CRL Flashcards
CRL
Crown-rump length(CRL) isan ultrasound measurement that is used during pregnancy. The baby is measured, in centimeters, from the top of their head (crown) to the bottom of their buttocks (rump). 1 The limbs and yolk sac are not included in the measurement
NT
Nuchal translucency (NT) is the sonographic appearance of a collection of fluid under the skin behind the fetal neck in the first-trimester of pregnancy. The term translucency is used, irrespective of whether it is septated or not and whether it is confined to the neck or envelopes the whole fetus. In fetuses with chromosomal abnormalities, cardiac defects and many genetic syndromes the NT thickness is increased.
NT- 2
Screening by NT can detect about 80% of fetuses with trisomy 21 and other major aneuploides for a false positive rate of 5%. The combination of NT and maternal serum free β-hCG and PAPP-A improves the detection to 90%. There is now evidence that the detection rate can increase to about 95% and the false positive rate can be reduced to 3% by also examining the nasal bone, ductus venosus flow and tricuspid flow.
Cell free DNA
Cell-free DNA are short fragments of DNA released into the bloodstream through a natural process of cell death. During pregnancy, the mother’s blood contains cell-free DNA (cfDNA), both from her own tissue, and from the fetus via the placenta. Approximately 2-20% of total cfDNA in maternal blood is placental.
MSS
The maternal serum screening test is a blood test offered to pregnant women to look out for different protiens , antigens,etc and check the elevated levels of them and further testing. It helps to inform them of the chance of their unborn child having Down syndrome, Edward syndrome or a neural tube defect
Euploid fetus
Euploid: a euploid or “normal” results means that 23 pairs of chromosomes were detected in the embryo biopsy. Aneuploid: an aneuploid or “abnormal” result means that at least one chromosomal abnormality was detected in the embryo biopsy.
Acrania
Ultrasound diagnosis:
Absence of cranial vault and cerebral hemispheres.
Arachnoid cyst
Unilocular, avascular cyst that does not communicate with the lateral ventricles.
They are usually found in the midline between the cerebral hemispheres but about 10% are in the posterior fossa behind the vermis.
Associated abnormalities:
Arachnoid cysts are usually isolated. There are rare associations with chromosomal defects, mainly trisomy 18 or 12, and agenesis of the corpus callosum.
Blake’s pouch cyst
Expansion of the 4th ventricle into the cisterna magna resulting in a unilocular, avascular cyst in the posterior fossa – ‘key-hole’ sign in the transverse cerebellar view.
Vermis: normal size with mild to moderate upward rotation.
Cisterna magna: normal.
Differential diagnosis: mega cisterna magna (>10 mm; normal vermis), arachnoid cyst (cyst in the cisterna magna with mass effect on surrounding structures; normal vermis).
Associated abnormalities:
It is usually an isolated finding.
Risk of chromosomal abnormalies, mainly trisomy 21, in up to 5% of cases but usually in the presence of other suggestive markers
Brain teratoma
Irregular solid mass, with cystic and/or calcified components, distorting the brain anatomy.
Cerebellar dysplasias
gestational age.
The small cerebeum is due to disruption in the white matter of either the vermis (vermian dysplasia) or the cerebellar hemispheres (hemispheric dysplasia).
Associated abnormalities:
The two most common vermian dysplasias are:
Joubert syndrome: autosomal recessive mutation of chromosome 9q34; The condition is associated with neurodevelopmental delay.
Rombencephalosynapsis: sporadic abnormality; complete absence of the vermis with fusion of the cerebellar hemispheres, absent cavum septum pellucidum, ventriculomegaly and migration disorders. The condition is associated with severe neurodevelopmental delay.
Choroid plexus cysts
Single or multiple cystic areas (>2 mm in diameter) in one or both choroid plexuses of the lateral cerebral ventricles.
Associated abnormalities:
Associated with increased risk for trisomy 18 and possibly trisomy 21.
Corpus callosum agenesis
Absence of the septum cavum pellucidum and tear-drop appearance of dilated posterior part of the lateral ventricles (‘tear drop’) in the standard transverse view of the brain at >18 weeks’ gestation.
Complete or partial (usually of the posterior part) absence of the corpus callosum in a mid-sagittal view of the brain.
Abnormal course of the pericallosal artery.
The normal length of the corpus callosum at 20 weeks’ gestation is 18-20 mm
Preeclampsia
Preeclampsia (PE) is a multisystem syndrome developing during the second half of pregnancy. It is characterised by hypertension and proteinuria or in the absence of proteinuria the finding of maternal organ dysfunction.
Preeclampsia 1
hypertension before 20 weeks’ gestation) proteinuria or maternal organ dysfunction should develop after 20 weeks’ gestation.
