Friday, March 12, 2021

Perinephric Abscess Case File

Posted By: Medical Group - 3/12/2021 Post Author : Medical Group Post Date : Friday, March 12, 2021 Post Time : 3/12/2021
Perinephric Abscess Case File
Eugene C. Toy, MD, Lawrence M. Ross, MD, PhD, Han Zhang, MD, Cristo Papasakelariou, MD, FACOG

CASE 25
A 55-year-old male is admitted to the hospital for a suspected kidney infection. He is placed on intravenous antibiotic therapy but continues to have a temperature of 103°F after 3 days of therapy. The urine culture grows Escherichia coli, which is sensitive to the antibiotics being used. On examination, he appears ill and has marked left flank tenderness. Ultrasound depicts an abnormal collection of fluid around the left kidney.

What is the most likely diagnosis?
 What anatomical structure is involved?


ANSWER TO CASE 25:

Perinephric Abscess
Summary: A 55-year-old male continues with high fever and flank pain despite 3 days of broad-spectrum intravenous antibiotic therapy. The urine isolate of E. coli demonstrates in vitro sensitivity to the antibiotics used. Renal ultrasound shows fluid around the left kidney.
• Most likely diagnosis: Perinephric abscess

• Anatomical structure involved: Kidney and anatomically related structures


CLINICAL CORRELATION
This 55-year-old male who is suspected of having pyelonephritis is not improving despite appropriate antibiotic therapy. Pyelonephritis is an infection of the kidney parenchyma usually caused by an ascending infection of bacteria that advances from the urethra to the bladder, to the ureters, and then to the kidney. Kidney infection usually manifests as fever, flank tenderness, white cells in the urine, and serum leukocytosis. After 48 to 72 h, one would expect decreases in fever and flank tenderness. E. coli is isolated, which is the bacterium that most often causes urinary tract infections. The ultrasound examination is performed to rule out complications of pyelonephritis. The two most common complications would be a nephrolithiasis or ureterolithiasis (kidney stone) and perinephric abscess. Intervention is required before improvement is seen. The abscess must be drained, usually by placement of a percutaneous catheter under radiologic guidance.


APPROACH TO:
The Kidneys

OBJECTIVES
1. Be able to describe the anatomy of the kidneys and their fascial coverings and blood supply
2. Be aware of the structures next to the kidneys and their relations


DEFINITIONS
PERINEPHRIC ABSCESS: Collection of pus in the tissues surrounding the kidney

PYELONEPHRITIS: Usually a bacterial inflammation of the renal tissue, the calyces, or renal pelvis

NEPHROLITHIASIS: Presence of renal calculi or stones


DISCUSSION
The kidneys are paired retroperitoneal organs that are located in the paravertebral gutters. The left kidney lies slightly higher than the right, its hilum is at the level of L1, and its superior and inferior poles are at the 11th rib and L3, respectively. The hilum of the right kidney lies at the level of the disk between L1 and L2, and its inferior pole is nearly 1 to 2 cm superior to the iliac crest. Each kidney is an encapsulated solid organ, with an outer cortex and an inner medulla, with the latter arranged in renal pyramids. The hilum of each kidney leads to a space, the renal sinus, which contains fat, branches of the renal vessels, and the urine-collecting structures (minor and major calyces and renal pelvis). Within the sinus, the apex of the 6 to 12 renal pyramids is cupped by a minor calyx, which collects the urine produced. Typically, two to three minor calyces unite to form a major calyx, and two to three major calyces form the renal pelvis. The renal pelvis is continuous with the ureter at the inferior margin of the hilum (see Case 32 for the anatomy of the ureter).


Four muscles are related to each kidney posteriorly: the diaphragm superiorly and the transversus abdominis, quadratus lumborum, and psoas muscles inferiorly, from lateral to medial. The suprarenal glands and colon contact both kidneys anteriorly. The duodenum and liver also contact the right kidney anteriorly, and the stomach, pancreas, and spleen are related to the anterior left kidney.

Each kidney and suprarenal gland is encased in a renal (Gerota) fascia (Figure 25-1), which helps to maintain the position of the kidney. The renal fascia fuses with the fascia of the psoas muscle posteriorly and with the adventitia of the renal vessels anteriorly. Within the renal fascia is an accumulation of fat known as perirenal fat, which is continuous with the fat within the renal sinus. Pararenal fat surrounds each kidney external to the renal fascia. Pararenal fat is thick posterior to the kidney, but it is thin anteriorly between the renal fascia and parietal peritoneum.

Perinephric Abscess anatomy

Figure 25-1. The left kidney and surrounding fascia. (Reproduced, with permission, from Lindner HH. Clinical Anatomy. East Norwalk, CT: Appleton & Lange, 1989:444.)

Each kidney is supplied by a renal artery that arises from the aorta near vertebral level L2. As each artery nears the renal pelvis, it typically divides into five segmental arteries that enter the hilum to supply segments of renal tissue. The right renal artery is the longer artery, and both renal arteries lie posterior to the renal veins when entering the hilum. The renal veins exit the hilum anterior to the arteries, and the left vein is longer and crosses the midline. Both renal veins drain into the IVC. The left renal vein is unique in that the inferior phrenic, suprarenal, and gonadal veins drain into it (the IVC receives these veins on the right side).


COMPREHENSION QUESTIONS

25.1 During the removal of a patient’s kidney, you would observe which of the following as being most anterior within the renal sinus?
A. Renal arteries
B. Renal vein
C. Major calyx
D. Minor calyx
E. Renal pelvis

25.2 You wish to examine the hilum of the right kidney during surgery. Which of the following structures must be elevated and reflected to do so?
A. Stomach
B. Suprarenal gland
C. Ascending colon
D. Duodenum
E. Liver

25.3 To elevate the kidney within the renal fascia and the perirenal fat, the renal fascia must be reflected or incised from the fascia of which of the following muscles?
A. Diaphragm
B. Psoas muscle
C. Quadratus lumborum muscle
D. Transversus abdominis muscle
E. Iliacus muscle


ANSWERS

25.1 B. The renal veins lie most anterior within the renal sinus.
25.2 D. The duodenum lies immediately anteriorly to the hilum of the right kidney.
25.3 B. The renal fascia is fused posteriorly to the fascia of the psoas muscle.


ANATOMY PEARL
 The hilum of the left kidney lies at the level of L1.

References

Gilroy AM, MacPherson BR, Ross LM. Atlas of Anatomy, 2nd ed. New York, NY: Thieme Medical Publishers; 2012:172−175, 236. 

Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy, 7th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014: 290−292, 298. 

Netter FH. Atlas of Human Anatomy, 6th ed. Philadelphia, PA: Saunders; 2014: plates 308−310, 315.

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