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41 Transcutaneous Laryngeal Ultrasonography: Vocal Fold Ultrasound
vs. 33.3%, p=0.002) [11] (Fig.41.2). The true
vocal cords appear as two triangular hypoechoic
structures (the vocalis muscles), outlined medially by the hyperechoic vocal ligaments [2]. The
cords oscillate and move toward the midline during phonation, adduct during Valsalva maneuver,
and abduct upon relaxation. During normal respiration, the cords open upon inspiration to allow
an unobstructed ow of air (Video 41.1). When
paradoxical vocal fold motion abnormality is
present—the cords adduct during inspiration—
leading to stridor and dyspnea. The false vocal
cords lay parallel and cephalad to the true cords,
Fig. 41.2 Ultrasound probe position for imaging of vocal
cords at level of thyroid cartilage. Midline (left) and 30°
(right)
are more hyperechoic in appearance, and remain
relatively immobile during phonation but appear
to open and close with respiration [12].
473
Vocal Cord Motion - B mode Ultrasound / Transcutaneous Laryngeal
Ultrasonography (TLUS)
Image acquisition tips and tricks
Lowering of probe frequency
and increase gain at the time of VC scanning
Tilting of probe cephalocaudal
Sliding probe from the midline to 30 degrees
Valsalva maneuver —> TVC adducted on the midline, followed by
confirmation of bilateral mobility when the TVC abduct with inspiration
Motion evaluation using passive breathing is possible, but it is
more challenging and time-consuming because the TVC movement is
often subtle.
Application of Doppler ultrasound CDI or PWD for assessment of
movement, vibration, and airflow patterns
474
cd
A. Leibowitz and A. Oren-Grinberg
Vocal Fold Motion Abnormalities
All intrinsic muscles of the larynx, but the cricoarytenoid muscle, which is an abductor, are vocal
cord adductors. These (aside from the tensor cricothyroid muscle) are innervated by the recurrent
laryngeal nerve. Complete paralysis of the vocal
cord will result in a paramedian position, which
may be observed with static ultrasound of the
neck. Bilateral paralysis may manifest as dyspnea and respiratory distress. Absent movement
of the cords with phonation may also be observed
with ultrasound [3, 13]. Since this technique was
described in 1989, several studies have been carried out, evaluating the sensitivity and specicity
of this approach compared to indirect beroptic
laryngoscopy (IFL), which is considered the gold
standard, with varying levels of success. The vast
majority of these studies were conducted either
with healthy volunteers or patients undergoing
Thyroid and Parathyroid surgery [14–18]. The
accuracy and reliability of Trans Cutaneous
Laryngeal Ultrasonography (TLUS) for the
detection of motion abnormalities depends not
only on adequate visualization of the cords but
also identication of real-time movement of the
vocal cords and arytenoids, which may be challenging in patients in respiratory distress.
Therefore, the interpretation of these studies
when applied to the critical care setting should
call for some caution. Several studies report the
utility of B-mode TLUS either as a screening tool
or when laryngoscopy is not available, for the
identication of vocal cord motion abnormalities
[14–18] with reported sensitivity and specicity
of up to 100% and 98%, respectively [10, 14,
16–18], while other single-center studies report
poorer utility with values of sensitivity and specicity only in the 40–60% range and with a positive predictive value of 73% and negative
predictive value of 95% [19, 20]. This may be
explained in part, by the frame rate on most ultrasound machines which is signicantly lower than
the vibration frequency of the cords, as well as
the signicant variability in the ability to accurately detect the relevant structures. Further studies which included the addition of Doppler
imaging demonstrated improved accuracy. Ooi
etal. demonstrated the ability to identify vocal
fold palsy with color doppler imaging (CDI)
based on showing airow pattern asymmetry
[21], whereas Dedjecus etal. were able to identify all motion abnormalities by applying pulsed
wave doppler both in the horizontal and lateral
positions [15] (Fig.41.3). A recent meta-analysis
by Kim etal. which included 17 eligible studies
found that Transcutaneous laryngeal ultrasonography exhibited a pooled sensitivity of 0.91,
pooled specicity of 0.97, pooled negative predictive value of 0.99, and AUC of 0.94. The
SROC curve value was 0.9–1.00, suggesting
excellent diagnostic accuracy. Authors concluded
that given its accuracy—TLUS may be used in
certain situations as an alternative to IFL [16].
Phung et al. conducted a similar meta-analysis
with a more reserved conclusion with negative
ab
Fig. 41.3 Application of Doppler imaging for evaluation
of vocal fold motion. (a) Placement of ultrasound probe
on the lateral thyroid cartilage, with PW volume gate over
the vocal cord. (b) Registering vocal fold displacement
velocity with and without phonation (Dedecjus M,
Adamczewski Z, Brzeziński J, Lewiń
resolution ultrasonography of the vocal folds—a prospec-
ski A.Real-time, high-
tive pilot study in patients before and after thyroidectomy.
Langenbeck’s Arch Surg 2010;395(7):859–64.) (c) Color
Doppler Imaging (CDI) demonstrating normal air ow
patterns over both cords. (d) Paralyzed right vocal cord
adducted to midline, with asymmetric color triangle. (Ooi
LL, Chan HS, Soo KC.Color Doppler imaging for vocal
cord palsy. Head Neck 1995 Feb;17(1):20–3)
41 Transcutaneous Laryngeal Ultrasonography: Vocal Fold Ultrasound
475
predictive values ranging 60–100%, given the
limitations set forth by inter-user variability,
older age, and male gender. They conclude that
TLUS may be a good alternative in the postoperative setting in a young patient following
uncomplicated surgery with a normal voice on
clinical examination, to conrm recurrent laryngeal nerve integrity [22].
Paradoxical Vocal Cord Motion Disorder
Paradoxical Vocal Fold Motion Disorder
(PVCMD) is a condition where the vocal folds
adduct instead of abduct on inspiration.
Common symptoms include stridor, wheezing,
coughing, throat tightness, dyspnea, and respiratory distress. Many factors have been implied
in the underlying etiology of PVCM, among
them are lung factors, exercise, stressful events,
psychogenic, functional-neurologic, reux, or
idiopathic [23–26]. PVCMD is not an uncommon cause of post-extubation stridor in the postanesthesia recovery unit or the ICU [27].
Presentation may be confounded with other
causes of stridor, including glottic and subglottic edema, anaphylaxis, mucous plugging, and
airway obstruction. Typical inspiratory vocal
closure can be visualized without airway edema
or allergic features. Distinguishing PCVM from
other causes of respiratory distress is paramount, as this condition can often be treated
with anxiolytics and induction of a slow rhythmic pattern of breathing. Most often, when
properly diagnosed and treated, respiratory distress may be resolved, obviating the need for
invasive respiratory support. Several practitioners report that timely diagnosis has prevented
patients from being reintubated (personal communication). Denitive diagnosis is made with
IFL, which is a minimally invasive procedure,
though this is not always feasible in the uncooperative patient in distress. TLUS offers a noninvasive mode of diagnosis at the bedside.
Application of TLUS for PCVM has not been as
extensively studied—as in vocal cord paralysis,
although similar principles apply. Small-scale
feasibility studies have demonstrated the potential utility of this tool [12], and preliminary data
from clinical cases in the ICU are promising
[28]. A standard linear high-frequency probe
(6–13MHz) is placed horizontally over the thyroid cartilage. After identifying the laryngeal
structures—the opening and closing of the vocal
folds are noted and correlated with inspiration
and expiration. When a normal pattern is present—the cords will open on inspiration (Video
41.1). When PCVM is present, the cords will
adduct and close on inspiration, with the concomitant typical inspiratory stridor sound
(Video 41.2).
Summary Points
• Transcutaneous Laryngeal Ultrasonography
allows visualization of important laryngeal
structures, namely the thyroid cartilage, True/
False vocal folds, and arytenoid cartilages and
their function throughout the respiratory cycle
and during phonation.
• TLUS is a noninvasive alternative to indirect
exible laryngoscopy readily available to the
intensivist at the patient’s bedside and can
assist in diagnosing vocal fold motion abnormalities underlying respiratory distress and
stridor.
• Use of TLUS may be limited by patient habi-
tus, male gender, older age, and calcied thyroid cartilage. The application of spectral
Doppler modes may increase diagnostic
accuracy.
Pro-Tips
When PCVM is present, the cords will adduct
and close on inspiration, with the concomitant
typical inspiratory stridor sound.
Evolving Evidence
A recent meta-analysis of 17 eligible studies suggested TLUS had excellent diagnostic accuracy.
476
A. Leibowitz and A. Oren-Grinberg
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Gauger PG, Cohen MS, etal. Feasibility of surgeonperformed transcutaneous vocal cord ultrasonography
in identifying vocal cord mobility: a multi- institutional
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11. MMH F, Lang BH-H.A prospective study comparing the midline and lateral trans-laryngeal ultrasonography approaches in vocal cord assessment
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13. Amis RJ, Gupta D, Dowdall JR, Srirajakalindini A,
Folbe A.Ultrasound assessment of vocal fold paresis: a correlation case series with exible beroptic
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Anaesthesiol. 2012;21(4):493–8.
14. Cheng S-P, Lee J-J, Liu T-P, Lee K-S, Liu
C-L. Preoperative ultrasonography assessment of
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surgery. World J Surg. 2012;36(10):2509–15.
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16. Kim DH, Lee J, Seo Y, Kim SW, Hwang
SH. Perioperative transcutaneous laryngeal ultrasonography to assess vocal cord function in thyroid surgery. Am J Surg. 2022;223(5):893–9.
17. Wong K-P, Lang BH-H, Ng S-H, Cheung C-Y,
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18. Wang C-P, Chen T-C, Yang T-L, Chen C-N, Lin C-F,
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26. Kenn K, Balkissoon R.Vocal cord dysfunction: what
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27. Farley JD, Cheney M, Eckmann MS, Wallisch
B. Paradoxical vocal fold motion disorder in
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Focused Assessment
ofSonography inTrauma (FAST)
MonicaSaxena
42
Learning Objectives
1. Describe the components of the FAST exam
2. Review indications for the FAST exam
3. Explore the limitations of the FAST exam
Concept, Indications,
andLimitations
Concept
The FAST exam is used to detect intraperitoneal
uid in the abdomen and around the heart. The
exam has utility in critical care units as well as
the emergency department and inpatient oors.
The FAST exam was developed in the 1990s by
trauma surgeons [1]. Over time, it has become an
accepted protocol for patient evaluation in both
acute and critical care settings [2].
Supplementary Information The online version contains supplementary material available at https://doi.
org/10.1007/978- 3- 031- 80038- 2_42.
M. Saxena (*)
Department of Emergency Medicine, Stanford School
of Medicine, Stanford University, Stanford, CA, USA
e-mail: saxenam@stanford.edu
Indications
In general, a FAST exam is indicated in any clinical situation in which there is a concern for intraabdominal free uid or for hemorrhage [3]. An
extended version of the FAST exam, the E-FAST,
also examines the lungs for pneumothorax [4].
There are no absolute contraindications to obtaining a FAST exam. A relative contraindication is
performing a FAST exam when it delays or interferes with time-sensitive life-saving care.
Limitations
Though the FAST exam is now a standard part
of the evaluation of free uid in the hemoperitoneum and pericardial spaces, it is important to
note that urine, ascites, and bowel uid appear
similarly to free uid in ultrasound visualization
[5]. A determination of whether the nding is
free uid depends on the clinical presentation.
Also, the FAST exam has limited utility in evaluating for penetrating bowel or organ injury [6].
Additionally, there are limitations in detecting
free uid in mesenteric, diaphragmatic, or hollow viscus injuries. Also, in certain specic
clinical presentations, free uid detected on
FAST exam is not necessarily pathologic such
as identication of free uid in patients with
ventriculoperitoneal shunts and or peritoneal
dialysis catheters.
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
M. J. Lanspa, A. T. Levinson (eds.), Echocardiography and Ultrasonography in the ICU,
Respiratory Medicine, https://doi.org/10.1007/978-3-031-80038-2_42
477
478
M. Saxena
Views
There are 4 standard views in the FAST exam
that are used to evaluate for the presence of intraperitoneal uid: the hepatorenal recess, the splenorenal recess, the rectouterine (female)/
retrovesical (male) space, and the pericardium
[4]. The e-FAST exam includes the additional
view of the lungs to evaluate for pneumothorax
(Video 42.5).
The Hepatorenal Recess (Morrison’s Pouch)
The interface of the liver and kidney is often
referred to by the eponym of Morrison’s pouch.
Often this is the rst view obtained in the FAST
exam because it is one of the most dependent
areas in the body and uid from the peritoneal
cavity is likely to collect here rst before the
other views. For optimal evaluation, the patient
should be lying supine as uid will collect in the
most dependent areas of the body. To obtain the
view, either the phased array or curvilinear probe
can be used. The probe marker is aimed superiorly and the probe is angled between the 8th and
11th intercostal spaces in the mid-axillary line.
The entire renal hepatic interface should be visualized (Video 42.1). In particular, the inferior
liver tip and renal interface, called the paracolic
gutter, should be evaluated for free uid as uid
may initially collect here before spreading to
Morrison’s pouch. The hepatorenal recess should
also be used to evaluate for hemothorax by looking for uid above the diaphragm. If the depth of
the ultrasound image is decreased, the spine
appears as hyperechoic lines. Also, the space
above the diaphragm should be evaluated for
free uid. To evaluate for uid above the diaphragm (pleural effusion or hemothorax), the
depth of splenorenal interface is decreased so
that the vertebral bodies appear as hyperechoic
lines at the bottom of the screen. The probe is
then moved towards the patient’s head and visualization of the spine below the diaphragm
(“spine sign) is indicative of hemothorax or
pleural effusion.
The Splenorenal Recess
The spleen kidney interface is often the second
view obtained because uid can communicate
between the left and right upper quadrants.
Similar to the right-sided liver and kidney interface, either the phased array or the curvilinear
probe can be used to obtain the image. The probe
marker is aimed superiorly and placed in the posterior axillary line. The splenorenal interface is
visualized looking for any anechoic spaces indicating free uid. Next, the subphrenic space
(interface between the spleen and the diaphragm)
should be examined for free uid as this is the
rst place uid often collects in the left thorax
(Video 42.2). Finally, the left paracolic gutter at
the inferior tip of the spleen should also be evaluated for any free uid.
The Pericardial Space
Depending on the indication for fast exam, in
some instances, the pericardial space is the rst
view obtained, for example, if there is concern
for cardiac tamponade. The phased array probe is
used to obtain the image. The probe marker is
aimed towards the patient’s right side. The probe
is placed inferior and to the right of the patient’s
xiphoid process aiming the probe towards the
patient’s left shoulder. The edges of the pericardium should be evaluated for any pathologic free
uid presenting as a pericardial effusion (Video
42.3). When assessing the pericardium for uid,
the depth of the image should be set to at least
20cm to fully evaluate the borders of the heart
for any free uid.
The Pelvis
The common location of free uid in the pelvis is
different between females and males, though the
image is obtained in the same way. Similar to the
right and left thorax, either the curvilinear or
phased array probe can be used to obtain the
proper view. The probe marker should be pointing towards the patient’s right and the probe
42 Focused Assessment ofSonography inTrauma (FAST)
479
should be placed in the abdominal midline above
the pubic symphysis and the borders of the bladder should be fully visualized (Video 42.4). The
bladder should also be visualized with the probe
marker pointed towards the patient’s head,
sweeping the probe from left to right to fully
view the entire bladder. In females, the uterus
will be visualized superior to the bladder (or on
the right side of the screen) and free uid, if present, will commonly collect posterior to the uterus
(Pouch of Doulas) rst before collecting between
the bladder and uterus. In males, free uid often
collects in the retrovesical pouch which is a
potential anatomic space between the bladder
and the prostate which lies directly posterior
(inferior on the ultrasound screen) to the
bladder.
Pathologic Findings
As noted, free uid in a FAST exam is pathologic
in the following areas:
Pro-Tips: (Call-Out)
• In males, free uid often collects in the retro-
vesical pouch which is a potential anatomic
space between the bladder and the prostate
which lies directly posterior to the bladder
Summary Points
• In critical care settings, the FAST exam has
multiple applications.
• Specic indications include massive ascites,
ruptured viscus, spontaneous intra-abdominal
bleeding and intraperitoneal rupture of an AAA.
• The FAST exam is also useful in evaluating
undifferentiated hypotension or shock.
• Outside the critical care settings, the FAST
exam is part of standard practice when evaluating trauma patients who present with blunt
or thoracoabdominal trauma.
• The FAST exam is also useful to evaluate for
ruptured ectopic pregnancy.
References
Pericardial Fluid
Morrison’s pouch: The liver and kidney interface
in the right thorax
Right paracolic gutter: The space between the
inferior liver tip and the right kidney
Below the diaphragm: If vertebral bodies are
visualized below the diaphragm (“spine sign”),
this indicates free uid
Splenorenal recess: The spleen and kidney
interface in the left thorax
Subphrenic space: The space between the diaphragm and the spleen
Left paracolic gutter: The space between the
inferior tip of the spleen and the left kidney
Pouch of Douglas: Posterior to the uterus
Retrovesical pouch: The space between the
bladder and prostate
Evolving Evidence (Call-Out)
An extended version of the FAST exam, the
E-FAST also examines the lungs for
pneumothorax
1. Rozycki GS, Ochsner MG, Jafn JH, Champion
HR.Prospective evaluation of surgeons’ use of ultrasound in the evaluation of trauma patients. J Trauma.
1993;34:516–27.
2. Balmert N, Espinosa J, Arafeh M-O, Costello J,
Markle S.Integration of bedside ultrasound into the
ICU—a review of indications, techniques and interventions. J Emerg Crit Care Med. 2018;2:17.
3. Dawson M, Mallin M.Introduction to bedside ultrasound volumes 1 and 2. Lexington, KY: Emergency
Ultrasound Solutions; 2012.
4. Chapter 5. Trauma ultrasound: The FAST exam. In:
Reichman EF, editor. Emergency medicine procedures. 2nd ed. McGraw Hill; 2013. https://accesse-
mergencymedicine.mhmedical.com/content.aspx?boo
kid=683§ionid=45343641. Accessed 23 January
2022.
5. Chapter 5. Trauma ultrasound: the FAST exam. In:
Reichman EF, editor. Emergency medicine procedures. 2nd ed. The McGraw-Hill Companies; 2013.
https://accessemergencymedicine.mhmedical.com/
content.aspx?bookid=683§ionid=45343641.
Accessed 22 June 2024.
6. Quinn AC, Sinert R.What is the utility of the focused
assessment with sonography in trauma (FAST) exam
in penetrating torso trauma? Injury. 2011;42(5):482–7.
https://doi.org/10.1016/j.injury.2010.07.249.
Renal andBladder
Ultrasonography
fortheIntensivist
DavidN.Suwondo andCristianaBaloescu
43
Learning Objectives
1. Review the utility of using point-of-care ultrasound to diagnose hydronephrosis and urinary
retention
2. Discuss the limitations of point-of-care ultrasound for diagnosing hydronephrosis
Indications andLimitations
Indications
The incidence of acute kidney injury (AKI) among
patients admitted to the intensive care unit (ICU) is
rising, and a recent international study found that
AKI occurs in 57% of patients admitted to ICUs
worldwide [1]. The American College of
Radiology (ACR) Appropriateness Criteria for
Renal Failure recommend renal ultrasound for the
initial evaluation of unspecied AKI [2]. Although
point-of-care renal ultrasound is not generally
used to diagnose prerenal or intrinsic causes of
AKI, it can rapidly detect post-renal etiologies
through the presence of hydronephrosis. The overall rate of hydronephrosis among patients with
AKI is low, ranging from 5 to 10% [3, 4], but it
represents a reversible cause of AKI, for which
D. N. Suwondo (*) · C. Baloescu
Department of Emergency Medicine, Yale University
School of Medicine, New Haven, CT, USA
e-mail: david.suwondo@yale.edu;
cristiana.baloescu@yale.edu
early intervention is crucial, given the clear association between AKI and increased mortality risk
among ICU patients [1, 5]. Point- of- care ultrasound (POCUS) of the bladder can also be used to
accurately measure bladder volume and assess
bladder catheterization. Urinary catheter use has
been reported in 61% of ICU patients in the United
States, compared to 20% of non-ICU patients [6].
POCUS can be used to identify malposition of the
catheter balloon or tip, visualize catheter obstruction, or detect the presence of echogenic bladder
debris or clots. Among patients with abdominal
pain or urinary tract infection (UTI), POCUS of
the kidneys and bladder may be used to diagnose
an obstructing renal stone. This is especially useful
for patients unable to travel for CT scan. In patients
with urinary tract infections causing severe sepsis
or septic shock, identication of a suspected
obstructing stone may change management and
prompt urgent procedural intervention.
Limitations
In the absence of prior imaging or other information, the degree of hydronephrosis seen on ultrasound does not necessarily correlate with either
the acuity or the degree of urinary obstruction [7,
8]. The ureters are not easily imaged on transab-
dominal ultrasound due to overlying bowel gas,
and an obstructing ureteral stone may not be
directly visualized or measured. Moreover,
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2025
M. J. Lanspa, A. T. Levinson (eds.), Echocardiography and Ultrasonography in the ICU,
Respiratory Medicine, https://doi.org/10.1007/978-3-031-80038-2_43
481
482
D. N. Suwondo and C. Baloescu
hydronephrosis may be caused by other less common etiologies, such as malignancy, pregnancy,
ureteral reux, or diabetes [9]. Hydronephrosis
may not be immediately apparent despite acute
urinary obstruction in patients who are intravascularly depleted or who have signicantly
decreased renal function until after the patient is
adequately uid resuscitated, potentially leading
to a false negative study [7, 8]. Ultrasound evaluation of the bladder is signicantly limited by an
under-distended or empty bladder.
Anatomy andImaging Technique
Anatomy oftheKidneys
The kidneys are located retroperitoneally, at the
level of the T12–L3 vertebrae on the right and the
L1–L4 vertebrae on the left [10]. The kidneys
range from 9 to 12cm in length, 4 to 6 cm in
width, and 2.5 to 3.5cm in the anterior-posterior
dimension [7, 9, 10]. Each kidney is encapsulated
by a well-dened and smooth hyperechoic border
consisting of a brous capsule, perinephric fat,
and renal fascia (Gerota’s fascia) [7, 8]. Within
this capsule lies the renal parenchyma, composed
of the renal cortex peripherally and the renal
medulla (containing the renal pyramids and
papillae) centrally. At the center of the kidney lies
the renal sinus, which consists of the renal calyces and pelvis, renal vessels, and peripelvic fat
[10]. The renal sinus appears hyperechoic on
ultrasound due to the presence of peripelvic fat
along with the collapsed, nondistended calyces
and pelvis (Fig. 43.1b). The renal cortex is
slightly less echogenic than the liver or spleen,
and the renal medullary pyramids are hypoechoic
to the renal cortex [7–9]. Chronic kidney disease
(CKD) is associated with decreased kidney size
and decreased renal cortical thickness on ultrasound (Fig.43.1c), and both measurements have
been found to correlate with estimated glomerular ltration rate [11]. Both AKI and CKD are
associated with increased renal echogenicity on
ultrasound, although this nding by itself is neither sensitive nor specic [2].
Imaging theKidneys
A curvilinear low-frequency transducer is typically used to image the kidneys and bladder
while the patient is in a supine position. The
kidneys are rst imaged in the coronal plane,
which provides a long-axis view of the kidney.
In this plane, the kidney appears bean-shaped
(Fig. 43.1a). To image the right kidney, the
transducer is placed coronally in the anterior or
mid-axillary line, superior to the subcostal margin, with the probe indicator oriented towards
the patient’s head. The transducer is fanned posteriorly towards the patient’s back to view the
kidney, using the liver as an acoustic window.
To center the kidney on screen, the operator may
need to slide the transducer superiorly or inferiorly by one or two intercostal spaces. Rotating
the transducer in an oblique fashion to better
align the imaging plane parallel to the intercostal space prevents structures of interest from
being obscured by shadowing from overlying
ribs. In thin patients, using the phased-array
transducer may be helpful, as the entire footprint of the transducer can be placed in one
intercostal space without rib interference. The
left kidney is more difcult to image than the
right, due to the smaller acoustic window provided by the spleen and the presence of air in the
stomach; the left kidney is often found more
superior and posterior than the right kidney. The
transducer is placed coronally in the left posterior axillary line, one or two intercostal spaces
higher than on the right, with the probe indicator
oriented towards the patient’s head. Each kidney
should be scanned in long axis all the way
through from anterior surface to posterior surface by fanning the transducer. After obtaining
images along the long axis of the kidney, the
transducer is rotated 90 degrees with the probe
indicator oriented towards the anterior or posterior aspect of the patient to obtain short axis
views of the kidney in a transverse plane. In this
plane, the kidney appears circular (Fig.43.1d).
The operator should scan the kidney from superior pole to inferior pole by fanning the
transducer.
ab
cd
43 Renal andBladder Ultrasonography fortheIntensivist
483
Fig. 43.1 (a) Normal right kidney in long axis, showing
relationships with liver (L), psoas muscle (P), and vertebrae (V), and acoustic shadowing from a rib (R), (b)
Normal kidney in long axis, highlighting hypoechoic
renal parenchyma (asterisk) surrounding hyperechoic
renal sinus (arrow), (c) Left kidney in long axis, showing
relationship with spleen (S), with abnormal thinning of
the renal cortex (asterisk), which may be seen in chronic
Imaging theBladder
kidney disease, (d) Normal right kidney in short axis
(transverse plane), showing relationships with liver (L)
and gallbladder (G). Suwondo DN and Baloescu C.Renal
and Bladder Ultrasonography for the Intensivist. In:
Lanspa MJ and Levinson AT, editors. Echocardiography
and Ultrasonography in the ICU: A Comprehensive Text.
Springer; in preparation, 2022
a well-circumscribed round or rectangular
anechoic structure with posterior acoustic
The bladder, when empty or under-distended, is
located entirely in the pelvis behind the pubic
symphysis [12] and may be difcult to identify or
evaluate on ultrasound. When distended, the
bladder extends superiorly into the abdomen [12]
and is easily identiable. The bladder is imaged
in two planes: transverse and sagittal. To obtain a
transverse view of the bladder, the transducer is
placed in the midline suprapubic region, with the
probe indicator pointed towards the patient’s
right side. From here, the transducer is fanned
inferiorly towards the patient’s feet and the sound
beam is directed behind the pubic symphysis into
the pelvis to locate the bladder, which appears as
enhancement and with smooth hyperechoic
walls. The bladder wall ranges from 3 to 6mm in
thickness and varies with the degree of bladder
distension. Bladder wall thickening is a nonspe-
cic nding due to under-distension, cystitis,
elevated intravesical pressures secondary to
obstruction or neurogenic bladder, or malignancy
[9, 13]. The operator should fan the transducer
from superior to inferior to fully image the blad-
der in transverse view. To obtain a sagittal view
of the bladder, the transducer is rotated into a
sagittal plane in the midline suprapubic region,
with the probe indicator pointed towards the
patient’s head. From here, the transducer is tilted