Perirenal Abscess

Initially, fluid introduced into the perirenal space is evenly dispersed throughout the perirenal fat. Preferential flow then seeks the abundant fat dorsolateral to the lower pole of the kidney8,12 (Figs. 8-130 through 8133). The exudate is guided by gravity along the path of least resistance. This natural drainage is also illustrated in Figure 8-134, in which a portion of a large staghorn

Puncture Renal Cyst

Fig. 8—130. Coalescence of perirenal effusions.

This typically develops behind and somewhat lateral to the lower pole of the kidney. K = kidney; C = colon; PM = psoas muscle.

Puncture Renal Cyst

Fig. 8—131. Perirenal hematoma.

This clinical case, in the early CT experience, serves as an in vivo model documenting the flow and coalescence of perirenal effusions. Following percutaneous puncture of a left renal cyst (Cy), CT scan shows a collection of blood (arrow) localized to the perirenal fat behind the kidney.

Fig. 8—131. Perirenal hematoma.

This clinical case, in the early CT experience, serves as an in vivo model documenting the flow and coalescence of perirenal effusions. Following percutaneous puncture of a left renal cyst (Cy), CT scan shows a collection of blood (arrow) localized to the perirenal fat behind the kidney.

calculus has eroded through the kidney to ultimately seek out the area of rich fat behind and lateral to the lower pole. It is important to understand that the coalescence at this particular site forms the basis for the radiologic identification of most perirenal abscesses.8,12 As a rule, a single finding is nonspecific because it may be due to some other disease. But in combination, radiologic signs usually permit the correct diagnosis.162

Oblique Muscle Abscess

Fig. 8—132. Acute perirenal hematoma.

Unenhanced CT shows a high attenuation hematoma (H) posterolateral to the kidney, displacing it anteriorly, medially, and superiorly. The perirenal fascia is thickened, and there is tracking of blood along some of the bridging renal septa.

(Courtesy of Jay P. Heiken, M.D., Mallinckrodt Institute of Radiology, St. Louis, MO.)

Fig. 8—133. Perirenal hematoma after biopsy.

T1-weighted fat-suppressed postgadolinium MR image demonstrates subacute blood, low in signal intensity, localized in the perirenal fat behind the left kidney.

(Reproduced from Semelka RC, Ascher SM, Reinhold C: MRI of the Abdomen and Pelvis: A Text-Atlas. Wiley-Liss, New York, 1997, with permission.)

Fig. 8—133. Perirenal hematoma after biopsy.

T1-weighted fat-suppressed postgadolinium MR image demonstrates subacute blood, low in signal intensity, localized in the perirenal fat behind the left kidney.

(Reproduced from Semelka RC, Ascher SM, Reinhold C: MRI of the Abdomen and Pelvis: A Text-Atlas. Wiley-Liss, New York, 1997, with permission.)

Definition Staghorn CalculusRenal Abscess Mri

Fig. 8-134. Chipped piece of staghorn calculus (arrow).

This has gravitated to the rich perirenal fat behind and lateral to the lower pole of the kidney. Plain film with opaque ureteral catheter.

Fig. 8-134. Chipped piece of staghorn calculus (arrow).

This has gravitated to the rich perirenal fat behind and lateral to the lower pole of the kidney. Plain film with opaque ureteral catheter.

For practical application, roentgen signs may be divided into primary and secondary groups. Primary roentgen signs include the following (Figs. 8-135 through 8-140):

1. Loss of definition of the lower renal outline with increased density or an identifiable discrete mass in the region of the kidney.

2. Displacement and, perhaps, axial rotation ofthe kidney. The lower pole is displaced medially, upward, and anteriorly, and the kidney may be rotated about its vertical axis. On frontal supine films, the affected kidney may appear larger because of magnification; a lateral film will then document its anterior displacement. The suspected side should be dependent for the lateral view since in this position a kidney in its normal location does not project anterior to the lumbar spine.

3. Loss of the upper segment of the psoas muscle margin.

4. Extrinsic compression of the renal pelvis and proximal ureter. The mass tends to press from the lateral aspect so that the proximal ureter may also be displaced anteriorly over the psoas muscle as well as medially. Compression may be severe enough to cause dilatation of the upper collecting system.

5. Fixation ofthe kidney. Normal renal mobility of 26 cm can be shown on erect views or with respiratory excursions.163 A perirenal process tends to fix the kidney in most patients.

6. Extravasation into the perirenal space. Communication of the collecting system with the perirenal compartment is presumptive evidence of a perirenal abscess in all but the most acute circumstances. The extravasation may be demonstrated by retrograde pyelography or fistulography.

7. Displacement of contiguous bowel. A collection of pus in the perirenal compartment may produce a mass effect on adjacent intestine. On the right, the descending duodenum may be displaced medially and anteriorly and the hepatic flexure of the colon downward. On the left, the distal transverse colon may be displaced superiorly or inferiorly and the duodenojejunal junction medially.

8. Arteriographic findings. Arteriography has been of particular value in the past in cases where the conventional radiographic findings are uncertain or where primary renal infection is suspected to extend through the capsule. The angiogram may define the size and location of the abscess. Characteristically, the findings include an

Radiographic Pictures Renal Abscess

Fig. 8—135. Right perirenal abscess.

The infection is localized behind the lower pole, resulting in anterior, medial, and superior displacement of the kidney.

(a) The affected kidney appears larger because of the magnification resulting from its anterior displacement. There is loss of the renal outline and the hepatic angle. Extension of the infection along the ureter has caused mild ureteropelvic obstruction.

(b) On oblique projection, the abscess itself is visualized as a mass density. (Reproduced from Meyers. )

Fig. 8—135. Right perirenal abscess.

The infection is localized behind the lower pole, resulting in anterior, medial, and superior displacement of the kidney.

(a) The affected kidney appears larger because of the magnification resulting from its anterior displacement. There is loss of the renal outline and the hepatic angle. Extension of the infection along the ureter has caused mild ureteropelvic obstruction.

(b) On oblique projection, the abscess itself is visualized as a mass density. (Reproduced from Meyers. )

Fig. 8-136. Right perirenal abscess.

The collection in the dorsolateral fat near the lower pole displaces the kidney upward and medially, deflects the upper ureter medially, and obscures the proximal psoas margin. Note the loss of contrast of the perirenal fat and renal outline. (Reproduced from Evans et al.162)

Psoas Margin

Fig. 8-137. Perirenal abscess.

Retrograde pyelogram shows characteristic upward and medial displacement of the kidney and proximal ureter with axial rotation of the kidney by a large mass. There is loss of visualization of the renal outline and psoas margin. (Reproduced from Evans et al.162)

Psoas AbscessIliac Fossa Mass

Fig. 8—139. Extensive perirenal abscess draining into the iliac fossa beyond the confines of the renal fascia.

The abscess originated from a lower calyx (arrow) in a kidney involved by severe pyonephrosis.

Fig. 8—138. Large left perirenal abscess.

This displaces the lower pole anteromedially and results in renal magnification. Gross inflammatory disease involves the collecting system. (Reproduced from Meyers.8)

increased number and size of perforating arteries extending from the kidney, stretching of tortuous and prominent capsular and, perhaps, pelvic arteries around the margin of the abscess, and a contrast blush.

9. Infiltration of flank stripe. This indicates fulminating and widespread extension into the adjacent tissues.

Secondary roentgen signs include the following:

1. Scoliosis. This occurs in less than half the patients with perirenal abscess.

2. Restriction of diaphragmatic motility and pulmonary basilar changes. Nesbit and Dick164 showed that of 85 patients with perirenal abscess, 14 (16.5%) had pulmonary complications. These may vary from a minimal pleuritis to effusion, pneumonia, and nephrobronchial fistula. Excursion of the ipsilateral hemidiaphragm, especially its posterior segment, may be restricted or absent.

Fig. 8—139. Extensive perirenal abscess draining into the iliac fossa beyond the confines of the renal fascia.

The abscess originated from a lower calyx (arrow) in a kidney involved by severe pyonephrosis.

Other localization may be encountered (Fig. 8-141).

Treatment of perirenal abscesses is included in the discussion on pages 439 and 444.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • MARGARET EVANS
    How to diagnoserenal and parirenal abscess?
    6 years ago

Post a comment