Lab Tests and Imaging Services: When You Need Them and How to Prepare

You’ve been told you need blood work, an X‑ray, or maybe an MRI—now what? For many people, lab tests and imaging services feel mysterious and even a little intimidating. Yet they are some of the most common tools used in modern health care to understand what is happening inside the body.

This guide walks through what these tests are, why they’re ordered, and how to prepare so you can feel informed, calm, and confident at your next appointment.

What Are Lab Tests and Imaging Services?

Lab tests and imaging services are different ways of gathering information about your health.

• Lab tests analyze samples from your body—usually blood, urine, stool, or tissue.
• Imaging services create pictures of the inside of your body, using technologies like X‑rays, sound waves, magnets, or radioactive tracers.

Together, they help health professionals:

• Look for signs of disease or infection
• Monitor ongoing conditions
• Check how treatments are working
• Screen for potential health issues early

They don’t replace a physical exam or your medical history, but they often add essential details that can guide next steps.

Why and When Lab Tests Are Typically Ordered

Lab tests are a broad category. Understanding why they might be ordered can make them feel less random and more purposeful.

Common Reasons for Lab Tests

Health professionals may order lab tests to:

• Investigate symptoms (like fatigue, pain, fever, or weight changes)
• Monitor chronic conditions (such as diabetes, kidney disease, or thyroid disorders)
• Check organ function (liver, kidneys, heart, thyroid, etc.)
• Screen for conditions (such as anemia, high cholesterol, or infections)
• Support medication decisions (for example, checking levels of certain drugs)
• Before surgery or procedures, to ensure it’s safe to proceed

Types of Lab Tests You Might Encounter

Here are some of the most common categories and what they typically look for:

Not every test in these categories applies to every person. Which tests are used depends on your specific situation, symptoms, and health history.

Why and When Imaging Services Are Typically Ordered

Medical imaging shows structures inside the body that cannot be seen from the outside. Different imaging tools are better for different questions.

Common Reasons for Imaging

Imaging services may be ordered to:

• Look for fractures, sprains, or joint problems
• Investigate pain in areas like the head, chest, abdomen, or back
• Check for growths, lumps, or abnormalities
• Monitor the size or appearance of known conditions
• Guide certain procedures, such as biopsies or injections

Types of Imaging You Might Hear About

Here are some frequently used imaging methods and how they’re commonly used:

Each type has its own benefits, limitations, and preparation steps, which we’ll cover in more detail.

How to Prepare for Common Lab Tests

Preparation can affect how accurate and useful your results are. Not all tests require special preparation, but some do.

General Tips Before Any Lab Test

A few basics apply across many types of lab work:

• Ask ahead:

  • Do I need to fast?
  • Can I take my regular medications?
  • Are there foods or drinks I should avoid?

• Bring information:

  • A list of medications and supplements
  • Previous relevant test results if you have them

• Stay hydrated (when allowed):

  • Drinking water often helps with blood draws and urine samples.

• Wear practical clothing:

  • Short sleeves or loose sleeves can make blood draws easier.

Fasting Blood Tests

Many blood tests can be done at any time, but some require fasting for a certain number of hours. Fasting typically means:

• No food or drinks except water
• Sometimes no certain medications or supplements, if instructed

Fasting is commonly requested for:

• Lipid panels
• Certain glucose or metabolic tests

📝 Preparation pointers for fasting tests:

• Schedule the test earlier in the day if possible.
• Drink plain water unless told otherwise.
• Avoid gum, candy, or flavored drinks during the fasting period.
• Ask what to do about morning medications, especially if they must be taken with food.

Urine Tests

Urine tests can be used to check kidney function, look for infections, or monitor specific health conditions.

Common types:

• Random/spot urine sample – given at any time of day
• First-morning sample – often more concentrated and useful for some tests
• 24-hour collection – all urine over a full day is collected in a special container

💧 How to prepare:

• You may be asked to avoid certain foods or medications that can change urine color or composition.
• For clean-catch samples, you may be asked to follow specific cleaning instructions before collecting.
• For 24‑hour urine tests, you’ll typically get:
  • A collection container
  • Instructions on storage (often in a cool place)
  • A start and end time

Stool Tests

Stool (fecal) tests can help look for infection, blood, or digestive issues.

Preparation can include:

• Diet instructions a few days before (for some tests)
• Possible medication adjustments, especially drugs that affect digestion or bleeding

Most stool tests come with detailed collection instructions. Following them closely is important so the sample is usable.

Tissue or Cell Samples (Biopsies, Pap Tests)

Some lab tests analyze cells or tissue:

• Biopsies: A small piece of tissue is taken to look at under a microscope.
• Pap tests: Collect cells from the cervix for examination.

Preparation can vary widely based on the area being sampled. Often you’ll receive specific instructions about:

• Eating or drinking before the procedure
• Medications
• How to care for the area afterward

When in doubt, ask for written instructions you can review at home.

How to Prepare for Common Imaging Services

Imaging tests vary widely in how they’re performed and what preparation they require. Many are straightforward and brief, while others require more planning.

X‑rays

What to expect:

• Usually quick—often just a few minutes.
• You may stand, sit, or lie down depending on the body part being imaged.
• You’ll need to stay very still while the image is taken.

📌 Typical preparation:

• Remove jewelry, glasses, and any metal in the area being imaged.
• Wear comfortable clothing; you may be given a gown if needed.
• In many cases, no special diet or fasting is required.

If there is any chance of pregnancy, it is standard to mention this before an X‑ray.

Ultrasound

Ultrasound is often experienced as painless and noninvasive. A small device called a transducer is moved over the skin with gel or, in some exams, placed internally.

⏱ Preparation depends on the area being imaged:

• Abdominal ultrasound:

  • You may be asked not to eat or drink for several hours beforehand to reduce gas and improve image quality.

• Pelvic ultrasound:

  • You may be instructed to drink water and keep a full bladder, which helps improve visibility.

• Cardiac ultrasound (echocardiogram):

  • Often no major preparation; you might be asked to avoid caffeine or heavy meals in some cases.

Comfort tips:

• Wear loose, two-piece clothing to easily expose the area being scanned.
• Bring a light sweater or layer if clinics tend to feel cold.

CT (Computed Tomography) Scans

CT scans provide detailed cross-sectional images. Some use a contrast material (by mouth, injection, or both) to highlight certain structures.

🧾 Common preparation steps:

• Fasting:

  • You may be told not to eat or drink for several hours, especially if contrast will be used.

• Contrast questions:

  • You may be asked about past reactions to contrast dyes.
  • Information about kidney function can be relevant for certain contrast types.

• Clothing & metal:

  • Remove jewelry and wear clothing without metal fasteners or zippers, or change into a gown.

During the scan, you lie on a table that moves through a large ring-shaped machine. You’ll usually need to hold still and sometimes hold your breath briefly.

MRI (Magnetic Resonance Imaging)

MRI uses strong magnetic fields. Because of that, metal safety is especially important.

⚠️ Key preparation points:

• Metal screening:

  • You’ll be asked about implants, pacemakers, certain surgical clips, or metal fragments.
  • All jewelry, watches, hearing aids, and removable metal items are typically taken off.

• Clothing:

  • You may be given a gown. If you wear your own clothes, they usually must be free of metal snaps, zippers, underwire, or metallic prints.

• Food and drink:

  • Sometimes no special restrictions; other times, fasting is recommended depending on the type of MRI and whether contrast is used.

• Contrast considerations:

  • You may receive an injection with contrast material to improve image detail.

Many people find MRIs noisy and sometimes confining. To prepare:

• Ask if ear protection is provided (it usually is).
• Ask about options if you feel claustrophobic, such as open MRI designs or calming strategies.

Mammograms

Mammograms are specialized X‑rays of breast tissue typically used for screening or evaluation of concerns.

🎗 Preparation tips:

• On the day of the exam, avoid deodorant, lotions, or powders on the chest or underarm area, as these can appear on the images.
• Wear a two-piece outfit, since you’ll usually undress from the waist up.
• If breasts are sensitive, some people prefer to schedule the exam at a time when they tend to have less tenderness.

During the test, the breast is placed on a platform and gently compressed for a few seconds to spread out the tissue.

Nuclear Medicine and PET Scans

These imaging tests use a small amount of radioactive tracer. The tracer may be swallowed, injected, or inhaled, and images are taken as it travels through the body.

🧭 Typical preparation:

• You may be asked to avoid certain foods or drinks for a set period.
• In some cases, caffeine, alcohol, or tobacco are restricted.
• You might be instructed about medications to pause or continue.

After the scan, you may be given instructions like drinking plenty of fluids to help flush the tracer from your system.

Safety, Risks, and Common Concerns

It’s natural to wonder about radiation, side effects, or discomfort related to tests.

Radiation Exposure

Some tests involve radiation (for example, X‑rays, CT scans, and certain nuclear medicine procedures). In general:

• Imaging centers aim to use the lowest radiation level that still provides a clear image.
• Not every imaging question requires radiation; options such as MRI and ultrasound do not use ionizing radiation.

Health professionals typically weigh the benefits of the information gained against the amount of exposure involved. If you have questions, it is reasonable to ask how the test helps and whether alternatives exist.

Discomfort and Side Effects

Most lab tests and imaging procedures are tolerated well. Some common experiences include:

• Blood draws: brief needle pinch; possible minor bruising afterward
• Contrast injections: warm feeling, metallic taste, or brief sense of flushing
• Imaging positions: holding still or lying in certain positions can be uncomfortable for some people
• Compression (mammograms): temporary pressure, sometimes uncomfortable but typically short-lived

Any unusual sensations or strong reactions should be reported to the staff immediately during the test.

Understanding Your Results: What to Expect

Interpreting lab and imaging results often involves context—your symptoms, medical history, medications, and other findings.

How Results Are Typically Shared

Depending on the health care setting, results may be:

• Reviewed with you at a follow-up visit
• Delivered through a patient portal
• Shared by phone or letter

It’s common to see:

• Numbers with reference ranges on lab reports
• Descriptions like “normal,” “mildly elevated,” or “requires follow-up”
• Imaging reports that describe what was seen and how it compares to expectations

A value outside a “normal” range does not always mean something is wrong. Sometimes results slightly outside the typical range are still acceptable depending on the person and the situation.

Questions You Might Ask About Results

To better understand results, some people find it helpful to ask:

• What was this test looking for?
• Were any results outside the expected range?
• How do these findings fit with my symptoms or overall health picture?
• Are any next steps suggested, such as repeat testing or additional evaluation?

Practical Tips to Make the Process Easier

These simple strategies can make lab tests and imaging feel more manageable.

🧾 Before Your Appointment

• Write down questions you want to ask.
• Confirm:
  • Location and time
  • Whether you need to fast or adjust medications
  • If you should arrive early for paperwork
• Bring:
  • A list of medications and supplements
  • Any relevant previous reports if requested

🧍 During the Test

• Let staff know about:

  • Allergies or past reactions to test materials
  • Implants, medical devices, or pregnancy
  • Difficulty lying flat, staying still, or feeling confined

• Ask what you can expect:

  • How long it will take
  • What you will feel or hear
  • When you can resume normal activities

📄 After the Test

• Ask when and how results will be available.
• Keep a personal record of major tests and imaging for your own reference.
• Note any symptoms or issues you experience after the test and share them if needed.

Quick Reference: Common Tests and How to Prepare

Here’s a compact overview you can skim before appointments:

⛑️ Always follow the instructions you are given for your specific test, as they may differ from general patterns.

Key Takeaways to Feel More Prepared 👍

Here is a quick summary of practical points you can use right away:

• 🧠 Know the purpose: Understanding why a test or scan is ordered can make the process less stressful.
• ⏰ Ask about preparation: Fasting, medication adjustments, or special instructions can significantly impact accuracy.
• 💧 Hydrate when allowed: Water often helps with blood draws and urine tests.
• 🧥 Dress thoughtfully: Loose, comfortable clothing and minimal metal make many tests smoother.
• 🗣️ Speak up about concerns: Claustrophobia, past reactions, or discomfort are important to mention.
• 📂 Track your results: Keeping personal copies of key lab and imaging results can help you understand changes over time.
• 🔄 View results in context: Numbers and images are part of a bigger picture that includes how you feel and your overall health story.

Understanding lab tests and imaging services turns them from something mysterious into practical tools that support informed decisions about your health. By knowing when they’re used, what they involve, and how to prepare, you can take an active, confident role in your own health care experience.