Pathology of the GI Tract- SI and Colon (4) Flashcards
besides diarrhea and malabsorption, what other GI anomaly can occur in the small intestine and colon?
the small intestine and the colon are frequently affected by infectious and inflammatory disorders
where is the most common site of GI neoplasia in western populations?
the colon
when do the small and large intestines undergo rapid growth?
during weeks 4 and 5 of development
what are 2 common GI anomalies that occur during development?
gastroschesis and omphalocele
what are the two main symptoms related to pathology of the GI tract?
abdominal pain and GI hemorrhage
where do endoscopes of the upper GI usually stop?
they don’t go past the second portion of the duodenum
where do colonoscopes reach?
they don’t go further than the cecum
what is capsule endoscopy?
a capsule fitted with a disposable mini video camera can examine parts of the SI that standard scopes cannot reach
what 4 things could cause a mechanical obstruction?
hernias, adhesions, volvulus, or intussusception
where can abdominal obstruction occur?
may occur at any level, but the SI is most often involved because of its relatively narrow lumen
besides hernias, adhesions, volvulus, and intussusception, what else could cause mechanical obstructions?
tumors, infarction, and other causes of strictures (Crohn disease)
what are the 4 clinical manifestations of obstruction?
abdominal pain, distention, vomiting, and diarrhea
on a KUB, what is the sign of an obstruction?
air fluid levels
what is a functional bowel obstruction?
paralytic ileus- a temporary disturbance of peristalsis in the absence of mechanical obstruction
what is the most common etiology of functional bowel obstruction?
postoperative ileus
besides postoperative ileus, what else could cause paralytic ileus?
metabolic disturbances (hypokalemia), endocrinopathies (hypothyroidism), and certain drugs (anticholinergics)
how do you differentiate between a mechanical obstruction and a functional bowel obstruction?
the appearance is the same- it’s the clinical history that helps
what is the most frequent cause of intestinal obstruction worldwide?
hernias
what is the third most common cause of obstruction in the US?
hernias
what happens if there is increased pressure at the neck of the pouch of a hernia?
it may impair venous drainage of the entrapped viscus; the resultant stasis and edema increase the bulk of the herniated loop, leading to permanent entrapment and overtime arterial and venous compromise (strangulation) and infarction
what is the most common cause of intestinal obstruction in the US?
adhesions/fibrous bridges
how does one get adhesions/fibrous bridges?
they are most often acquired–> surgery, trauma, intra-abdominal infection, endometriosis
how does a volvulus present?
with features of both obstruction and infarction
where does a volvulus most often occur?
in large redundant loops of sigmoid colon, followed in frequency by the cecum, small bowel, stomach, or rarely, transverse colon
who tends to develop sigmoid volvulus in the industrialized world?
older patients, and a third of patients either have mental illness or are institutionalized
what is initial treatment of a sigmoid volvulus?
correction of fluid and electrolyte imbalance followed by endoscopic decompression
if a patient has a sigmoid volvulus, what are the indications for emergency laparotomy?
clinical signs and symptoms of colonic ischemia, failed decompression, and clinical features suggestive of colonic ischemia at colonoscopy
what is the most common cause of intestinal obstruction in children younger than 2 years of age?
intussusception
what is the pathophysiology of intussusception?
it occurs when a segment of the intestine, constricted by a wave of peristalsis, telescopes into the immediately distal segment
what happens if intussusception goes untreated?
it may progress to intestinal obstruction, compression of mesenteric vessels, and infarction
what are four causes of intussusception?
idiopathic, viral infection and rotavirus vaccination, intraluminal mass or tumor/polyps, 1% of CF patients
what is the treatment/management like of intussusception?
it varies by age and etiology
what are the vascular pathologies that can occur in the GI tract?
ischemic bowel disease and angiodysplasia
what are the major variables that determine the severity of ischemic bowel disease?
the severity of vascular compromise, the time frame during which it develops, and the vessels affected
what is a common area to see ischemic bowel disease?
the marginal artery–> around the splenic flexure
what is acute vascular compromise usually due to?
it is vascular obstruction–> thrombosis or embolism
what is chronic vascular compromise usually due to?
it is non obstructive–> cardiac failure, shock, dehydration, or vasoconstrictors
intestinal responses to ischemia occur in two phases, what are they?
hypoxic injury and reperfusion injury–> the one-two punch
what is the classic clinical presentation of acute ischemia?
most commonly in patients >70 and in females
how does acute ischemia present?
sudden onset of cramping left lower abdominal pain, desire to defecate, passage of blood or bloody diarrhea (hematochezia or BRB per rectum)
when evaluating a patient with acute abdominal ischemia, what is the evidence of infarction?
decreased bowel sounds, guarding or rebound tenderness
what is the classical clinical presentation of chronic ischemia?
abdominal pain that starts about 30 minutes after eating; pain worsens over an hour; pain goes away within one to three hours
what can untreated chronic mesenteric ischemia become?
it can become acute or lead to severe weight loss and malnutrition
what other things could resemble chronic mesenteric ischemia?
CMV, radiation enteritis, other abdominal emergencies such as acute appendicitis, perforated peptic ulcer, acute cholecystitis
what are 2 different outcomes of acute mesenteric compromise?
mucosal/ non-transmural infarcts and transmural infarcts
which type of acute mesenteric compromise is worse?
transmural; and worst outcome with superior mesenteric artery occlusion
what is angiodysplasia characterized by?
malformed submucosal and mucosal blood vessels that are dilated and thin walled
where is angiodysplasia most commonly found?
in the cecum or right colon, and usually, come to clinical attention after the 6th decade of life
while the prevalence of angiodysplasia is less than 1% in adults, why is it significant?
angiodysplasia accounts for 20% of major episodes of lower intestinal bleeding in older populations
what is the presentation like of angiodysplasia?
it can range from chronic and intermittent to acute and massive hemorrhage
