Radiology Flashcards
What position is a pneumoperitoneum best seen?
Upright radiograph
If a patient is too sick to be placed upright, what position can you see a pneumoperitoneum and where does is detect air?
- Left side down decubitus with a cross table lateral film
- detects air between the liver and right lower ribs
What do you definitely see with a pneumoperitoneum?
Air under the diaphragm
Where is air under the diaphragm best seen?
- On the right side because the liver offers a distinct outline between the free air and the soft tissues.
- On the left is can be difficult to distinguish from air in the stomach or splenic flexure
What is rigler’s sign?
- Both sides of the bowel wall are outlines by air - also called double wall sign
- requires a significant amount of free air within the abdomen
When air collects in morrison’s pouch, where is this referring to?
Inferior to the liver and above the right kidney
What is the biggest clue to look for if there is a soft tissue mass?
-Bowel displacement - lack of gas in an area that normally contains air
It is normal to see air scattered in 1-2 loops of small bowel that is of normal caliber. What is considered abnormal caliber?
Greater than 3 cm
Where do you almost always see air?
Stomach, rectum, and sigmoid
Name the air fluid levels for the stomach, small bowel, and large bowel.
Stomach - yes unless supine
Small bowel - 2 or 3 levels allowed
Large bowel - not typically seen
What causes abnormal gas patterns?
- Ileus
- Mechanical obstruction - small or large bowel
What is Ileus?
Bowel dilatation without mechanical obstruction
What is the main key in looking for a mechanical small bowel obstruction (SBO)?
Disproportionate air in the small bowel
What do u see in a Large bowel obstruction (LBO)?
- Air seen to the point of obstruction
- Little to no air in the rectum and sigmoid colon
- Little to no gas in the small bowel unless the ileocecal valve is incompetent - Large bowel may then decompress into the small bowel and cause an apparent SBO
Causes of small bowel obstruction
ABCs A: Adhesions B: Bulges/hernias C: cancer-intrinsic and extrinsic V: volvulus
