This document discusses emphysematous pyelonephritis (EPN), a severe necrotizing infection of the renal parenchyma that causes gas accumulation. EPN most often occurs in diabetics, especially women, and presents similarly to acute pyelonephritis but has a more fulminating course. Diagnosis is made through CT scan and treatment involves aggressive antibiotics, fluid resuscitation, and either percutaneous drainage or emergency nephrectomy depending on severity and patient stability. Prognosis has improved with current treatments but mortality remains around 20-25% if not promptly recognized and treated.

1. Emphysematous
Pyelonephritis (EPN)
DR. ANEES PUTHAWALA

2. Emphysematous pyelonephritis (EPN)
• Acute severe necrotizing infection of the renal
parenchyma that causes gas accumulation in the tissues.
• First case reported by Kelly and Maccullum in 1898 .
• Since then terms such as ‘renal emphysema’,
‘pneumonephritis’ as well as ‘emphysematous
pyelonephritis’
• In 1962, Schultz and Klorfein suggested the use of
‘emphysematous pyelonephritis’ as the preferred term

3. • EPN most often occurs in persons with diabetes mellitus,
especially women.
• Presentation is similar to that of acute pyelonephritis
• But often has a fulminating course, and can be fatal if not
recognized and treated promptly

4. Epidemiology
• Mean age of patients with EPN is 55 years, with a range of 19-81 years.
• 6 times more common in women.
• Ninety-five percent of patients have diabetes.
• In most patients, the diabetes is uncontrolled, with high levels of glycosylated
hemoglobin (72%) or of blood sugar.
• Renal stones are another predisposing condition and therefore affect the frequency of
EPN
• Left kidney is affected more commonly than the right. Bilateral cases have also been
reported.

5. Other reported factors associated with the development of EPN are
• drug abuse,
• neurogenic bladder
• Alcoholism
• anatomic anomaly like polycystic kidney disease

6. Aetiology
• Enteric gram-negative facultative anaerobes.
• Escherichia coli- 66% of patients, and
• Klebsiella species- 26% of patients.
• Proteus, pseudomonas, and streptococcus species are other organisms found in
patients with EPN.
• Mixed organisms are observed in 10% of patients.
• Rarely, fungi (eg, aspergillus fumigatus, candida species) and protozoa (entamoeba
histolytica) have been isolated in patients with EPN.

7. Pathogenesis
• Various factors involved in the pathogenesis of this condition have
been suggested, including
• high levels of glucose within the tissues,
• the presence of gas-forming microorganisms,
• impaired vascular blood supply,
• reduced host immunity,
• the presence of obstruction within the urinary tract

8. Pathophysiology
• Urinary tract infections are common in persons with diabetes,
• Factors that predispose to EPN in persons with diabetes may include
uncontrolled diabetes, high levels of glycosylated hemoglobin, and
impaired host immune mechanisms.
• High tissue glucose levels- provide the substrate for microorganisms such
as E. Coli, producing carbon dioxide by the fermentation of sugar
• Diabetic microangiopathy may also contribute to the slow transport of
catabolic products and may lead to accumulation of gas

9. • Fermentation products from tissue necrosis produces
• Nitrogen , carbon dioxide, hydrogen, and oxygen
• Huang et al concluded that mixed acid fermentation is the mechanism of gas
production, based on the presence of hydrogen.

11. RISK FACTORS

13. • Pathological examination of the kidney reveals features of
• abscess formation,
• foci of infarctions,
• vascular thrombosis,
• numerous gas-filled spaces and
• areas of necrosis surrounded by acute and chronic inflammatory cells
implying septic infarction.
• H&E stains reveal extensive suppurative inflammation, necrosis,
abscess formation and gas bubbles. Large colonies of Gram negative
bacilli can also be seen.

14. Gross examination of emphysematous pyelonephritis:
(a) specimen of enlarged kidney with loss of cortex and medulla with
adherent perirenal fatty tissue (highlighted by arrow),
(b) foci of abscess within parenchyma (highlighted by arrow),
(c) abscess extending toward capsule(highlighted by arrow)

15. (a) confluent abscess seen on external surface of the kidney,
(b) friable necrotic parenchyma (arrow),
(c and d) hemorrhagic infarct on external surface and cut surface
of
the kidney,
(e) a pyonephrotic cavity with purulent exudate lining the cavity

16. Signs and symptoms
• Fever (79%)
• Abdominal or flank pain (71%)
• Nausea and vomiting (17%)
• Dyspnea (13%)
• Acute renal impairment (35%)
• Altered sensorium (19%)
• Shock (29%)
• Other possible findings include the following:
• Crepitus over the flank area may occur in advanced cases of EPN
• Pneumaturia is uncommon unless emphysematous cystitis is present
• Subcutaneous emphysema and pneumomediastinum have been reported
• Comorbidities include alcoholism, malnourishment, renal calculi, and diabetic ketoacidosis

17. Diagnosis
• Laboratory findings include :
• Leukocytosis
• Pyuria
• Infected urine
• Thrombocytopenia
• An elevated creatinine level
• Positive blood culture results

19. • Although plain radiography and ultrasound may suggest EPN,
computed tomography (CT) of the abdomen is more sensitive, allows
for more accurate staging of the disease and is considered the gold
standard for diagnosis.
• Ultrasonography and plain radiograph of the abdomen are only
accurate in 59% and 52% of cases, respectively, so abdominal CT is
necessary for early diagnosis and further management of EPN.

20.  A nuclear renal scan should be performed to assess the
degree of renal function impairment of the involved kidney
and the status of the contralateral kidney before going for
nephrectomy after diversion.

21. XRAY
• May show mottled gas within renal
fossa or
• Crescentic gas collection within
gerota's fascia.
• Linear gas shadows along
paraspinal region may also be seen,
representing retroperitoneal air.

22. USG
•May show an enlarged
kidney with coarse echoes
within renal parenchyma
or collecting system
•Dirty echogenic foci with
reverberation /ring-down
artifacts representing air
('dirty shadowing') may
also be seen

24. • Acc to Wan et al classification
Type I emphysematous pyelonephritis has a 65-70% mortality rate
versus 15-20% for type II, although transformation from type I to type II
has been observed following conservative treatment

25. CT image
• Type 1
• Greater than one-third renal
parenchymal destruction
• Streaky or mottled appearance of gas
• Intra- or Extrarenal fluid collections are
characteristically absent
• It is usually more aggressive and lead to
death shortly, if not intervened early
• Mortality 70%

26. • Type 2
• Destruction of less than one-third of
the parenchyma
• Renal or extrarenal collections
associated with bubbly or loculated
gas, or gas within pelvicalyceal system
or ureter
• Mortality 20%

28. Risk factors
• Thrombocytopenia,
• Elevated serum creatinine levels,
• Altered sensorium,
• Shock

29. Approach Considerations
• If extremely ill and need resuscitative measures in the intensive care
unit,
• including oxygen,
• intravenous (IV) fluids, and
• correction of acid-base imbalances, along with glycemic control.
• Systolic blood pressure should be maintained above 100 mm Hg, with
fluid or inotropic support if required.
• Surgical intervention should be performed only after stabilization of
the cardiorespiratory status.
• Prompt initiation of empiric IV antibiotic therapy is critical.
• broad spectrum, primarily target gram-negative bacteria,

30. ANTIBIOTICS
• Class 1 – A third-generation cephalosporin, with or without amikacin,
plus percutaneous catheter drainage in patients with obstructive
uropathy
• Class 2, 3, and 4 without risk factors – A third-generation
cephalosporin, with or without amikacin, plus percutaneous catheter
drainage
• Class 2, 3, and 4 with risk factors – Carbapenem with or without
vancomycin plus percutaneous catheter drainage

31. • Conservative treatment using percutaneous drainage with antibiotics is
indicated as follows:
• Patients with compromised renal function
• Early cases associated with gas in the collecting system alone and patient is in
otherwise in stable condition
• Class 1 and class 2 EPN
• Class 3 and class 4 EPN - In the presence of fewer than 2 risk factors (eg,
thrombocytopenia, elevated serum creatinine levels, altered sensorium, shock)
• DOUBLE DJ STENT

32. Percutaneous drainage
• Significant advances in the percutaneous catheters used made it
possible to have percutaneous drainage(PCD) as a treatment option
for EPN, which was first shown by Hudson et al.
• Subsequent case studies have shown patients being successfully
treated with PCD when used in addition to medical management,
with significant reduction in the mortality rates.
• PCD helps to preserve the function of the affected kidney in about
70% of cases.

33. • PCD should be performed on patients who have localized areas of gas and in
whom functioning renal tissue is believed to be present.
• A pigtail drain of at least 14 Fr in size should be inserted, either with USG or CT
guidance but ideally with CT guidance which has a better success rate when
compared with an ultrasonography.
• An abscess with loculations or multiple abscesses is not a contraindication for
PCD, as more than one catheter can be used to drain all loculations.
• The abscess, which is technically easier to access and would significantly reduce
the pressure on the viable renal tissue, should be targeted first with PCD.

34. • During the last decade there has been a gradual shift toward a nephron-
sparing approach with PCD, with or without elective nephrectomy at a later
stage.
• The treatment strategies include MM alone, PCD plus MM, MM plus
emergency nephrectomy, and PCD plus MM plus emergency nephrectomy.
• Patients on PCD plus MM benefit from follow-up CT in 4 to 7 weeks as
recommended by Chen et al. to look for air/fluid collections.
• This will also be helpful in planning a nephrectomy for non-responders to
PCD plus MM.

35. • In a meta analysis of the management strategies, the most successful
management was MM with PCD (80–100%), which was also
associated with the lowest mortality at 13.5% ( P<0.001).
• In the small proportion of patients managed with MM and PCD,
subsequent nephrectomy will be required and in these patients the
reported mortality is 6.6%.

36. Nephrectomy
• Indication
• Treatment of choice for most patients
• No access to percutaneous drainage or internal stenting (after
patient is stabilized)
• Gas in the renal parenchyma or "dry-type" EPN
• Possibly bilateral nephrectomy in patients with bilateral EPN
• Class 3 and class 4 EPN: In the presence of more than 2 risk factors

37. Prognosis
Untreated cases of emphysematous pyelonephritis (EPN) result in death.
• An overall EPN mortality rate of 19%.
• Reported significant treatment success rates with percutaneous drainage and antibiotics (66%)
and with nephrectomy (90%).
• Factors associated with a poor prognosis in patients with
• Altered level of consciousness,
• multiple organ failure,
• hyperglycemia, and
• leukocytosis.
• EPN that receives only medical treatment may lead to uncontrollable sepsis that requires surgical
intervention.
• Perinephric abscess and renal failure are other possible complications.

40. • In conclusion, EPN is a potentially lifethreatening condition which is most
commonly associated with poorly controlled diabetes.
• It requires a high index of suspicion in patients not responding to the routine
management of pyelonephritis.
• It is a radiological diagnosis and CT is the best investigation.
• Aggressive resuscitation should be done and the condition is currently treated by
MM along with PCD mostly commonly.
• Some patients may not respond and emergency nephrectomy may be required.
• Reported mortality figures have improved since the 1970s but still are at 20-25%

41. THANK YOU