulation
