Case Presentation: A previously healthy 22-year-old male with a family history of Crohn’s disease presented with acute onset of lower abdominal pain and bloody diarrhea. He estimated that he had around seven episodes of loose stools with bright red blood but no mucus for two days. He did not have any fevers, emesis, recent travel history, antibiotic use, or sick contacts. The patient had never experienced these symptoms before. He had meals from local restaurants recently, but he had been to these restaurants before and others who had consumed the same food had not reported any symptoms. On admission, his vitals were notable for a temperature of 36.9 degrees Celsius, blood pressure of 159/92, and tachycardia of 110. Physical exam was significant for mild periumbilical tenderness to palpation without rebound or guarding. There were no rashes, petechiae, erythema nodosum, joint tenderness, oral ulcers, or mucosal bleeding. Labs were notable for WBC 15.7 x 10^9/L, lactate 2.5 mmol/L, C-reactive protein 3.47 mg/dL, erythrocyte sedimentation rate 10 mm/hr, Cr 0.8 mg/dL, CO2 23.5 mMol/L, and chloride 100mMol/L. CT A/P with contrast showed moderate colonic thickening from the cecum to the splenic flexure with surrounding inflammatory changes compatible with colitis. Given his imaging findings, clinical presentation, and family history of Crohn’s disease the plan was to proceed with colonoscopy to evaluate for inflammatory bowel disease (IBD). However, later in the admission his stool studies for GI pathogens returned positive for E. coli producing Shiga toxin 1 and his colonoscopy was no longer indicated. The patient received supportive care and was discharged home. His symptoms had resolved at his outpatient visit one week later.

Discussion: In this case, the medical team was initially biased by the patient’s family history of Crohn’s disease in a first-degree relative and of other autoimmune diseases. Crohn’s disease typically presents with chronic diarrhea without gross blood, right lower quadrant pain, and constitutional symptoms such as fatigue and weight loss. Ulcerative colitis (UC) presents with chronic diarrhea that may be bloody and colicky abdominal pain, urgency, tenesmus, or incontinence. Anemia, vitamin or mineral deficiencies, and extraintestinal manifestations can also be seen with both types of IBD (1). However, this patient’s presentation with an acute symptom onset, grossly bloody stools, lack of systemic symptoms or extraintestinal manifestations, and non-specific physical exam findings, lacked the cardinal symptoms of IBD and were more consistent with an infectious etiology (2). This is an example of anchoring, relying too heavily on one piece of data, due to this patient’s family history. It also exemplifies premature closure, assigning a diagnosis prior to collecting all the data. This patient may have undergone an unnecessary colonoscopy and evaluation for IBD if the diagnostic evaluation for infectious diarrhea had not been completed.

Conclusions: Cognitive biases have been associated with diagnostic inaccuracies and ultimately suboptimal clinical management. By recognizing these cognitive biases and maintaining a broad differential diagnosis, providers may be able to reduce unnecessary testing; thereby, practicing high-value care and providing better patient care.