Scan technique ii

Indications for 2nd & 3rd trimester scanning

• Assigning dates
• Assessing foetal growth, amniotic fluid volume, foetal heart motion & foetal presentation.
• Assessing placental position & texture.
• For review of foetal anatomy
• To detect the presence of adenexal masses or cysts or uterine myomas

Scan technique

• Bi parietal diameter measurement of the foetal head –BPD
• BPD measurement is more accurate in the first trimester.
• BPD is the distance between the anterior & posterior tables of the skull.
• It is measured perpendicular to the mid line echo (falx)

 

Femoral length measurement -FL

• Is more accurate in the third trimester.
• Is the longest length of the shaft of the femer in an image completely separate from the overlying foetal skin.

 

Abdominal circumference measurement –AC

• AC measurement is the most useful measurement in assessing the foetal growth. This measurement is the most useful in assessing foetal growth retardation.
• AC is measured in an image in the plane of the foetal umbilical artery & the foetal stomach.

 

 

Liquor volume assessment

• Liquor volume is measured by adding the vertical lengths of the liquor pools in all four quadrants.
• The images should be measured with no intervening foetal parts.

The average of the all four measurements is regarded as the liquor volume

 

• When the liquor volume measurement is increased > 8 it is considered as hydramios
• When the liquor volume is < 2 it is considered as oligo hydramnios

Report

• Should document whether live or not, single or multiple pregnancies, presentation &lie.
• Placenta whether anterior, posterior, lateral, fundal or placenta previa.
• Following measurements of the fetus should be documented.
• BPD, FL, AC
• Liquor volume should be measured & documented.
• Whether the fetus is normal or abnormal should be documented