Chapter 21: Ultrasonography Flashcards
What are the types of US?
A-mode B-mode M-mode Doppler Duplex US
What is an A-mode US?
The simplest
Spikes along a line represent the signal amplitude at a certain depth
Used mainly in ophthalmology
What is a B-mode US?
Mode most often used in diagnostic imaging
Each echo is depicted as a dot, and teh sonogram is made up of thousands of these dots
Can depict real time motion
What is M-mode US?
Used to show moving structures such as blood flow or motion of the heart valves
What is a Doppler US?
Uses the Doppler effect to assess blood flow
Used for vascular US
Pulsed Doppler devices emit short bursts of energy that allow for an accurate localization of the echo source
What is a duplex ultrasonography?
Used in vascular studies
Refers to the simultaneous use of both grayscale or color Doppler to visualize the structure of and flow within a vessel and spectral Doppler to quantitate flow
What are the advantages of US?
No ionizing radiation
No known long term side effects
“Real time” images
Produces little to no patient discomfort
Small, portable, inexpensive, and ubiquitous
What are the disadvantages of US?
Difficulty penetrating through bone
Gas-filled Structures reduce its utility
Penetration may be difficult in obese patients
Dependent on the skills of the operator doing the scanning
What are the uses of US for pregnancy?
Fetal presence and gestational age Fetal abnormalities and viability The presence of multiple pregnancies Placental localization Amniotic fluid volume Intrauterine growth retardation Helping to guide invasive studies such as amniocentesis, chorionic villus sampling, and intrauterine transfusions
What are CNS abnormalities diagnosable using US?
Hydrocephalus Abnormalities of prosencephalon A genesis of the corpus callous Intrauterine infections Cysts Meningomyelocele Anencephaly
What skeletal abnormalities can be diagnosed on US?
Dwarfism Skeletal dysphasia Achondroplasia Osteogenesis imperfecta Asphyxiating thoracic dysplasia Limb anomalies
What GI abnormalities can be diagnosed using US?
Esophageal atresia Tracheoesophageal fistula Duodenal atresia Small and large bowel obstruction Abdominal wall defects Congenital diaphragmatic hernias Choledochal cyst
What Genitourinary tract abnormalities can be diagnosed using US?
Renal agenesis Congenital ureteropelvic junction and ureterovesical junction obstruction Bladder outlet obstruction Multicystic dysplastic Kidney Poly cystic kidney disease
What cardiac anomalies can be diagnosed with US?
Hypoplastic left heart syndrome Tricuspid atresia Endocardium cushion defects Ebstein anomaly Tetralogy of Fallot Transposition of the great vessels Coarctation of the aorta Cardiac arrhythmias
What three components are there of a sonogram?
Production of a high frequency sound wave
Reception of a reflected wave or echo
Conversion of the echo into the actual image
Define echogenic
A tissue that reflects many echoes and is usually depicted as bright or white on the sonogram
Define sonolucent
A tissue that has few or no echoes and usually depicts as being dark or black
How do gallstones appear on US?
They are characteristically echogenic and produce acoustical shadowing because they reflect most of the signal
What is biliary sludge?
Biliary sludge can be found in the lumen of the gallbladder and is often associated with biliary stasis; it is also echogenic but doesn’t produce acoustical shadowing
What is the appearance of obstructive uropathy?
A dilated calyceal system
How does medical renal disease appear on US?
The renal parenchyma becomes more echogenic than the liver and spleen which is the opposite of how it is normally
How does US diagnose a scrotal torsion?
By demonstrating the absence of flow in the torsed testicle
How large is the normal abdominal aorta on US?
< 3 cm.
What are the most common tumors of the uterus?
Leiomyomas confined to the myometrium; uterine masses are solid
What are the most common masses in the ovary?
Functional cyst
How does an adenomyosis appear on US?
The uterus is enlarged and contain myometrial cystic spaces, a thickened posterior uterine wall, and decreased uterine echogenic its
What are functional cysts and how do they appear on US?
Follicular cysts and corpus luteum cysts of the ovary
They are well defined, thin walled, anechoic structures with homogenous internal fluid density; they can contain echogenic material if hemorrhage occurs into the cyst
What are nonfunctional cysts of the ovary?
Dermoid cyst
Endometriosis
Polycystic ovaries
What is Pelvic Inflammatory Disease (PID)?
Is a term used to describe a group of infectious diseases affecting the uterus, Fallopian tubes, and ovaries
Most begin as transient endometritis
Where is ascites best visualized on US?
Right upper quadrant between the liver and diaphragm
How would you see appendicitis on an US?
Appendix may be blind-ending, aperistaltic tube with a 6 mm or more diameter
It is noncompressible and may be tender when palpate with the probe
A fecalith may be present in 30% of the cases
Where are ectopic pregnancies usually seen on US?
Tubal locations and occur near the fimbriated (ovarian) end
How do you determine a molar pregnancy?
Uterine size that is disproportionately large for the dates of gestation and B-HCG levels >100,000
