The Diagdoor blog

CT urogram: an examination of the kidneys, ureters, and bladder

A CT urogram, also known as a CT urography or urological CT scan, is performed in a medical imaging clinic or hospital on an outpatient basis. 

It uses X-rays to observe the urinary tract, specifically: 

• the kidneys ;
• the ureters (the tubes connecting the kidneys to the bladder);
• the bladder.

It may be performed with or without the injection of an iodine-based contrast agent, depending on the reason for the examination. 

The device consists of a large ring through which the examination table slides. Inside, an X-ray tube rotates around the body to capture images, without the patient feeling a thing.

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From diagnosis to follow-up: when a CT urogram is required

Pain, blood in the urine, infection: when the scan helps reach a diagnosis

A CT urogram may be prescribed to identify the cause of a symptom or to locate an abnormality.

It is primarily used in the following cases:

• a renal colic : sudden, unilateral lower back pain;
• a hematuria : presence of blood in the urine;
• a suspicion of kidney stones ;
• recurrent urinary tract infections , especially when they are resistant to treatment;
• an abnormality detected by ultrasound or physical examination.

It can also be used to perform an assessment of the urinary tract before surgery or following an abdominal or lower back injury.

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Follow-up CT urography for identified tumors or stones

CT urography can also be used to monitor a condition or abnormality that has already been diagnosed, such as a stone or a tumor.

For example, it may be requested as part of the follow-up for kidney or bladder cancer to measure tumor progression over time and adjust treatment if necessary.

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Preparing for a CT urogram: medical history to report

Before your appointment, it is important to report:

• a pregnancy that is ongoing or possible;
• any allergies known, particularly to an iodinated contrast agent;
• a metformin treatment (diabetes medication): whether to continue or interrupt it depends on your kidney function and will be decided by the medical team.

A creatinine test is required before the exam for patients with known kidney disease, high blood pressure, or diabetes. It ensures that the contrast agent can be injected safely.

Aside from these precautions, preparing for a urological CT scan is straightforward. Fasting is generally not required unless specifically instructed by the imaging center. Remember to bring your prescription and any previous imaging or lab results.

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A quick, multi-phase exam

A CT urogram typically lasts between 15 and 20 minutes. Depending on whether an injection is required, the procedure may involve up to four stages:

1. Positioning. The patient lies on their back and removes any jewelry or metal objects. An IV line is inserted if an injection is planned.
2. Initial non-contrast images. This series helps identify potential stones, which are more visible without contrast agent.
3. Injection of the iodinated contrast agent. The agent is injected intravenously. A temporary feeling of warmth throughout the body or a metallic taste in the mouth is common and harmless.
4. Post-injection images at various intervals. Several series are performed to observe the tissues and then the excretion of the agent through the urinary tract.

The exam is painless. You will need to remain still and hold your breath a few times during each series of images.

What is the purpose of an iodinated contrast agent injection?

Injecting a contrast agent is not always necessary; it depends on the reason for the exam. 

• Without a contrast agent, imaging allows for the visualization of basic anatomy and fixed structures such as kidney stones and hematomas.
• With a contrast agent, it allows for the analysis of soft tissues, blood flow, and functional aspects such as the flow of urine into the bladder.

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After a CT urogram: no special monitoring required, results sent to the referring physician

No special monitoring is required after a CT urogram. It is simply recommended to stay well-hydrated in the hours following the exam to help eliminate the contrast agent.

The images are analyzed by a radiologist, who writes a report sent to the referring physician. The turnaround time ranges from a few hours to a few days, depending on the center.

If the report indicates an abnormality, the referring physician will explain the results to the patient. If necessary, they will suggest further testing or a referral to a specialist.

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A second opinion to better understand your CT scan results

Once you have your results, additional insight can help you gain clarity before moving forward. 

A urologist second opinion can be useful when:

• the report mentions an abnormality you would like to better understand;
• you want a second specialized look before committing to a treatment;
• several additional tests are proposed and you are unsure about the next steps;
• surgery is being considered following the results.

The urologist will be able to review your file with a fresh perspective to supplement your doctor's opinion, without calling it into question.

Knee injection: a targeted injection to relieve pain

A knee injection is a medical procedure that involves injecting medication directly into the joint, or in the immediate vicinity, using a fine needle. 

The goal is to deliver the product as close as possible to the painful area. The injection thus allows for a more targeted pain-relieving effect than oral medication.

The procedure is performed by a doctor, sometimes under ultrasound or fluoroscopic guidance to precisely visualize the needle's path. It is carried out in a clinic or imaging center and does not require hospitalization.

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Inflammatory flare-ups or pain resistant to treatment: when to consider an injection

A knee injection aims to relieve gonalgia (knee pain) associated with inflammatory flare-ups. 

It may be considered in various situations: ‍

• knee osteoarthritis (gonarthrosis);
• chronic rheumatism (rheumatoid arthritis, gout, etc.);
• inflammation of the synovial membrane (synovitis) ;
• other joint inflammation (for example, related to a meniscus injury) ;
• inflammation of the structures surrounding the joint (bursitis, tendon issues, etc.

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Injections are often recommended: 

• when pain persists despite oral treatment (painkillers, anti-inflammatories) and/or physical therapy sessions;
• to temporarily relieve pain while awaiting surgery.

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A simple procedure performed in a few minutes

A knee injection generally takes about ten minutes. The steps are as follows: 

1. Preparation and disinfection. The skin around the knee is carefully disinfected to minimize any risk of infection. In some cases, a local anesthetic is administered.
2. Potential aspiration. If fluid has accumulated in the joint, the doctor may drain it before the injection.
3. Product injection. The chosen medication (corticosteroid, hyaluronic acid, or other) is injected directly into the joint.
4. Imaging guidance : the injection can be performed under fluoroscopic or ultrasound guidance.

After the injection, a brief observation period may be required before returning home. The doctor will also explain what to expect following the procedure and which symptoms would necessitate a follow-up consultation.

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Corticosteroid, hyaluronic acid, or PRP injections: different approaches

Different types of products can be injected depending on the situation:

• Corticosteroids (cortisone) have a powerful and rapid anti-inflammatory effect, which is particularly useful during a painful flare-up accompanied by swelling. 
• Hyaluronic acid, also known as viscosupplementation, is a natural component of the fluid that lubricates the joint (synovial fluid). Its effect is more gradual.
• Platelet-rich plasma (PRP) is prepared from the patient's own blood. This treatment is not currently officially recommended, although its use is becoming more common in practice.

Only corticosteroid injections are covered by health insurance. Regardless of the product chosen, intra-articular injections act on pain but have no effect on the structure of the cartilage.

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Comparison table

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Potentially effective, yet temporary and delayed relief

The effectiveness of an injection varies depending on the product used and the stage of joint damage:

• Corticosteroids provide rapid relief, felt within a few days, but the effect generally wears off after four to six weeks.
• Hyaluronic acid acts more slowly, with noticeable improvement after several weeks, but effects that can last for several months.
• Effectiveness tends to decrease as joint damage becomes more advanced. 

The French Society of Rheumatology recommends not exceeding 3 to 4 corticosteroid injections per year in the same joint. It advises against repeating hyaluronic acid injections if the initial injections have had no effect.

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Reduced risks, to be monitored in the following days

Like any invasive procedure, knee injections carry risks. These remain limited when aseptic conditions are maintained.

• Post-injection reaction : a temporary increase in pain within 24 to 48 hours following the injection, which then subsides spontaneously.
• Joint infection (septic arthritis) : this is the most serious complication, but it remains rare (1 case per 50,000 procedures according to the French Society of Rheumatology). It manifests as intense pain, marked swelling, local heat, and sometimes fever, and requires an emergency consultation.
• Side effects related to corticosteroids, such as a temporary rise in blood sugar levels in diabetic patients.
• A hematoma at the puncture site, which is not particularly serious.

It is recommended to keep the knee relatively rested for 48 hours after the injection. Walking is still possible in reasonable amounts. 

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Before or after an injection, a second opinion for peace of mind

Knee injections are part of a more comprehensive care plan. Depending on the cause of your pain, several options may be considered, and their expected benefits can vary from person to person.

A second opinion can help clarify things when:

• an injection is recommended and you want to better understand its purpose, expected benefits, and limitations in your specific situation;
• several types of injections (corticosteroids, hyaluronic acid, or PRP) are being discussed and you want to understand the differences between them;
• an injection is being considered to delay surgery;
• pain persists after an initial round of injections;
• multiple causes could explain your symptoms, making the choice of treatment more complex.

In these situations, a second opinion provides an additional perspective to help you better understand your treatment options and move forward with confidence. It does not call your doctor's opinion into question; it complements it.

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