1 Foundations of Diagnostic Testing and Patient Preparation

Preparation begins with clear instructions

Good preparation supports patient safety and helps produce reliable test results. Preparation varies by test, so follow the specific instructions from the ordering clinician and testing facility. If instructions are unclear, or the patient could not follow them, tell the care team before testing.

Consent and patient understanding

A signature alone does not establish Informed consent. The patient needs information they can understand to make a voluntary decision. If a patient has unanswered questions or does not understand what is planned, pause the procedure and contact the responsible clinician before proceeding. Consent requirements vary by procedure and applicable policy.

Verify identity before testing

Before collecting a blood specimen, use at least Two person-specific identifiers, such as the patient’s name and date of birth, and match them to the order. Do not use a room number as an identifier. Label the specimen in the patient’s presence according to facility policy.

Assess the patient’s current condition

Complete a Baseline assessment before testing. Assess the patient’s current condition and report a new or concerning change, such as new dizziness, to the responsible clinician. Relevant baseline information may include symptoms, vital signs, medical conditions, current medications, allergies, and pregnancy possibility when relevant to the test. This information helps the team determine whether the test can proceed safely and provides context for interpreting findings.

Review medicines and supplements

Medication instructions depend on the test and the patient’s condition. Patients should disclose prescription medicines, over-the-counter medicines, vitamins, and supplements, and ask the care team how to manage them. Some tests require medication adjustments, but patients should not stop or change medicines on their own, even when they have been told to fast.

Confirm fasting requirements

Not all blood tests require Fasting. Confirm whether it is required and for how long, and follow the specific directions about water and other restrictions. Plain water is allowed for many fasting blood tests, but the patient’s own instructions take priority. If the patient ate or drank something they were told to avoid, they should report it rather than conceal it.

Follow preparation for the specific test

MRI

MRI safety screening checks for implants, devices, or metal that may pose a risk. The patient should report implants or devices, complete the screening, and remove items as directed.

Colonoscopy

Colonoscopy preparation typically includes a prescribed Bowel preparation plan. Patients should discuss medicines or supplements with the clinician; medication changes should be directed by the clinician.

CT with contrast

For a CT with intravenous contrast, report any prior contrast reaction, kidney disease, allergies, and medicines. Ask what happened during a previous reaction and communicate that information to the radiology team. The team assesses contrast risks and determines appropriate precautions or alternatives; do not assume an allergy label or prior reaction automatically determines the plan. CT preparation varies, so follow the facility’s specific eating and drinking instructions.

Coordinate a safe testing plan

Before a diagnostic test, verify identity, confirm that required consent is understood, assess relevant baseline information, and review medicines, fasting instructions, allergies, and test-specific risks. Do not guess about preparation or independently stop a medicine. Clarify uncertainties with the care team and report any instructions the patient could not follow.