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CLINICAL PATHOLOGY > Ultrasonography > Flashcards

Ultrasonography Flashcards

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1
Q

What are ultrasound waves?

A

Sound waves with frequencies higher than the human audible range (20kHz)

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2
Q

How far do ultrasound waves travel in a patient?

A

Only a few centimetres

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3
Q

Describe the pulse echo principle

A

The ultrasound/ probe transducer has two functions:

  1. Emits a soundwave
  2. Recieves echos from the original wave

When ever an ultrasound passes through a tissue it can

  • be reflected
    • OR
  • pass through and continue propagating
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4
Q

What is the fate of ultrasound waves when they can pass through tissue?

A
  • Can be reflected
    • OR
  • Pass through and continue propagating
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5
Q

What affects how much of the sound wave is reflected?

A

TISSUE DENSITY

  • Dense tissue (like bone, gas) will reflect the sound waves at a high amplitude producing a white image
  • Less dense tissue (fluid, amniotic fluid, urine) will not reflect, and ultrasound waves propagate producing a black image
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6
Q

List some advantages of ultrasound use?

A
  • No radiation
  • No documented side effects
  • Usually non-invasive (sometimes invasive if trans-vaginal or endo-anal)
  • Widely accessible
  • Results available immediately
  • ‘Real time’ imaging
  • Well tolerated
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7
Q

List some disadvantages of ultrasound use?

A
  • Ultrasound image is highly dependant on patient habitus (e.g weight)
  • Effectiveness is operated dependant
  • No known side effects
  • Training is more resource intensive
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8
Q

What are some clinical applications of ultrasounds?

A

Mainly:

  • Obstetrics (pregnancy, childbirth, postpartum period)
  • Gynaecology
  • Abdominal
  • Urinary

Also:

  • Trauma = POCUS
  • Testicular
  • Breast
  • Head and Neck
  • Vascular
  • Cardiology
  • Musculo-skeletal
  • Lungs
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9
Q

Describe the advantage of using an ultrasound over X-ray/CT scans in obstetric imaging

A

Doesnt use ionising radiation

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10
Q

Describe the 12 week scan ultrasound scan in obstetrics

A
  • Foetus is approximately 45-84mm in length
  • First routine scan offered to most low risk pregnancies
  • Detects ‘viability’, number of foetus’, gross anatomy, detectable major abnormalities, morphology of ovaries and an accurate gestational age of foetus
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11
Q

Describe some pathologies picked up on a 12 week scan

A

Anencephaly = Some or all foetal brain, skull and scalp is missing

Omphalocele/ exomphalos = Herniation of abdominal tissue (part of the intestine will protude through the abdominal wall at birth)

Body stalk defect = Extreme form of herniation, where abdominal organs will have herniated through abdomen and develop outside of the cavity

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12
Q

What does a blighted ovum/ missed miscarriage on an ultrasound represent?

A
  • Something may have gone wrong in the pregnancy that has prevented the foetus from growing and there is scanning of an empty sac
  • The empty sac will have caused all the same symptoms of pregnancy + positive pregnancy test
    • ​Hence Ultrasound (12 week scan) is the first sign that something in the pregnancy has gone wrong
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13
Q

What is the probabillity of getting a miscarriage?

A

High at 3 weeks

Decreases after that, once we get to 12 weeks the probabillity is extremely low

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14
Q

What is a cystic hygroma and molar pregnancy?

A
  • Cystic hygroma = fluid filled cysts of resulting from blockage in the lymphatic vessels will not form properly
  • Molar pregnancy = Non-viable fertillised egg implants in uterus and fails to come to term, foetus doesnt form properly and baby doesnt develop

Both picked up on 12 week scan

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15
Q

What genetic disease can we also screen for at 12 weeks?

A

We can scan for DOWNS SYNDROME (needs a blood test + scan)

  • Scan we carry out a foetal nuchal translucency screening
    • Measures size of nuchal pad at the nape of the foetal neck
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16
Q

What is the frequency of Down’s Syndrome?

A

Around 2 per 2000 births

However increased risk in older women

  • 1:1500 at 20 years
  • 1:800 at 30 years
  • 1:270 at 35 years
  • 1:100 at 40 years
  • 1:50 at 45 years and over
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17
Q

At around what time do we need to carry out the foetal nuchal translucency screening for downs syndrome?

A

Between 11 weeks and 13 weeks (+ 6 days)

After 13 weeks the lymphatic system will have developed and drained the fluid from the back of the neck

(Reminder nuchal translucency should not be confused with nuchal fold thickness test which is carried out between 16-24 weeks)

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18
Q

Describe what a nuchal translucency is?

A

Appearance of the collection of fluid under the skin behind the foetal neck in the first trimester of pregnancy.

THE MORE FLUID THERE IS THE INCREASED CHANCE OF A GENETIC ABNORMALITY

This fluid will go on to form part of the lymphatic system

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19
Q

What is another marker of Down’s Syndrome at 12 weeks?

Study These Flashcards
A

No nasal bone

20
Q

What is the purpose of a 20 week scan?

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A

Helps 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:

  • placenta localisation
  • foetal biometry
  • fibroid monitoring
  • liquor assessment
21
Q

What are some abnormalties that can be picked up from a 20 week scan?

Study These Flashcards
A
  • Spina bifida - neural tube defect, incomplete closing of the spine and membranes around the spinal cord, gap in lumbar- sacral spine
  • Achondroplasia - short limbed dwarfism (torso is normal length)
  • Low lying placenta - implantation os placental over cervical opening
  • Talipes (Club foot) - foot turns inwards
  • Anhydraminios (complete or near complete lack of aminiotic fluid), Oligohydramnios (not enough aminiotic fluid)/ Polyhydramnios (too much amniotic fluid)
22
Q

What is spina bifida?

What can severe spina bifida lead to?

Study These Flashcards
A
  • Neural tube defect, where the baby’s spine and spinal cord doesnt develop properly
  • There is incomplete closing of the spine and the membranes surrounding the spinal cord
  • There is a gap in the lumbar sacral spine
  • Can lead to:
    • Paralysis
    • Incontinence
    • Difficult walking
    • Other chromosomal abnormalities
23
Q

How is an ultrasound used to detect for spina bifida?

Study These Flashcards
A

Detected via a skull ultrasound before getting to the spine

  • The cerebellum will be pulled down because the spinal cord is protuding through the back which will pull at the base of the brain and disrupt the shape
24
Q

How do we treat spina bifida?

Study These Flashcards
A

Carried out in utero to repair gaps in the babys spine so they are closed before the baby is born

Not taking folic acid can be one of the causes of an increased risk of spina bifida

25
What is achondroplasia?
* Genetic disorder which results in short-limbed **dwarfism** * Torso is the same length and there is bowing of long bones * Thickened soft tissue surrounding long bones * On 20 week scan * **Frontal bossing** (forehead protuding is a characteristic of achondroplasia)
26
Describe the implications of a low-lying placenta
* Implantation of the placenta over the internal os (or lower region of uterus) * If placenta is within 2.5cm of cervix = more scans required * IMPLICATION * If placenta is not raised then a C-section may be required
27
Describe Talipes (club foot)
* Where the **foot turns inwards** * Can affect one or both feet * Causes * **Mechanical** → Due to position in the womb, foot may be trapped * **Chromosomal abnormalities** (Downs syndrome-21, Patau Syndrome-13, Edwards Syndrome-18)
28
What is the treatment of Talipes (club foot)
Ponseti Method Ligaments, joints and tendons are stretched after gentle manipulations. A plaster cast is applied after each manipulation to retain the degree of correction and soften ligaments
29
What is polyhydramnios often caused by?
Gestational diabetes
30
What is the umbilical arterial doppler assesment used for?
Used as a marker of **placental insufficiency** (failure of nutrient delivery) and consequent **intrauterine growth restriction (IUGR)** or **suspected pre-eclampsia**
31
How is an ultrasound used to detect an early pregnancy?
* Foetal pole is detected as an area of thickening along periphery of yolk sac * Minimum 1-2mm in length for detection (5-6 weeks) * Cardiac activity should be detected routinely from 4-5 mm (6 weeks)
32
What is an ectopic pregnancy? What are some causes?
An ectopic pregnancy is when the egg has implanted outside the uterus, usually in the fallopian tubes Causes * Surgery * PIDS (pelvic inflammatory disease) * Endometriosis
33
How do multiple pregnancies occur?
They are caused by the delay in the fertilized egg reaching the womb before implanting
34
What is the difference between dichorionic and monochorionic twins?
Dichorionic = Type of twin pregnancy where each twin has its own chorion (membrane surrounding amniotic sac), amniotic sac and placenta Monochorionic = Twins will share the same placenta
35
What are conjoined twins and twin-twin transfusion syndrome?
Conjoined twins = monozygotic twins who are born conjoined Twin-twin transfusion syndrome = Imbalance in the blood flow between monozygotic twins who share one placenta, there is a dominant twin
36
What prenatal diagnostic test genetic screening can be carried out for chromosomal abnormalities
1. Chorionic villus sampling = placental sample taken 2. Aminocentesis = Amniotic fluid sample is taken From this we can test the genetics of the baby from what we pick up in the sample but also comes with a **miscarriage risk**. Reminder of **non-invasive technique → cffDNA (cell free foetal DNA**) DNA fragments in maternal plasma (10 weeks onwards), foetal DNA can be separated from maternal DNA and amplified via PCR/NGS
37
Describe fibroids
* Are benign tumours of the uterus * Muscular and can be caused by pregnancy * Can become a mechanical obstruction to babys exist in pregnancies * Many can grow until the blood supply they recieve can no longer support further growth, but others can get very large and require surgical intervention
38
What are some causes of post-menopausal bleeding?
* Uterine polyps * Endometrial cancer * Ovarian cancer *
39
What other organs can we use an ultrasound for?
* Liver * Kidney * Aorta (abdominal) * Pancreas * Spleen * Gallbladder
40
What is an AAA and what is characterised by? What is the treatment of an AAA?
Abdominal aortic anuerysm - when the aorta becomes abnormally large or balloons outward * Defined as aneurysmal when reaching 3cm * Surgery required when aneurysm meets 5.5cm in AP (anteroposterior) diameter Treatment * EVAR = endovascular aortic repair, stent is inserted in areas of weakness
41
How do gallstones come about? What is required for a gallstone ultrasound?
They are caused by an imbalance in the chemical makeup within the bile (high cholsterol/bilirubin). Patients will need to fast for 4 hours before, so gallbladder fills up with bile giving us the black space (fluid) which allows us to see the stones (bright white dots which are dense)
42
What can a urinary tract ultrasound used to test for?
* Polycystic kidney disease * Renal calculi (kidney stones) * Enlarged prostate * Ectopic kidney
43
What can a testicular ultrasound be used to detect?
44
What can a breast ultrasound be used for?
* Under the age of 35, breast tissue tends to be **denser.** * **Difficulty diagnosing** breast lumps on **mammograms** as differentiation between solid and fluid filled areas is relatively poor. * Ultrasound can make differentiation at an improved rate (about 30% increased). Ultrasound also enables core biopsies to be taken of breast lumps to allow for histological investigation for classification of the lump.
45
How can an ultrasound be used in DVT?
* Can be used to exclude or confirm the presence of a deep vein thrombosis in cases of pain or swelling in lower limbs * It is often used as a screening tool for DVT in post operative patients and those with pulmonary embolus
46
What are the uses of a musculo-skeletal ultrasound?
* muscle/tendon tears * inflammation * nerve entrapments * soft tissue lumps * cysts * hernias * paediatric CHD * infant torticollis (neck twisting) * early RA * joint effusions * injection guidance (contrast therapeutic) and many more
47
Explain POCUS (point of care) ultrasound FAST (focus assesment with sonography of trauma)
POCUS-FAST * **Focused Assessment with Sonography for Trauma** (FAST) scan is a point-of-care ultrasound examination performed at the time of presentation of a **trauma patient.** * Ultrasound is becoming first and foremost prevalent over going to CT for trauma patients. * Ultrasounds can detect as little as 20ml of free fluid compared to 200ml required with plain X-rays

CLINICAL PATHOLOGY (52 decks)

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