Page 272 - Medicine and Surgery

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268 Chapter 6: Genitourinary system

Clinical features Vesicoureteric reflux (VUR) where urine refluxes back
Symptomsareinitiallyasforpyelonephritis.Thediagno- up from the bladder into the ureter, due to an incom-
sis of renal abscess should be suspected in those patients petent vesicoureteric junction, is common, affecting 1%
whoare seriously unwell, who have a known underlying of neonates and 30–45% of young children who present
renal abnormality and in those who do not improve after with a urinary tract infection (UTI). Reflux due to high
5daysofappropriate antibiotic treatment. pressure can also develop in patients with obstruction
due to urethral valves and after spinal cord injury. The
Investigations severity of the VUR predicts the risk of developing renal
Urine microscopy and culture. Urinalysis may be nor-
damage.
mal if the abscess does not communicate with the uri- There is a strong familial incidence of VUR, siblings
nary collecting system. mayhavea30–40%riskofalsobeingaffected,andinfants
FBC and differential. U&Es and creatinine.
born to mothers with VUR may have an even higher risk.
Blood culture.

Renal ultrasound scan or CT will demonstrate a thick-

Pathophysiology
walled cavity, often filled with necrotic material. It
In reflux nephropathy, the papillae are damaged, and the
may not be possible to differentiate it from a renal
calyces become dilated and ‘clubbed’. As areas of the kid-
cell carcinoma. CT with contrast usually shows in-
ney are chronically or recurrently infected, they become
creased contrast in a ring around the abscess. USS or
scarred, leading to loss of nephrons. As renal function
CT-guided aspiration and/or drainage are useful to
deteriorates, hypertension may follow, which acceler-
provide a specimen for microscopy and culture, and
ates the renal damage by hypertensive-induced vascular
may be useful therapeutically.
change. Unilateral chronic pyelonephritis does not cause
renal impairment, as long as the other kidney is normal
Management
an adequate GFR is maintained. However, hypertension
Antibiotic choice is as for pyelonephritis, until culture
may lead to damage to the single functioning kidney.
results are known. In large abscesses (>3 cm) medi-
cal therapy alone is often insufficient, and percutaneous
drainage or even partial or total nephrectomy may be Clinical features
required. Longer courses of antibiotics are usually re- A single proven UTI in early childhood should be inves-
quired, often 1–2 months. tigated for any underlying congenital abnormality pre-
disposing to reflux, to assess the degree of VUR and any
scarring which has already occurred. Recurrent UTI’s
Chronic pyelonephritis (reflux in adults should also be investigated. If the diagnosis
nephropathy)
is missed (often the UTI’s are asymptomatic), then pa-
Definition tients present later in life with hypertension, proteinuria
Chronic pyelonephritis is the damage caused to the and/or renal impairment.
kidneys by persistent or recurrent infection. The term
should largely be replaced by ‘reflux nephropathy’, the
most common form. Macroscopy
The kidneys are smaller than normal, with an irregular,
blunted, distorted pelvicalyceal system and areas of scar-
Incidence/prevalence
ring 1–2 cm in size. The poles tend to be more affected.
Accountsforabout15%ofcasesofend-stagerenalfailure
and is an important cause of hypertension in later life.
Microscopy
Aetiology Areas of interstitial fibrosis with chronic inflammatory
The development of chronic pyelonephritis requires cell infiltration. The tubules are atrophic or dilated and
there to be infections in a kidney with an underlying the glomeruli show periglomerular fibrosis. Some may
anatomical abnormality, such as reflux or stones. be hyalinized in response to damage.