GI 4 Flashcards
what 4 general causes can elicit intestinal obstruction?
- mechanical
- developmental
- inflammatory
- tumour
what are the three mechanical obstructions of the intestine?
- intussusception
- volvulus
- adhesions
strangulation is sometimes also considered a mechanical obstruction of the intestine
Explain intussusception
intussusception occurs when a part of the intestine folds in over an adjacent section –> like a compression. This occurs due to ‘loose’ mucosa’
80% of cases occur in children 2 years or younger
impacts blood flow - ischemia, hypoxia, pain, vomiting
relatively easy to fix
Explain Volvulus
volvulus occurs when there is a twist in the gut which may cause a knot or dilation. There may be a congenital predisposition involved but not always.
small twistings can be fixed by the mesentery regaining organization –> in volvulus this fails
horses and dogs are predisposed to this
explain adhesions
adhesions are inappropriate extra-intestinal connects of the intestine to an adjacent part of the intestine or to another organ. These are outside of the intestine obstructions.
- involves the mesentery, and the serosa
- obstructs the movement of gut or dilation of gut
what may cause an adhesion?
healed or ongoing inflammation - connections via scar tissue?
explain strangulation
- nothing is wrong with the intestine
- part of the abdominal muscle is herniated
- if the intestine moves through this muscle, and then the muscle contracts, it pinches off the intestine.
this is the 0.5 mechanical obstruction
congenital issues: explain Atresia
atresia is a congenital abnormality in which the intestinal tube fails to form a contiguous lumen. i.e. =====| |======= –> there should not be a gap.
this is very rare and has very early diagnosis
what is Hirschsprung’s disease aka congenital aganglionosis
congenital aganglionosis (Hirschsprung’s) is the failure of a certain section of the ENS to develop in the colon! This region becomes non-propulsive and obstructs the fetuses large intestine.
typically affects the most distal region of the colon
upstream of the band of constriction causes intestinal distention and risk of toxicity
histology: the absence of intramural ganglia
how do we fix Hirschsprung’s disease?
surgical excision of the non-functional colon region and reattachment of two functional regions. the joining of two entities in medicine = anastomosis
t or f, the ENS has redundancy
true - explains why resection of some of the colon is fine for curing congenital aganglionosis
what are the two types of pain in the GI tract
- colic - on/off cramping pain
- unremitting pain - non-stop pain
signs of GI problems
usually arise from muscles contracting against objects that will not move
the progression of a mechanical obstruction has many consequences… what are they? (6)
pain and vomiting
upstream contractions above the obstruction will increase intra-luminal pressure
vascular supply compromised - ischemia
no downstream water/ion resorption
lack of motility (ileus) –> this allows bacterial overgrowth which can cause perforation and peritonitis.
what is ileus?
functional paralysis (loss of motility) in the intestine
- it can lead to obstruction
- or associated with disease
when does ileus commonly occur?
after surgery of the intestine
- spontaneous reversal occurs
true or false ileus is not associated with colic pain. It is also not associated with any reflex contractions
true - also no bowel sounds
true or false - ileus is a major cause of ICU cases
true - long ileus is associated with bacterial overgrowth perforation sepsis peritonitis shock etc
what is the peritoneum?
a thin layer that lines the abdominal and pelvic cavities. It responds to and plays a role in inflammation
it is thin, highly vascularised and highly innervated
it can be involved in adhesions
what are the parietal peritoneum visceral peritoneum mesentary omentum
parietal peritoneum –> the portion that actually lines the abdominal and visceral cavities (peritoneal cavity)
visceral peritoneum –> covers external surfaces of intestinal tract
mesentery –> this connects the intestine to the abdomen
omentum –> this is a loose sheet which can mobilize. it plays an important role in sealing off abscesses.
what is peritonitis?
inflammation of the peritoneal cavity
- often omentum then mobilizes to the site of inflammation
- peritonitis can lead to perforations
what two things can cause perforations?
chemical irritants
bacterial perforitis
what is the guarding reflex?
omentum mobilization to seal off peritonitis
ascites guarding ileus systemic infection signs of?
bacterial peritonitis
no infection - chemical peritonitis
what are the two kinds of peritonitis?
a. chemical peritonitis
- caused by hemorrhage and blood
- caused by perforated ulcer
- caused by rupture of any organ
b. bacterial peritonitis
