Lower GI Flashcards
What are common mimics of appendicitis in adults?
IBD Pancreatitis Cholecystitis Gastroenteritis Nephrolithiasis Perforated duodenal ulcer Pyelonephritis Cecal diverticulitis Meckel's diverticulitis
What are common mimics of appendicitis in women?
Pelvic inflammatory disease
Ovarian torsion
Mittelschmerz: physiologic mid-cycle pain
Ruptured ectopic
What are mimics of appendicitis in kids?
Mesenteric lymphadenitis Yersinia enterocolitica Pneumococcal pneumonia Gastroenteritis Intussusception
What is most important thing to do in a woman presenting with RLQ pain?
Test beta hCG to rule out ruptured ectopic pregnancy
What is the first symptom of appendicitis?
anorexia
What is typical sequence of appendicitis symptoms?
Anorexia
vague peri umbilical abdominal pain
vomiting
shift to RLQ pain
What is significance of absent bowel sounds in appendicitis?
Paralytic ileus secondary to inflamed/infected bowel
What is Rovsign’s sign?
RLQ pain with palpation of LLQ: stretching abdominal wall triggers pain in inflamed underlying RLQ parietal peritoneum
What is psoas sign?
RLQ on passive extension of R hip or active flexion of R hip
What is obturator sign?
RLQ pain on internal rotation of the hip
Where is McBurney’s point?
1/3 of distance between ASIS to umbilicus = incision site of open appendectomies
What explains shift from midline periumbilical pain to RLQ pain in appendicitis?
Stretching of visceral (PSNS/SNS) to parietal (somatic) nerves
Why is hyperesthesia of skin a sign of acute appendicitis?
Parietal peritoneum: spinal nerves T10-12 innervate. Area of skin supplied by those nerves on the R can become very sensitive to touch (cutaneous hyperesthesia)
What is a closed loop obstruction? What happens?
- Loop of bowel is obstructed at 2 points: no outlet for bowel contents and pressure.
- Bowel continues to distend until venous pressure exceeded by arterial inflow
- Ischemia and infarction ensue
What causes the closed loop obstruction in acute appendicitis in kids or adults?
Kids: lymphoid hyperplasia
adults: fecalith
What is one presentation of appendicitis in kids?
- viral URI
2. true onset of acute appendicitis
What are the key labs to draw for suspected appendicitis?
1 CBC to look for WBC elevation with left shift
2 CRP
3 beta hCG to rule out pregnancy
4 UA: may show pyuria without bacteruria
When is imaging indicated? And what type?
When diagnosis is unclear
Men/non pregnant women: CT scan
Pregnant women/children: US
What does appendicitis look like on CT?
Periappendiceal fat stranding
Appendiceal diameter > 6 mm
May show free fund or phlegm
What is definitive treatment for appendicitis?
Laparoscopic or open appendectomy
What is role for pre- and post-op antibiotics for acute non-perforated appendicitis?
a single dose of pre-operative antibiotics
post-op: do not exceed 24 hours
What is role for antibiotics for acute perforated appendicitis?
IV antibiotics until fever and leukocytosis resolved (3-5 days)
How to proceed if doing laparoscopic appendectomy and appendix appears normal?
Take it out anyway EXCEPT in regional enteritis (Crohn’s) involving the cecum, because of high risk of developing a cecal fistula
What is the most sensitive test for appendicitis
CT scan
What is the pathophysiology of perforated appendicitis?
Closed-loop obstruction creating an ischemic mucosal wall and not a direct result of increased intraluminal pressure
What to think of in a patient with signs and symptoms of appendicitis and extensive diarrhea?
Yersinia enterocolitica = pseudoappendicitis
Does an abnormal UA rule out appendicitis?
No! Pyuria is common in appendicitis
What is the differential for a lower GI bleed?
- Diverticulosis
- Neoplastic
- Iatrogenic from biopy/colo
- Colitis: infectious, ischemic, inflammatory, radiation
- Angiodysplasia
- Anorectal (hemorrhoids, fissures)
What is always a concern with lower GI bleed, so much so that we always do something else?
large upper GI bleed is the cause, so place NGT to aspirate for blood or coffee grounds
What is the most common cause of lower GI bleed?
Diverticulosis
What to evaluate for: watery progressing to bloody diarrhea?
EHEC
What is the pneumonic/causes for most common cause of LGIB?
H-DRAIN: Hemorrhoids Diverticulosis Radiation colitis Angiodysplasia Infectious/ischemic/IBD Neoplasms/polyps
What is the most common cause of LGIB in a patient > 50?
diverticulosis
angiodysplasia
malignancy
What is the most common cause of LGIB in a younger patient?
Infectious
Hemorhoids
Anal fissures
IBD
How does diverticular bleeding present?
Arterial: acutely with large amounts of blood
How do angiodysplasia or colon cancer present with respect to bleeding?
Anemia or dark stools
What does dark maroon blood, mixed with stool, tell us about the possible location of bleeding?
Upper GI, small intestine, R colon
What does copious bright red blood (hematochezia) tell us about the possible location of the bleeding?
Right colon, rectum, anus, massive upper GI bleed with rapid transit
What does spots of blood on toilet paper or dripping after defection tell us about location of bleed?
rectum, anus
What does scant, dark red blood tell us about location of LGIB?
Angiodysplasia
What does occult blood in the stool suggest about location of bleed?
Polyp, colorectal cancer
Diverticula in the L vs. R colon are most likely to have what outcomes?
Right: more likely to bleed
Left: more likely to get infected
What is an occult bleed?
No blood seen per rectum: only detected by fecal occult blood testing or iron-deficiency anemia
What is tenesmus? When would it likely present?
Sense of incomplete evacuation of stool. Most often seen with UC/infectious etiology
Why is a past history of LGIB on prior colonoscopy important?
Angiodysplasia and diverticulosis patients present with chronic bleeding.
- Colon cancer arises from a polyp and takes many years to transform into a malignancy: so <5 years with normal screening colo makes cancer unlikely
Why is a history of pelvic radiation or prior aortic surgery important when working up LGIB?
- Damage to rectal mucosa –> radiation proctitis
- Aortic surgery can erode aortic graft into duodenum –> aortoduodenal fistula
What medications can exacerbate GI bleeds?
Anticoagulants (warfarin, aspirin, clopidogrel)
NSAIDS
can both exacerbate GI bleeding
What is the implication of abdominal tenderness on physical examination for LGIB?
Suggests colitis (IBD, ischemic or infectious). * Unusual with diverticulosis/angodysplasia
What suggests upper GI bleed on history and PE?
Vomiting blood or coffee grounds + maroon or black stools
What suggests lower GI bleed on history and PE?
Bright red blood per rectum
How does ischemic colitis classically present?
left sided abdominal pain + bloody diarrhea in elderly patients with low flow states (dehydration, heart failure, shock, trauma)
What re risk factors for diverticulosis?
- Older people
- Poor diet
- Obese
- Connective tissue disorders
What is a diverticulum? What is the pathophysiology of its rupture?
Saclike protrusion through the colonic wall: as it herniate: vasa recta become draped over the dome of diverticulum: separated from lumen by mucosa only! Chronic damage/stress on luminal side leads to arterial wall weakness and rupture
What causes a diverticulum?
High intraluminal pressure in the colon: mucosa and submucosa can herniate through the muscular layer of the intestinal wall (false diverticulum)
What is most common site for diverticula?
sigmoid colon
What is the natural history of a diverticular bleed?
75% stop bleeding spontaneously, but each episode of bleeding increases the risk of a future bleed
What is diverticulitis?
Micro or macroperforation of a diverticulum
What is angiodysplasia?
- Focal submucosal areas of thin, weak and dilated vessels in the GI tract.
- Increases with age due to weakness in vascular walls
What conditions is angiodysplasia associated with?
vWF disease
aortic stenosis
chronic kidney disease
What type of bleeding does angiodysplasia cause?
- Small in quantity/occult
- Results in iron deficiency anemia or heme-positive stools
- Usually less bleeding since venous in origin
What causes ischemic colitis?
- Decreased blood flow to colon due to ischemia, most often in watershed areas such as splenic flexure.
- Usually not transmural
What factors can precipitate ischemic colitis?
dehydration, heart failure, shock, CV surgery, hypercoaguable states, extreme exercise, hemodialysis
What is the natural history of ischemic colitis?
Most resolve with supportive care
Minority of cases with require resection for transmural infarction
What are most commonly affected territories of ischemic colitis vs. acute mesenteric ischemia?
Ischemic colitis: watershed areas
AMIL: ligament of Treitz to mid transverse colon
What is the natural history of acute mesenteric ischemia?
Usually leads to small bowel necrosis requiring resection: high mortality
What layers of bowel are affected in ischemic colitis vs. acute mesenteric ischemia?
Ischemic: usually mucosa only
AMI: often transmural
How do we diagnose ischemic colitis?
Colonoscopy often shows mucosal changes
How do we diagnose acute mesenteric ischemia?
CT scan: small bowel wall thickening, occlusion of SMA and gas in intestinal wall
What are initial management steps in LGIB?
- 2 large bore IVs
- Send labs: type and cross, CBC, chemistry and INR/PTT
- If sig blood loss: crystalloid + pRBCs as needed
What is next step for LGIB management after large bore IVs and fluid resuscitation?
- NGT placement to rule out UGIB
- If positive for blood: EGD
Where should LGIB patient be admitted if hemodynamically unstable? What else should be done?
ICU
Do thorough workup to find source of blood
What is first diagnostic test for LGIB in an unstable patient? Is it effective?
Colonoscopy: can fail to visualize due to lack of bowel prep, but can determine general location (if colon or proximal to cecum)
If colonoscopy cannot identify location of LGIB, what are the other options?
Arteriography
Tagged red blood cell scan using technetium-99m (nuclear scintigraphy)
How do we look for blood in the small bowel?
Meckel’s nuclear scan
Capsule endoscopy
Enteroscopy
If a LGIB patient’s bleeding has not stopped and patient is unstable, what is the next step?
Emergent laparotomy + total colectomy leaving rectum and end ileostomy (assuming bleeding is in colon)
What if arteriography localizes the source of bleeding in LGIB but is unable to stop the bleeding with embolization?
Surgery: resection determined by localization
What are indications for surgery for LGIB? (3)
1 Hemodynamically unstable, despite resuscutation
2 Massive bleeding >6 units pRBC
3 Active bleeding with failure of embolization
What is the differential for a change in bowel habits?
Colorectal cancer IBS IBD Celiac INtestinal pseudoobstruciton Thyroid disease Drugs Infectious diarrhea
What are the 3 things that make you think colon cancer until proven otherwise?
Change in bowel habits
Weight loss
Anemia
How does R sided colon cancer classically present?
Iron deficiency anemia
How does L sided colon cancer classically present?
Obstructive symptoms: pencil thin stools, constipation
How does rectal cancer classically present?
Hematochezia
What is recommended screening for colon cancer?
Colonoscopy every 10 years: ages 50-75
What is colon cancer screening for those with colorectal cancer in a first degree relative?
Colonoscopy at age 40 or 10 years prior to diagnosis in 1st degree relative
What other screening test are there, besides colonoscopy?
Flexible sigmoidoscopy (Every 5y, plus FOBT every 3y) FOBT (Annually) Barium enema with sigmoidoscopy (every 5y) CT colonography (every 5y) Capsule endoscopy (every 5y)
What other screening test is an option, per the USPST?
Flexible sigmoidoscopy every 5 years + FOBT every 3 years
How does colon cancer rank in terms of most common cancers in USA and the highest overall mortality?
3rd most common incidence
3rd highest mortality
In what side of colon cancers is melena more common?
Right sided
Why is rectal examination important in evaluation of suspected colorectal cancer?
1 May be able to feel the mass of a low rectal cancer
2 Can assess location
What are the two types of non-neoplastic polyps?
Hyperplastic
Juvenile / hamartomatous
What is the most common type of polyp?
Hyperplastic
How can colon cancers develop (2 pathways)?
- Adenoma carcinoma sequence
2. Microsatellite instability
What is the adenoma carcinoma sequence?
- Loss of APC tumor suppressor
- K-ras mutation
- loss of p53
How does colon cancer arise?
Epithelial proliferation and dysplasia (adenomatous polyps)
What features of an adenoma are associated with increased malignant risk?
Polyp size, architecture, severity of dysplasia
Which types of adenoma have the highest risk of malignancy, and what are the other two types?
Villous and Sessile serrated
> tubulovillous > tubular
Why do we use 10 year interval for colonoscopy screening?
Adenoma to carcinoma sequence takes about 10 years
What are the most common metastatic sites for colon and rectal cancer?
Liver
Rectal:
- Lungs (inferior rectal to IVC via internal iliac)
- Inguinal lymph nodes (via systemic veins)
- Spine and brain (via sacral veins)
What are the 4 heritable conditions associated with colon cancer?
HNPCC/Lynch syndrome
FAP
Garner’s syndrome
Turcot syndrome
What conditions are associated with Gardner’s syndrome?
Osteomas Colonic polyps (cancer by 4th to 5th decade)
What conditions are associated with Turcot syndrome?
Cafe au lait spots
Malignant CNS tumors
Neoplastic colon polyps
At what age should first-degree family members of FAP patients begin colonoscopy screening?
Age 10
What is the criteria to identify those who may have Lynch syndrome?
3-2-1-1
3+ relatives with cancer of colon, endometrium, small bowel or pelvis
2+ successive generations affected
1+ relatives diagnosed before 50
1+ should be a first degree relative of the other two
What is a synchronous vs. metachronous tumor?
- Synchronous is a second primary cancer present at the time of diagnosis
- Metachronous: primary cancers that develop elsewhere in the colon 6+ months after primary resection
How is colorectal cancer diagnosed?
Colonoscopy and tissue biopsy
In a patient with suspected colon cancer, is there a role for testing blood in stool?
No
What is the role of CEA?
An adjunct to other modalities to look for tumor recurrence: NOT for screening
Once we establish diagnosis of colon cancer, what labs to draw?
CEA Liver enzymes (look for mets)
What conditions can elevate CEA?
Colon cancer + MANY GI and other inflammatory conditions (+ smoking)
Once we establish diagnosis of colon cancer, what imaging should be done?
CT abdomen, chest and pelvis to look for mets
Once we establish diagnosis of rectal cancer, what imaging should be done?
- Transrectal ultrasound
- MRI
Better for staging
In a locally advanced rectal cancer, what neoadjuvant therapy is pursued and why?
Chemo and radiation to shrink tumor/downstage it and increase the chance for sphincter preservation, reduce recurrence rate
What is the staging system for colon cancer?
TNM
What is the operation and artery ligation for right sided colon cancer?
R colectomy
Ligation of ileocolic artery
What is the operation and artery ligation for transverse colon cancer?
Transverse colectomy or extended R colectomy with location of ileocolic and middle colic arteries
What is the operation and artery ligation for descending colon cancer?
Left colectomy with ligation of IMA
What is the operation and artery ligation for sigmoid colon cancer?
Left colectomy with ligation of IMA
What is the management of benign polyps?
Polypectomy and reassess in 1-5 years
What is the management for colon cancer (3)?
- R/L colectomy
- Bowel prep before colectomy
- Post op chemo for locally advanced disease and/or positive lymph nodes
What is bowel prep and why is it done?
Prepares colon for surgery
- Removes all stool - prevents stool spillage into peritoneum during surgery
- Provides better visualization of colon
When should bowel prep NOT be used?
Patient suspected of having an obstruction
what is the management of rectal cancer?
- w/in 3cm dentate: abdominal perineal resection: remove entire distal rectum including sphincter (colostomy)
- > 3cm from dentate: low anterior resection removing part of rectum through abdomen
How many lymph nodes should be resected?
12 minimum
why is radiation used for rectal cancer and not colon?
Colon is too large: would have to irradiate organs that often cause complications
What are the major complications of R colectomy?
Injury to ureters
Injury to duodenum
Anastomotic leak
How does anastomotic leak present?
w/in 1st week of surgery: fever, abdominal pain, tenderness, ileus and leukocytosis
What is treatment for suspected anastomotic leak?
CT scan or OR urgently with exploration, washout and stony diversion
What are the major complications of L colectomy?
Injury to ureters
Injury to spleen
Anastomotic leak
Is it useful to follow CEA levels after surgery?
Yes: every 3 months for first 3 years after surgery
What is the difference between obstipation and constipation?
Constipation: infrequent stools < 3 per week, usually hard
Obstipation: complete absence of gas or stool per rectum
What clues on history and physical distinguish between SBO and LBO?
SBO: vomiting, hyperactive bowel sounds
LBO: Pronounced distention, less or late onset vomiting, decreased bowel sounds
Why is history of neurologic or psychiatric disorders important in evaluation of abdominal disease?
Drugs used to treat can affect colonic motility and predispose to chronic constipation, elongation of sigmoid and volvulus + colonic pseudoobstruction
What is the presentation of Ogilvie’s syndrome?
- Massive abdominal distention over several days
- N /V
- UNLIKE LBO: classic in someone already hospitalized in post-op setting
What are the 5 F causes of abdominal distention?
Fat Feces (impaction) Fetus Flatus (ileus/obstruction) Fluid (ascites)
How do we tell between flatus and fluid?
Tympanitic (gas) or dull (fluid) to percussion
What are the most common causes of LBO in USA?
- Colon cancer
- Diverticulitis
- Volvulus
How does LBO present?
gradual and severe abdominal distention
obstipation
vomiting
How does uncomplicated vs. complicated volvulus present?
Non: Normal vitals, mental status and non-tender abdomen
Complicated: severe abdominal pain, fever, tachycardia, toxic appearance, peritoneal signs and leukocytosis
What are important things to look for in H&P for patient with suspected LBO?
Abdominal scars
Hernias
Rectal exam
* Need to assess for other differentials!
What causes sigmoid volvulus?
Acquired stretching of the sigmoid
- Neuropsychiatric disease
- Institutionalization
- Chronic constipation
- Long term anticholinergic use
- High fiber diet
- Pregnancy
Where in colon is cancer most likely to cause LBO?
Left due to smaller diameter
What is the difference between malrotation and volvulus?
Malrotation: congenital: bowel not in the normal position or properly attached: prone to twisting and obstruction. Asymptomatic if bowel/mesentery don’t twist
Volvulus: manifestation of malrotation if the small bowel twists, or w/out malrotation
What is etiology of cecal vs. sigmoid volvulus?
Cecal: congenital partial malrotation: cecum and R colon are not fixed
Sigmoid: acquired due to progressive stretching and redundancy of sigmoid colon (twisting on narrow mesentery)
What are risk factors for sigmoid volvulus?
Anticholinergic (impair motility)
Neurologic/psych diseases (chronic constipation and stool retention)
CF
Chagas disease
High fiber diet (bulky stools that stretch colon)
What is complicated volvulus?
Bowel ischemia and sequelae like gangrenous bowel and sepsis
What are the symptoms/signs of complicated volvulus?
Severe diffuse abdominal pain Fever Tachycardia AMS Marked tenderness to palpation with peritoneal signs Labs: infection
What are the first steps in workup of suspected LBO?
Labs: CBC, lactate, chemistries
What labs suggest LBO in appropriate clinical context?
Leukocytosis with left shift
Lactic acidosis
What is the first imaging recommended for suspect LBO?
Plain abdominal (supine and upright) and upright CXR (free air under diaphragm)
What signs on XR suggest sigmoid volvulus?
Coffee bean sign or omega, bent inner tube, kidney bean sign
What signs on XR suggest cecal volvulus?
Comma or kidney bean sign
If LBO diagnosis is unclear with plain X-ray, what is the next step?
CT with oral and IV contrast: volvulus will show whirl sign with mesenteric twisting and dilated colon
What are the initial steps in management of LBO after diagnosis has been made?
IVF resuscitation
Place Foley to monitor urine output
NGT for symptomatic relief if vomiting
What is the definitive treatment for uncomplicated sigmoid volvulus?
- Detorsion of volvulus with endoscopy: gradual advanced through the closed loop by decompressing with gas
- Semi-elective resection
What is the definitive treatment for complicated sigmoid volvulus?
Emergent laparotomy with resection due to suspicion for colonic ischemia and/or perforation. DO NOT attempt endoscopic detorsion
What is the definitive treatment for cecal volvulus?
- No detorsion attempted due to higher rates of failure and bowel necrosis
- Take to OR for R colectomy
What is an alternative option to reduce volvulus (vs. endoscopic detorsion)?
Contrast enema, but does not offer mucosal inspection benefit
What are the complications of surgery for volvulus treatment?
Wound infection
Anastomotic leak
Recurrence
W/o detorsion/resection: ischemia, perforation and sepsis
What signs suggest ischemic bowel?
Bowel wall thickening
Mesenteric edema
Pneumatosis
Portal venous gas
What are the key features of diverticulitis?
LLQ pain/tenderness on exam
Fever
Leukocytosis
What are the risk factors for diverticulitis?
Obesity
Advanced age
Diet low in fiber, high in fat and high in red meat
How is diverticulitis diagnosed?
Clinically: LLQ pain/tenderness, fever, leukocytosis
Where are diverticula most frequently located? Where are they more prone to infection? More likely to bleed?
Frequent: Sigmoid
Infected: Left/sigmoid
Bleed: Right
Do diverticula occur in the rectum? Why or why not?
No: because taenia coli coalesce into circumferential band
Are sigmoid diverticula true or false diverticula? which layers?
False: only mucosa and submucosa
What are the complications of diverticulitis?
Abscess, perforation, fistula, stricture, LBO
What are the etiologies of fistula?
FRIEND: Foreign body Radiation Infection/inflammation Epithelialization Neoplasm Distal obstruction
What is uncomplicated vs. complicated diverticulitis?
Diverticulitis with complications = complicated. Abscess, obstruction, peritonitis, fistulization
Why might sigmoid diverticulitis present with RLQ pain?
Especially long or redundant sigmoid colon on the right side of the abdomen
What imaging is recommended for diverticulitis? Is it needed for diagnosis?
CT scan, and no
What imaging is containdicated in the setting of diverticulitis? Why?
Barium enema
Colonoscopy
Due to increased risk of new perforation or exacerbation of existing perf
What is the first management step of suspected acute diverticulitis?
Is it complicated or not: assess for SIRS criteria.
What is the management of uncomplicated diverticulitis without SIRS?
Discharge home on oral antibiotics and clear liquid diet
What is the management of uncomplicated diverticulitis with SIRS?
Admit, placed NPO and given IV antibiotics, fluids and analgesia
In a patient with uncomplicated diverticulitis and SIRS, what is the subsequent management after admission if there are no complications?
No complication: d/c with dietary modification
In a patient with uncomplicated diverticulitis and SIRS, what is the subsequent management if she fails to improve?
Failure to improve: repeat CT scan to look for abscess, or take to OR for colon resection
In a patient with uncomplicated diverticulitis and SIRS, what is necessary 4-6 weeks after discharge and why?
Colonoscopy to rule out malignancy and IBD
What is the management for complicated diverticulitis?
Depending on complication
- Urgent surgery
- CT guided drainage
- Delayed surgery
Which complicated diverticulitis patients need urgent surgery? What type?
- Diffuse peritonitis due to free colonic perforation
- Diseased colon removed and end colostomy performed
- Reverse colostomy 12 weeks later
How do we treat diverticulitis complicated by a localized abscess <4cm?
<4cm: bowel rest + antibiotics
How do we treat diverticulitis complicated by a colovesical fistula?
IV antibiotics followed by:
- Resect affected colon segment
- Repair bladder
How do we treat diverticulitis complicated by a localized abscess >4cm?
> 4cm: CT-guided percutaneous drainage (to stabilize/reduce inflammation before surgery down the line)
How do we treat diverticulitis complicated by free perforation with diffuse peritonitis?
Emergent colectomy with end colostomy
How do we treat diverticulitis complicated by LBO?
Urgent colectomy with end colostomy
How is elective surgery for sigmoid diverticulitis different than urgent or emergent?
Elective: primary anastomosis
Emergent/urgent: no anastomosis (temporary end colostomy) followed by anastomosis at a later date
What structure is at great risk of damage during sigmoid colon resection?
Ureters!