Assessment of Second Trimester Flashcards
BPD is an accurate predictor of gest age before
20 w
BPD is measured in a place that passes through the
3rd ventricle and thalami
BPD is above the level of the
orbits and cerebellum
BPD is below the level of the
ventricular atrium
BPD landmarks
falx, 3rd ventricle, thalamic nuclei, cavum septum pellucidi and atrium of lateral ventricle
Measure BPD perpendicular to
falx, placing calipers from outer margins of upper cranium to the inner margin of lower cranium
HC is a reliable measurement independent of
cranial shape
HC measure in a plane that must include the
CSP and tentorial hiatus
HC measured parallel to the base of
skull, placing the calipers on the outer margins of the cranium
Measurement of the HC cannot always be obtained in what plane
BPD
Cehaplic Index is devised to determine the
normality of the fetal head shape
Ceaphlic Index is abnormal when less than ____ or greater than ____
74%
83%
ABD predictor of
fetal growth not gest age
Most difficult measurement to obtain
ABD
ABD measurement location
slightly superior to CI at junction of lt and rt PV or demonstrate a short length of umb vein, lt PV, and fetal sto
Measure at ABD circumference at level to include
liver
parallel to fem shaft placing calipers at level of fem ehad cartilage and dist fem condyle
Femur length measurement
Alpha- fetoprotein is produced by
fetus
AFP is found in
amniotic fluid and maternal serum
AFP normal value varies with
gest age
- fetus older than expected
- multiple gest
- open neural tube defect
- abd wall defect
- cystic hygroma
- renal anomalies
- fetal demise
Causes of High AFP
- fetus younger than expected
- chromosomal abnormalities
- trophoblastic disease
- long standing fetal demise
- chronic maternal hypertension or diabetes
Causes of low AFP
Oxygenated blood leaves the placenta and enters the fetus through the
umbilical vein
After entering the abd, blood courses through the
ductus venosum reaching the rt atrium of the heart
blood travels from the rt and lt atrium through
foramen ovale
From the left atrium to the left ventricle, blood ascends the
AO distributing blood to the fetal tissue
Approx half of the blood leaves through the
umb arteries and goes back to plac for reoxygenation
- junction of ant, occipital, and temporal horn
- located slightly inf to level of BPD
- evaluated for ventricular enlargement
Atrium of lateral ventricles
- hyper thin ventricle wall
- hyper choroid plexus
- measured perpendicular to ventricle walls from glomus of choroid plexus to lateral ventricular wall
- measures b/t 6 - 10 mm throughout pregnancy
- choroid plexus should almost fill the lateral ventricle
Atrium of lat ventricle sono appearance
- presence exclused almost every subtle midling brain malformation
- filled with cerebral spinal fluid
- found at level of BPD
- located inf to ant horns of lat ventricles
- closes by 2 yrs of age
Cavum Septi Pellucidi
Cavum Septi Pellucidi sono appearence
small anechoic box located in midline portion of ant brain
- consists of vermis and two lateral horns
- located in post fossa
- assists in balance
Cerebellum
Cerebellum sono findings
dumbell shaped echogenic structure located in midline of post fossa
- echogenic cluster of cells
- important in the production of cerebrospinal fluid
- found at level of BPD
- located inferior to ant horns of lat ventricle
- chroid plexus cysts will normally regress by 23 gest age
Choroid Plexus
- hyper structures located within each lat ventricle
- lie along the atrium of lat ventricle
- cyst my be displayed within choroid
Choroid plexus sono findings
fluid filled spaces located between the underface of cerebellum and medulla oblongata
Cisterna Magna
CM sono findings
- AP
- begins ossification around 11 gest w
- ovoid in shape
Cranium
cranium sono appearence
hyper outline surrounding the brain
- intrahemisphere fissure
- separates the cerebral hemisphere
Falx Cerebri
Falx cerebri sono findings
echo midline linear structure
- soft tissue thickness between the calvaria and posterior skin line
- measured in the axial plane at a level to include the cerebellum, CM, and Cavum speti cellucidi
- accurate up to 20 w
- thickening assoc w/ anueploidy
Nuchal Thickness
Nuchal Thickness sono findings
thickness
Thalami
provide synopsis b/t cerebellu and post brain
- hypo ovoid structures in midportion of brain located in each hemisphere
- 3rd ventricle is located b/t each individual thalamus
Thalami Sono findings
- muscle seperating thorax and abd cavities
- courses ant to post
Diaphragm
- curvilinear hypo structure
- abd content lie inf
- chest contents lie sup
Diaphragm sono findings
- apex points toward left side of body at 45 degree angle
- rt ventricle most ant
- lt atrium most post
Heart
- lies midline in chest
- hyper ventricular and atrial septa
- 120-160 bpm
- hyper focus w/in ventricle is most likely the papillary muscle
Heart sono findings
- serve as lat border to heart
- lie sup to diaphragm
Lungs
- moderately echo
- homo
- increases in echo as gestation progressess
Lung sono findings
- signifies genitourinary system is working
- bladder fills and empties every 30 - 60 min
- should be vis by 13 w
Bladder
- round anechoic structure located centrally in inf pelvis
- variable in size
Bladder sono appearance
- meconium begins to accumulate in the small bowel
- small bowel becomes vis in late second trim
- large bowl becomes vis in 3rd trim
Bowel
- moderately echo
- hyper compared to liver
- hyper compared to bone
- distinguished after 22 w
Small bowel sono app
large bowel sono appearence
hypo to small bowel
- vis peaks around 20-32 gest w
- signifies the presence of biliary tree
Gallbladder
- elongated fluid filled structures
- located inf and to rt of umb vein
gallbladder sono appearance
- urine formation begins near the end of 1st trim
- may be identified as early as 15 wks
- consistently identified by 20 w
Kidneys
- iso or hypo locaed on each side of spine
- bilateral
renal pelvis should contain small amount of fluid
Kidneys sono appearance
Kidneys renal pelvis measurements
> 4 mm up to 33 w
> 7 mm from 33 w to term
liver
- largest organ in torso
- reflect change in fetal growth
liver sono appearence
- moderately echogenic structure
- left love is larger than rt lobe
- occupies most of upper abd
- reliabily vis by 13 w
- signifies normal fetal swallowing sequence
Stomach
- anechoic structure located in the LUQ
- size and shape will vary with recent swallowing
- echogenic debris w/in sto may be vis
Stomach sono appearance
- placental insertion generally located in midportion of plac
Umb cord insert
- smooth abd wall at umb insert
- umb vein courses sup toward liver
- umb arteries arise from hypogastric arteries on each side of bladder
Umb cord instert sono appearance
Long bones start ossification by
11 w
pelvis iliac wings ossify at
12 gest w
pelvic ischium ossifies by
20 w
Spine widens near the base of the____ and tapers near the _____
skull
sacrum
ossification of spine should be complete by
18 w
What surrounds and protects the fetus?
Amniotic fluid
Amniotic fluid provides important info on
fetal renal and plac function
What becomes the major producer of AF through shallowing and urine after 16 w
Fetus
length of cx determines
competence
length of cx is measured b/t
internal os and external os
normal cx length
2.5 - 4cm
What communicates between fetus and mother
placenta
The placenta provides
nutrition and products of metabolism to fetus
Whats the connecting lifeline between fetus and plac
Umb cord
How many arteries and veins in umb cord
2 arteries
1 vein
umb cord enters the
lt portal vein
umbilical arteries arise from
internal iliac arteries
hypogastric
umb cord normally insert into the
midportion of plac
umb cord is covered in
Whartons jelly
plac is hyper compared to
myo
plac thickness
umb artery
- low resistive near fetal insert
- high resistive near plac insert
umb vein
- continuous flow through stystole and diastolic
- flow is directed from plac to the fetus