Test Preparation Guides
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Learn what to expect when visiting the Emergency Department. Learn More
Overview
Preparation matters. The right fasting, the right hydration, the right time of day — these affect the accuracy of your test result. A poorly prepared test sometimes has to be repeated, which costs time, money, and inconvenience. This page summarises the preparation for the most common tests at St. Stephen’s Hospital. For each test, the dedicated test page has the full detail; this guide gives the essentials in one place.
General principles
- Bring your doctor's prescription, ID proof, and previous reports.
- Tell us about all medications and supplements — not just prescription medicines.
- Drink plain water normally — being well-hydrated is good for almost every test.
- Wear loose, comfortable clothing. Avoid jewellery and metal accessories if having a scan.
- Arrive 15 to 30 minutes before your scheduled time for registration.
- Tell us if you are pregnant, might be, or are breastfeeding.
Fasting requirements
Tests that usually require fasting (8 to 12 hours)
- Fasting blood sugar (FBS)
- Lipid profile (cholesterol, triglycerides)
- Liver Function Test (LFT) — usually fasting
- Iron studies
- Upper abdominal ultrasound (gallbladder, liver, pancreas)
- Endoscopy, colonoscopy, bronchoscopy (6 to 8 hours)
Tests that do NOT require fasting
- Complete Blood Count (CBC)
- HbA1c (3-month sugar)
- Thyroid profile
- Most hormones (other than fasting-specific ones)
- Kidney Function Test alone
- ECG, ECHO, standard X-Ray, MRI (most)
Hydration requirements
Tests that need a full bladder
- Pelvic ultrasound (uterus, ovaries, bladder, prostate)
- Lower abdominal ultrasound in some cases
- Recommendation: 4 to 6 glasses of water 1 to 2 hours before the scan. Do not empty your bladder until after.
Tests that need extra hydration
- CT or MRI with contrast — drink extra water for the day
- Kidney function tests — be well-hydrated the day before
Medication considerations
Most medicines can be taken as usual. Some — particularly blood thinners before invasive procedures, certain inhalers before PFT, biotin before thyroid tests, iron before iron studies — need to be paused. Never stop a medication without first checking with the team.
Common medication-related rules
- Blood thinners (aspirin, clopidogrel, warfarin, apixaban, etc.): tell us before any biopsy, endoscopy, or angiography. Some may need to be stopped a few days before.
- Diabetes medication (especially metformin): may need to be paused before contrast CT scans.
- Thyroxine (Eltroxin, Thyronorm): take it AFTER the thyroid blood test, not before.
- Inhalers: for PFT, certain inhalers are paused — your team will confirm which and for how long.
- Biotin supplements (often in skin/hair products): stop 3 days before any thyroid test.
- Iron supplements: stop 24 hours before iron studies; stop 5 to 7 days before a colonoscopy.
Frequently asked questions
Tell the team — they will decide whether the test can still be done. For some tests (a CBC, for example) it does not matter. For others (fasting glucose, lipid profile) the test should be rescheduled. Doing it anyway gives a result that is not useful.
Plain water is generally allowed and encouraged. Coffee, tea, juice, and milk are not — they affect blood sugar, lipids, and many other tests.
Most medications can be taken with a small sip of water. Specific exceptions — thyroxine before a thyroid test, oral diabetes medicines before fasting glucose, blood thinners before procedures — are listed above. When in doubt, ask before the day.
For routine urine tests, menstrual blood can interfere with results — it is usually worth waiting unless the test is urgent. For pelvic ultrasound, it is usually fine, though abdominal ultrasound may give clearer images. Tell the team and they will advise.
Avoid heavy exercise within 24 hours of muscle-related blood tests (creatinine, CPK, LFT) and within a few hours of an ECG. Light walking is generally fine.