EM@3AM: Inflammatory Bowel Disease

Welcome to EM@3AM, an emDOCs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

Answer: Inflammatory Bowel Disease

Background:

• Inflammatory Bowel Disease (IBD) is characterized by a chronic inflammatory state of the gastrointestinal (GI) tract
  • Includes Crohn’s disease (CD) and ulcerative colitis (UC)¹
• UC classically involves the rectum and can extend proximally through the entire colon in a continuous pattern (in contrast to skip lesions seen in CD)
• Early detection and treatment are crucial for limiting the risk of life-threatening complications¹

Etiology:

• The exact cause of IBD is unknown
  • Current evidence suggests multifactorial pathogenesis including host microbiota imbalance, genetic susceptibility, and environmental factors³
•  Gut Microbiota
  • Natural gut bacteria play an important role in overall digestive function. Slight imbalances in gut flora could impair gut homeostasis and function predisposing patients to a chronic inflammatory state
  • Minor changes in diet, antibiotics, probiotics, stress, surgery, and other factors can disrupt the protective intestinal mucosal barriers, altering the microbiome and predisposing the colon to chronic inflammation⁴
  • Enteric infections, particularly Salmonella and Campylobacter species have been shown to damage mucosal barriers, alter the microbiome, and increase patient risk for developing IBD within a year of infection⁵
• Genetic Factors
  • Individuals with a 1st-degree relative diagnosed with IBD are roughly 4 times more likely to develop IBD compared to those without affected family members⁶
  • Genome-wide association studies (GWAS) have identified over 200 genetic risk loci for IBD, 23 of which are specific to UC⁷
• Environmental Factors
  • Diet: Diets with high levels of saturated fats, sugars, and artificial additives are associated with both UC and CD development
    • Increased fruit and vegetable consumption appears to be protective⁸
  • Medications: Prolonged antibiotic courses, as well as daily NSAID and/or oral contraceptive use, increase lifetime risk of developing UC⁹
  • Smoking: Has been shown to be protective against UC but increases the risk for CD
  • Stress: High frequency and prolonged duration of psychological stress has been linked to earlier disease onset and faster progression of symptoms⁸

Epidemiology:

• UC
  • In 2023, the prevalence of UC was estimated to be 5 million cases around the world, with incidence increasing worldwide¹⁰
  • The incidence of UC is 8.8-23.1 per 100,000 person-years in North America¹¹
  • UC has a higher prevalence than CD
    • UC prevalence in the United States is 1.0% (95% CI 0.5,1.4%; 1.9 million persons)¹²
  • Bimodal age distribution with the 1st peak occurring during the 2nd or 3rd decade of life, and the second peak between 50 and 80 years¹³
  • Sex does not appear to affect the overall incidence until the age of 45, where males demonstrated a significantly higher incidence of UC compared to females of the same age¹⁴
• CD
  • The annual incidence of CD in North America is 3-20 per 100,000 person years¹⁵
    • Higher incidence among young adults with approximately 2/3 of patients diagnosed prior to age 40
    • Patients diagnosed later than age 40 appear to have higher rates of colonic involvement¹¹
  • CD prevalence is 0.3% in the United States (95% CI 0.1,0.4%; 578,000 persons)¹²
  • Bimodal age distribution with 1st peak between 2nd and 3rd decade of life and the second between 5th and 6th decade¹⁶

Clinical Presentation:

• IBD presenting signs and symptoms
  • Bloody diarrhea
  • Colicky abdominal pain relieved by defecation
  • Uveitis with associated eye pain and/or vision changes
  • Oral Ulcers
  • Tenesmus
  • Nausea
  • Fatigue
  • Weight loss
  • Rectal urgency⁸
  • Joint pain
  • Delayed growth in children with IBD¹⁷
  • Primary sclerosing cholangitis (PSC) has been associated with IBD, particularly UC, and presents with
    • Pruritus
    • Jaundice
    • RUQ pain
    • Fatigue
    • Weight loss
    • Dry mouth and eyes
    • Hepatosplenomegaly (progressed disease)¹⁸
•  Distinguishing IBD from irritable bowel syndrome (IBS), a common mimic
• IBS can be a common mimic of IBD
  • IBS diagnostic criteria per Rome IV
    • Abdominal pain at least one day per week, during the previous 3 months, with at least 2 of the following
      • Pain associated with bowel movements, change in stool frequency, change in stool appearance¹⁹
    • Overlapping symptoms
      • Recurrent abdominal pain related to defecation and/or food intake, diarrhea, nausea, and tenesmus²⁰
    • Differentiating factors
      • Blood in stool, strictures, fistulas, weight loss, elevated inflammatory markers, leukocytosis and anemia
        • Primary difference is mucosal inflammation seen on endoscopy only in IBD²¹
•  Physical exam
  • Often unremarkable in early or mild disease; otherwise can present with:
    • Vital signs: Tachycardia, fever, and possible hypertension from dehydration are common
    • Abdominal tenderness, distension, guarding
    • Pallor (due to anemia)
    • Weight loss, malnutrition
    • Occult blood on digital rectal exam
    • Mucus and/or blood in stool
    • In CD, abscesses, anal fistulas, or rectal prolapse may be detected on rectal exam
    • Toxic megacolon can occur in both CD and UC (more commonly in severe UC) and is a surgical emergency characterized by:
      • Severe abdominal pain, distension, fever, fatigue, and decreased bowel sounds^22,23
    • Of patients diagnosed with IBS, approximately 30% of them initially present to the ED while the majority are typically diagnosed through primary care or referred to a gastroenterologist²⁴

Labs: 

• CBC to evaluate for leukocytosis and/or anemia
  • Iron deficiency anemia common
  • Thrombocytosis is also frequently observed in IBD patients
    • Platelet count can directly correlate to severity of disease²⁵
• CMP to evaluate for electrolyte abnormalities
  • Elevated liver function tests (LFTs)²⁶ and renal function,²⁷ as well as hypoalbuminemia,²⁸ may be observed
• ESR/CRP should be obtained in suspected IBD patients²⁹
• Stool studies should be obtained in initial workup for IBD and significant exacerbations³⁰
  • Intestinal inflammatory markers to differentiate IBD from inflammatory bowel syndrome (IBS) and monitor disease activity
    • Fecal calprotectin²⁵
    • Fecal lactoferrin³¹
  • Clostridium difficile toxin testing³²
  • GI PCR
    • Should be utilized to differentiate enteric pathogen infection vs. IBD exacerbation³³
      • Patients on immunotherapy are at increased risk for CMV colitis³⁰
    • Ova and parasite (O&P) should be considered in the setting of appropriate travel history or contaminated water exposure³⁴
•  Other labs to consider:
  • Lactic acid
  • Magnesium
  • Phosphorous
  • HIV (early HIV infection can present with many similarities to IBD)
    • Fevers, night sweats, oral ulcers, abdominal pain, diarrhea, rash, and joint involvement
  • Monospot if oral sores are present
  • Anti-TTG for celiac disease as part of the initial workup³⁰
• There should be no significant lab derangements in IBS patients, in contrast with IBD patients

Imaging:

• CT abdomen and pelvis (A/P) with contrast is recommended in these patients when there is suspicion for abscess, fistula, obstruction, perforation, acute abdomen, bleed, and/or other complications^28,33
  • WBC >12 is a positive predictor for clinically significant CT findings in CD and should be utilized given leukocytosis and the proper clinical scenario²⁹
  • Approximately 26% of CT scans in IBD patients identify actionable findings such as abscesses, fistulas, obstructions, and choledocholithiasis³⁰
  • CD patients with leukocytosis and previous ileal disease have clinically significant findings 47% of the time³⁰
    • Overall, 32.1% of CTs have actionable findings³⁰
  • CT scans in UC patients may be less beneficial, with 63.2% showing no significant findings and less than 2% revealing UC-related complications²⁹
    • Only 12.6% of scans show actionable results²⁹
•  POCUS has a limited role in the evaluation of IBD patients although it can be utilized to evaluate for abscesses and free fluid if CT imaging is unavailable^35,36
•  Imaging findings will be normal in IBS patients, helping distinguish this condition from IBD

Diagnosis:

• The following should raise suspicion for IBD
  • Constellation of symptoms
    • Most common:
      • Diarrhea
      • Hematochezia and/or stool with mucous
      • Abdominal pain or cramping
      • Tenesmus and urgency
    • Fatigue and fevers
    • Weight loss, anorexia, failure to thrive
    • Fistulas, fissures, abscesses
    • Extraintestinal manifestations (EIMs): arthritis, skin disorders, uveitis^37,38
      • Primary EIMs occur in 25-40% of IBS patients. Primary manifestations include findings involving the skin, eyes, joints, and liver
      • When secondary manifestations are included (i.e., all other abnormalities outside of the GI lumen), nearly 100% of patients have at least one EIM at time of diagnosis³⁹
  •  Lab results
    • Anemia, leukocytosis, and thrombocytosis on CBC
    • Electrolyte abnormalities, hypoalbuminemia, elevated LFTs, and decreased renal function
    • Elevated inflammatory markers (CRP and ESR)
    • Elevated fecal calprotectin/lactoferrin and exclusion of infectious causes^37,38
  • CT imaging revealing
    • Bowel wall thickening, mural hyperenhancement, engorged vasa recta (comb sign), fat stranding, and mesenteric lymphadenopathy^37,40
•  Definitive diagnosis
  • Comprehensive approach requiring endoscopy and biopsy
    • Will also help differential IBD from IBS
  • Histologic evaluation of biopsy used to differentiate between CD and UC
    • Magnetic resonance (MR) and CT enterography may eventually be used to assess extent of disease²³

Treatment:

• All patients should receive IV fluids if volume-depleted and unable to tolerate oral intake
• Electrolytes and anemia should be corrected as indicated²⁹
• IV corticosteroids should be reserved for acute severe UC and CD flares⁴¹
  • Should only be administered if recommended by GI
• Oral steroids, like prednisone, can be given for short-term outpatient management if recommended by GI⁴²
  • Special attention should be given to taper steroids appropriately for longer courses to avoid hypoadrenalism²⁹
• Antibiotics are only required if suspected sepsis, abscess, or superimposed infections⁴¹
  • Gram negative and anaerobic coverage is required (i.e., ciprofloxacin + metronidazole, piperacillin-tazobactam)⁴¹
• Pain control and antiemetics as needed
• CT A/P w/ contrast is not always required but have a low threshold for imaging in systemically unwell patients or concerned for complication
• In cases of toxic megacolon, surgery should be consulted early due to the risk of perforation and hemorrhage
  • The majority of toxic megacolon cases do not improve with medical management alone and prompt surgical intervention improves mortality outcomes⁴³
• Interventional radiology (IR) or surgical consultation may be required for management of intra-abdominal abscesses⁴⁴

Disposition:

• Approximately 60% of ED visits related to IBD result in admission
• Findings that may warrant admission:
  • Leukocytosis, fever, significant pain, anemia, malnourishment, AKI, or electrolyte derangements
  • Any abdominal findings requiring surgical intervention, such as bowel obstruction and abscess require admission⁵¹
  • Admission is highly dependent on clinical presentation and judgment, but the presence of the above findings can play a part in decision-making⁵¹
  • For those tolerating oral intake and without the aforementioned abnormalities, clinicians may consider discharge after shared decision making with the patient

Prognosis:

• UC
  • Extent of colitis is predictive of colectomy⁵²
  • 1-year and 5-year colectomy rates of 2% and 13% respectively⁵²
  • Estimated rate of PSC is 4%. Significantly worse prognosis with increased risk of colorectal cancer, biliary cancer, and mortality^52,53
  • 44% recurrence rate within the 1st year⁵⁴
  • 3-month and 12-month mortality rates of 0.84% and 1.01%, respectively⁵⁵
• CD
  • Small bowel involvement (particularly ileal), strictures, and penetrating disease have a worse prognosis with higher surgical rates⁵³
  • Roughly 1/3 of patients require hospitalization within the 1st year of diagnosis⁵³
  • 1-year and 5-year surgery rates as high as 13% and 25%, respectively⁵²
  • 50% recurrence rate within the 1st year⁵³
  • Annual mortality rate of 1.6% compared to 1% in age and sex-matched controls⁵⁶
• General prognostic factors
  • Young age, high CRP, and high fecal calprotectin are prognostic of severe disease^53,57

Pearls:

• The combination of diarrhea, blood in stool, abdominal pain, and tenesmus should raise concern for IBD
• Weight loss and anemia should also raise suspicion
• Laboratory work-up in the ED should include inflammatory markers and stool studies
• If there is no concern for an intra-abdominal emergency, CT A/P is unnecessary and imaging work-up can be deferred to the outpatient setting
• ED care for IBD flares is mainly supportive
  • Corticosteroids should be discussed with GI, and antibiotics added in patients with suspected infection

Further Reading:

Further FOAMed:

• https://www.emdocs.net/inflammatory-bowel-disease-emergency-department/
• https://www.emdocs.net/em3am-inflammatory-bowel-disease/
• https://www.emdocs.net/em3am-toxic-megacolon/

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