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494
M. Salama and A. Mohamed
The common bile duct is divided into segments with the rst or most proximal segment
lying anterior to the portal vein, the second segment travels between the porta hepatis and the
head of the pancreas, while the third segment is
entirely intrapancreatic. The right and left hepatic
ducts which converge into the CBD can also be
visualized on US, but should be <2mm in size.
The measurement of the CBD should be done
from the largest visualized portion in the longitudinal plane and its upper normal limit is 6–10mm,
being closer to 10in older patients.
Pro Tip Call-Out
Gallbladder wall thickness of more than 4mm is
abnormal.
Pro Tip Call-Out
Add 1mm for every decade; the patient is over
40years old. Normal CBD is <4mm for patients
under 40. For a 50-year-old patient, a normal
CBD is <5mm!
of value is in patient with delayed gastric emptying, where feeding is discontinued or restarted
depending on the ndings on the US.In ileus and
bowel obstruction, the antrum is severely distended with very thin walls and lack of peristalsis
can also be noted.
The appearance of the gastric contents could
also be of value, although reliability is limited.
For example, in a patient with undifferentiated
shock, a distended stomach on ultrasound
could signal upper gastrointestinal bleeding as
the cause. If blood is present in the stomach,
the antrum would be distended, and the uid
would have a heterogenous appearance to the
hypoechoic or anechoic appearance of simple
uid.
Air around the stomach has the appearance of
A lines similar to the A line pattern visualized
while performing lung ultrasound. An A line pattern around the stomach can be a sign of viscous
perforation, in the right clinical scenario. If clinically indicated, further imaging with an upright
CXR should be obtained.
Diagnostic Applications
Stomach
Clinical decision making, including intubation,
could depend on the patient’s stomach contents
and therefore assessing gastric distention in the
ICU is benecial. This is best done by measuring
the antrum size in the epigastric area. If the
antrum is collapsed and the gastric walls are
touching, then the stomach is most likely empty.
In case of stomach fullness, the antrum would be
distended and rounder and the stomach wall
would be thinner.
The contents could be quantied by calculating the cross-sectional area of the antrum (CSA)
using the formula of the area of an ellipse
(∏×r1×r2) where r1 is the anterolateral radius
and r2 is the craniocaudal radius.
If the stomach is distended, the decision to
empty the stomach to decrease the risk of periintubation aspiration, for example by inserting an
NG tube prior to intubation, could be made.
Other situation where stomach distension may be
Liver
In a diseased liver, the most noticeable change is
usually the loss of homogeneity. In cirrhosis, the
liver has a coarsened echotexture and nodular
appearance with or without surrounding ascites.
Elevated liver enzymes can signal acute hepatitis
which can be further conrmed with an US.The
most sensitive sign for hepatitis is hepatomegaly
of over 16cm and attenuated brightness sometimes described as a “starry sky”. Hepatomegaly
with increased echogenicity is seen in hepatic
steatosis where liver enzymes are normal or
mildly elevated.
A mass seen on the liver has a wide differential (Fig.44.4). Clear, anechoic mases are more
likely to be cysts while heteromorphic masses
with or without air are more likely to be abscesses.
Hypoechoic hepatic focal lesions in high-risk
patients are suspicious for hepatocellular carcinoma or metastasis and may be associated with
enlarged porta hepatic lymph nodes or para- aortic
lymph nodes. Using color ow doppler, the vas-
44 Gastric, Biliary, andHepatic Ultrasound intheICU
Fig. 44.4 A liver mass
is seen. Color doppler
can be used to assess its
vascularity and help
characterize it further
495
cularity of these masses can be analyzed and can
show neovascularization.
The portal vein ow can be abnormal with low
velocity combined with increased caliber being
diagnostic in portal hypertension. Advanced disease leading to stagnation or even reversal of ow
in the portal vein is a sign of grave prognosis.
Biliary System
Gall stones can be seen in the gallbladder as
hyperechoic structures with hypoechoic shadowing. They may be asymptomatic or may cause
biliary colic that resolves spontaneously.
Repositioning the patient while looking at the
stones to ensure they are mobile and moving
freely is sometimes useful. Stones that migrate to
the CBD can cause bile stasis and subsequent
cholecystitis.
Even if the probe is not able to detect actual
stones in the CBD due to poor visualization,
CBD dilation of over 10mm is sometimes enough
for a diagnosis. A double channel or parallel
channel sign often results when the CBD is dis-
tended and represents the hepatic artery. In this
case, color doppler may be needed to differentiate between the two. In cases of severe obstruction, the biliary structure proximal to the CBD
can also be visualized including intrahepatic
ducts.
Other ndings that may point towards gallstones include gallbladder sludge which is heterogenous uid within the gallbladder. Gallbladder
sludge is often a precursor to stones.
Cholecystitis or inammation of the gallbladder can be calculous or, more commonly in the
ICU, acalculous, without gallstones. Acalculous
cholecystitis is associated with sepsis, blood
transfusions, shock, major surgery, and trauma.
When the gallbladder is inamed, it will
appear distended (>12 mm) and its walls will
appear thick (>3 mm) (Fig. 44.5). Gallbladder
sludge or stones may be seen as well as uid
between the gallbladder and the liver or pericholecystic uid. If the patient is awake, asking them
to take a deep breath with the probe in place
while pressing on the gall bladder using the US
probe will illicit Murphy’s sign and they will feel
pain on inspiration.
496
Fig. 44.5 A gall
bladder with thickened
walls. Measuring the
wall diameter can help
narrowing the diagnosis
M. Salama and A. Mohamed
Summary Points
• POCUS can have diagnostic utility for the
intensivist in the evaluation of abdominal
pathology
• POCUS can be used to identify abnormal
stomach contents and perforated viscous
• Acute cholecystitis is demonstrated by sonographic Murphy’s sign, dilated CBD, gallbladder wall thickening, and gallbladder
sludge, +/− gallstones
• Loss of liver homogeneity is a sign of a hepatic
pathology and warrants additional workup
Question(s)
A 38-year-old female presents to the Emergency
Department with abdominal cramping, nausea,
and decreased oral intake. Her vitals are HR 95,
BP 118/56, RR 18, Temp 100.8. A POCUS is
performed demonstrating acute cholecystitis.
Which of the following ultrasound ndings is
not consistent with a diagnosis of acute
cholecystitis?
A. Presence of gallstones
B. Heterogeneous uid in the gallbladder
C. Gallbladder wall measurement of 5mm
D. Common bile duct measurement of 4mm
Answer: (D). Visualizing gallstones on ultrasound in a symptomatic patient is supportive of a
diagnosis of acute cholecystitis. Hetergenous
uid in the gallbladder is consistent with gallbladder sludge, another nding in acute cholecystitis.
Normal gallbladder wall size is less than 4 mm,
therefore in a 48 year old female, a size of 5mm is
abnormal and consistent with acute cholecystitis.
Normal CBD measurement is less than 6mm, a
CBD measuring 4mm would therefore not be consistent with a diagnosis of acute cholecystitis.
Ultrasound Guidance
forAbdominal Procedures
BelalNoureddine andKristinDwyer
45
Learning Objectives
1. Describe how to perform paracentesis using
ultrasound guidance
2. Examine the use of ultrasound to help place
Blakemore and Minnesota Tubes
Paracentesis
Paracentesis is a bedside procedure in which
ascitic uid is obtained from the peritoneal space.
The goal is either therapeutic, large volume
removal of ascites to relieve symptoms of abdominal pain, early satiety, and shortness of breath
caused by increased intraabdominal pressure, or
diagnostic, small volume uid removal aimed at
assessing infection such as spontaneous bacterial
peritonitis (SBP), malignancy, or cirrhosis.
Paracentesis is not indicated for patients with
concern for a surgical abdomen. Relative contraindications include evidence of increased risk for
Supplementary Information The online version contains supplementary material available at https://doi.
org/10.1007/978- 3- 031- 80038- 2_45.
bleeding complications such as an international
normalized ratio (INR) >2.0 or platelets <20,000
109/L.Additionally, caution should be taken with
patients with distended bowel due to the risk of
bowel injury as well as in patients with overlying
cellulitis.
Ultrasound-guided paracentesis allows the
operator to visualize the deepest and most favorable pocket of peritoneal uid to avoid bowel and
other intra-abdominal organs, offering a superior
safety prole to the blind approach [1]. In addition, abdominal ultrasound can identify as little as
100 mL of intra-abdominal free uid, allowing
the operator to conrm the presence of ascites in
the setting of abdominal pain and distention
before inserting a needle unnecessarily (Fig.45.1).
The use of ultrasound has been shown to
increase the likelihood of success for paracentesis
from 61% to 91% [1], and to signicantly reduce
the incidence of adverse events including infection,
hematoma, and seroma from 4.7% to 1.4% [2, 3].
B. Noureddine
Internal Medicine Group, Orlando Health,
Orlando, FL, USA
e-mail: belaln@umich.edu
K. Dwyer (*)
Emergency Medicine, Warren Alpert Medical
School of Brown University, Providence, RI, USA
© 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_45
497
498
Fig. 45.1 Ultrasound
image of ascites uid
B. Noureddine and K. Dwyer
Fig. 45.2 Paracentesis kit
Technique
After obtaining informed consent, collect the
materials/kit (Fig.45.2) for the procedure. Not all
below listed materials are required for a diagnostic paracentesis:
• Local anesthetic, needle, and syringe
• Antiseptic solution
• Fenestrated drape
• Paracentesis needle
• Scalpel
• 3-way stopcock
45 Ultrasound Guidance forAbdominal Procedures
499
Table 45.1
Test
Appearance Clear straw or
Total protein <25g/L <25g/L
Serum-ascites
albumin
gradient
(SAAG)
LDH
Glucose N N
Cell counts
Bacterial
culture
Ascitic uid analysis
Causes of ascites
Cirrhosis Congestive Heart
milky
≥1.1g/dL ≥1.1g/dL
↓ ↓ or N ↑ ↑ or N ↑ or N
≥250/μL or N ≥250/μL
+ or −
Failure (CHF)
Clear to pale
yellow
• 50mL syringe
• Tubing set with rolling clamp
• Drainage bag
• Specimen vials
• Collection bottles
Before commencing, instruct the patient to
empty their bladder. Place the patient in the
supine or lateral decubitus position. The lower
lateral quadrant is preferred and placing the
patient on their side may aid in identifying the
largest pocket.
To evaluate for ascites, the operator can use
the curvilinear or phased array probes, which are
both high penetration, low-frequency probes.
Place the transducer in the transverse position
with the orientation marker facing the operator’s
left. Slide the probe up and down the abdomen in
a lawnmower-type motion to nd a suitable
pocket. Prep and drape the skin in the usual sterile fashion and administer local anesthetic to the
skin, subcutaneous tissue, and down to the
peritoneum. Ultrasound guidance decreases the
likelihood of hitting an abdominal vessel or other
abdominal contents such as the viscera [4, 5].
The operator can either insert their needle at
the pre-marked location or they can use direct
ultrasound visualization for real-time procedure
guidance. Insert the needle or catheter perpendicular to the skin and consider using the z-track
technique: once the skin is punctured, lift the skin
caudally and then advance the needle. If a cathe-
Malignancy SBP
Milky or
bloody
≥25g/L ≥25g/L ≥25g/L
<1.1g/dL <1.1g/dL <1.1g/dL
↓ ↓ ↓
Cloudy or
turbid
+
Pancreatitis
Milky, cloudy or
turbid
ter is being inserted, the operator should make a
small nick with an 11 blade in the skin and soft
tissue to allow for catheter passage. Pull back on
the syringe the needle/catheter as you advance
until ascitic uid begins to ll the syringe.
Advance the catheter into the peritoneal cavity
and withdraw the needle. If performing a diagnostic paracentesis, withdraw the catheter once
an adequate specimen volume has been obtained.
If performing a therapeutic tap, connect the tubing to remove larger volumes of ascites. For large
volume paracentesis >5 liters, strong consideration should be given to administering albumin.
The specimen should be sent to the lab for
analysis of cell count with differential, gram
stain, and culture. Additional analysis to consider
includes albumin, protein, glucose, lactate dehydrogenase (LDH), and cytology. SBP is diagnosed with an ascitic uid absolute
polymorphonuclear neutrophil (PMN) count
>250 cells/mm3 or a positive uid culture.
Traditional empiric treatment includes coverage
for Escherichia.Coli and Klebsiella Pneumoniae
with a third-generation cephalosporin, such as
ceftriaxone. Prophylactic antibiotics should be
considered for patients with ascitic uid protein
concentration <1 g/dL, variceal bleed, or prior
SBP [6, 7] (Table45.1).
Complications from paracentesis are uncommon but include persistent ascitic leak, abdominal wall hematoma, bladder or bowel perforation,
vessel injury, hypotension, or infection [8].
500
B. Noureddine and K. Dwyer
Blakemore/Minnesota Tubes
A Blakemore tube is a tube that can be inserted
through the oropharynx or nasopharynx, typically in the intubated patient, and advanced into
the stomach to tamponade gastric or esophageal
bleeding. This is generally reserved for use in
unstable patients with uncontrolled bleeding,
usually from gastric or esophageal varices, who
are unable to get to the endoscopy suite. A
Blakemore tube has three ports (gastric balloon,
esophageal balloon, and gastric suction port) on
one end and two balloons on the other end. A
Minnesota tube is similar to a Blakemore tube;
however, it has a larger gastric balloon and both
gastric and esophageal aspiration ports [9].
Endoscopy by a gastroenterologist is the gold
standard for treating acute variceal bleeding, but
the Blakemore/Minnesota tube can be used as a
rescue measure if endoscopy is unsuccessful or
unavailable (Fig.45.3).
To place a Blakemore tube, rst secure the
patient’s airway and elevate the head of the bed if
a
b
Fig. 45.3 (a) Blakemore tube (b) Minnesota tube
possible. Deate and lubricate the tube after
inating to conrm that there are no balloon
leaks. Mark the tube before insertion to identify
how far to insert it (~50centimeters (cm) above
the esophageal balloon). The tube is advanced
until the operator is condent that one balloon is
in the stomach and the other balloon is in the
esophagus.
Next, ll the gastric balloon with approximately 50milliliters (mL) of air through the port
while auscultating over the stomach and lungs.
Traditionally, a chest radiograph (X-ray) is
obtained to conrm balloon placement in the
stomach before inating with an additional
200mL of air. Ultrasound can be used instead to
assess balloon placement and ination. Next,
apply traction to aid the inated balloon in the
tamponade of the bleeding vessel. Ensure that the
tube does not move more than an inch with traction, as this may indicate more ination is
required. Using the gastric suction port, evaluate
for ongoing bleeding below the gastric balloon.
With continued gastric bleeding, consider additional balloon ination. To evaluate esophageal
bleeding, a nasogastric (NG) tube must be
inserted to identify continued bleeding above the
gastric balloon.
A Minnesota tube, functionally similar to a
Blakemore tube with the exception an expanded 500
mL gastric balloon capacity and inclusion of both
gastric and esophageal suction ports, may also be
used to tamponade emergent bleeding. Additionally,
the presence of the esophageal suction port obviates
the need for separate NG tube insertion. The esophageal balloon can be inated to a pressure of
20–40millimeters of mercury (mmHg).
While the standard of care is to conrm gastric balloon placement with X-ray before ination, this results in signicant delays to
therapeutic tamponade. In a hemodynamically
unstable patient, bedside ultrasound may be
able to more rapidly conrm placement and
location of the balloon, as well as provide assistance with real-time position adjustments. At
present, there is little evidence to support the
use of ultrasound for balloon localization, as
this is such an infrequently performed procedure [10, 11].
45 Ultrasound Guidance forAbdominal Procedures
Fig. 45.4 Ultrasound images of the trachea and esophagus during tube placement
501
To locate the tube with ultrasound, use a highpenetration low-frequency probe, such as the curvilinear or phased array probe. Place the probe in
the sagittal plane in the mid-epigastrium aiming
to the patient’s left to nd the gastroesophageal
junction (GEJ). Rotate counterclockwise, and
this view will conrm the passing of the tube
through the lower esophageal sphincter (LES)
into the stomach [10]. In the hemorrhaging
patient, the stomach is likely full of blood, allowing for better identication of the balloon as
blood provides a good medium for ultrasound
waves. Anteriorly in the supine patient, there may
be interference from air which will obscure the
operator’s view. To nd the best view, slide along
the costal margin aiming towards the stomach. In
the lateral view, the operator can conrm that the
balloon is located below the diaphragm as it is
being inated [12].
Further, as the Blakemore or Minnesota tube
is being advanced, the linear probe can be placed
on the anterior neck in the transverse view with
the marker to the patient’s right. In this view, the
trachea and esophagus can be visualized and passage of the tube through the esophagus can also
be viewed [10] (Fig.45.4).
Potential complications of this procedure
include inating the gastric balloon above the
diaphragm, resulting in damage or rupture of
the esophagus or trachea. In addition, prolonged placement (>24–36hours) may result in
pressure necrosis, and 50% of patients will
experience rebleeding [13, 14].
Gastrostomy Tube
A Gastrostomy tube (G-tube) allows for enteral
nutrition, as an alternative to parenteral nutrition,
in patients with the inability to tolerate oral intake
due to obstruction from head and neck tumors,
neurologic decline, or esophageal damage due to
stricture formation, obstructive malignancy,
trauma, or surgery. A G-tube has three ports
(medicine, feeding, balloon) on one end and one
balloon with a bumper on the other end [15, 16]
(Fig.45.5).
G-tubes can be placed percutaneously via
endoscopy, radiologically, or with ultrasound.
G-tube placement may be performed transorally
in the anterograde “pull-type” route or transabdominally in the retrograde “push-type” fashion.
Of these percutaneous modalities, ultrasound is
emerging as the favored technique in conjunction
with radiologic placement via the “push-type”
route, as ultrasound allows for real-time visualization of abdominal structures, thereby decreasing uoroscopy time and minimizing radiation
exposure to both the patient and the operator
[18]. Endoscopic G-tube placement is limited by
the requirement of deep sedation and is contraindicated in the setting of head and neck malignancy due to obstruction and the risk of gastric
seeding.
Placing a G-tube in the retrograde abdominal
fashion begins with the patient in the supine position. Using a curvilinear low-frequency ultrasound probe, hold the transducer in the transverse
502
Fig. 45.5 A standard gastrostomy tube (from Cook etal.
[17])
position with the orientation marker facing the
operator’s left. Fan the probe to identify key
abdominal structures, including the margins of
the liver and the gastric antrum, and mark them
on the skin. An NG tube is inserted, and carbon
dioxide is administered through it for insufation
of the stomach [18, 19].
Following gastric insufation, fanning of the
probe can locate a percutaneous access window, favored near the linea alba. A gastropexy
device is then, under ultrasound guidance,
placed to internally afx the stomach against
the anterior abdominal wall. With the stomach
in view, a large-bore needle is inserted in the
center of the gastropexy site, visualized in realtime with ultrasound. Under continuous uoroscopy, a guidewire is inserted, the needle
entry tract is dilated, and then the G tube is
inserted. After this, the G tube balloon is
inated, and contrast is inserted to conrm its
placement.
B. Noureddine and K. Dwyer
Potential complications of this procedure
include through-and-through puncture of the
colon, and less frequently, the liver. Additionally,
puncture of the liver increases the risk of
abscess formation via the introduction of skin
ora. The use of ultrasound both before the procedure to survey the liver margins and during
the procedure to guide needle placement in
real-time can help to mitigate these severe complications [20, 21].
Summary Points
• Ultrasound guidance for therapeutic and diag-
nostic paracentesis increases procedural safety
by identifying the best ascites pocket to avoid
injury to bowel and intra-abdominal organs.
• Placement of balloon tamponade devices for
unstable patients with massive upper gastroin-
testinal bleeds is an uncommon procedure.
Traditionally balloon placement is conrmed
by X-ray, but more data are needed to deter-
mine whether a bedside ultrasound can more
rapidly conrm balloon location accurately.
• Gastrostomy tubes are most commonly per-
formed percutaneously with radiologic guid-
ance. There is emerging evidence that this
procedure can be augmented with ultrasound
guidance.
Questions
1. A 31-year-old female with a past medical his-
tory of chronic Hepatitis C infection, intravenous drug abuse, and bipolar disorder presents
after being found down for an unknown
amount of time. Initial vitals are BP
96/43mmHg, HR 63bpm, RR 7bpm, Temp
95.7F, and 92% O
saturation on room air. On
2
visual inspection, the patient appears in pain
and is holding her abdomen, which on physical exam is noted to be grossly rigid and distended with localized epigastric erythema,
and tender to palpation in all quadrants.
Bedside ultrasound is performed and
shows a shrunken liver and a large ascites
pocket with an air uid level. Complete blood
count is notable for Hemoglobin 10.6 g/dL,
Hematocrit 35%, White Blood Cells
45 Ultrasound Guidance forAbdominal Procedures
503
27 × 109/L, and Platelets 12 × 109/L. The
remaining lab work is in process. Urine HCG
is positive.
As part of the infectious workup, the
patient is planned for bedside paracentesis
under point-of-care ultrasound (POCUS)
guidance. While POCUS guidance increases
the safety of paracentesis, which of the following is an absolute contraindication to paracentesis in this patient?
A. Pregnancy
B. Abdominal Cellulitis
C. Severe Thrombocytopenia
D. Concern for Peritonitis
E. Hypotension
Answer: (D). Pregnancy, abdominal cellulitis, thrombocytopenia, and hypotension are
all relative contraindications that require careful consideration prior to performing a paracentesis. However, the presence or strong
suspicion of a surgical abdomen is an absolute
contraindication to performing a
paracentesis.
2. A 56-year-old male presents to the emergency
room overnight with 3days of progressively
worsening nausea and vomiting, which has
been mostly yellow liquid. Past medical history is notable for chronic marijuana use,
osteoarthritis managed with daily ibuprofen,
and alcohol use disorder. While history is
being obtained, the patient experiences an
aggressive episode of vomiting which
develops into persistent bouts of large volume
hematemesis.
The patient reports feeling lightheaded and
subsequently stops answering questions. Stat
vitals are notable for BP 83/29 mmHg, HR
125bpm, RR 14bpm, and 89% peripheral O2
saturation. Central access is rapidly obtained,
four units of O-negative packed red blood
cells are ordered stat, and a 2-L crystalloid
bolus begins infusing. The patient is intubated
for airway protection and the gastroenterologist on-call is paged for urgent endoscopic
intervention but has to travel from offsite.
Despite uid resuscitation and ongoing
blood transfusion, repeat blood pressure is
75/21mmHg and HR is 127bpm. The deci-
sion is made to place a Minnesota tube to
tamponade the bleeding until the gastroenterologist arrives. Which of the following is
true about point-of-care ultrasound
(POCUS) guidance for balloon tamponade
placement in the unstable patient?
A. POCUS is established as superior to X-ray
for conrming balloon placement in the
stomach prior to ination
B. POCUS may be able to save time as an
alternative to X-ray for conrming balloon placement in the unstable patient
C. Balloon tamponade should be used for all
hematemesis patients with a blood pressure of <90mmHg, even if endoscopy is
available
D. All of the above
Answer: (B). There is emerging evidence
that POCUS may be able to expedite conrmation of gastric balloon placement and minimiize radiation expsoure; however, at the
time of writing, X-ray remains the gold standard. Additionally, when readily available,
endoscopy is the superior modality for locating and treating upper gastrointestinal bleeds
in both stable and unstable patients.
References
1. Nazeer SR, Dewbre H, Miller AH.Ultrasound-assisted
paracentesis performed by emergency physicians vs
the traditional technique: a prospective, randomized
study. Am J Emerg Med. 2005;23(3):363–7. https://
doi.org/10.1016/j.ajem.2004.11.001.
2. Patel PA, Ernst FR, Gunnarsson CL. Evaluation of
hospital complications and costs associated with
using ultrasound guidance during abdominal paracentesis procedures. J Med Econ. 2012;15(1):1–7. https://
doi.org/10.3111/13696998.2011.628723.
3. Rodriguez Lima DR, Yepes AF, Birchenall Jiménez CI,
Díaz MAM, Rojas DIP.Real-time ultrasound-guided
thoracentesis in the intensive care unit: prevalence of
mechanical complications. Ultrasound J. 2020;12:25.
https://doi.org/10.1186/s13089- 020- 00172- 9.
4. Hatch N, Wu TS, Barr L, Roque PJ.Advanced ultrasound procedures. Crit Care Clin. 2014;30(2):305–29,
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https://doi.org/10.1016/j.ccc.2013.10.005.
5. Mayeaux EJ. Abdominal paracentesis [Internet].
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Available from: https://5minuteconsult.com/