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Repost: Useful Link for Ultrasound Antenatal

quote from http://www.ultrasoundpaedia.com/normal-2ndtrimester/
BPD and Head Circumference

fetal HeadThe correct plane for the measurement of the head circumference (HC) and bi-parietal diameter (BPD)must include the cavum septum pellucidum, thallamus and choroid plexus in the atrium of the lateral ventricles.

BPD: Measure outer table of the skull to the inner table.
HC: Measure around the outer table of the skull.

Cerebellum, cisterna magna and nuchal foldPosterior Fossa
 The correct plane for measuring the nuchal fold is to have cavum septum pellucidum (CSP) and the cerebellar hemispheres in the image.
  • The cerebellar diameter should approximately equal the weeks of gestation. (EG 19weeks=19mm)
  • Normal cisterna magna is less than 10mm.
  • A normal nuchal fold is less than 6mm (between 17-20weeks).

    Choroids and lateral ventricles

    The LATERAL VENTRICLES should be less than 10mm in diameter (best measured at the occipital horn).
    The CHOROID PLEXII should be homogeneous. Small, and sometimes multiple, choroid plexus cysts are a common finding on high resolution equipment. They are of doubtful significance as an isolated finding.

    FACE: Ensure there is symmetry with a normal inter-orbital distance.
    Coronal Nose and Lips

    NOSE & LIPS: From the 'face' image, rotate the probe to visualise the nose and lips front on.
    2 distinctly seperate nodules and in intact hypoechoic upper lip should be seen. 2 distinctly septate nostrils and an intact hypoechoic top lip.

    Abdominal CircumferenceAbdominal Circumference
    The Abdominal Circumference must include the portal section from the umbilical  vein, the stomach and a true cross section of the spine with 3 ossification centres. It should be circular in shape.

    Situs heart and stomach left sideDiaphragm
    First, confirm that the organs are correctly sited right vs left.
    An axial plane through the chest and upper abdomen shows the heart and stomach on the same side (which has been proven to be the left).
    In  a coronal plane, confirm the presence and position of heart, stomach and bladder. Also check the diaphragm.Ensure that there is no herniation of abdominal contents into the thorax.

    Transverse Kidneys Kidney longitudinal

    Confirm the presence and position of both kidneys. Be cautious not to mistake the adrenal glands which are quite large. Look for the anechoic renal pelvis. The renal pelvis TS diameter should be less than 5mm.
    The kidneys must be measured in a sagittal or coronal plane.  Utilise colour/power doppler to confirm renal arteries and help identify the kidneys in a larger patient.

    UMBILICAL CORD                                                                          

    Cord insertion and 2 umbilical arteries Male and female Gender
    Cord insertion
    Ensure the abdominal wall around the cord insertion is intact and that no bowel has herniated into the cord.
    Use power doppler to confirm the presence of 2 umbilical arteries forking around the bladder. (Be careful not to slip into a more coronal plane and mistake the iliac arteries.)
    There is an obvious penis identified at 18-20 weeks. Shown on the mouseover is the 3 parallel white stripes of the external genitalia of the female vulva.
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    FETAL SPINE      

    Coronal Spine Spine sagittal
    Check for any scoliosis.
    Cervico-thoracic spine:Check the ribs for symmetry.
    Lumbar/sacral spine: In coronal, visualise the sacral taper and pelvic bones.
     Ensure there is a uniform, intact posterior skin edge.
    Transverse Spine
    The 3 ossification centres of the spine should be visible from neck to the lumbo-sacral junction. A smooth intact skin line should be visible throughout.
    Beware overlying cord mimicking a meningocoele.

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    Femur length femur measurement

    Femur  Length

    The Femur length should only be measured when the femur is horizontal (beam is perpendicular) and shadows evenly- at least from both ends.
    tibia and fibula foot perpendicular to the lower leg
    Lower limbs
    Confirm the presence and equal size of the tibia and fibula bilaterally.
    The foot should not be seen. A rounded base at the base of the leg when seen front on. If you can see the tibia, fibula and foot in one plane, suspect talipes. Rotate 90degrees to see the sole of the foot and the toes.
    The foot should be perpendicular to the tibia and fibula.

    Arms Hand ultrasound
    Upper limbs
    Similar to the leg, confirm the presence and size of length of the 3 long bones in each arm.
    The fist is often clenched. Ideally watch the hand open/close and check for 5 fingers/knuckles on each side.Check for the presence of the 5th middle phalanx.

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    The cervix must be measured from the internal os to the external os.
    Cervix Length
    The echogenic mucous plug is readily visible in the cervix.
    Measure the length of the cervix. It should be at least 30mm, and contain no fluid.
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    Placenta Placenta to Cervix measurement
    Placental bed

    • Locate the placenta (anterior V's posteror or lateral)
    • Ensure there is a myometrial rim of 3mm or more under the placenta (otherwise suspect placenta percreta/accreta).

    The placenta tip must be greater than 3cm from the internal os.

    Placental Contraction
    Uterine contraction
    Beware of uterine contractions mimicking a low lying placenta.




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