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Investigations – Kidney


Ultrasound¬†is the simplest imaging test. ‘Jelly’ is placed on the side and front of your tummy which allows the radiologist to slide a probe over your skin. It uses sound waves to generate an image. There is no radiation used and therefore it is safe, even for pregnant ladies.

CT scanning gives much more detail but does utilise radiation. Performed without contrast injection it is the best test to look for stones and will define the number, size and position within the urinary tract. If intravenous contrast is also given then even more detail is available. This is helpful to define precise anatomy and to assess abnormalities such as tumours. The scan can also check for spread of tumours to other areas. This scan takes between 10 & 30 minutes. The patient lies on a narrow bed that is moved through a large white ring (often likened to a large polo mint!)

MRI scans are used less often but can be helpful for complex lesions which have not been characterised by other scans. They use magnets rather than radiation and for this reason may not be used for some patients with certain types of pacemaker. This scan takes between 30 & 45 minutes. The patient lies on a narrow bed that is moved through a tunnel. It is quite noisy and claustrophobic.

Nuclear medicine scans are used to define the split function between kidneys (normal is approx 50:50 for left and right kidney). They can also help define if a kidney is obstructed

Urine tests

A simple dip test can be carried out in the clinic. These look for evidence of blood, infection and protein.

A formal urine test can be sent the lab in a sterile pot where the sample is assessed microscopically looking for blood and white cells. Some of it is also put to culture to see if any bacteria grow in number. If they do then antibiotics can be tested against them to ascertain which would be the best treatment for that patient.

Urine cytology is occasionally used to look for evidence of cancer. The sample is assessed under a microscope to look for abnormal cells. It is a specific test but not very sensitive.

Blood tests

A simple blood test can be used to give a good estimate of your overall kidney function. The results are usually available within 24 hours