Mod 5-6 LB Obstruction and LB Ileus Flashcards
What are most bowel obstructions caused by? What percentage?
- Primary colonic cancers that have grown to proportions that have completely blocked the lumen of the bowel.
- 70%
What kind of obstruction is a primary colonic cancer obstruction?
Mechanical obstruction
What is more acute, LB obstrution or SB obstruction?
SB obstruction is more acute
*LB obstruction progresses over a longer period of time before the patient presents in significant discomfort.
What else causes most cases of LB obstructions besides colonic cancers (2)?
- Diverticular disease
- Volvulus
The clinical symptoms of LB obstruction is the same as SB obstruction with the exception of what?
Nausea and vomiting - not as common in LB obstruction.
What is the most common symptoms of a LB obstruction?
Pain and distention (to expand by stretching)
What does the radiograpic appearance of a LB obstruction depend on?
The function of the ileocecal valve
Describe radiographic appearance with a functioning ileocecal valve.
- A large dilated colon and little small bowel gas
- Colon distal to obstruction site is usually free of air and of normal size.
Describe radiographic appearance if ileocecal valve is not competent.
Both LB and SB will be gas filled simulating a dynamic ileus.
What is a major danger in LB obstruction?
Perforation
If the ileocecal valve is competent, the colon becomes what?
A closed loop and increasing pressure cannot be relieved.
Where is the most likely site for rupture and when does it commonly occur?
The cecum when it exceeds 10 cm in diameter.
Who can tolerate more distention w/o perforation?
Those with chronic obstruction or ileus such as Hirschsprung’s disease (mega colon).
What is colonic ileus?
- A distention of the LB w/o signs of obstruction
- The SB is not invovled
What does colonic ileus usually accompany or follow?
An acute abdominal inflammatory process or abdominal surgery.
What exam may need to be done with LB obstruction? Why?
- Low pressure BE to demonstrate the site of the obstruction
- Identify the cause or determine the cause of distended bowel - ileus or obstruction.
What are hte most common sites for LB volvulus? Why?
- Sigmoid and Cecum
- Less firmly attached in the abdomen (i.e. they are more moveable than othe rparts of the LB)
What is a volvulus?
LB or SB with the same mechanism - the bowel twists upon itself and causes an obstruction.
What are the clinical symptoms of a LB volvulus?
Same as LB obstruction (or LB ileus???)
What is the effect of radiographic technique in volvulus?
Obstruction produces air and air is easy to penetrate. Decrease technique.
If you were looking at a radiograph wt both bowels filled with air, what simple question would help make an initial decision about whether the process is mechanical obstruction or dynamic ileus?
Has the patient had surgery in the past few days?
