Ultrasound scanning guidelines
Dating Scan for increased risk from maternal serum screening (MSS)
- A scan may be requested after maternal serum screening (MSS) indicates an increased risk for chromosomal abnormalitiy (down syndrome, neural tube defect, abdominal wall defect)
- Often performed about 16 weeks gestation (this is when MSS is performed)
- The primary purpose of this scan is to provide accurate dates for the pregnancy
- In addition to fetal biometry, a limited assessment of anatomy should be performed if there is an increased risk of NTD/abdominal wall defect
Assess:
- Fetal number
- Fetal cardiac activity
- Placental position
- Liquor volume
- Adnexae
- Cervix
- Fetal biometry
Documentation:
- Placental views long / trans
- Internal os view in the midline with a measurement to lower placental edge
- Deepest pool of liquor with AP measurement
- Full length of fetal head and body
- BPD, HC, AC, FL
- Fetal heart in thorax / clipstore of fetal heart activity +/- M-mode
Additional Documentation - for increased risk of NTD/abdominal wall defect on MSS
- Fetal cord insertion
- Coronal or sagittal views of the entire spine
- Trans assessment of entire spine
- Cerebellum / Cisterna Magna
- Choroid plexus / lateral ventricle measurement at trigone
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