UT 505 Final Study Guide

UT 505 - MSK

Triangulate

Imaging in two perpendicular planes to determine location of FB

Radiopaque

• FB or structure in which radiation cannot pass through easily

• Blocks radiation → appears white/gray

• Ex: metallic FB

Radiolucent

• FB or structure that allows radiation to pass through easily

• Appears black or dark gray

• Ex: air, soft tissue, abscesses, dental pulp

Specificity

• How well an exam documents normal findings for people without disease or pathology

• Exam’s ability to identify “normal” and confirms absence of disease

In vivo

Biological process that occurs within a living organism or natural setting

Strangulated hernia

• Contents compressed → compromised blood supply → ischemia, necrosis, obstruction

• Increased mortality & morbidity

• US appearance 

  • Thickened bowel wall, absent vascular flow, free fluid, no peristalsis

Valsalva maneuver

• Increases intra-abdominal pressure

• Have patients “bare down” like they’re preparing to take a punch to the abdomen

• Contents move distally → hernia widens

  • Contents move back toward abdomen and sac narrows during relaxation

• Key maneuver when looking for hernia due to dynamic study

Lipoma

• Most common benign tumor of abdominal wall

• Fatty and benign

• Soft, palpable, painless

• US appearance: 

  • Strongly echogenic - isoechoic

  • Difficult to distinguish from subcutaneous fat

Sarcoma

• Malignant tumor of abdominal wall

• Types: liposarcoma, rhabdomyosarcoma, fibrosarcoma

• Limited clinical symptoms → very large upon discovery

• Ultrasound appearance: 

  • Hypoechoic or isoechoic to muscle

  • Heterogeneous

Hematoma

• Collection of blood in tissue 

• Indication: trauma, pain, palp mass, ecchymosis, decreasing hematocrit

• Can be uni or bilateral

• US appearance:

  • Heterogeneous 

  • Hypoechoic to hyperechoic

  • Fluid-fluid levels

    • Fluid can contain echogenic debris

• Blood work is used to differentiate between hematomas and abscesses

T/F: hematomas and abscesses appear similarly on US

True

T/F: decreasing hematocrit is associated w/ hematoma formation

True

T/F: decreasing white blood cell count is associated w/ abscess formation

False

Acute phase of foreign body

• Foreign body present < 3 days

• Immediately after injury → air or dirty shadowing

• 24 hrs after injury → hypoechoic ring/halo develops

Intermediate phase of foreign body

• Foreign body present 3 - 10 days

• Fluid replaces air

• Most pronounced hypoechoic halo

Chronic phase of foreign body

• Foreign body present > 10 days

• Dense granular material develops around FB

• Inflammatory response → clean shadowing similar to bone

Organic foreign bodies

• Made of biological plant material or animal products

• Ex: thorns, wood, bee stinger, barb

Inorganic foreign bodies

• Man-made products made of minerals

• Ex: glass, gravel, plastic, pencil lead

Metallic foreign bodies

• Products w/ metallic alloy

• Ex: wires, needle, fish hook, etc.

Clean shadowing

• Caused by attenuation of an object 

• Ex: stones, metals, bone, needle

Dirty shadowing

Caused by refracting properties of gas bubbles or impedance of gas

Hernia

• Protrusion of part/structure through the tissue normally containing it

• Cause: anything that increases pressure in abdomen

  • Ex: obesity, heavy lifting, coughing, straining

• Dynamic US study - diagnosis requires movement of hernia contents via Valsalva maneuver

Hernia characteristics

• Reducible

• Irreducible

• Incarcerated

• Strangulated

Reducible hernia

Hernia contents can be pushed back in w/ pressure

Irreducible hernia

Hernia contents cannot be pushed back in w/ pressure

Incarcerated hernia

Hernia is irreducible but still has vascularity

Strangulated hernia

Hernia is irreducible and has no vascularity

Parts of a hernia

• Sac - consists of diverticulum of peritoneum

• Sac covering - intestines, fat, omentum, etc.

• Contents - layers of abdominal wall

Two main types of hernias

• Ventral

  • Anterior and lateral abdominal wall

  • Types: umbilical, paraumbilical, epigastric, hypogastric, and incisional (subtype is parastomal)

• Groin

  • Ilioinguinal crease and adjacent areas

  • Types: indirect inguinal, direct inguinal, femoral, and Spigelian

Umbilical hernia

• Most common ventral hernia

• Common in women and children

Epigastric hernia

Occurs in the linea alba above umbilicus

Hypogastric hernia

Occurs in the linea alba below umbilicus

Incisional hernia

• Delayed complication from surgery

• Most commonly occur due to vertical incisions

• Subtype: parastomal

Complications of ventral hernias

• Strangulation

• Incarcerated or non-reducible

Inguinal hernias

• Most common location for a hernia (~75% of all hernias)

• Location: near internal inguinal ring, surrounding inferior epigastric vessels (IEV)

  • Medial to IEV: direct inguinal hernia

  • Lateral to IEV: indirect inguinal hernia

Direct inguinal hernia

• Occurs medial to IEV

• Acquired hernia

• Affects elderly men w/ weakened transversalis fascia

• Appear immediately when standing

Indirect inguinal hernia

• Most common form of hernia

• Occurs lateral to IEV

• Congenital hernia

• 20x more common in men than women

• Can extend into the scrotum in men and labia majora in women

• More likely to become strangled than direct inguinal

• ⅓ are bilateral, but are more common on the right side if unilateral

Femoral hernia

• Protrusion of transversalis fascia - medial to CFV

• More common in women (especially w/ pregnancy)

• High risk of incarceration and strangulation

  • Because they are long w/ narrow neck

Spigelian hernia

• Rare

• Almost all occur at the inferior end of semicircular line, inferior to arcuate line where posterior sheath is absent 

  • ~ About 2 cm from the inguinal crease

• High frequency of incarceration

• Hard to diagnose because it occurs between the muscle or fascial layers of the wall rather than protruding through the wall

Linea semilunaris

Curved line on the ventral abdominal wall parallel to midline and halfway between side of the body that marks the lateral border of the rectus abdominis muscle

Abdominal wall complications after hernia repair surgery

• Hematoma

  • Most common reason for abdominal lump after hernia repair

• Abscess

• Seroma

• Recurrent hernia

Abscess

• Caused by cuts, scrapes, crushing injuries, surgical trauma, etc.

  • Abdominal wall abscesses are usually a surgical complication

• Clinical presentation - redness, pain, swelling, elevated WBC (AKA leukocytosis)

• US appearance:

  • Heterogeneous

  • Hypoechoic fluid w/ echogenic debris

  • Irregular borders

  • Posterior enhancement

  • Peripheral hypervascularity

Seroma

• Collection of serum in the tissue 

• Results from a surgical incision or liquefaction of a hematoma 

• Distinct from hematomas because they contain no red blood cells 

• US Findings: 

  • Anechoic cystic structure

  • Well-circumscribed

  • Posterior enhancement

Scrotal hernia

Indirect inguinal hernia → can extend down to the scrotum