Radiological investigations in nephrolithiasis and: a narrative review

Nephrolithiasis and ureterolithiasis are increasing in incidence and prevalence worldwide, which are significant clinical challenges in management. Radiological assessments are vital in early diagnosis and effective management to decrease morbidity and healthcare costs. This narrative review explores the role of various radiological investigations in nephrolithiasis and ureterolithiasis, focusing on their clinical implications and limitations. Plain X-ray of the kidney, ureter, and bladder (X-ray KUB) is a widely available, relatively inexpensive modality with limited sensitivity, mainly for smaller stones. However, it is most beneficial when assessing follow-up patients diagnosed with renal or ureteric calculi, but it is less effective in acute ureteric colic. Intravenous Urogram/Intravenous Pyelography (IVU/IVP) is an obsolete investigation and has largely been replaced by newer modalities due to numerous drawbacks. Ultrasonography (USG) is a widely available, relatively lowcost, non-invasive radiological modality without ionising radiation, considered first-line for children and pregnant patients. However, its sensitivity and specificity are traditionally lower than computed tomography and largely depend on the operator and patient factors. Computed tomography kidney, ureter, and bladder (CT-KUB) is the gold standard for diagnosing urolithiasis. It offers high sensitivity, specificity, and the ability to calculate the exact size and stone composition, but it comes with substantial radiation exposure. However, low-dose and ultralow-dose CT (LDCTKUB) protocols reduce radiation to the patient significantly, compromising image clarity. Magnetic Resonance Urography (MRU) is a second-line investigation in obstructive uropathy, particularly in pregnancy and children. It provides vital anatomical and functional information without ionising radiation. Urology and radiology professionals should collaborate to identify individualised and optimal radiological investigations, considering the risks and benefits associated with each modality.