Ultrasonagraphy Flashcards
Define Ultrasound (US)
Sound waves with frequencies higher than the human audible range,
Describe limits of frequencies
The upper limit is considered to be approximately 20kHz
< 20Hz = infasound
20Hz < audible < 20kHz
20kHz < ultrasound < 200mHz
Functions of US probe
First emit a sound wave
Then to receive the echoes from the original wave.
= This is the foundation principle of all Ultrasound applications and technology.
Describe pulse escho principle
Whenever the ultrasound wave passes through a tissue boundary it can be reflected or will pass through and continue propogating
Adjacent tissues with varying densities will reflect more of the sound wave,
adjacent tissues with similar densities will reflect less..
Eg Air in lungs creates a poor image
Describe relation of amplitude to reflections
High amplitude – strong reflections
Low amplitude – Poor reflections / no reflections
List clinical applications of US
Abdominal
Gynaecology
Urinary
Trauma - POCUS
Obstetrics
Testicular
Lungs
Musculo-skeletal
(MSK)
Breast
Head/Neck
Cardiology
Vascular
Advantages of US
Widely Accessible
Results can often be
Available immediately –
Bedside
No radiation
“real time” imaging
No documented side effects
In humans
Well tolerated
Usually non invasive
Disdvantages of US
Training is more resource intensive
For departments compared to other modalities
Ultrasound image quality is highly
Dependant on patient habitus
Effectiveness and accuracy
Are highly operator dependant
No known side effects?
Why have a selection of transducers
Increased choice of technical variables allows for optimisation of your image
Choice over sector width, scan depth (resolution), patient habitus, field of view..
Describe characteristics of 12wk obstetric US scan
-Fetus is approximately 45-84mm in Length (11+2wks – 14wks) -First routine scan offered to most low Risk pregnancies -Detects ‘Viability’, number of fetus’, Gross anatomy, detectable major Abnormalities, morphology of ovaries And an accurate gestational age of The fetus.
Down’s syndrome define
Down’s syndrome is caused by a change in one of the genes in the egg before it is fertilised by the sperm (at the time of conception)
This is usually a completely random happening, though it is more common in older mothers
Throughout the world, the frequency of DS is about 3 per 2000 births.
Fetal nuchal translucency (NT) function
- when should it be performed
Fetal nuchal translucency (NT) screening uses
ultrasound to measure the size of the nuchal pad at
the nape of the fetal neck. It should be performed
between 11 weeks and 13 weeks + 6 days
The purpose of the 20 week scan in England is to identify abnormalities which:
- may indicate the baby has a life-limiting condition
- may benefit from antenatal treatment
- may require early intervention following delivery
Other standard aims of 20 wk scan in England
Other standard aims;
Placenta localisation
Fetal Biometry
Fibroid Monitoring
Liquor Assessment
Spina bifida = define
Spina bifida is when a baby’s spine and spinal cord don’t develop properly in the womb = a gap in the spine
a type of neural tube defect
Cause not kbut a lack of folic acid before and in the early stages of pregnancy is a significant risk factor.
Spina bifida = risk factor
Lack of folic acid before and in the early stages of pregnancy is a significant risk factor.
Achondroplasia define
Achondroplasia is a genetic disorder that results in dwarfism.
Thickened soft tissue surrounding the long
bones
What do we measure in 20 wk scan
In England at the 20 week scan we measure
The distance from the lowest edge of the
Placenta to the internal OS of the cervix.
Describe the effect of low lying placenta
f the placenta is within 2.5cm of the cervix
Then future scans are required. If the placenta
Does not raise higher closer to the due date then a C-Section may be required.
Talipes - define
= club foot. It is a deformity of the foot and ankle = congenital
Talipes - chance of getting it
If one parent had the Condition as a baby their Own baby would have a 1 in 30 chance of also Having talipes
Umbilical Artery Doppler Assessment – function
Umbilical Artery Doppler Assessment –
Can be used to highlight the affects of pre-eclampsia and intrauterine growth restriction (IUGR)
Is used more frequently now as is being suggested we can improve perinatal mortality and morbidity.
Characterisics of EPU - US
-The fetal pole is detected as an Area of thickening along the periphery Of a yolk sac -Minimum of 1-2mm in length for Detection (5-6 wks) -Cardiac Activity should be detected Routinely from 4-5mm (6wks)
Reasons for PW to be referred to GP
-Pregnant women can be referred by their GPs in cases of lower abdominal/pelvic pain,
Bleeding, confirmed history of recurrent miscarriage and sometimes due to previous
Obstetric history issues.
Ectopic pregnancy - define + association
When an egg implants outside of the
Uterine cavity it is know as an ectopic
pregnancy
Associated with severe pain and
also bleeding
Ectopic pregnancy - cause
Can be caused by tubal damage
from surgery, PIDS, endometriosis
Multiple pregnancy cause
Multiple pregnancy usually caused by delays
In the fertilized egg reaching the womb before implanting.
Fibroids - composition and growth
Fibroids consist of fibrous muscular tissue, many eventually grow until the
blood supply they receive can no longer support further growth,
but others can
get very large and require surgical interventions ( myomectomy / uterine
embolisation / hysterectomy)
Uterine polyps - define and link to cancer
-Uterine Polyps – growths from the inner
Wall of the womb which extend throughout
The cavity and into the cervix and vagina.
Usually benign but on rare occasion some
Can turn cancerous. Surgery would be
Considered.
Aneurysmal aorta definition
A section of abdominal aorta is defined
As aneurysmal when reaching 3cm in
AP diameter.
AAA monitoring
AAAs are monitored in specialised clinics
And surgery is often considered once the
Aneurysm meets 5.5cm in AP diameter.
EVAR - define + advantages
EVAR – Endovascular Aortic Repair
the placement of a stent-graft into the aneurysm through a small hole in the blood vessels in the groin.
less invasive + faster recovery
Describe development of cirrhosis
Fatty liver = deposits of fat cause liver enlargement
Liver fibrosis = scar tissue forms + more liver cell injury occurs
Cirrhosis = scar tissue makes liver hard and unable to work properly
Gallstones define
Gallstones are small stones, usually made of cholesterol, that form in the gallbladder
Gallstones cause
Usually caused by an imbalance in the
Chemical make up within the bile in the
Gallbladder (high cholesterol / bilirubin)
Murphy’s sign purpose
Murphy’s sign is one of the tests used on patients presenting with an acute abdomen to ascertain whether the abdominal pain is being caused by an inflamed gallbladder.
The need for a breast US
> 35 breast tissue tends to be denser, this leads to difficulty with diagnosing the nature of breast lumps on mammograms
as differentiation between solid and fluid filled areas is relatively poor
ultrasound can make the differentiation at an improved rate (about 30% increased)
US relation to breast tissue biopsies
Ultrasound also enables core Biopsies to be taken of breast Lumps to allow for histological Investigation to allow for Classification of the lump.
US use in DVT
US is used to exclude or confirm the presence of a deep vein thrombosis in cases of pain and swelling in the lower limbs
It is often also used as a screening tool for DVT in post operative patients
and those with known pulmonary embolus to find the source of the clot
Colour flow doppler use in DVT
Using colour flow doppler we Can demonstrate that the Femoral vein is completely Occluded by the lack of colour In this region
Applications of MSK US
Applications :
-Muscle/tendon tears
-Inflammation
-Nerve Entrapments
-Soft tissue lumps
-Cysts
-Hernias
-Paediatric CHD
-Infant Torticollis (neck twisting)
-Early RA
-Joint effusions
-Injection Guidance (contrast and
Therapeutic)
-and many more…
POCUS - define
Point of Care Ultrasound – Focused Assessment with Sonography of Trauma
FAST is an ultrasound scan protocol undertaken at the time of presentation of a trauma patient.
US vs plain X-ray
Ultrasound can detect as little as 20ml of free fluid, compared to the 200ml required with plain X-Ray
