A Case Report on Distinguishing Emphysematous Pyelitis and Pyelonephritis on Point-of-care Ultrasound

Abstract

Introduction:
Point-of-care ultrasound (POCUS) in the emergency department (ED) is being performed with increasing frequency. The objective of this study was to demonstrate how utilization of POCUS can help the emergency physician recognize emphysematous pyelitis (EP) and emphysematous pyelonephritis (EPN).

Case report:
A 60-year-old female presented to the ED with normal vital signs and intermittent left-sided flank pain that radiated to her groin. She also had a history of obstructive nephrolithiasis. Within 20 minutes of arrival she became febrile (101.2°Fahrenheit), tachycardic (114 beats per minute), tachypneic (21 breaths per minute), and had a blood pressure of 114/82 millimeters mercury. POCUS was conducted revealing heterogeneous artifact with "dirty shadowing" within the renal pelvis, which was strongly suggestive of air. The emergency physician ordered a computed tomography (CT) to confirm the suspicion for EP and started the patient on broad-spectrum antibiotics. The CT showed a 1.3-centimeter calculus and hydronephrosis with foci of air. The patient received intravenous antibiotics and had an emergent nephrostomy tube placed. Urine cultures tested positive for pan-sensitive Escherichia Coli. Urology was consulted and a repeat CT was obtained to show correct drainage and decreased renal pelvis dilation.

Conclusion:
Distinctly different forms of treatment are used for EP and EPN, despite both having similar pathophysiology. In EP, air can be seen in the renal pelvis on POCUS, as in this case study, which distinguishes it from EPN. In the case of our patient, the use of POCUS was useful to aid in rapid differentiation between EP and EPN.

Full text

UC Irvine
Clinical Practice and Cases in Emergency Medicine
Title
A Case Report on Distinguishing Emphysematous Pyelitis and Pyelonephritis on Point-of-care
Ultrasound
Permalink
https://escholarship.org/uc/item/9rk4b719
Journal
Clinical Practice and Cases in Emergency Medicine, 5(1)
ISSN
2474-252X
Authors
Mazumder, Proma
Al-Khouja, Fares
Moeller, John
et al.
Publication Date
2021
Supplemental Material
https://escholarship.org/uc/item/9rk4b719#supplemental
License
https://creativecommons.org/licenses/by/4.0/ 4.0
Peer reviewed
eScholarship.org Powered by the California Digital Library
University of California

Volume V, no. 1: February 2021 35 Clinical Practice and Cases in Emergency Medicine
Case RepoRt
A Case Report on Distinguishing Emphysematous Pyelitis and
Pyelonephritis on Point-of-care Ultrasound
Proma Mazumder, BS*°
Fares Al-Khouja, MS†°
John Moeller, MD‡
Shadi Lahham, MD, MS‡
Section Editor: Melanie Heniff, MD, JD
Submission history: Submitted September 15, 2020; Revision received October 20, 2020; Accepted November 5, 2020
Electronically published December 31, 2020
Full text available through open access at http://escholarship.org/uc/uciem_cpcem
DOI: 10.5811/cpcem.2020.11.49892
Introduction: Point-of-care ultrasound (POCUS) in the emergency department (ED) is being
performed with increasing frequency. The objective of this study was to demonstrate how utilization
of POCUS can help the emergency physician recognize emphysematous pyelitis (EP) and
emphysematous pyelonephritis (EPN).
Case Report: A 60-year-old female presented to the ED with normal vital signs and intermittent
left-sided ank pain that radiated to her groin. She also had a history of obstructive nephrolithiasis.
Within 20 minutes of arrival she became febrile (101.2°Fahrenheit), tachycardic (114 beats per
minute), tachypneic (21 breaths per minute), and had a blood pressure of 114/82 millimeters
mercury. POCUS was conducted revealing heterogeneous artifact with “dirty shadowing” within the
renal pelvis, which was strongly suggestive of air. The emergency physician ordered a computed
tomography (CT) to conrm the suspicion for EP and started the patient on broad-spectrum
antibiotics. The CT showed a 1.3-centimeter calculus and hydronephrosis with foci of air. The patient
received intravenous antibiotics and had an emergent nephrostomy tube placed. Urine cultures
tested positive for pan-sensitive Escherichia Coli. Urology was consulted and a repeat CT was
obtained to show correct drainage and decreased renal pelvis dilation.
Conclusion: Distinctly different forms of treatment are used for EP and EPN, despite both having
similar pathophysiology. In EP, air can be seen in the renal pelvis on POCUS, as in this case study,
which distinguishes it from EPN. In the case of our patient, the use of POCUS was useful to aid in
rapid differentiation between EP and EPN. [Clin Pract Cases Emerg Med. 2021;5(1):35–38.]
Keywords: Point-of-care ultrasound; emphysematous pyelitis; emphysematous pyelonephritis.
INTRODUCTION
Emphysematous pyelitis (EP) is a rare complication of
pyelonephritis that results from gas-forming bacteria localized
to the renal pelvis or renal collecting system.1 Emphysematous
pyelitis is a relatively benign condition when compared to
emphysematous pyelonephritis (EPN). While EP involves an
infection of the renal pelvis by gas-forming bacteria, EPN
consists of a necrotizing infection of the renal parenchyma as
well. Both EP and EPN are rare complications of acute
pyelonephritis. However, EPN can have devastating outcomes
Touro University Nevada, School of Osteopathic Medicine, Henderson, Nevada
University of California, Irvine, School of Medicine, Irvine, California
University of California, Irvine, Department of Emergency Medicine, Orange, California
Co-rst authors
*
†
‡
°
with mortality rates as high as 80% if treated with antibiotics
alone.2 The clinical presentation of both entities is remarkably
similar, consisting of fever, chills, ank pain, dysuria,
vomiting, and lethargy.2
Historically, the only method of differentiation between
EP and EPN has been computed tomography (CT) that
demonstrates air within the renal parenchyma. It is important
to distinguish EPN from EP due to the increased morbidity
and mortality associated with EPN, as well as the different
treatment course for each condition.2,3 In this report, we

Clinical Practice and Cases in Emergency Medicine 36 Volume V, no. 1: February 2021
Distinguishing Emphysematous Pyelitis and Pyelonephritis with POCUS Mazumder et al.
CPC-EM Capsule
What do we already know about this clinical
entity?
Emphysematous pyelitis (EP) and
emphysematous pyelonephritis (EPN) are
diagnosed through computed tomography
(CT); treatment differs despite similar
pathophysiology.
What makes this presentation of disease
reportable?
The ultrasound video clip demonstrates key
ndings such as reverberation artifact and
“dirty shadowing” to show EP.
What is the major learning point?
Ultrasound may be useful to differentiate
pathology for EP and EPN.
How might this improve emergency medicine
practice?
Using ultrasound may expedite diagnosis of
EP and EPN to better guide course of therapy
before conrming with CT.
demonstrate the utility of point-of-care ultrasound (POCUS)
to diagnose EP in a female presenting with symptoms
suggestive of pyelonephritis.
CASE REPORT
A 60-year-old female with an extensive history of
obstructive nephrolithiasis presented to our emergency
department (ED) with left-sided ank pain. She described her
pain as intermittent and sharp in nature, with radiating pain to
the groin. Associated complaints included dysuria and gross
hematuria. Initial triage vitals were normal; however, within
20 minutes of arrival she became febrile to 101.2° Fahrenheit,
tachycardic to 114 beats per minute, tachypneic to 21 breaths
per minute, and a blood pressure of 114/82 milligrams
mercury. On exam she was in mild distress, with diaphoresis
and left costovertebral angle tenderness.
Point-of-care ultrasound performed in the ED showed
unilateral moderate hydronephrosis with echogenic debris in
the renal pelvis (Video). Specically, the isolated debris in the
renal pelvis was heterogeneous with both hyperechoic and
isoechoic artifacts; mobile hyperechoic foci with “dirty
shadowing” were highly suggestive of air in the renal pelvis.
Blood cultures were obtained, and given suspicion for EP,the
emergency physician initiated broad-spectrum antibiotics and
consulted urology while waiting for the results of a
conrmatory CT.
The CT demonstrated a 1.3-centimeter calculus and
hydronephrosis with foci of air, raising suspicion for a
hemorrhagic or infectious etiology (Image). The patient was
admitted for intravenous antibiotics and emergent nephrostomy
tube placement by interventional radiology. Blood cultures were
positive for gram-negative rods. Urine cultures revealed
pan-sensitive Escherichia coli. The patient was evaluated by the
urology service, with repeat CT showing appropriate drainage
of infection and decreased renal pelvis dilation.
DISCUSSION
Emphysematous infections of the renal and genitourinary
collecting systems can be life threatening and rapidly
progress to sepsis without aggressive intervention.4
Emphysematous pyelonephritis is characterized by a necrotic
infection of the renal parenchyma. Infection with gas-
forming microbes will result in the presence of gas in the
collecting system and perinephrotic tissue.5 Acute EPN can
result in greater complications then EP due to the increased
rate of sepsis. The primary cause of mortality in EPN is
complications related to sepsis.5
Although both EP and EPN have similar
pathophysiology and epidemiological risk factors, the overall
prognosis of each pathology and diagnostic criteria are
unique. Specically, EP has a signicantly lower mortality
rate (18-20%) as compared to the nearly twofold increase in
mortality associated with EPN (25-42%). 4,6,7 The clinical
presentation of EP can be similar to that of pyelonephritis,
with symptoms ranging from fever, chills, hematuria, and
vomiting to renal angle tenderness.1 In contrast, the
presentation of EPN is typically more ominous, frequently
Image. Computed tomography of the abdomen and pelvis
showing an enlarged left kidney with hydronephrosis as well as air
in the renal pelvis (white arrow).

Volume V, no. 1: February 2021 37 Clinical Practice and Cases in Emergency Medicine
Mazumder et al. Distinguishing Emphysematous Pyelitis and Pyelonephritis with POCUS
presenting with vital sign abnormalities, sepsis, and shock if
left untreated.8
Computed tomography is considered the best modality for
differentiating EPN from EP, as it can consistently
differentiate the existence of gas in specic locations within
the renal excretory system, including renal parenchyma, renal
pelvis, and perinephric spaces.3 Although there have been a
few case reports of the adjunctive roles of ultrasound and
kidney, ureter, and bladder radiographs in differentiating EP
from EPN, to our knowledge the reported use of POCUS by
an emergency physician for rapid identication of EP is
unique. Given routine delays in CT imaging in a busy ED, the
role of POCUS in helping physicians differentiate between a
benign and life-threatening condition has evolved.
POCUS for both EP and EPN demonstrates a
reverberation artifact projecting posteriorly from a
hyperechoic focus (emphysema). The hyperechoic focus is
due to free air bubbles with lateral and axial blooming.9 The
reverberation artifact from the hyperechoic gas bubbles gives
a sonographic appearance of “dirty shadowing.” Dirty
shadowing is described as superimposed echoes from free gas
that give a large radius of curvature of the surface struck by
the sound beam.10 This results in the characteristic dirty
shadowing that projects from a hyperechoic focus of free gas
with a larger curvature and acoustic noise within the shadow.
In contrast, “clean shadowing” is related to solid surface
material, such as nephroliths, that creates a clean shadow with
no inltrative artifact.10 Characteristics of EP on POCUS that
distinguish it from EPN include the presence of “dirty
shadowing,” which is isolated to the renal pelvis.11 In
comparison, sonographic ndings of EPN are similar;
however, reverberation artifact is present extending toward the
renal parenchyma, not isolated to the renal pelvis as in EP. At
times, emphysema into the parenchyma and renal cortex can
become so extensive that adequate visualization of the pelvis
and uropelvic junction can be challenging.12
Current treatment of EP consists of the use of broad-
spectrum antibiotics, urology evaluation, and nephrostomy
tube placement in cases of obstructive processes.13 In contrast,
EPN requires aggressive interventions. Delays in recognition
and/or diagnosis by the provider can result in increased
morbidity or mortality. POCUS can help facilitate the prompt
diagnosis and treatment of both EP and EPN, resulting in
improved patient outcomes.1,2,14
CONCLUSION
Point-of-care ultrasound can be used successfully by
emergency physicians to rapidly differentiate between
emphysematous renal infections, thus expediting care in
critically ill patients. This case report further characterizes the
sonographic appearance of emphysematous pyelitis, as well as
comparing the subtle differences in ultrasound imaging,
presentation, and treatment of EP from the far deadlier
emphysematous pyelonephritis.
Video. This video clip shows a coronal ultrasound of the left
kidney presented in the case report. As seen, there is an obvious
hypoechoic dilation of the renal pelvis with blunting of the calyces
consistent with moderate hydronephrosis. Also visualized in the
clip is a heterogeneous collection of debris. The isoechoic sedi-
ment likely represents purulent material in the clinical setting of
infection. The hyperechoic foci, with posterior “dirty shadowing,”
corresponds to air. The foci of air are isolated to the renal pelvis
consistent with the diagnosis of emphysematous pyelitis.
The authors attest that their institution requires neither Institutional
Review Board approval, nor patient consent for publication of this
case report. Documentation on le.
Address for Correspondence: Shadi Lahham, MD, MS, University
of California, Irvine, Department of Emergency Medicine, 333
The City Boulevard West Suite 640, Orange, A 92868. Email:
slahham@uci.edu.
Conicts of Interest: By the CPC-EM article submission
agreement, all authors are required to disclose all afliations,
funding sources and nancial or management relationships that
could be perceived as potential sources of bias. The authors
disclosed none.
Copyright: © 2021 Mazumder et al. This is an open access article
distributed in accordance with the terms of the Creative Commons
Attribution (CC BY 4.0) License. See: http://creativecommons.org/
licenses/by/4.0/
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