Lower GI pathology Flashcards
The following abdominal x-ray shows _
The following abdominal x-ray shows air-fluid levels suggesting bowel obstruction
* The obstruction point appears to be in the descending colon, possibly sigmoid colon
A “bowel obstruction” typically refers to a
(mechanical/non-mechanical) blockage of the bowels
A “bowel obstruction” typically refers to a
mechanical blockage of the bowels
A non-mechanical obstruction of the bowels is called _
A non-mechanical obstruction of the bowels is called ileus
Ileus is a non-mechanical bowel obstruction due to _
Ileus is a non-mechanical bowel obstruction due to lack of movement or peristalsis of the bowel
* Presents like a bowel obstruction
* Common after surgery
Bowel obstruction is more common in the (small/large) bowel
Bowel obstruction is more common in the small bowel
* Roughly 80% of B.O
* The small bowel has a smaller lumen so it is easier to obstruct
The most common overall cause of small bowel obstructions in adults is _
The most common overall cause of small bowel obstructions in adults is adhesions
* Other causes: hernias, malignancy, stricture, volvulus
Incarcerated hernias are also common causes of bowel obstructions, most commonly in the (small/large) bowel
Incarcerated hernias are also common causes of bowel obstructions, most commonly in the small bowel
Volvulus is a more common cause of a bowel obstruction in the (small/large) bowel
Volvulus is a more common cause of a bowel obstruction in the large bowel
The most common site of volvulus in adults is the _
The most common site of volvulus in adults is the sigmoid colon
* The sigmoid colon becomes “droopy” and loops around itself
The most common cause of bowel obstruction in children is _
The most common cause of bowel obstruction in children is intussusception
* Usually in children < 3 years old
_ can predispose children to intussusception
Meckel’s diverticulum can predispose children to intussusception
Aside from intussusception, _ and _ are two common causes of bowel obstruction in children
Aside from intussusception, volvulus and foreign body ingestions are two common causes of bowel obstruction in children
* Crohn’s disease with strictures is also possible
* Adhesions and malignancy are uncommon in kids
Volvulus in children is more often due to _
Volvulus in children is more often due to congenital malrotation
Clinical signs of bowel obstruction:
Clinical signs of bowel obstruction:
* Colicky abdominal pain
* Abdominal distension
* Nausea
* Vomiting
* Lack of stool output
* Lack of flatus
On physical exam, bowel obstructions may present with distended abdomen, _ on percussion, and _ bowel sounds
On physical exam, bowel obstructions may present with distended abdomen, tympany on percussion, and high pitched bowel sounds
Initial management of bowel obstruction includes _
Initial management of bowel obstruction includes:
1. NPO in case of surgery
2. NG tube for suction to decompress the bowel
3. IV fluids to maintain intravascular hydration
Further evaluation of a bowel obstruction following NG tube decompression involves:
Further evaluation of a bowel obstruction following NG tube decompression involves:
1. CT imaging
2. Surgical consultation
(True/False) GI motility drugs/ laxatives may be utilized in the case of an acute mechanical bowel obstruction
False; GI motility drugs/ laxatives may be utilized in the case of an acute mechanical bowel obstruction
Individuals with a history of _ have a risk for adhesions and bowel obstructions
Individuals with a history of prior abdominal surgery have a risk for adhesions and bowel obstructions
* Adhesions are fibrous bands outside the bowel that cause the bowel to be tethered
Bowel torsion or twisting is called _
Bowel torsion or twisting is called volvulus
Adults tend to have _ volvulus; children tend to have _ volvulus
Adults tend to have sigmoid volvulus; children tend to have cecal volvulus
Coffee bean sign on abominal xray is pathopneumonic for _
Coffee bean sign on abominal xray is pathopneumonic for sigmoid volvulus
Scarring inside the bowel is called a _
Scarring outside the bowel is called _
Scarring inside the bowel is called a stricture
Scarring outside the bowel is called adhesion
Colon cancer is the _ most common cancer in the US
Colon cancer is the third most common cancer in the US
* It is the second deadliest cancer in the US
Risk factors of colon cancer:
Risk factors of colon cancer:
* Hereditary
* Male
* Type 2 diabetes
* IBD
* Smoking
* Alcohol
* Obesity
* Abdominal radiation
Positive factors that improve colon cancer risk:
Positive factors that improve colon cancer risk:
* Aspirin/ NSAID use
* Menopausal hormone therapy
* Statin use
* Physical activity
* Whole grains, dietary fiber
* Fish, nuts, calcium
There are two pathways for the pathogenesis of colon cancer, _ and _
There are two pathways for the pathogenesis of colon cancer:
1. Conventional adenoma-carcinoma pathway
2. Microsatellite instability pathway
70-90% of colon cancers develop via the _ pathway
70-90% of colon cancers develop via the adenoma-carcinoma pathway (polyps)
It is easier to screen for colon cancer that develops via the (adenoma- carcinoma pathway/ microsatellite instability pathway)
It is easier to screen for colon cancer that develops via the adenoma-carcinoma
* This is the slower growing form (10-20 years)
The colon cancers that develop via microsatellite instability pathway are harder to screen because they develop in _ years
The colon cancers that develop via microsatellite instability pathway are harder to screen because they develop in 1-5 years
The following shows an adenoma with _ histology
The following shows an adenoma with villous histology
The following shows an adenoma with _ histology
The following shows an adenoma with tubular histology
The following shows an adenoma with _ histology
The following shows an adenoma with tubulovillous histology
Low- grade dysplasia (adenoma) is characterized by _ and _
Low- grade dysplasia (adenoma) is characterized by loss of mucin and increased mitotic figures
Characterize by the stage of carcinoma
Early adenoma –> late/ high-grade adenoma –> carcinoma
The first line testing option for colon cancer is either direct visualization of the colon via _ or stool based test via _
The first line testing option for colon cancer is either direct visualization of the colon via colonoscopy or stool based test via fecal immunohistochemistry
FIT stands for _ and “cologuard” is a _ test
FIT stands for fecal immunohistochemistry and “cologuard” is a stool DNA test
If FIT or cologuard comes back abnormal, _ is still needed
If FIT or cologuard comes back abnormal, colonoscopy is still needed
Why is colonoscopy beneficial over FIT?
Colonoscopy offers…
* Higher sensitivity
* Diagnostic and therapeutic (polyp removal)
* Less frequent
FIT testing is done every _ years, colonoscopy is done every _ years
FIT testing is done every 1-3 years, colonoscopy is done every 5-10 years
* Colorectal cancer screening starts at age 45
Lynch syndrome has _ inheritance pattern
Lynch syndrome is autosomal dominant
(Lynch syndrome/ familial adenomatous polyposis) has a dramatic phenotype
Familial adenomatous polyposis has a dramatic phenotype
FAP is inherited in _ pattern
FAP is autosomal dominant
FAP involves the _ gene and _ signaling pathway
FAP involves the APC gene and Wnt signaling pathway
* We get too much wnt signaling
Lynch syndrome is also called _
Lynch syndrome is also called hereditary nonpolyposis CRC
Lynch syndrome increases the risk of the following (3) cancers:
Lynch syndrome increases the risk of:
1. Colorectal
2. Endometrial
3. Ovarian
Also associated with pancreaticobiliary, gastric, small bowel, GU, skin, brain
Colorectal cancer on colonoscopy
FAP, gross specimen
FAP
(True/ False) Lynch syndrome is also called hereditary non-polyposis colorectal cancer because it does not involve polyps
False; Lynch syndrome can have few polyps but it does not involve polyposis
The mutations in lynch syndrome are in _ genes
The mutations in lynch syndrome are in mismatch repair genes
* MLH1, MSH2, MSH6, PMS2
Patients with (lynch syndrome/ FAP) tend to present at a very young age with cancer
Patients with FAP tend to present at a very young age with cancer (20s, 30s)
* Patients with lynch syndrome are typically middle aged or older
Patients with (FAP/ Lynch syndrome) have 100% lifetime risk of cancer
Patients with FAP have 100% lifetime risk of cancer
Patients who present with hundreds of polyps in the colon may have _
Patients who present with hundreds of polyps in the colon may have FAP
FAP associated cancers include (3):
FAP associated cancers include:
1. Gastric
2. Duodenal
3. Thyroid
Expected physical exam findings for peritonitis include:
Peritonitis:
* Rigidity
* Rebound tenderness
* Pain with movement
* Pain with “stretching” of the peritoneal cavity
Primary peritonitis is _
Primary peritonitis is direct infection of the peritoneum
* This is typically a bacterial infection
* Called spontaneous bacterial peritonitis SBP
Primary peritonitis is typically seen in patients with _
Primary peritonitis is typically seen in patients with cirrhosis
We treat primary peritonitis with _
We treat primary peritonitis with antibiotics
* Recall that this is a direct infection of the peritoneum
Secondary peritonitis is due to _
Secondary peritonitis is due to severly inflamed or infected abdominal organ that comes in contact with peritoneum
Causes of secondary peritonitis include:
Causes of secondary peritonitis include:
* Appendicitis
* Cholecystitis
* Severe/perforated diverticulitis
* Bowel perforation
* Ovarian torsion or abscess
* Perforated peptic ulcer
Hematemesis suggests (upper/lower) GI bleed
Hematemesis suggests upper GI bleed
Coffee ground emesis suggests (upper/lower) GI bleed
Coffee ground emesis suggests upper GI bleed
Bright red blood per rectum suggests (upper/lower) GI bleed
Bright red blood per rectum suggests lower GI bleed
Melena suggests (upper/lower) GI bleed
Melena suggests upper GI bleed
Hematochezia suggests (upper/lower) GI bleed
Hematochezia can suggest either upper or lower GI bleed
Upper vs lower GI bleeding is delineated by _ landmark
Upper vs. lower GI bleeding is delineated by ligament of Treitz
The ligament of Treitz offers support at the end of the _ and beginning of the _
The ligament of Treitz offers support at the end of the duodenum and beginning of the jejunum
Causes of upper GI bleeding:
Causes of lower GI bleeding:
Small bowel (“mid bowel”) bleeding may present with _ colors
Small bowel (“mid bowel”) bleeding may present with maroon, black, or bright red stool
Anal fissures are small cuts/breaks in the _
Anal fissures are small cuts/breaks in the anorectal mucosa (anoderm)
* Like a paper cut in the anus
Anal fissures will cause _ type of bleeding
Anal fissures will cause bright red bleeding on the outside of the stool
Anal fissures can be caused by _
Anal fissures can be caused by trauma/stretching of anal mucosa
* Ex: hard stool
Deep anal fissures can cause _ spasm
Deep anal fissures can cause anal sphincter spasm
First line treatment for anal fissures includes treating the underlying cause with _ , or soothing measures like _
First line treatment for anal fissures includes treating the underlying cause with fiber, water, laxatives (constipation) , or soothing measures like sitz baths, topical analgesic
We can use a smooth muscle relaxant like _ or _ to reduce anal sphincter spasms
We can use a smooth muscle relaxant like nifedipine or nitroglycerin to reduce anal sphincter spasms
Refractory cases of anal fissures may require _
Refractory cases of anal fissures may require botox
What are hemorrhoids?
Hemorrhoids are normal vascular structures in the anal canal
Hemorrhoids arise from a channel of _ that drains into the superior and inferior _ veins
Hemorrhoids arise from a channel of arteriovenous connective tissue that drains into the superior and inferior hemorrhoidal (rectal) veins
Hemorrhoids are only considered pathologic when they become _
Hemorrhoids are only considered pathologic when they become enlarged, cause pain, or bleed
* Possibly caused by straining or constipation
(External/ Internal) hemorrhoids are more likely to bleed
Internal hemorrhoids are more likely to bleed
(External/Internal) hemorrhoids are more likely to cause pain
External hemorrhoids are more likely to cause pain
External hemorrhoids have _ innervation
External hemorrhoids have somatic afferent innervation (why they are painful)
Internal hemorrhoids are less likely to cause pain because they are innervated by _
Internal hemorrhoids are less likely to cause pain because they are innervated by pelvic splanchnic afferent (visceral) nerves
What does it mean that irritable bowel syndrome is a functional disorder?
There is no organic cause of IBS nor is it related to any structural abnormalities
* Instead it is a functional disorder liely related to gut-brain axis disorder
Irritable bowel syndrome is associated with an increase in _ leading to osmosis into the gut lumen
Irritable bowel syndrome is associated with an increase in short chain carbohydrates (lactose, sucrose) leading to osmosis into the gut lumen
How do short chain carbohydrates lead to the gas and cramping associated with IBS?
- Short chain carbohydrates get metabolized by gut bacteria –> gas
- An increase in luminal water expands the GIT, causes abdominal pain and intestinal smooth muscle spasms
IBS is associated with an increase in visceral hypersensitivity; this is why abdominal pain is often relieved _ when?
IBS is associated with an increase in visceral hypersensitivity; this is why abdominal pain is often relieved following bowel movements
IBS often presents with:
IBS often presents with:
* Abdominal pain
* Consipation, diarrhea
* Changes in stool consistency and frequency
IBS is diagnosed using the _ criteria
IBS is diagnosed using the Rome IV criteria
What is the Rome IV criteria for IBS?
- Recurrent abdominal pain (at least once per week for 3 months)
And at least 2 of the following:
a. Symptoms related to defecation
b. Change in stool frequency
c. Change in stool form/ appearance
Create a ddx for RUQ pain
Create a ddx for LUQ pain
Create a ddx for RLQ pain
Create a ddx for LLQ pain
IBS-D is _
IBS-D is diarrhea predominant
* This means that the bowel pattern is diarrhea 25% of the time
IBS-C is _
IBS-C is constipation predominant
* This means that the bowel pattern is constipation 25% of the time
IBS-M is _
IBS-M is mixed diarrhea and constipation
* Alternating periods
The first line treatment for IBS with abdominal pain is _
The first line treatment for IBS with abdominal pain is an anti-spasmodic like hyoscyamine or dicyclomine
* These have anti-cholinergic effects
How do we manage IBS?
IBS directed therapies (overview)
_ is a congenital failure of neural crest cell migration to the myenteric and submucosal plexus in the rectum
Hirshsprung disease is a congenital failure of neural crest cell migration to the myenteric and submucosal plexus in the rectum
A baby with hirschsprung disease may present with:
A baby with hirschsprung disease may present with:
* Abdominal distention
* Failure to pass meconium within 48 hours
* Constipation
* Bilious vomiting
Hirschsprung disease causes defective relaxation and peristalsis of the rectum and distal sigmoid colon leading to _
Hirschsprung disease causes defective relaxation and peristalsis of the rectum and distal sigmoid colon leading to proximal megacolon
Hirschsprung disease can present with _ sign on digital rectal exam
Hirschsprung disease can present with squirt sign on digital rectal exam
* Explosive expulsion of feces with empty rectal vault
Hirschsprung disease is diagnosed via absence of _ cells on _ biopsy
Hirschsprung disease is diagnosed via absence of ganglion cells on rectal suction biopsy
Hirschsprung disease is associated with _ syndrome and _ mutations
Hirschsprung disease is associated with down syndrome and RET mutations
Necrotizing enterocolitis is a condition in which the bowel becomes _
Necrotizing enterocolitis is a condition in which the bowel becomes gangrenous, we see inflammation and ischemic necrosis of ileum and colon
Necrotizing entercolitis is associated with _ infants
Necrotizing entercolitis is associated with premature, low-birth-weight, formula-fed infants
* Babies with immature immune systems and get overgrowth of bacteria from formula
Acute mesenteric ischemia is _
Acute mesenteric ischemia is critical blockage of arterial blood flow to the intestines –> necrosis
The most common cause of mesenteric ischemia is an embolic occlusion of the _ artery
The most common cause of mesenteric ischemia is an embolic occlusion of the superior mesenteric artery
* Supplies the small intestine
* Caused by valvular disease, atrial fibrillation
Signs of acute mesenteric ischemia:
Signs of acute mesenteric ischemia:
* Pain out of proportion to physical exam
* Red currant jelly stools
* Decreased bowel sounds
Can progress to transmural infarction, perforation, shock
Atherosclerosis of the celiac artery, SMA, or IMA may lead to _
Atherosclerosis of the celiac artery, SMA, or IMA may lead to chronic mesenteric ischemia
Chronic mesenteric ischemia is associated with _ type pain
Chronic mesenteric ischemia is associated with postprandial epigastric pain
* Need increased blood flow after consuming a meal –> pain
Colonic ischemia most often occurs in _ areas
Colonic ischemia most often occurs in watershed areas
_ and _ are two watershed areas of the colon that are more likely to experience ischemia
Splenic flexure and rectosigmoid junction are two watershed areas of the colon that are more likely to experience ischemia
Colonic ischemia may be diagnosed by cramping abdominal pain, hematochezia, and _ sign on abdominal xray
Colonic ischemia may be diagnosed by cramping abdominal pain, hematochezia, and thumbprint sign on abdominal xray
Normal colonic mucosa is lined by _ epithelium and is rich in _ cells
Normal colonic mucosa is lined by simple columnar epithelium and is rich in goblet cells
Increase number of cells is _
Increase number of cells is hyperplasia
Change in the physiologic cell type is called _
Change in the physiologic cell type is called metaplasia
Disordered cell growth is called _
Disordered cell growth is called dysplasia
(Sessile/ pedunculated) polyps are more likely to be malignant or have malignant potential
Sessile polyps are more likely to be malignant or have malignant potential
* Villous = sessile
A serrated polyp can often progress to colon cancer via the _ pathway
A serrated polyp can often progress to colon cancer via the microsatellite instability pathway
Adenoma-Carcinoma sequence (3):
Adenoma-Carcinoma sequence (3):
1. Loss of APC
2. Mutation of KRAS
3. Loss of TP53
Apple core constriction = colorectal cancer
The most common location for colon cancer is in the _
The most common location for colon cancer is in the rectosigmoid
* Causes reduced stool caliber
_ is a GI pathogen that may increase the risk of colon cancer
Streptococcus bovis is a GI pathogen that may increase the risk of colon cancer
The most common location of colon cancer metastasis is the _
The most common location of colon cancer metastasis is the liver
Lynch syndrome involves a mutation in DNA mismatch repair genes which leads to _ pathway of colorectal cancer
Lynch syndrome involves a mutation in DNA mismatch repair genes which leads to microsatellite instability
