Lower GI

Crohns disease: can involve anywhere in the GI tract. transmural inflammation. can present with skip areas and it may spare the rectum. It can have different types of behaviors ( strictures-->obstructions, fistulizing, perianal disease), extra intestinal manifestations (erythema nodosum, ankylosing spondylitis, pyoderma gangrenous). It is also associated with primary sclerosing cholangitis (PSC)

Chronic diarrhea & malapsorbtion

IBD

Functional bowel disease & IBS

chronic diarrhea: Persistent alteration of stool consistency between types 5-7 on Bristol stool chart and increased frequency of > 4 weeks duration

Malabsorption: impaired digestion of nutrients w/in the intestinal lumen/enterocytes and or impaired transport of nutrients form intestinal lumen into circulation

causes of chronic diarrhea = many. malabsorption is one important cause. Malapsorption will cause diarrhea w/bulky foul-smelling bowel movements and weight loss

DDX for chronic diarrhea. good history taking is so important! when where and how did diarrhea start. you need to know what has already been done

normal Bowel movements. 1) balance between water entering and being absorbed ( small bowel mainly and a little in the colon. do there is a 02.-.3 L leaving/ day
2) normal anal sphincter 3) if anatomy/motility are normal no partially digested or absorbed nutrients reach the anus.

A. ABNORMAL WATER BALANCE: 1) increased gastric secretions: gastronomy: gastrin tumor --> increased gastrin--> stomach secreting large amounts of acid. (can also be caused by histamine).

2) increased small bowel secretions: VIPoma (Verner-morrison syndrome)- excessive vast-intestinal peptide secretion by neuroendocrine cell --> increased intestinal secretions (T4, calcitonin, T3 are other causes)

Decrased small bowel absorption: infections/inflammation (giardiasis, cyclosporine, cryptosporidium), lack of bile/digestive enzymes ( liver disease, pancreatic insufficiency, lactose/fructose deficiency), abnormal mucosa ( celiac/crohn's daises), non- absorbable food components (laxatives), short bowel syndrome, intestinal ischemia, drugs, malignancies

decreased colonic absorption: inflammatoin/infection ( C. diff,) , abronomal colonic mucosa, ischemia and IBS

B. Abnormal anal sphincter: childbirth, pelvic floor/nerve injury, post rectal sphincter surgery (churns disease)

Abnormal anatomy:review every survey of the GI tract, document what was removed and what was connected to what (draw a road map) example: gastric bypass surgery, resections to to IBS, oncological surgeries

Abnormal motility: increased dud to drugs and infections

Classifications of diarrhea: osmotic: only occurs with oral intake, no intake no diarrhea; secretory-continues while fasting (hormones) stops with discontinuation of causative drugs; exudative- with blood and pus ( crowns, UC); steatorrhea- likely biliar/pancreative; weight loss; favors an upper GI cause; large volume; favors small bowel source, malabsorption. Not every day - IBS; only in morning with couple of stools-IBS; gas and bloating with milk; lactose, urgency/soiling;anal sphincter dysfunction; abnormal anatomy after surgery; short bowel syndrome, dumping syndrome after gastric bypass, bile acid malabsorption after ill resection/cholecystectomy

Physical exam: fever- infection/inflammation, rash-ulcerative colitis, crohn's, celiac, mastocytosis RECTAL EXAM IS VERY IMPORTANT. INSPECTING BOWEL IS IMPORTANT.

TESTS: 72 hour FECAL fat collection: critical . start 100 g fat diet 2 days before collection. 24-48 hour is too short; may miss important stool portion. Benefits: if patient complies diarrhea is a real problem for patient, accurate stool volume measurement and it provides stool fat content (should be less than 7g)

Treatment: depends on the cause!

What is IBD? chronic inflammatory conditions characterized by relapsing and remitting episodes of inflammation in the gut.

demographic/geographic pattern. more common in industrialized countries (Western European cultural heratige). Demographics: ashkenazi jewish populations. protective (black and hispanic populations). peak diagnosis is 35 or younger. Crohn's is more common in women and ulcerative colitis is more common in men. both diseases are becoming more common.

pathophysiology: interplay between genetics, envirmonment and immune system disturbance. there is a predisposition genetically in some families otherwise it is completely sportatic. Environmental triggers ( smoking for Crohn's but protective for UC) . western diet, NSAIDS, oral contraceptives. Possible pathophysiology: immunologic dyregulation ( epithelial barrier breaks down, excessive immune cell recruitment and activation--> increased cytokine and infmmatory cell trafficking to the intestine)

Ulcerative colitis (UC): exclusively involves the colon. infmmation is limited to mucosal layer. generally it occurs in a continuous pattern and almost always involves the rectum. it may have extra intestinal manifestations ( mouth ulcers , uveitis, skin ulcers, pulmonary disease) there is an association with primary sclerosing cholangitis (PSC).

typical presentation : bloody diarrhea with tenesmus ( feeling like you have to poop but can't empty completley). physical exam is normal or LLQ tenderness. complications : fulminant colitis and toxic megacolon in extreme cases its marked by fever dilated colon and can be complicated by perforation.

Workup: history including travel NSAID use. lab: CBC (anemia) BUN (electrolyte status, kidney injury) , CRP, ESR, stool studies ( rule out infection). diagnosis is made with ileocolonoscopy ( colonoscopy + examine ileum) and biopsy

Expected findings: using Mayo score. decreased vascular pattern nd redness ( Mayo 1=mild), emergence of erosions ( Mayo 2= moderate disease ), spontaneous bleeding ulcerations (Mayo 3- severe)

Histologically: crypt branching/dialation, nuetrophilic infiltrations (mild), moderate: crypt and abccess and lymphocytic, severe; complete loss of crypts & dense lymphocytic infiltrate

Treatment: mild: 5 aminosalicyclic acid, moderate/severe: biologics ( IV, subcutaneous) , JAK 1 and 3 inhibitor (oral) (tofacitinib-specific for UC ), immunomodulatiors ( usually used in combo with medications listed above), surgery( 20% will eventually need colon removed =CURE). for flares : steroids, (prednisone). Colorectal cancer screening is important (more frequent than general population due to long standing inflammation)

Typically presents with crampy abdominal pain, diarrhea, weight loss; physical examination abdominal tenderness especially RLQ/ can have perianal disease and extra intestinal manifestations. Workup is generally the same as it is for UC. you just want to take extra care at the small intestine.

Endoscopy findings: ulcerations (earlier lesions seen), large ulcers interspersed with normal mucosa, cobblestone appearance with nodules, strictures due to fibrosis.

Treatment: mild- gut specific steroid (budesomide); moderate-severe; biologic, immunomodulators, surgery (not a cure but 50% require surgery (segmental resection/colectomy). treat flares with steroids/antibiotics. tofecitamab not approved for thrones disease

Diagnosis is done via colonoscopy and imaging

What is it? chronic illnesses where GI tract appears normal but the way it function is abnormal. it can involve all parts of the GI tract. The most common type of GI disorders. They exists on a continuum. can have more than one functional dx at a time.

IBS

everyone will experience sometime in their life, women more common than men, its seen all across the world, it may coincide with other entities ( psychiatric disorders, fibromyalgia, past trauma/abuse

pathophysiology: not fully understood. there is some altered gut signaling at the neurotransmitter, nerve and muscle level. right now dx is clinically defined. there are a complex number of contributors that can cause this : genetics, culture, environemnt, stress, personality traits, altered motility, immune disfunction, gut microbiota.

Diagnosis: abdominal chronic pain that is intermittent + change in bowel habits. it should be without alarm features/red flag symptoms, can be associated with abdominal bloating and/or visible distention. different subtypes/diarrhea, constipation or mixed predominance.

Criteria is based on Rome IV criteria: recurrent abdominal pain (1day/week or more in the last 3 months, symptoms ongoing for at least 6 months and any of the two additional criteria (related to defecation, change in stool frequency, or consistency). the DX may require you to rule out other conditions as it can overlap with other diseases.

Treatment: disease course can be variable course. prognosis; good symptoms can impact quality of life and daily functionality. treatment is supportive and non-curative. multidisciplinary approach: avoiding triggers for loose stools/bloating, low FODMAP diet [diet low in germinable oligosacharrides, polysaccharides], insure adequate sleep, treatment of mood disorders, support for processing of past and current trauma. Medical management: look at the symptoms and manage using medications based off of the symptoms. stool consistency: fiber, antidiarrheals, laxatives, antispasmodics (Abdominal cramping), SSRI (smaller doses for GI symptoms)