Gastroenterology

Update on State-of-the-Art Imaging and Stool Tests for IBD in the ED

The approach to a suspected inflammatory bowel disease (IBD) flare in the ED involves a thorough diagnostic workup and addressing potential serious complications of the underlying disease.

Although care may be transferred to an inpatient team, early ED workup utilizing state-of-the-art methods can facilitate earlier definitive intervention, significantly impacting hospital course and outcomes.

Case
A 32-year-old female presents to the ED with 10 days of nausea, emesis, abdominal cramps, bloody diarrhea 10-12 times daily, and 7-pound unintended weight loss. She has had Crohn’s disease (CD) since age 23 and no prior surgeries. She has received infliximab every 8 weeks for the last 4 years. Her last flare was 2 years ago, after which she received intravenous steroids. Temperature is 100.2ºF, heart rate 102, blood pressure 90/58, respiratory rate 16, and oxygen saturation 98%. She is lying in the right lateral decubitus position, has dry mucous membranes, and has right lower quadrant and suprapubic tenderness to palpation with guarding but no rebound. The remainder of the physical exam is within normal limits.

Introduction
IBD is a chronic relapsing-remitting auto-inflammatory condition that includes Crohn’s disease (CD) and ulcerative colitis (UC) caused by environmental exposures in genetically susceptible individuals. CD can affect any part of the gastrointestinal tract from the mouth to the anus and is more heterogeneous than UC, which begins at the rectum and can extend proximally into the colon. Extraintestinal manifestations include rheumatic, mucocutaneous, ocular, hepatobiliary, renal, pulmonary, and pancreatic disorders.1 IBD is increasing in incidence and prevalence and is associated with ED visits,2 healthcare utilization, and costs.3

The differential diagnosis for a suspected IBD flare should be broad4 and include specific complications such as: fistulae, intra-abdominal abscess, stricture, obstruction, perforation, infection (opportunistic or non-opportunistic), toxic megacolon, NSAID-induced colitis, nephrolithiasis, malignancy, and hepatopancreatobiliary disorders. Abdominal examination of skin, scars, ostomies, masses, fistulae, and direct anal visualization is crucial, as well as appropriate laboratory tests and imaging.

Diagnostic Studies
Workups are extensive for suspected IBD flares and include imaging as well as laboratory tests requiring blood and stool samples. Stool samples can be logistically challenging to collect, and results may be required before antimicrobial or immunosuppressive therapy. Thus, early collection of stool samples in the ED is highly consequential, especially before symptomatic or other treatment, as earlier initiation of IBD therapy during flare is associated with better outcomes.5

Stool Studies: A stool sample can be used to evaluate for gut infections and general inflammation, which is an important distinction when considering antimicrobials or immunosuppression for IBD. An enteric pathogen polymerase chain reaction panel and C. difficile toxin testing account for most relevant organisms. Calprotectin is a calcium and zinc binding protein found in phagocytic cells and most abundant in neutrophils, effectors of acute inflammation.6

Fecal calprotectin is a recently developed stool analyte measured by enzyme-linked immunosorbent assay preferred by gastroenterologists over the nonspecific inflammatory markers C-reactive protein and erythrocyte sedimentation ratio. While fecal calprotectin is not specific to IBD, its elevation reflects inflammation specific to the gut, due to IBD, celiac disease, infectious colitis, intestinal cystic fibrosis, colorectal cancer, NSAID use, alcohol use, and/or another process.

Thus, elevated fecal calprotectin without other indicators can suggest an IBD flare, with levels correlating to clinical, endoscopic, and histologic inflammation and a negligible false negative rate.

Normal fecal calprotectin levels suggest a non-inflammatory process, such as irritable bowel syndrome or an extra-intestinal disorder. Sensitivity and specificity depend on disease severity and cutoff values and are generally considered high by specialists. Therefore, use of fecal calprotectin can obviate the need for urgent colonoscopy. Next-generation adaptations are being developed to improve accuracy, rapidity, and ease of sample acquisition.7

Imaging Studies: Imaging modalities utilized in IBD include plain film radiograph, computed tomography, magnetic resonance imaging, magnetic resonance enterography, ultrasound, esophagogastroduodenoscopy, colonoscopy, flexible sigmoidoscopy, and anoscopy.

IBD is a chronic disease often diagnosed at an early age, meaning patients have increased risk of cancer with cumulative radiation exposure due to frequent radiographic scans.8 It is important to balance the risks of exposure to diagnostic radiation and to bowel preparation required for endoscopy with the sensitivity and specificity of each modality. Magnetic resonance enterography is preferred for IBD patients under 35 years of age9 and is gaining favor for other patients as well. As technology and training improve, point-of-care ultrasound is increasingly utilized and has been shown to detect important IBD complications, such as bowel strictures and pericolic abscesses, in the ED.10

Special Considerations for Initial Management
Symptoms can be severe and debilitating even if not visually apparent. IBD patients may have had their symptoms dismissed or attributed to a psychosomatic condition. Assume symptoms are pathophysiologic until proven otherwise. While definitive management of an IBD flare typically occurs under care of specialist teams following admission to the hospital,9,11,12 initial steps should be taken in the ED to stabilize the patient.

Surgery is avoided when possible in CD due to worse outcomes, but can be curative in UC. Avoid making abrupt changes to outpatient medications without consultation, as these regimens can be complex and extensively titrated. Avoid antibiotics unless there is high suspicion for infection, as certain antibiotics are associated with poor IBD outcomes. The gut-selective steroid budesonide may be used for mild to moderate flares, as it has reduced side effects compared to systemic steroids.

Most patients with severe IBD flares will be admitted to the hospital. Risk scores are being developed utilizing indexes at presentation to help determine disposition. For instance, presence of tachycardia and hypoalbuminemia were associated with complex disease and admission in a recent study.13 Close follow-up with a gastroenterologist following discharge is critical, without which patients have increased ED visits.14

Take-Home Points

  • Maintain a broad differential diagnosis for IBD flare, including complications such as fistulae, abscesses, stricture, obstruction, and infection.
  • Prompt initiation of appropriate workup in the ED facilitates earlier intervention and better outcomes.
  • Obtain stool samples as early as feasible for laboratory testing.
  • Prioritize magnetic resonance and ultrasound over radiographic imaging modalities to reduce cumulative radiation exposure.

References

  1. Rogler G, Singh A, Kavanaugh A, Rubin DT. Extraintestinal Manifestations of Inflammatory Bowel Disease: Current Concepts, Treatment, and Implications for Disease Management. Gastroenterology. 2021;161(4):1118-1132.
  2. Ballou S, Hirsch W, Singh P, et al. Emergency department utilisation for inflammatory bowel disease in the United States from 2006 to 2014. Aliment Pharmacol Ther. 2018;47(7):913-921.
  3. Park KT, Ehrlich OG, Allen JI, et al. The Cost of Inflammatory Bowel Disease: An Initiative From the Crohn’s & Colitis Foundation. Inflamm Bowel Dis. 2020;26(1):1-10.
  4. Goldstone RN, Steinhagen RM. Abdominal Emergencies in Inflammatory Bowel Disease. Surg Clin North Am. 2019;99(6):1141-1150.
  5. Noor NM, Sousa P, Paul S, Roblin X. Early Diagnosis, Early Stratification, and Early Intervention to Deliver Precision Medicine in IBD. Inflamm Bowel Dis. Published online September 4, 2021:izab228.
  6. Bjarnason I. The Use of Fecal Calprotectin in Inflammatory Bowel Disease. Gastroenterol Hepatol (N Y). 2017;13(1):53-56.
  7. Mortensen JH, Sinkeviciute D, Manon-Jensen T, et al. A specific calprotectin neo-epitope (CPa9-HNE) in serum from inflammatory bowel disease patients is associated with neutrophil activity and endoscopic severity. J Crohns Colitis. Published online March 19, 2022:jjac047.
  8. Griffey RT, Fowler KJ, Theilen A, Gutierrez A. Considerations in Imaging Among Emergency Department Patients With Inflammatory Bowel Disease. Ann Emerg Med. 2017;69(5):587-599.
  9. Cushing K, Higgins PDR. Management of Crohn Disease: A Review. JAMA. 2021;325(1):69-80.
  10. Esterson A, Alpert EA, Gabrieli S, Granat N. Sonographic assessment of inflammatory bowel disease in the emergency department: A case series and review of the literature. J Clin Ultrasound. 2021;49(3):277-281.
  11. Glick LR, Cifu AS, Feld L. Ulcerative Colitis in Adults. JAMA. 2020;324(12):1205-1206.
  12. Rosiou K, Selinger CP. Acute severe ulcerative colitis: management advice for internal medicine and emergency physicians. Intern Emerg Med. 2021;16(6):1433-1442.
  13. Verma A, Varma S, Freedberg DE, Axelrad JE. A Simple Emergency Department-Based Score Predicts Complex Hospitalization in Patients with Inflammatory Bowel Disease. Dig Dis Sci. 2022;67(2):629-638.
  14. Nguyen GC, Bouchard S, Diong C, Promoting Access and Care through Centres of Excellence (PACE) Network. Access to Specialists and Emergency Department Visits in Inflammatory Bowel Disease: A Population-Based Study. J Crohns Colitis. 2019;13(3):330-336.

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