hello in this episode of an approach to symptoms I'll be discussing an approach to acute diarrhea as with other videos in this series this will focus on adult and teen patients it does not completely apply to younger pediatric age groups to begin how do we Define acute diarrhea well even for the one word diarrhea medicine does not have a uniform definition labeling a person's bowel movements as diarrhea can be based upon the number of them within 24 hours the stool volume within 24 hours or their subjective consistency while there are published definitions that are more specific than this for example exactly how many bowel movements or what precise stool volume is necessary in practice we typically just take the patient's word at face value if they come reporting diarrhea they have diarrhea with the one caveat that one occasionally needs to distinguish diarrhea from fecal incontinence which is an entirely separate problem but which some patients will sometimes interpret as diarrhea regarding whether the diarrhea is acute once again there is no uniform definition for this but most commonly diarrhea is considered acute if it has been present for less than two weeks when it comes to a diagnostic framework for diarrhea whether we are discussing acute or chronic there are two major categories non-inflammatory diarrhea consists of watery stool which may or may not be associated with abdominal pain fever and sepsis are relatively uncommon in contrast inflammatory diarrhea is likely present if the stool has gross blood or mucus inflammatory diarrhea usually presents with concurrent abdominal pain and fever and or science of sepsis are relatively common acute inflammatory diarrhea is sometimes known as dysentery I actually discourage the use of this word in the absence of a specific microbial diagnosis since it strongly implies an infectious etiology which is usually but not always the case although the corresponding video on an approach to chronic diarrhea also discusses the distinction between osmotic versus secretary versus malabsorptive versus hypermotility types of diarrhea that Paradigm does not apply well to acute diarrhea moving through specific ideologies non-inflammatory diarrhea can be caused by viruses including norovirus rotavirus enteric adenoviruses cytomegalovirus which is primarily seen in patients with significant immunocompromise and as most recently observed SARS cov2 or the virus responsible for covid bacterial etiologies include C difficile and important bacteria that classically causes diarrhea following antibiotic usage which can feel a bit paradoxical but what happens is antibiotic therapy substantially reduces the load of so-called good bacteria in the guts since C diff is not affected by most antibiotics any seed of bacteria present at the time will flourish in the absence of competition for nutrients the highest risk antibiotics for causing C diff colitis are clindamycin fluoroquinolones broad spectrum penicillins and third generation cephalosporins the E coli specifically the enterotoxicogenic enteropathogenic and entero aggregative subtypes the distinguishing clinical pathologic and epidemiologic features of the five major pathologic E coli subtypes is a complicated subject which is outside the scope of this video and their categorization is not as clear-cut as this chart will imply other bacteria in this category include listeria vibrio cholera which is responsible for the disease cholera which is associated with huge outbreaks in areas of war and natural disaster and vibrio Para hemolyticus so far all of these bacteria have caused diarrhea through infection within the GI system but some bacteria can cause diarrhea not through direct infection but rather by creating preformed toxin in food prior to consumption and it's the ingested toxin that actually causes illness bacteria which are Infamous for doing this include staph aureus and B serious features of the presentation that suggest toxin ingestion to be the mechanism of illness or nausea and vomiting that begins within a few hours of food ingestion and which is more prominent and begins before the diarrhea although a large number of protozoa can cause diarrhea the most common are Giardia and cryptosporidium not all non-inflammatory diarrhea is infectious in origin non-infectious causes of acute non-inflammatory diarrhea include medications the most commonly implicated are antibiotics antibiotic Associated diarrhea is caused by disruption of normal gut Flora but it does not necessarily lead to seed of colitis specifically most diarrhea that is triggered by antibiotics is not C diff even though it is important to test for C diff in this situation other common drug culprits include anti-neoplastic drugs colchicine NSAIDs magnesium containing antacids ppis and H2 blockers and the SSRI class of antidepressants lastly psychosocial stressors can also lead to acute diarrhea when it comes to inflammatory diarrhea it can be caused by a wide variety of bacteria including enteroinvasive and enterohemeragic subtypes of E coli the latter of which is sometimes used synonymously with the term sugar toxin producing E coli though a microbiologist might split hairs here and point out that eheck is technically a subgroup Within s-tech eheck includes the particularly dangerous E coli subtype o157h7 which is associated with an acutely life-threatening condition called hemolytic uremic syndrome other bacteria here include campylobacter shigella usinia and non-typhoidal salmonella the major protozoa which is associated with inflammatory diarrhea is entamoeba histolytica regarding non-infectious inflammatory diarrhea a relatively uncommon but important cause in hospital medicine is ischemic colitis this is a good place to mention that any cause of chronic diarrhea can present acutely so the entire list of etiologies for chronic diarrhea could be considered within this whole chart as well however most causes of chronic diarrhea typically have a gradual onset such as seen with most malabsorption syndromes whereas the relatively rapid onset of diarrhea can be seen with a first presentation of inflammatory bowel disease another important point is that these two broad categories are not precise for example pathogens that are more classically associated with inflammatory diarrhea can cause watery diarrhea early in their course and severe C diff infections along with all forms of E coli can be associated with sepsis overall the most common causes of acute diarrhea in both the United States and the rest of the world is believed to be norovirus other common causes are the various subtypes of E coli and campylobacter in the developing World other particularly notable pathogens include vibrio cholera shigella and entamoeba an identification of the specific pathogen causing acute diarrhea is not always critical but there are some classic associations between epidemiology and clinical features and a suggested organism I won't read through this chart for you but you can pause the video and read through it if you'd like there is one particular form of acute diarrhea which is worth mentioning separately traveler's diarrhea as name implies this is diarrhea that develops while a person is traveling out of the geographic area in which they normally reside classically involving travel to a resource limited location with sub-optimal Sanitation risk factors for developing it include travel during the warm and wet season buying food from Street vendors and consuming salads and raw vegetables common etiologies for travelers diarrhea include enterotoxic E coli campylobacter and norovirus although it's very common luckily it is usually relatively mild and self-limited I'm going to bring it back to discussing the general assessment of an undifferentiated patient with diarrhea what are the things that you'll want to ask about during the history how long has the diarrhea been present for so you can accurately frame it as either acute versus chronic what are the characteristics of the stool for example is it watery versus Bloody or with mucus so you can start framing it as non-inflammatory versus inflammatory are other symptoms present particularly fever nausea and vomiting and abdominal pain another symptom to ask about is called tonismus which is a sensation of needing to have a bowel movement when there is nothing actually right there ready to be expelled this is typically seen with inflammatory diarrhea in their past medical history of particular importance is anything related to immunocompromise which could place them at higher risk of unusual pathogens or at a higher risk of a more severe course also ask about recent infections of C diff and ask about prior episodes of seemingly acute diarrhea in the event that the patient actually is presenting with chronic episodic diarrhea which has an entirely different diagnostic framework a medication history is essential particularly asking about recent antibiotic use have they recently consumed any high risk food such as unpasteurized Dairy undercooked meat or raw shellfish has there been any environmental exposures particularly swimming in streams and lakes and as just discussed a recent travel history moving to the physical exam as always start with the vitals and include orthostatics as a very rough screen for volume depletion the remainder of the exam should focus on further assessment of volume status and an abdominal exam unless the patient is unusually ill has severe chronic disease of some kind or there are unusual features in the history suggesting that diarrhea is a manifestation of a systemic disease additional components of the exam are unlikely to be helpful diagnostic testing for patients with acute diarrhea is Complicated by a variety of options which are not equally available in all Health Care Systems depending on where one practices some of these May simply not be options or due to their cost may be reserved only for the sickest of patients among tests that may be considered are stool culture which can identify most bacterial infections some U.S Hospitals now have available a multiplex panel that uses molecular methods such as PCR to test for many different bacterial viral and protozoal pathogens all at once although such Multiplex panels are extremely Broad and convenient one does need to be cognizant of the risk of false positives test for C diff if the patient has risk factors for this different Healthcare Systems have different options for C diff testing including the possible inclusion of C diff on the multiplex panel in some situations a bloody diarrhea particularly where a multiplex panel is not available there may be utility in using stool microscopy to look for entamoeba in patients with severe bloody diarrhea a CBC can be helpful to ensure a patient is not developing significant anemia as well as to look for thrombocytopenia that can be a sign of E coli Associated hemolytic uremic syndrome and in patients with unusually high volume diarrhea a chemistry panel can look for Associated electrolyte imbalances particularly hypokalemia tests that are generally not indicated in acute diarrhea any form of Imaging endoscopy fecal leukocytes lactoferrin calprotectin or testing stool for occult blood that last one on testing for occult blood might be a little debatable but personally if a patient still visibly appeared completely non-bloody whether or not it was quite positive would not change my personal approach to them now let me show you a flowchart which summarizes my stepwise approach to acute diarrhea the first question I consider is whether the patient has risk factors for C diff specifically relatively recent antibiotic use or previous C diff infection for this specific question recent typically means within the last three months give or take if yes test for C diff and if positive you're done with the diagnostic workup on the other hand if the patient has either no risk factors per C diff or testing was negative next ask whether or not the patient has evidence of inflammatory diarrhea or severe disease irrespective of subtype this includes severe abdominal pain bloody stool fever and or hypovolemia consider whether they have any risk factors for a worse outcome this includes age of 70 or above Advanced heart failure or pulmonary hypertension which will make them more prone to hemodynamic instability with large changes in intravascular volume significant immunosuppression meaning diseases like HIV and organ transplantation pre-existing inflammatory bowel disease and pregnancy and also consider whether there are any public health concerns related to the patient's presentation meaning are they part of a new suspected outbreak of a foodborne illness despite many things being listed in this box the majority of patients meet none of these criteria in which case you should just monitor them and treat symptoms if the patient improves fantastic you're done if the illness is self-limited and outside of a major outbreak there is no need to identify a specific pathogen on the other hand if the patient does not improve after several days or if the patient has any of the preceding features you should perform a stool culture and or a multiplex panel if available in addition if the patient has bloody diarrhea you should also consider direct testing for Shiga toxin as a quick screen for enterohemologic E coli particularly if this is not included in an available Multiplex panel also directly test for entamoeba which might be a PCR test a Liza test or stool microscopy depending on your health care System although this flowchart makes it seem like the preceding C diff test and the subsequent tests are done sequentially this more represents the thought process in practice if all these tests were indicated they would all be ordered at once in addition regarding C diff it only rarely causes bloody diarrhea therefore in the event that the patient has bloody diarrhea C diff risk factors and test positive for C diff while initiating seed of treatment I would also look at these tests as well if a diagnosis is made at this point great go ahead and treat if not Monitor and treat symptoms if the patient fails to improve after the following one to two weeks consider the initiation of a workup for new onset chronic diarrhea the key takeaway points for this video acute diarrhea can be classified as either non-inflammatory which is characterized by watery bowel movements and minimal systemic symptoms or inflammatory characterized by bowel movements with either blood or mucus and often fever or other signs of sepsis the overall most common etiologies of acute diarrhea are norovirus campylobacter and the various types of E coli C diff is an important etiology among hospitalized and recently hospitalized patients the majority of patients presenting with acute diarrhea do not warrant immediate testing patients who do warrant stool culture and or Multiplex PCR plus or minus blood tests include those with inflammatory diarrhea severe volume depletion severe chronic disease including immunosuppression or those in situations in which an outbreak is suspected foreign