Common Urological Investigations | PSA | Cystoscopy

There are many types of investigations within urology, ranging from blood tests to nuclear medicine scans. In clinical practice, some are used far more frequently than others, with some requiring specialist input. Urological tests can often overlap with renal investigations due to the nature of the pathology.

It is not essential to be able to interpret the more complex investigations, but it is good to have a basic understanding of tests you may come across within this specialty.

Bedside investigations

Bladder diary

A bladder diary is typically a three-day diary recorded by the patient, used to assess bladder function. The diary specifically looks at the total volume input, urinary frequency and urinary volume over each 24 hour period.

This is beneficial when a patient presents with urinary incontinence, helping to establish micturition patterns and determining the next steps for treatment. 

Digital rectal examination

A digital rectal examination (DRE) is key for determining the size, shape and texture of the prostate. The peripheral zone is where most cancers arise, which can be palpated anterior to the rectum. A DRE is one of the first-line investigations for any male patient with urinary symptoms.

Not all prostate cancers are palpable, specifically those that are not in the peripheral zone. This examination is an adjunct to formulating differential diagnoses. 

Urine investigations

Urinalysis

Urinalysis is a preferred initial screening tool to identify signs of infection (raised nitrites, leukocytes). The majority of patients presenting to the emergency department will have this done.

It is not typically recommended in patients with catheters, as they are prone to colonise various bacteria. If a urinary tract infection (UTI) is suspected, a culture should be sent. 

Microscopic haematuria can be a sign of infection; other causes include menstruation, ureteric stones or malignancy.

Urine culture

Urine culture enables the identification of the causative organism of a renal or urinary tract infection, allowing for targeted antibiotic treatment.

Albumin-creatinine ratio

Albumin-creatinine ratio (ACR) is a urinary test commonly used in renal medicine; a raised ACR often indicates a pathological process occurring at the podocytes (e.g. diabetes mellitus).

This is particularly helpful when monitoring renal transplant patients to assess graft function. If elevated, this raises suspicion of rejection or other disease processes within the transplanted kidney. 

Blood tests

Urea and electrolytes

Raised urea and creatinine can indicate renal impairment, which can be acute or chronic. This may be due to pre-, intra- or post-renal pathology.

Urology mainly manages obstructive pathology, such as ureteric compression from a tumour, ureteric stones, urinary retention, etc.

Prostate-specific antigen (PSA)

Often used to aid in the diagnosis of and monitor prostate cancer.

Not all cases of elevated PSA are confirmatory of malignancy and can be related to benign diseases (e.g. benign prostatic hyperplasia, prostatitis, urinary tract infections). Therefore, an isolated PSA does not always indicate malignancy, and it is often advised to be repeated if the test has been sent during a time of infection. 

Radiological investigations

Ultrasound (US)

Ultrasound is preferred in children due to the lack of ionising radiation.

It can be useful initially to identify any signs of obstruction (e.g. renal calculi, abscess, or hydronephrosis), and it is also used in paediatrics to assess bladder development and detect abnormalities (e.g. cysts, tumours, etc.).

Ultrasound can be useful as a bedside test for post-void residual volume scans, should concerns arise over urinary retention. In adults, if the post-void scan shows >200 mL in the bladder, this is considered abnormal and catheterisation should be considered.

X-ray (XR)

X-ray is a common initial investigation (particularly of the kidney, ureters, and bladder (KUB)) to identify radio-opaque stones or staghorn calculi.

Intravenous urography (IVU) is a form of X-ray, but is rarely performed if CT is available and tends not to be performed within the UK. This technique utilises contrast to visualise the course of the ureters and assess for ureteric obstruction, particularly in relation to ureteric calculi. 

A micturating cystourethrogram (MCUG) also uses X-rays and is often used in children to determine structural or anatomical variations (e.g. posterior urethral valves). This is often requested in conjunction with a DMSA or MAG3 scan to establish if the anatomical abnormality has impaired the kidney function due to back-pressure. 

Computerised tomography (CT)

A CT KUB is a non-contrast scan. This is the preferred initial investigation for symptoms of renal colic, as it is a quick way to assess for calculi and obstruction.

CT urography uses contrast to illustrate the urinary system in more detail, however, this requires a higher dose of radiation in comparison to a CT KUB. This is a preferred scan if there is a suspicion of urothelial carcinoma. 

Multi-phase or triple-phase CT includes non-contrast, nephrographic and excretory phases. This is similar to CT urography, however the multiple phases allow identification of the contrast pattern at multiple points. This helps to further evaluate a renal mass by determining its precise location and composition.¹

Magnetic resonance imaging (MRI)

MRI urography can be used to delineate the urinary tract in a similar fashion to CT urography. This is often requested if patients are pregnant, young, or have an allergy to the contrast used in CT. 

Prostate MRI can help diagnose prostate cancer, guide biopsy sites and assist with surveillance. A ‘prostate MRI’ typically refers to a multiparametric MRI (mpMRI), which differs from a standard MRI. A standard MRI only highlights T1- and T2-weighted images; an mpMRI includes T2-weighted, diffusion-weighted, and dynamic contrast-enhanced imaging to allow for higher sensitivity and specificity in detecting prostate cancer.²

Nuclear medicine scans

Dimercaptosuccinic acid (DMSA)

Static renal scintigraphy images the renal cortex by administration of a radiotracer. Due to the retention of this substance, the level of renal scarring can be determined. This may be requested pre-operatively to assess renal function if the patient is scheduled for a partial or complete nephrectomy.³

Diethylenetriamine pentaacetate (DTPA)

Dynamic renal scintigraphy assesses for mechanical obstructions, perfusion abnormalities, and renal function. It is often performed when the patient requires concurrent measurements of glomerular filtration rate.

Mercaptoacetyltriglycine (MAG3)

Similar to a DTPA scan, however, MAG3 is the preferred agent for imaging-only studies and is recommended for those with impaired renal function, as it exhibits higher levels of extraction at the proximal convoluted tubules, meaning that more radiotracer is filtered out compared to DTPA.⁴

Endoscopy

Cystoscopy

Provides direct visualisation of the urethra and bladder, and is the gold standard for investigating signs and symptoms relating to bladder cancer.

This can be flexible or rigid. Flexible is typically used in the context of diagnosis and under local anaesthesia; rigid is used for biopsies and resection.

Ureteroscopy

Provides direct visualisation of the urethra, bladder, ureter and renal pelvis. This has similar functions to a cystoscope and is the primary intervention for urolithiasis.

It can be flexible or semi-rigid. Semi-rigid is for the distal ureter, whereas the flexible scope is better suited for the mid to proximal ureter. Ureteroscopy can also be performed retrograde (via the urethra) or antegrade (via a percutaneous nephrostomy).

Other

Uroflowmetry

A non-invasive technique to measure the flow rate and volume of urine excretion. This is performed by urinating through a funnel, whereby the flow transducer allows data collection on the volume, time, and therefore, the flow rate. This can help with clarification of detrusor weakness and/or a potential poor stream. 

Urodynamic studies

Urodynamic studies assess bladder function relating to storage and emptying. This can be achieved via standard urodynamics or video urodynamics (VUD), which differ in their use of fluoroscopic imaging during bladder filling.⁵ 

Urodynamic studies are more invasive than uroflowmetry, as they require a rectal and bladder probe to analyse specific pressures throughout the micturating cycle. This study is beneficial if there are concerns of an overactive bladder. 

Reviewer

Mr Grenville Oades

Urology Consultant

Editor

Dr Jamie Scriven

References

1. Walizai T. CT renal mass (protocol). 2025. Available from: [LINK].
2. Feger J, Knipe H, Mahmud A, et al. Prostate MRI (an approach). Radiopedia. 2025. Available from: [LINK].
3. Fahrenhorst-Jones T. Renal imaging in nuclear medicine. 2024. Available from: [LINK].
4. Aktaş A, Aras M, Çolak T, et al. Comparison of Tc-99m DTPA and Tc-99m MAG3 Perfusion Time-Activity Curves in Patients with Renal Allograft Dysfunction. Transplantation Proceedings. 2006. Available from: [LINK].
5. Yao M, Simoes A. Urodynamic Testing and Interpretation. StatPearls. 2023. Available from: [LINK].