Diagnosis of Neural tube defect
Diagnostic Test list for Neural tube defect:
The list of medical tests
mentioned in various sources as
used in the diagnosis of Neural tube defect
includes:
- Antenatal ultrasound tests
Neural tube defect Diagnosis: Book Excerpts
Diagnosis of Neural tube defect: medical news summaries:
The following medical news items
are relevant to diagnosis and misdiagnosis issues for Neural tube defect:
Diagnostic Tests for Neural tube defect: Online Medical Books
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for more information about diagnostis of Neural tube defect.
Neural tube defects:
Diagnosis
(Professional Guide to Diseases (Eighth Edition))
Confirming diagnosis
Amniocentesis can detect elevated alpha fetoprotein (AFP) levels in amniotic fluid, which indicates the presence of an open NTD. Measuring acetylcholinesterase levels can confirm the diagnosis. (Biochemical testing will usually miss closed NTDs.) Because 5% to 7% of NTDs are associated with chromosomal abnormalities, a fetal karyotype should be done in addition to the biochemical tests.
Maternal serum AFP screening in combination with other serum markers, such as human chorionic gonadotropin (HCG), free beta-HCG, or unconjugated estriol, may be offered to some patients who aren't scheduled for amniocentesis, such as those with a lower risk of NTDs and those who will be younger than age 34½ at the time of delivery. Although this screening test can't diagnose either an open NTD or a chromosomal abnormality, it can estimate a fetus's risk of such a defect. Most patients with abnormal maternal serum AFP levels won't have an affected child; however, they may be at increased risk for perinatal complications, such as premature rupture of the membranes, abruptio placentae, or fetal death.
Ultrasound may be used when the fetus has an increased risk of an open NTD based on either the family history or abnormal serum screening results; however, this test alone can't identify all open NTDs or ventral wall defects.
If the NTD isn't diagnosed before birth, other tests are used to make the diagnosis. For example, spina bifida occulta is commonly overlooked, although it's occasionally palpable and spinal X-ray can show the bone defect. Myelography can differentiate it from other spinal abnormalities, especially spinal cord tumors.
Myelomeningocele and meningocele are obvious on examination; transillumination of the protruding sac can sometimes distinguish between them. (In meningocele, it typically transilluminates; in myelomeningocele, it doesn't.) In myelomeningocele, a pinprick examination of the legs and trunk shows the level of sensory and motor involvement; skull X-rays, cephalic measurements, and computed tomography (CT) scan demonstrate associated hydrocephalus. Other appropriate laboratory tests in patients with myelomeningocele include urinalysis, urine cultures, and tests for renal function starting in the neonatal period and continuing at regular intervals.
In encephalocele, X-rays show a basilar bony skull defect. CT scan and ultrasonography further define the defect.
» READ BOOK EXCERPT ONLINE »
Source: Professional Guide to Diseases (Eighth Edition), 2005
Spinal cord defects:
Diagnosis
(Handbook of Diseases)
The diagnosis varies with the type of defect.
Spina bifida occulta
Although often overlooked, spina bifida occulta is occasionally palpable, and a spinal X-ray can show the bone defect. Myelography can differentiate it from other spinal abnormalities, especially spinal cord tumors.
Meningocele and myelomeningocele
Meningocele and myelomeningocele are obvious on examination; transillumination of the protruding sac can sometimes distinguish between them. (In meningocele, it typically transilluminates; in myelomeningocele, it doesn’t.)
In myelomeningocele, a pinprick examination of the legs and trunk shows the level of sensory and motor involvement; skull X-rays, cephalic measurements, and a computed tomography scan demonstrate associated hydrocephalus.
Other appropriate laboratory tests in patients with myelomeningocele include urinalysis, urine cultures, and tests for renal function starting in the neonatal period and continuing at regular intervals.
Although amniocentesis can detect only open defects, such as myelomeningocele and meningocele, this procedure is recommended for all pregnant women who have previously had children with spinal cord defects; these women are at an increased risk for having children with similar defects. If these defects are present, amniocentesis shows increased alpha-fetoprotein levels by 14 weeks’gestation.
Ultrasonography can also detect or confirm the presence and extent of neural tube defects.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
Neural tube defects:
Diagnosis
(Handbook of Diseases)
Amniocentesis may detect elevated alpha-fetoprotein (AFP) levels in amniotic fluid, which indicates the presence of an open neural tube defect. Measuring acetylcholinesterase levels can confirm the diagnosis. (Biochemical testing will usually miss closed NTDs.) Because 5% to 7% of NTDs are associated with chromosomal abnormalities, a fetal karyotype should be done in addition to the biochemical tests.
Maternal serum AFP screening in combination with other serum markers — such as human chorionic gonadotropin (HCG), free betaHCG, or unconjugated estriol — may be offered to some patients who aren’t scheduled for amniocentesis, such as those with a lower risk of NTDs and those who will be younger than age 34 ½ at the time of delivery. Although this screening test can’t diagnose either an open NTD or a chromosomal abnormality, it can estimate a fetus’s risk of such a defect. The majority of patients with abnormal maternal serum AFP levels won’t have an affected child, but they should be offered diagnostic testing by amniocentesis. If the amniocentesis results are normal, abnormal AFP levels may still indicate an increased risk of perinatal complications, such as premature rupture of the membranes, abruptio placentae, or fetal death. Ultrasound may be used when the fetus has an increased risk of an open NTD, based on either the family history or abnormal serum screening results; however, this test alone can’t identify all open NTDs.
If the NTD isn’t diagnosed before birth, other tests are used to make the diagnosis. For example, spina bifida occulta is commonly overlooked, although it’s occasionally palpable and spinal X-ray can show the bone defect. Myelography can differentiate it from other spinal abnormalities, especially spinal cord tumors.
Meningocele and myelomeningocele are obvious on examination; trans-illumination of the protruding sac can sometimes help distinguish between them. (In most patients with meningocele, it can be transilluminated; in those with myelomeningocele, it can’t.) With myelomeningocele, a pinprick examination of the legs and trunk shows the level of sensory and motor involvement; skull X-rays, cephalic measurements, and computed tomography (CT) scan demonstrate associated hydrocephalus. Other appropriate laboratory tests for patients with myelomeningocele include urinalysis, urine cultures, and tests for renal function starting in the neonatal period and continuing at regular intervals.
With encephalocele, X-rays show a basilar bony skull defect. CT scan and ultrasonography further define the defect.
» READ BOOK EXCERPT ONLINE »
Source: Handbook of Diseases, 2003
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