Clinical presentation and course characteristics
Emphysematous infections represent a formidable group of diseases with a rather insidious onset. The clinical picture is often nonspecific, so patients may not receive adequate care for a long time. Main symptoms include lower back pain, chills, and low-grade fever (low-grade fever). In addition, patients complain of dysuria and note unexplained weight loss.
The insidiousness of the process lies in its ability to spread unhindered beyond the organ. Inflammation can spread to the perinephric space (perinephric space) or the extensive retroperitoneum (retroperitoneum). The situation is often aggravated by severe complications and comorbid conditions. Clinical practice describes cases associated with such infections with transitional cell carcinoma (transitional cell carcinoma), pronounced hematuria, massive retroperitoneal hemorrhage, and dangerous renal vein thrombosis.
Radiological signs of emphysematous forms
Imaging plays a crucial role in detecting gas in the urinary tract.
- Emphysematous pyelitis: axial unenhanced CT (unenhanced CT) is used for diagnosis. A typical sign is the visualization of an air locule (air locule) located inside the dilated left renal pelvis. Surrounding tissues actively react to inflammation: radiologists describe pronounced stranding (stranding) of the peripelvic and paranephric adipose tissue, as well as thickening of the paranephric fascial planes.
- Emphysematous pyelonephritis: in some cases, primary information is provided by a plain radiograph (plain radiograph). For example, in a 38-year-old woman with uncontrolled diabetes mellitus, the image will show pathological soft tissue darkening. Against this background, areas of air lucencies (air lucencies) caused by gas accumulation are visible. These gas shadows are projected onto the left hypochondriac, lumbar, and even iliac regions.
Visualization of xanthogranulomatous pyelonephritis (XGP)
Xanthogranulomatous pyelonephritis is another severe form of destructive lesion for which computed tomography is indicated in absolutely all patients. The method is strictly necessary for a quality preoperative assessment, primarily for reliably documenting the extrarenal spread of the disease.
Characteristic CT signs that convincingly indicate the development of XGP include:
- The organ appears as a non-functioning and significantly enlarged kidney.
- A central calculus is visualized inside the contracted renal pelvis (contracted renal pelvis). Often this is a massive staghorn calculus (staghorn calculus).
- There is a paradoxical expansion of the renal calyces (expansion of the calyces).
- Multiple pathological collections (renal parenchymal collections) are detected in the parenchyma.
- Pronounced inflammatory changes and stranding in the perinephric fat are determined (perinephric fat stranding).
Briefly: answers to topical questions
What is the difference between emphysematous pyelitis and emphysematous pyelonephritis in terms of gas localization?
The main difference lies in the involvement of the renal parenchyma.
| Disease | Gas localization |
|---|---|
| Emphysematous pyelitis (emphysematous pyelitis) | Gas is detected in the collecting system/renal pelvis; the renal parenchyma is not involved. |
| Emphysematous pyelonephritis (emphysematous pyelonephritis) | Gas is represented by small vesicular or linear clusters originating from the renal papillae, with involvement of the renal parenchyma. |
What are the stages of emphysematous pyelonephritis according to CT data?
According to computed tomography, two types (stages) of emphysematous pyelonephritis are distinguished:
- Type 1 — characterized by parenchymal destruction with the presence of loculated gas (loculated gas), while fluid collections in the kidney itself or paranephric tissue are absent.
- Type 2 — loculated gas in the parenchyma is detected in combination with a fluid collection in the kidney or paranephric space. This type has a more favorable prognosis.
Which retroperitoneal spaces are involved in the extrarenal spread of emphysematous infection?
With extrarenal spread of emphysematous infection, the process can spread:
- into the perinephric space (perinephric space);
- into the retroperitoneum (retroperitoneum).
What is the treatment strategy for emphysematous pyelonephritis depending on the stage?
The sources do not describe a specific treatment strategy depending on the specific CT stage (type), but general approaches to the therapy of emphysematous pyelonephritis are indicated:
- Conservative-instrumental treatment — in addition to systemic antibiotic therapy, CT-guided drainage is used (this is especially relevant for patients with a solitary kidney).
- Surgical treatment — radical nephrectomy is indicated in the absence of an effect from ongoing therapy, as well as to prevent severe complications.
For the typical CT picture of xanthogranulomatous pyelonephritis, remember the structure contrast: 'Contracted pelvis with a stone inside, but expanded calyces outside' against the background of a non-functioning huge kidney.
Class and exam questions
Why is CT mandatory in suspected XGP?
Computed tomography is critically important for preoperative preparation, as only this method allows reliable documentation of the extrarenal spread of the pathological process.
How does emphysematous pyelonephritis look on a plain radiograph?
It manifests as pathological soft tissue darkening with specific areas of lucency that form due to gas accumulation in the hypochondriac, lumbar, and iliac regions.
Where is gas localized in emphysematous pyelitis according to unenhanced CT data?
In pyelitis, the air bubble is localized directly inside the dilated renal pelvis against the background of stranding of the surrounding peripelvic adipose tissue.
What else to study on this topic
- Features of the pathogenesis of gas formation in Escherichia coli infections
- Association of emphysematous infections with transitional cell carcinoma
- Differential diagnosis of renal parenchymal collections in XGP
- Algorithm for preoperative assessment of extrarenal spread on CT
- Management tactics for patients with concomitant renal vein thrombosis
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