Differentialdiagnoser

Differentialdiagnoser, or differential diagnoses, is a method in medicine for listing and evaluating all plausible conditions that could explain a patient’s symptoms, signs, and test results. The aim is to identify the most likely diagnosis while excluding serious alternatives that require urgent treatment.

Process: clinicians collect history and perform a physical examination to generate a broad differential. This list is then prioritized by likelihood and potential seriousness. Targeted investigations—laboratory tests, imaging, and other studies—are chosen to confirm or exclude high-priority possibilities. As information evolves, the differential is revised, and treatment decisions are guided by the most probable diagnoses and the need to address dangerous conditions promptly.

Key concepts include pretest probability and Bayesian reasoning: diagnostic tests are interpreted in light of how likely a condition was before testing. Decision rules or diagnostic pathways can help structure the process and reduce omissions. Clinicians must balance common causes with rare but critical conditions and consider patient context, prevalence, and local patterns.

Limitations and challenges: incomplete data, time pressure, and cognitive biases such as anchoring or premature closure can impair judgment. A well-documented differential diagnosis improves communication and safety, ensuring monitoring for red flags and timely escalation when necessary. Examples commonly discussed include chest pain (myocardial infarction, pulmonary embolism, aortic dissection) and abdominal pain (appendicitis, diverticulitis, pancreatitis).