ultrasonography Flashcards
What is ultrasound?
Sound waves with frequencies higher than the human audible range
The upper limit for audible sound is considered to be approximately 20kHz
predominantly, how does the ultrasound equipment get to the patient?
it is wheeled - can be taken to a patients bedside, which is an adv. if they aren’t mobile
can attach via USB to an iPhone – means paramedics have access to ultrasound equipment, and and search and rescue teams can take ultrasound images as soon as they find a patient and make their intial assessment, and the images can be sent to a trauma centre
describe the pulse echo principle
the probe/transducer emits a sound wave, and then receives echoes from the original wave
whenever the ultrasound wave passes through a tissue boundary it can be:
- reflected back to the probe
- pass through the boundary and continue propagating through the body
adjacent tissues with varying densities will reflect more of the sound wave
the info that gets reflected back will be picked up by the transducer/probe and will be translated into an image
what affects the brightness of an ultrasound image?
the amount of reflection: higher amount of reflection = brighter image
bright white relates to bone, predominantly around the facial bones and spine
what does a dark image mean?
dark image means no information to be seen, nothing is reflecting back
dark areas = fluid
name some clinical applications of ultrasound
cardiology abdominal urinary gynaecology lungs trauma vascular head/neck breast/testicular trauma
why do we use ultrasound?
- usually non invasive
- no radiation
- no documented side effects
- “real time” imaging
- results available immediately
- widely accesible
why might we not use ultrasound?
training is resource intensive
accuracy is user dependent
ultrasound image quality is dependent on patient habits
there are many types of probes/transducers - why is this?
means you can get the most optimum image
for example, scanning something deep in the body means you would use a lower freq probe, and scanning something peripherally means you would use a higher freq probe
also, can use high frequency tipped probes and do an internal scan (intra vaginal scan on uterus or cervix), means you can see things in much finer detail
probe + catheter – take images of the lumen of a blood vessel wall
all pregnant women in the UK are offered scans when?
at 12 and 20 weeks - 99% attendance rate
purpose of a 12 week scan?
- making sure there is a fetus there and it has a heartbeat – “viability”
- checks number of fetus’ and gross anatomy ie. anecephaly, where the cranial vault hasn’t formed so the brain tissue leaks out into the fluid outside of the baby
- omphalocele is mid-gut herniation, which means mid-gut wall hasn’t closed properly and the content of their abdomen can become exterior to the body – can contain organs i.e. the liver
how many pregnancies end in miscarriage?
1 in 4
what is a blighted ovum?
a missed miscarriage
take a normal pregnancy test and it will be positive, your body will produce hormones to make you feel pregnant, periods will stop, gestational sac will grow but it will be empty
everything up until the ultrasound scan will make this person feel as if they’re pregnant
ask the patient to come back just in case the fetus is too small to be seen and they came too early to have a scan
12 week Scan - Downs Syndrome screening?
optional part of the scan
Fetal nuchal translucency screening- uses ultrasound to measure the size of the nuchal pad at the nape of the fetal neck
Increased thickness of the sac of fluid = increased risk of downs syndrome
given a number and combined with a blood test generates a risk factor for the patient (eg. 1 in 30, 1 in 1000)
The purpose of the 20 week scan?
to identify abnormalities:
- may indicate the baby has a life-limiting condition
- may benefit from antenatal treatment
- may require early intervention following delivery
ALSO
- Placenta localisation
- Fetal Biometry
- Fibroid Monitoring
- Liquor Assessment
baby is a bit bigger at 20 weeks, can get an idea of the finer anatomy and pick up some of the finer pathologies
estimate the weight of the baby based on the tummy circumference and measuring length of 1 thigh bones
name some anomalies that can be seen in a 20 week scan
- Spina Bifida
- gap in spinal column which causes the spinal nerves and connective tissue to bulge through the spine and sit posterior to the baby’s back - Achondroplasia
- dwarfism with varying degree of severity
- x-ray shows slight bowled limbs, long bones bowed and shortened - Low Lying Placenta/Placenta Previa
- placenta is usually out of the way of the internal os, as thats how the baby will leave, but here its sat on top of the cervix
- baby won’t leave the cervix without tearing up the placenta
- patient will need a c-section - Talipes (Club Foot)
- -we have to make sure the baby moves the foot into a normal position, so you could do a 30 min scan or ask them to come back for another scan
Polyhydramnios and Anhydramnios/ Oligohydramnios?
poly - a lot of amniotic fluid in the sac, often indicative of gestational diabetes or BP issues in the mum
anhy/oligo – no fluid/less amniotic fluid in the sac, poor prognosis as we cannot introduce fluid into the system– usually caused by some underlying chromosomal abnormality
what is an ectopic pregnancy?
it is when an egg implants outside of the
uterine cavity
-associated with severe pain and bleeding
-can be caused by tubal damage
(from surgery, PIDS, endometriosis)
-treatment depends on the
Individual, medical or surgical - most common decision is termination
multiple pregnancy - how does it happen and what are the complications?
Multiple pregnancy usually caused by delays in the fertilized egg reaching the womb before implanting
risk of growth restrictions (ie being too small), being competitive with each other and stealing each others blood supply is very high, so need serial scanning every 2 weeks
Conjoined twins
very rarely have a positive outcome
Twin to Twin Transfusion Syndrome
share a placenta
-rare, serious
how can a cleft lip be seen?
3D imaging
risks with amniocentisis
1 to 3 % miscarriage risk – don’t have to do them but only if really have to
uses of ultrasound in Gynecology – fibroids, what are they?
fibrous muscular tissue, grow and grow until the blood supply they receive can no longer support growth, some require surgical intervention
can cause heavy or irregular periods
in pregnancy, if a fibroid is large enough it can create a physical obstruction to the cervix, or if its really large enough having that amount of muscular tissue pushing against the area where the baby is growing will cause restriction on the baby being able to grow
hormones helping the baby to grow can expedite the growth of the fibroids – important to monitor fibroid growth
uses of ultrasound in gynecology – Post Menopausal Bleeding?
uterine polyps – growths from the inner wall of the womb which extend into the cervix and vagina.
usually benign but on rare occasion some can turn cancerous - surgery considered
polyps will continue to grow as they have a single feeder vessel – a larger blood vessel that supplies o2 to them – doppler ultrasound will pick this up
abdominal ultrasound - aortic screening?
Patients over a certain age will be offered screening of their aorta
larger aorta size means its aneurysmal or pre-aneurysmal, and will be monitored over time
if the diameter of the aorta is over 3cm, patient is referred to vascular consultant and diameter is measured over time
if gets to 5cm they are offered a procedure, a graft through the aorta to divert where the blood flow is going, stops putting pressure on the aneurysm
abdominal ultrasound - Liver Cirrhosis/Ascites?
people on long term medication/heavy drinkers/drugs – do they have cirrhosis/fibrosis of the liver?
different levels of drugs and alcohol can increase level of fat inside the liver, and more fat or fibrotic tissue inside the liver can decrease its function
over time this can become extreme
cirrhosis, liver looks more speckled
abdominal ultrasound - gallstones?
- caused by an imbalance in chemical make up in bile in the gallbladder (high cholesterol / bilirubin)
- pain after eating (fatty food especially)
- occasional pain in right shoulder
- black pouch and inside is bright white speckles which are denser – US waves reflect more, therefore appear brighter
urinary tract ultrasound - what can it detect?
- Polycystic Kidney Disease
- full of cysts, black areas which are pockets of fluid, grow over time
- effectiveness of the kidney over time is massively reduced - enlarged prostate
- renal calculi
Testicular Ultrasound - what can it detect?
lumps
- usually little cysts, completely benign
could be testicular cancer
Breast Ultrasound?
Under the age of 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)
Ultrasound also enables core biopsies to be taken of breast lumps to allow for histological investigation to allow for classification of the lump.
Vascular ultrasound?
used to exclude/confirm presence of a deep vein thrombosis when patient has in pain and swelling in lower limbs
also used as DVT screening tool in post operative patients and those with known pulmonary embolus (to find the source of the clot)
Musculo-Skeletal Ultrasound?
Applications :
- Muscle/tendon tears
- Inflammation
- Nerve Entrapments
- Soft tissue lumps
- Cysts
- Hernias
- Paediatric CHD
- Infant Torticollis (neck twisting)
POCUS – FAST
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.
