URINARY Section 4: Infection Flashcards
This is a clinical diagnosis. However, you do end up diagnosing it. The trouble
starts in most cases as a retrograde infection - germs climb up into the kidney via the ureter from the bladder.
Pyelonephritis
Pyelonephritis
Vague focally reduced areas of enhancement with associated periphephric stranding
striped kidney (striated nephrogram) - seen best on an excretory phase . These wedge shaped areas are related to decreased perfusion.
Striated Nephrogram DDx:
Acute ureteral obstruction
Acute pyelonephritis
Acute renal vein thrombosis
Radiation nephritis
Acutely following renal contusion
Hypotension (bilateral)
Infantile polycystic kidney (bilateral)
Striated Nephrogram
Striated Nephrogram is not specificfor infection - infact it is seen in like a million billion ba-gillion different things — butfor the purpose o f multiple choice, think about anything thatfucks with bloodflow or causes edema
In the setting
of acute pyelonephritis, the areas of reduced enhancement (stripes) classically involve
a complete wedge of renal parenchyma, extending from medulla peripherally all the wav to the capsule.
Renal infracts vs acute pyelonephritis
Infection - extends all the way to the capsule
Infarct - spares the capsule
Pyenophritis + obstruction =
Pyonephrosis
Pyelonephritis is classically associated with stones, but remember the actual cause is a retrograde infection.
Renal infection + obstruction =
Emergency
Urgent Decompression - percutaneous nephrostomy
is the vocab word used for an infected or obstructed collecting system
Pyonephrosis
Fluid-Fluid level in the collecting system can be seen on US.
Renal abscess
round or geographic low attenuation collections that do not enhance centrally, but do have an enhancing rim
If renal abscess is > 3cm = ?
Drainage
Spectrum of renal infection
Chronic Pyelonephritis
renal scarring, atrophy and cortical thinning, with hj^ertrophy of residual normal tissue
Chronic Pyelonephritis
Basically, you have a small deformed kidney, with a bunch of wedge defects, and some hypertrophied areas.
Emphysematous Pyelonephritis
gas formation within or surrounding the kidney
Emphysematous Pyelonephritis
Echogenic foci with dirty shadowing
The gas is localized to the collecting system.
Emphysematous Pyelitis
It’s more common in women, diabetics, and people with urinary obstruction.
Emphysematous Pyelitis
Radiographic finding is gas outlining the ureters and dilated calyces.
This is ischemic necrosis of the renal papillae, most commonly involving the medullary pyramids.
Papillary Necrosis
the most common cause of papillary necrosis
Diabetes
can occur with:
pyelonephritis (specially kids)
Sickle Cell
TB
Analgesic use
Cirrhosis
Papillary necrosis
Filling defect in the calyx
The appearance of a necrotic cavity in the papillae with linear streaks of contrast inside the calyx has been called a “lobster claw sign. ”
50% of patients with this disease develop papillary necrosis
Sickle cell patients
Chronic destructive granulomatous process + Staghorn calculi acting as nidus for recurrent infection
Xanthogranulomatous PYelonephritis (XGP)
XGP associations
Poas abscess + minimal perirenal infection
Xanthogranulomatous Pyelonephritis (XGP)
“Bear paw”
Non-function kidney - Tx = nephrectomy
This is the most common cause of renal impairment in AIDS
HIV nephropathy
CD4 count in HIV nephropathy
CD4 < 200
HIV nephropathy
Normal echotexture excludes the disease (this entity is essentially always bright).
Loss of the renal sinus fat appearance has also been described (it’s edema in the fat, rather than loss of the actual fat).
Big and Bright kidneys
HIV nephropathy
in HIV positive patient who is clinically in nephrotic syndrome (massive proteinuria).
To show you the kidney is big, what whill they show?.
they will have to put calibers on the kidney (longer than 12 cm)
Calibers on anything should be a clue that the size being displayed is relevant.
punctate (primarily cortical) calcifications.
Disseminated Pneumocystis Pneumonia
The most common extra-pulmonary site of infection in TB
Urinary tract
Earliest finding of renal TB?
Moth eaten calices
Calyceal blunting (“moth eaten calices”) is the earliest finding. Remember the normal calyx should have a “gentle cup shape” — not all pointy and shit.
“earliest described sign” in renal PTB?
Calyx Distortion / Papillary Necrosis
This is the most characteristic sign of renal TB.
“cavity” formation.
Focal stenosis of an infundibulum can result in the absence of opacification of the calyx
Phantom calyx
Infundibulum Stenosis can also be diffuse and result in caliectasis in renal TB
Scarring at the renal pelvis can cause an uplifted appearance of
“Kerr Kink” of the renal pelvis
“Putty kidney”
autonephrectomized end stage TB kidney.
Renal TB spectrum of severity.
Nonspecific findings that help you zero in on the choice of renal TB
multiple calcified mesenteric lymph nodes + calcified adrenal glands
