The clinical workup: from first complaint to diagnosis

Every case starts the same way: a person, a problem and a short sentence that frames it. A 67-year-old woman presents with shortness of breath. Everything that follows, the questions, the examination and the tests, is a structured way of shrinking the list of things that sentence could mean.

This guide walks through that process, the clinical workup, the way it is taught in medical school and used on the wards. It is also exactly the loop you run in Stat!'s Syndrome game.

Start with hypotheses, not with a checklist

Experienced clinicians do not collect every possible fact and then think. They start generating possible diagnoses within seconds of hearing the presenting complaint, then ask the questions that best separate those possibilities. Researchers call this hypothetico-deductive reasoning: propose, test, revise.

For shortness of breath in an older adult, an early list might include heart failure, a flare of chronic obstructive pulmonary disease (COPD), pneumonia, pulmonary embolism and anemia. None of those is confirmed yet. The point of the list is to tell you what to ask next.

The history does most of the work

In a classic 1975 study of medical outpatients published in the BMJ, the history alone pointed to the final diagnosis in about four out of five patients. Examination and tests mattered, but mostly to confirm or refine what the history had already suggested. Later studies have found similar results. That is why clinicians spend so long talking before they start examining.

A complete history usually covers:

• Presenting complaint: the main problem, in the patient's words.
• History of the presenting complaint: when it started, how it has changed and what makes it better or worse. For pain, many students use the mnemonic SOCRATES: site, onset, character, radiation, associated symptoms, time course, exacerbating and relieving factors, and severity.
• Past medical history: previous illnesses, operations and hospital stays.
• Medications and allergies, including over-the-counter drugs and supplements.
• Family history: conditions that run in families, such as early heart disease or some cancers.
• Social history: smoking, alcohol, recreational drugs, occupation, travel and home situation.
• Review of systems: a quick sweep through each body system to catch anything missed.

Pertinent positives and pertinent negatives

A symptom that is absent can be as useful as one that is present. If you suspect pneumonia, the absence of fever and cough makes it less likely. If you suspect heart failure, the absence of ankle swelling and breathlessness when lying flat counts against it. Clinicians record these deliberately as pertinent negatives.

In Syndrome, a finding marked absent is not a wasted question. It removes diagnoses from your list just as surely as a positive finding adds weight to others.

Red flags

Some features change how urgently a problem needs attention, whatever the final diagnosis turns out to be. Examples include chest pain with fainting, a sudden "worst ever" headache, weakness on one side of the body, vomiting blood, and unexplained weight loss with night sweats. Recognizing red flags early is one of the main goals of a good history.

The examination: vital signs first, then targeted

The physical examination begins with the vital signs: temperature, heart rate, blood pressure, breathing rate and oxygen saturation. They are fast, cheap and often the first sign that someone is seriously unwell. (Our guide to vital signs covers them in detail.)

After that, the examination is guided by your hypotheses. For shortness of breath you would listen to the heart and lungs, look at the neck veins, check the legs for swelling and look for signs of a clot. The classic sequence for each system is inspection, palpation, percussion and auscultation: look, feel, tap and listen.

Investigations: order tests to answer a question

Tests are most useful when you know what you will do with the result. Before ordering one, it helps to ask: Which of my possible diagnoses would this result make more or less likely? A test that cannot change your thinking is rarely worth doing.

Investigations fall into a few broad groups:

• Bedside tests, such as an electrocardiogram (ECG), a finger-prick glucose or a urine dipstick.
• Laboratory tests, such as a full blood count, kidney function, liver tests or cardiac markers. See reading lab results.
• Imaging, from a chest X-ray to ultrasound, CT and MRI. See imaging basics.
• Specialised tests, such as biopsies, cultures, genetic tests or lung function testing.

No test is perfect. Some are good at ruling a disease out when negative, others at ruling it in when positive, and the same result can mean different things in different patients. Our guide to differential diagnosis explains how clinicians account for that.

Putting it together: the problem representation

Before settling on a diagnosis, clinicians often summarize the case in a single sentence called a problem representation. It uses precise descriptive words, sometimes called semantic qualifiers: acute or chronic, one-sided or both sides, constant or intermittent.

A 67-year-old woman with a long smoking history presents with two days of worsening breathlessness, productive cough and fever, with crackles at the right lung base.

That sentence already points strongly towards pneumonia, and it tells you which test to order next: a chest X-ray. Compare it with a 67-year-old woman presents with sudden breathlessness and sharp chest pain on breathing in, three days after hip surgery, which raises pulmonary embolism to the top of the list.

Worked example: a short workup

Here is how the loop plays out for our breathless patient.

1. First hypotheses: heart failure, COPD flare, pneumonia, pulmonary embolism, anemia.
2. History: two days of productive cough and fever, no leg swelling, no recent surgery or travel. Pneumonia moves up; pulmonary embolism and heart failure move down.
3. Examination: temperature 38.6 °C, breathing rate 24 per minute, oxygen saturation 91%, crackles at the right base. Pneumonia is now the leading diagnosis, and the vital signs show it is significant.
4. Investigations: a chest X-ray shows consolidation in the right lower lobe; blood tests show a raised white cell count and C-reactive protein. The diagnosis of pneumonia is confirmed, and the numbers help judge how unwell she is.

Notice that each step was chosen because it separated the possibilities, not because it was next on a list.

How this maps onto Syndrome

Syndrome gives you a presentation and lets you run the workup yourself:

• Symptoms stand in for the history.
• Vitals stand in for the bedside examination.
• Labs and imaging are your investigations.

Each finding comes back labeled: symptoms are present or absent, blood tests high, low or normal, and vitals and imaging normal or abnormal. Investigations are free, but you only get six diagnosis attempts, so the winning strategy is the clinical one: form a short list early, pick the question that best splits it, and only commit to a diagnosis once the findings point clearly one way. Our Syndrome guide covers the game's rules and strategy in detail.