ConditionChildren's health
Rachischisis
Rachischisis is a severe neural tube defect in which the spinal column and spinal cord fail to close, leaving the cord exposed along part or all of the back. When the whole spine is open, often together with an open skull (anencephaly), it is called craniorachischisis, the most severe form. It occurs in the first month of pregnancy, is usually detected on ultrasound, and most affected pregnancies end in miscarriage or stillbirth. Folic acid before conception and in early pregnancy greatly reduces the risk of all neural tube defects.
Also called: Open spine, spinal dysraphism (severe form), complete spina bifida, craniorachischisis, rachischisis totalis
At a glance
- What it is
- A failure of the neural tube to close along the spine, leaving the spinal cord exposed.
- Most severe form
- Craniorachischisis, involving both skull and spine.
- When it happens
- By the end of the fourth week after conception, often before pregnancy is known.
- Diagnosis
- Prenatal ultrasound, raised maternal serum AFP, and fetal MRI.
- Prevention
- 400 micrograms of folic acid daily before and in early pregnancy. Higher doses for higher-risk pregnancies.
When to get help
See a doctor within a day or two
- An abnormal ultrasound or raised AFP result in pregnancy: arrange prompt specialist fetal medicine review
Book a routine appointment
- Planning pregnancy: start folic acid at least 1 month before conception
- Previous pregnancy affected by a neural tube defect: ask about a higher folic acid dose (often 4 mg daily) before trying to conceive
- Taking valproate or other anticonvulsants and planning pregnancy: review medicines with your doctor
- Grief and counseling support after a diagnosis or pregnancy loss
What rachischisis means
Rachischisis is one of the neural tube defects. The term comes from the Greek rhachis (spine) and schisis (split). During early development, a flat plate of tissue rolls up to form the neural tube, which becomes the brain and spinal cord. This closure is complete by about 28 days after conception.
If the tube does not close:
- at the head end, the result is anencephaly
- along part of the spine, it causes open spina bifida (myelomeningocele) or myeloschisis, often with Chiari II malformation
- along most or all of the spine, it is rachischisis
- along both the brain and the entire spine, it is craniorachischisis
In rachischisis, the spinal cord tissue is a flat, open plate on the back without skin, bone or membranes covering it.
How rachischisis differs from other neural tube defects
| Defect | Location | Usual outcome |
|---|---|---|
| Spina bifida occulta | Small gap in a vertebra, skin intact | Usually no symptoms |
| Meningocele | Sac of membranes, cord in place | Often good after surgery |
| Myelomeningocele | Sac containing spinal cord | Survival likely, with paralysis and other needs |
| Rachischisis (partial) | Long segment of open cord, no sac | Severe, often not compatible with life if extensive |
| Craniorachischisis | Entire brain and spine open | Not compatible with life |
| Anencephaly | Brain and skull | Not compatible with life |
Causes and risk factors
Neural tube defects result from a combination of genetic and environmental factors:
- low folate before and in early pregnancy
- previous pregnancy with a neural tube defect
- family history
- certain medicines: valproate and carbamazepine
- pre-existing diabetes with high blood sugar in early pregnancy
- obesity
- high body temperature early in pregnancy (fever, hot tubs)
- some genetic variants affecting folate metabolism and planar cell polarity genes, particularly in craniorachischisis
Diagnosis
- maternal serum alpha-fetoprotein (MSAFP): raised in open neural tube defects, usually tested at 15 to 20 weeks
- ultrasound: severe defects can often be seen in the first trimester. Detailed scans at 18 to 22 weeks show the spine and characteristic skull and brain signs
- fetal MRI for detailed assessment
- genetic testing may be offered to look for chromosomal conditions
Outlook and care
Extensive rachischisis and craniorachischisis are not compatible with long-term survival. Many pregnancies end in miscarriage or stillbirth, and babies born alive usually survive a short time. Parents receive counseling about options, which may include continuing the pregnancy with perinatal palliative care or ending the pregnancy, depending on their values and local law.
Limited or segmental forms are rare and very severe, and care is individualized by specialist teams.
Prevention
Folic acid is the most important preventive step:
- The CDC and USPSTF recommend that everyone who could become pregnant take 400 micrograms of folic acid daily, starting at least 1 month before conception and continuing through the first 2 to 3 months of pregnancy.
- People who had a previous pregnancy affected by a neural tube defect are usually advised to take a higher dose, often 4 mg daily, under medical guidance.
- Food fortification with folic acid in many countries has lowered rates of neural tube defects substantially.
- Control blood sugar before pregnancy if you have diabetes, and review anticonvulsant medicines with your doctor.
Frequently asked questions
What does rachischisis mean?
Rachischisis means a split or open spine. It is a severe neural tube defect in which the spinal cord and the bones around it do not close during early development, leaving the cord exposed along part or all of the back.
What is craniorachischisis?
Craniorachischisis is the most severe neural tube defect, in which both the brain and the entire spinal cord remain open. It is not compatible with life, and most affected pregnancies end in miscarriage or stillbirth.
What causes rachischisis?
It results from a failure of neural tube closure in the first month of pregnancy, influenced by genetics and environmental factors such as low folate, certain anticonvulsant medicines, pre-existing diabetes, obesity and high fever in early pregnancy.
Can rachischisis be prevented?
The risk of neural tube defects can be greatly reduced by taking 400 micrograms of folic acid daily from at least 1 month before conception through early pregnancy. Higher doses are recommended after a previously affected pregnancy.
How is rachischisis diagnosed?
It is usually diagnosed by prenatal ultrasound, often in the first or early second trimester. A raised maternal serum alpha-fetoprotein level can also point to an open neural tube defect, and fetal MRI provides more detail.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Neural tube defects; Folic acid recommendations
- US Preventive Services Task Force: Folic acid supplementation to prevent neural tube defects (2023)
- National Institute of Child Health and Human Development (NICHD): Neural tube defects
- March of Dimes: Neural tube defects
- American College of Obstetricians and Gynecologists (ACOG): Neural tube defects (Practice Bulletin 187)