A DMSA renal scan is a nuclear-medicine test used to assess functioning renal cortex, relative uptake, and areas that may represent renal damage or scarring. DMSA stands for dimercaptosuccinic acid, a compound that localizes in functioning kidney cortex.
During the scan, a tiny amount of a radioactive tracer is injected into your vein. After waiting a few hours for the kidneys to absorb the tracer, a specialized camera takes images. Areas of healthy kidney tissue will absorb the tracer and glow, while scarred or damaged areas will not.
Common Indications for a DMSA Renal Scan
- Checking for kidney scarring caused by recurrent urinary tract infections (UTIs) or kidney infections (pyelonephritis).
- Evaluating children with vesicoureteral reflux (VUR), where urine flows backward from the bladder to the kidneys.
- Investigating congenital kidney abnormalities (such as an ectopic or horseshoe kidney).
- Assessing the relative function of each kidney (determining if one kidney is doing more work than the other).
What exactly does a DMSA renal scan show?
The scan shows functioning renal cortex and estimates the relative contribution of each kidney. Areas of reduced uptake may represent scarring but can also be affected by acute infection, congenital change, movement, or technical factors; the percentages are estimates, not exact measurements of total kidney function.
How should I prepare for a DMSA renal scan?
Fasting is not usually required, but follow the department's instructions. Hydration advice should account for any fluid restriction. For a child, bring suitable comfort or distraction items and ask beforehand whether immobilization or, rarely, sedation is anticipated.
Do I need to stop taking medication?
Do not stop prescribed medicines on your own. Give the team a complete medicine history, including antibiotics and the timing of any recent urinary infection, because these details affect scheduling and interpretation.
What happens when I arrive for my scan?
You will go to the nuclear medicine suite. A nurse will insert an IV line and inject the DMSA tracer. You will then have a 2 to 3 hour waiting period to allow the kidneys to absorb the tracer. You can leave the clinic during this wait, eat, and drink normally.
How is the procedure performed?
After the waiting period, you will return. You will lie flat on your back on a scan table. A large gamma camera will be positioned close to your abdomen and back. The camera will take images for about 15 to 20 minutes. You must lie completely still. The camera does not touch you or emit any radiation.
How long does a DMSA renal scan take?
The imaging part takes about 20 minutes. However, including the 2 to 3 hour waiting time after the injection, the entire process takes about 3 hours.
Is there any discomfort?
The scan itself is painless. You will feel a brief pinch from the IV needle during the injection. The tracer does not cause any side effects or sensations.
Are there risks?
The tracer exposes the patient to ionizing radiation; the administered activity is adjusted for children. The dose should not be equated with a generic X-ray because exposures differ by examination and patient. Follow the team's hydration, toileting, and contact advice.
Can children have this scan?
Yes. This scan is very commonly performed on young children who have had severe urinary tract infections. Pediatric teams are specially trained to insert IV lines gently and make children comfortable on the scan table.
Can I have this scan if I am pregnant?
Pregnancy Precaution
Tell the team if you are pregnant or may be pregnant. The examination is generally deferred when a suitable alternative can answer the question, but an urgent test may be considered after individual justification.
When will I get my results?
A nuclear medicine specialist will analyze the images. A report will be sent to your referring doctor (often a pediatrician or urologist) within 24 hours.
What if the scan finds something?
If the scan shows kidney scarring or reduced function in one kidney, your referring doctor will discuss management. This may involve long-term antibiotics to prevent infections, further urological testing, or surgery to correct urinary reflux.
What are the important limitations and safety checks?
DMSA estimates cortical uptake and differential function; it does not directly measure overall glomerular filtration. Acute infection, congenital variants, obstruction, patient motion, and scan timing can mimic or obscure defects. Results should be correlated with the timing of infection, ultrasound, urine and blood tests, and the clinical history.
Preparation and radiation precautions are radiopharmaceutical- and protocol-specific. Tell the department before the tracer is given if you are or may be pregnant, are breastfeeding, care for a young child, or recently had another nuclear-medicine test. Do not stop medicines, fast, interrupt breastfeeding, or follow a fixed distancing period based only on a general webpage; obtain written instructions for the exact tracer, activity, and examination from the nuclear-medicine team.
Questions to ask your nuclear-medicine team
- Which radiopharmaceutical and protocol will be used, and what clinical question should the study answer?
- What exact fasting, hydration, medicine, diabetes, pregnancy, or breastfeeding instructions apply to me?
- Will CT be included, will contrast be used, and how does that change preparation and radiation exposure?
- What written precautions apply afterward, when will the signed report be ready, and who will explain any next step?
Sources and further reading
- RadiologyInfo.org: General nuclear medicine
- RadiologyInfo.org: Preparing for a nuclear-medicine examination
- IAEA: Basics of quality management for nuclear medicine practices
Conclusion
A DMSA scan is a highly precise way to check for kidney damage and scarring. Remember to drink plenty of fluids before and after the scan, and prepare for the 2 to 3 hour waiting time between the injection and imaging.