From the Guidelines
A KUB pyelogram is not the first-line imaging modality for evaluating the urinary system, and its use should be limited to specific situations where advanced imaging techniques like CT urography or MR urography are contraindicated or unavailable. This is because CT urography and MR urography provide superior detail and reduced radiation exposure compared to KUB pyelograms 1. However, in patients with relative or absolute contraindications to multi-phase CT, such as renal insufficiency, contrast allergy, or pregnancy, combining MRI with retrograde pyelograms (RPGs) can provide an alternative evaluation of the entire upper tracts 1.
Some key points to consider when evaluating the urinary system include:
- The use of RPGs, which can provide a safe way to evaluate the entire urothelium for filling defects, obstructions, or irregularities in patients who are not candidates for CT urography or MR urography 1
- The combination of RPGs with MRI can provide an adequate upper tract evaluation for clinical decision-making in patients who cannot tolerate CT urography or MR urography 1
- The importance of considering individual patient circumstances, such as compromised renal function or contraindications to MRI, when selecting an imaging strategy 1
In general, the decision to use a KUB pyelogram or other imaging modality should be made on a case-by-case basis, taking into account the patient's specific needs and circumstances, as well as the availability of imaging options in the clinical setting 1.
From the Research
KUB Pyelogram
- A KUB pyelogram, also known as a kidney, ureter, and bladder X-ray, is a diagnostic imaging test used to visualize the urinary tract and detect kidney stones or other abnormalities 2.
- The test involves taking X-ray images of the kidney, ureter, and bladder to identify any blockages or stones in the urinary tract.
- According to a study published in 2009, plain X-ray KUB and ultrasound scan (USS) are commonly used investigations for identifying urinary stone disease, with USS showing higher sensitivity and specificity than plain X-ray KUB 2.
Diagnostic Accuracy
- The diagnostic accuracy of KUB pyelogram can vary depending on the size and location of the kidney stone, as well as the quality of the X-ray images.
- A study published in 2018 found that low-dose and ultra-low-dose CT scans can provide effective methods of identifying urinary tract stones, with high diagnostic accuracy, sensitivity, and specificity maintained despite significant radiation dose reduction 3.
- Another study published in 2022 found that the effective dose for KUB plain radiography was 0.22 mSv, which is relatively low compared to other imaging modalities such as CT scans 4.
Comparison with Other Imaging Modalities
- KUB pyelogram can be compared with other imaging modalities such as ultrasound, CT scans, and MRI for the diagnosis of kidney stones.
- A study published in 2016 found that noncontrast CT of the abdomen and pelvis provides the most accurate diagnosis of kidney stones, but exposes patients to ionizing radiation, while ultrasonography has a lower sensitivity and specificity but does not require radiation 5.
- Another study published in 2022 found that gadolinium-based contrast agents can be incorporated into kidney stones, and the concentration of gadolinium in kidney stones can be correlated with prior contrast agent administration and stone composition 6.