DSA 5: Melena, Hematochezia Flashcards
what are the differential diagnoses for lower gastrointestinal bleed (LGIB) in patients UNDER 50?
- infectious colitis
- anorectal disease (anal fissures, hemorrhoids)
- inflammatory bowel disease
- meckel diverticulum
what are the differential diagnoses for lower gastrointestinal bleed (LGIB) in patients OVER 50?
- malignancy
- diverticuLOsis (outpouchings in colon wall, painless)
- angiectasis
- ischemic colitis (profuse, painful bleeding)
LGIB is defined as that arising below/distal to what?
ligament of Treitz
LGIB is less likely to present with what, when compared to UGIB?
shock or orthostasis requiring transfusions
what is the dx and tx of LGIB?
- dx: colonoscopy in stable patients, vitals, CBC
- tx: 2 large bore IV’s, fluid bolus if signs of shock
what is the most common cause of major LGIB?
diverticulosis
- herniation or saclike protrusions of the mucosa through the muscularis (painless)
- most common in sigmoid colon
what is the dx and tx of diverticulosis?
- dx: colonoscopy in stable patients, once bleeding subsides
- tx: self-limited, high-fiber diet, large bore IV’s
chronic relasping idiopathic inflammation of the GI tract
- genetics and immune mechanisms play important role
- increased intestinal permeability
- irreversible impairment of GI structure/function
IBD
what is characterized as a Th1- and Th17-type disease?
Crohn’s
- driven by the production of TNF/IFN-gamma (Th1) and IL17 (Th17)
what is viewed as a Th2-type disease?
Ulcerative colitis
- increased mucosal expression of IL5 and IL13 (Th2 cytokines) produced by natural killer T cells
what region does Crohn’s usually present?
ileum and colon (may affect the entire GI tract)
what region does Ulcerative Colitis (UC) usually present?
**limited to the colon*
what is the wall appearance in Crohn’s?
thick, with strictures and fat-wrapping
- deep, knife-like ulcers
“skip lesions” primarily in small intestine and colon (most commonly in ileum and cecum)
what is the wall appearance in UC?
thin
- superficial, broad-based ulcers
- loss of haustra, crypt distortion
originates in the rectum and progresses proximally
what is seen during endoscopy of Crohn’s disease?
cobblestoning
what is seen during endoscopy of UC?
pseudopolyps
- mucosal
- colon only
- continuous lesions
- bloody diarrhea
- tenesmus/fecal urgency*
- crypt abscess
- toxic megacolon (complication)
- smoking protective**
UC
- transmural
- anywhere along GI tract
- skip lesions
- often without blood
- acute ileitis (mimics appendix)
- strictures (obstruction)
- aphthous ulcers intervening with normal mucosa -> cobblestoning
- smoking worsens disease**
- CARD15/NOD2 on xsome 16p
Crohn’s
70% of patients with UC have antibodies against what serum marker?
ANCA
60-70% of patients with Crohn’s have antibodies against what serum marker?
saccharomyces cerevisiae (ASCA)
what is the tx for Crohn’s?
- corticosteroids, immune-modulating agents, biologic agents
- antibiotics
what is the tx for UC?
corticosteroids, immune-modulating agents, biologic agents
what are the 3 mainstays of therapy for IBD?
- 5-aminosalicylic acid derivatives
- corticosteroids
- immunomodulating agents
acute vascular obstruction that leads to sudden onset of cramping/left lower abd pain, desire to defacate, passage of blood or bloody diarrhea (hematochezia or bright red blood per rectum)
- older pts with atherosclerotic dz most common
- young pts with vaso-occlusive recreational drug use (cocaine)
- abd Xray shows thumb-printing thickening of colonic wall
ischemic colitis
what is the most common area for ischemic colitis?
watershed area of splenic flexure
what is the tx of ischemic colitits?
NPO, IV fluids, surgical resection
periumbilical pain out of proportion to tenderness (physical exam isn;t impressive, but they are writhing in pain)*
- food fear (abd pain worse after eating)
- thumb-printing on abd Xray
acute mesenteric ischemia
what is the dx and tx of acute mesenteric ischemia?
- dx: CT angiography diagnostic study of choice
- tx: laparotomy indicated to restore intestinal blood flow obstructed by embolus or thrombosis
- post-op anticoagulation indicated in mesenteric venous thrombosis
associated with straining during bowel movements (constipation or pregnancy)
- bright red blood per rectum, usually only drops on tissue or in toilet
- seen on anal inspection or anoscopy
hemorrhoids
what are the tx of hemorrhoids?
- tx: bulk laxatives, stool softeners, sitz bath, witch hazel
- bleeding may require rubber band ligation, or surgery
what is the main complication of hemorrhoids?
- *thrombosed external hemorrhoid**
- may be precipitated by coughing, heavy lifting, or straining
- acute onset very painful, gradually eases over 2-3 days
severe, tearing pain during defecation followed by throbbing discomfort that may lead to constipation d/t fear of recurrent pain
- may be associated hematochezia, with blood on stool or toilet paper
- confirmed by visual inspection of the anal verge (DRE may be painful and may not be possible)
anal fissures
what is the tx of anal fissures?
goal is to promote effortless, painless bowel movements
- fiber supp
- sitz baths
- topical anesthetics may provide temporary relief
- surgery in extreme cases
how are most cases of proctitis transmitted?
sexually, especially by anal-receptive sex
where should Neisseria gonorrhoeae swab specimens be taken from?
- rectal swab
- pharynx and urethra in men
- pharynx and cervix in women
how is Treponema pallidum diagnosed?
SYPHILIS!
- dx: dark-field microscopy or fluorescent antibody testing from the chancre or condyloma
- VDRL (STI test - venereal disease research lab) or RPR (rapid plasma reagent) is positive in 75% of primary cases and 99% of secondary cases
what is a common cause of anorectal infection, that is diagnosed by viral culture, PC, or antigen detection assays of vesicular fluid
HSV type 2
condylomata ACUMINATA, aka anal condylomas, aka genital warts must be distinguished from what?
condyloma LATA (secondary syphilis) or anal cancer
- biopsies should be obtained from large or suspicious lesions
bleeding, pain, perianal mass
- HPV is etiologic
- W > M, but MSM at increased risk
- anal cancer*
- tx: radiation plus chemotherapy
- abdominal-perineal resection with permanent colostomy for recurrent lesions
poor anal hygiene associated with fistulas (also overzealous cleaning), fissures, prolapsed hemorrhoids, skin tags, minor incontinence
- perianal itching and discomfort
- dx on external inspection or anoscopy
perianal pruritus
what is the tx of perianal pruritus?
- *education**
- avoid spicy foods, coffee, chocolate
- appropriate cleaning after BM
- topical glucocorticoid, antifungal agent if indicated
what are the four major pathologic groups of polyps?
- mucosal adenomatous polyps (70%)
- mucosal serrated polys
- mucosal nonneoplastic polyps
- submucosal lesions
adenomatous polyps and serrated polyps have what?
significant clinical implications
what 4 criteria are important to consider for hereditary colorectal cancer and polyposis syndromes?
- family hx of colorectal cancer, more than 1 family member
- personal or family hx of colorectal cancer at an early age (under 50)
- personal or family hx of multiple polyps (more than 20)
- personal or family hx of multiple extracolonic malignancies
- *hundreds to thousands** of colonic adenomatous polyps and adenocarcinoma
- 90% have mutation in APC gene (AD)
- 8% have mutation in MUTYH gene (AR)
- soft tissue tumors of the skin, congenital hypertrophy of retinal pigment epithelium (detected at birth)
familial adenomatous polyposis (FAP)
what is the tx of FAP?
- *complete proctocolectomy with ileoanal anastomosis** before the age of 20
- prophylactic colectomy recommended to prevent otherwise inevitable colon cancer
early onset colorectal cancer, polyps undergo rapid transformation over 1-2 years from normal tissue -> adenoma -> cancer
- DNA base-pair mismatches (MLH1, MSH2, MSH6, PMS2)
Lynch syndrome (Hereditary nonpolyposis colon cancer)
what is the tx of Lynch syndrome?
subtotal colectomy with ileorectal anastomosis (followed by anal surveillance of the rectal stump)
- prophylactic hysterectomy and oophorectomy is recommended in women older than 40, or once they have finished child bearing d/t high risk of other cancers
completely asymptomatic polyps
- chronic occult blood loss may lead to iron deficiency
- large polyps may ulcerate, resulting in intermittent hematochezia
non-familial adenomatous and serrated polyps
what is the gold standard diagnostic tool for polyps?
colonoscopy
- remains the best test in most patients to detect and treat (polypectomy) colorectal polyps
hamartomatous polyps throughout the GI tract, not malignant, may become large and bleed
- mucocutaneous pigmented macules on the lips, bucal mucosa and skin
Peutz-Jeghers syndrome (AD)
- serine threonine kinase 11 gene
more than ten juvenile hamartomatous polyps located most commonly in the colon
- increased risk adenocarcinoma
familial juvenile polyposis (AD)
- loci on 18q and 10q (MADH4 and BMPR1A)
hamartomatous polyps and lipomas throughout GI tract
- trichilemmomas (benign warty papules) and cerebellar lesions
PTEN multiple hamartoma syndrome (Cowden disease)
when does the American Cancer Society recommend to start regular colorectal cancer screening?
age 45, colonoscopy every 10 years
- people in good health, with life expectancy more than 10 years
what does the American Cancer Society recommend for colorectal cancer screening in patients ages 76-85?
decision to screen in based on a person preferences, life expectancy, overall health, and prior screening history
NOTE: people over age 85 should no longer get screened
what is the recommended screening timeline for pt with first degree relative with colorectal cancer, or adenomas diagnosed at age <60, or two first-degree relatives at any age?
colonoscopy every 5 years, beginning at age 40**
- or 10 years before the age of the youngest affected relative
what is the recommended screening timeline for pt with first-degree relative with colorectal cancer diagnosed at age >60, or by two second-degree relatives with colorectal cancer?
same as average-risk (colonoscopy every 10 years), but begin at age 40
what is the recommended screening for pt with family hx of familial adenomatous polyposis?
annual screening by sigmoidoscopy, beginning age 10-12
what is the recommended screening for pt with family hx of hereditary nonpolyposis colorectal cancer?
colonoscopy every 1-2 years, beginning at age 20-25, or 10 years younger than youngest age of colorectal cancer diagnosis in family
what is the second most common internal cancer in humans?
colon cancer
what do most colon cancers arise from?
adenomatous polyps
there is a high prevalence of colon cancer in patients with what type of bacteremia?
- *Streptococcus bovis**
- MUST screen for colon cancer!
how does left-sided colon cancer usually present?
- rectal bleeding
- altered bowel habits (narrowing, constipation, diarrhea, tenesmus)
- abdominal or back pain
how does right-sided colon cancer usually present?
- anemia
- occult blood in stool
- weight loss
- perforation, fistula, volvulus, inguinal hernia
what causes painless bleeding ranging from melena or hematochezia to occult blood loss
- is most commonly in pts over 70 years old, with chronic renal failure or aortic stenosis
arteriovenous malformations (AVM)
what is the dx for AVM?
CBC with iron studies (will show iron deficient anemia)
- triggers us to do endoscopy, upper EGD, lower colonoscopy, capsule
what is intussusception?
telescoping bowel
- rare, more common in kids
- causes jelly consistency BM currant jelly stool
remnant of Vitelline duct
- Rule of 2’s
- adults may present with intestinal obstruction, rectal bleeding, intussusception, perforation, or diverticular inflammation
- dx: technetium-99m scan
Meckel’s diverticulitis
