Basic principles of ultrasound. Terms used in ultrasound. Advantages of ultrasound. Definition of acute abdomen. Differential Diagnosis. Abdominal ultrasound technique. USG findings in most common pathologies. Conclusion.

1. By Dr Vishwanath R S
Vydehi Hospital, Bengaluru
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Unrestricted

2.  Basic principles of ultrasound.
 Terms used in ultrasound.
 Advantages of ultrasound.
 Definition of acute abdomen.
 Differential Diagnosis.
 Abdominal ultrasound technique.
 USG findings in most common
pathologies.
 Conclusion.
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3. Sound: It is the result of mechanical energy traveling through matter
as a wave producing alternating compression and rarefaction.
Pressure waves are propagated by limited physical displacement of the material
through which the sound is being transmitted.
http://www.physics.uc.edu/~sitko/CollegePhysicsIII/14-Sound/Sound.htm
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4.  In nature, acoustic frequencies span a range from less than 1 Hz
to more than 100,000 Hz (100 kHz).
 Human hearing - 20 to 20,000 Hz.
 Ultrasound differs from audible sound only in its frequency, and it
is 500 to 1000 times higher than the sound we normally hear.
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5. 5

6. ECHOGENECITY:
Echogenicity refers to the ability of tissues to reflect (echo)
ultrasound waves.
Anechoic: no echoes and sonolucent—appears
black on ultrasound.
Hypoechoic: less reflective and low amount of
echoes when compared with neighbouring
structures, appears as varying shades of darker
Gray.
Hyperechoic: highly reflective and echo rich when
compared with neighbouring structures, appears as
varying shades of lighter gray; the term echogenic
is often used interchangeably .
Isoechoic: having similar echogenicity to a
neighbouring structure (Figure 1-3)
Post acoustic shadowing: Failure of the sound beam to
pass through an object, e.g. a bone does not allow any
sound to pass through it and there is only shadowing seen
behind it.
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7.  Homogeneous: organ parenchyma is uniform in
echogenicity .
Ultrasound Texture:
 Inhomogeneous or heterogeneous: organ
parenchyma is not uniform in echogenicity.
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8. Advantages of ultrasound:
 Can be used as 1st line investigation of choice for
definitive diagnosis.
 US does not require ionizing radiation.
 The spatial resolution of a high-frequency US image is
higher than that of a
CT image.
 The dynamic, real-time qualities of US are unique.
 It can be done in the Emergency Ward, High Care Units
and the Operating Room, and with the present generation
of small, battery-assisted, hand-held units, in fact
anywhere.
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9. Acute abdomen
Definition:
An acute abdomen is defined as severe abdominal pain
of unclear etiology that is less than 24 hours duration.
Differential diagnosis of an acute abdomen includes a wide
spectrum of disorders.
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10. Gallstones and gall
bladder related
disease
Appendicitis, obstruction
of caecum, ectopic
pregnancy, ovarian cyst
Peptic ulcer,
perforation of ulcer,
pancreatitis
Diverticulitis, ulcerative
colitis, ectopic pregnancy
Cystitis, urinary retention,
testicular torsion
Early appendicitis, small
bowel obstruction,
gastroenteritis
Small bowel
obstruction,
gastroenteritis
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11. Frequencies of Diagnoses Causing Acute
Abdomen in Studies Reported in the Literature
http://radiology.rsna.org/content/253/1/31/suppl/DC1
As the examination proceeds, it is possible to correlate the
US findings with the clinical data, the laboratory results,
other imaging studies and the information provided by the
patient.
Doing so, the long list of possible differential diagnoses
will continuously narrow down until a definitive diagnosis
is established, or at least, direction is given to subsequent
imaging studies.
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12. Technique:
US examination in patients with acute abdominal
pain requires a specific technique of graded
compression. In this way fat and bowel are
displaced or compressed.
This technique also allows assessing the rigidity
of a structure by evaluating its
reaction upon compression. In order to avoid
pain, the compression should be
applied slowly and gently, similar to the classic
palpation of the abdomen.
The entire abdomen is examined to exclude disease of
gallbladder, pancreas, kidney, aorta, stomach, small and
large bowel, appendix, uterus and ovaries.
A moderately filled bladder allows better survey of the
distal ureters, and of uterus and ovaries in women.
Transvaginal US may be used for gynecological
conditions.
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13. ULTRASONOGRAPHIC FINDINGS

14. ACUTE APPENDICITIS:
 Most common acute presentation to ED
 Right lower quadrant pain, tenderness and leukocytosis.
 Appendectomy with out preoperative imaging - Normal appendix removed.
 Delayed surgery in patients with atypical presentation may result in complications.
 Laparotomy resulting in removal of normal, non inflamed appendices – 16% to 47%
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15. Normal appendix:
At sonography the normal appendix is less frequently
visualized, with results varying between 0-82% [1],
reflecting the operator dependency of sonography.
One of the most important imaging criteria in the
evaluation of appendicitis is the outer diameter of the
appendix
A normal appendix has a maximum outer diameter of 6
mm, is surrounded by homogeneous non-inflamed fat,
and often contains intraluminal gas.
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16. Sonographic findings:
IDENTIFY APPENDIX
Blind ended.
Noncompressible.
Aperistaltic tube.
Gut signature.
Arising from base of cecum.
Diameter greater than 6 mm.
SUPPORTIVE FEATURES
Inflamed perienteric fat.
Pericecal collections.
Appendicolith.
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17. NORMAL APPENDIX INFLAMED APPENDIX
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18. Spectrum of appearances in appendicitis
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19. Appendicular perforation
• Loculated pericecal fluid.
• Phlegmon/Abscess.
• Prominent pericecal fat.
• Circumferential loss of submucosal layer
of the appendix.
.
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20. Acute Pancreatitis:
An acute inflammatory process of the pancreas with variable involvement of
other regional tissues or remote organ systems associated with raised pancreatic
enzyme levels in blood and/or urine.
The clinical spectrum of AP ranges from a benign, self-limited
disorder (75% of patients) to severe pancreatitis that may be fulminant and
quickly cause death from multiorgan failure.
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21. The myriad other causes of AP include neoplasm, infection, pancreas divisum,
toxins, drugs, and genetic, traumatic, and iatrogenic (endoscopy, postoperative)
factors.
Abdominal sonography and contrast-enhanced computed tomography (CECT) are
the two most useful imaging modalities in patients with AP.
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22. After a careful search of the gallbladder and bile duct for stones, the entire pancreas
should be scanned. After scanning the pancreas, peripancreatic pathology should be
sought in the lesser sac, anterior pararenal spaces, and
transverse mesocolon.
The parenchyma is usually isoechoic or hyperechoic compared with hepatic parenchyma.
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23. 23

24. ACUTE
CHOLECYSTITIS:
Acute cholecystitis is a relatively common disease,
accounting for 5% of the patients
It is caused by gallstones in more than 90% of patients.
Impaction of the stones in the cystic duct or the
gallbladder neck results in obstruction, with luminal
distention, ischemia, super infection, and eventually
necrosis of the gallbladder.
Clinically, patients present with a prolonged, constant
RUQ or epigastric pain associated with RUQ tenderness.
Fever, leucocytosis, and increased serum ALP and
bilirubin levels may be present.
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25. Sonography is currently the most practical and accurate method to diagnose acute cholecystitis.
Sonographic findings
Thickening of the gallbladder wall (>3
mm).
Distention of the gallbladder lumen
(diameter >4 cm)
Gallstones
Impacted stone in cystic duct or
gallbladder neck
Pericholecystic fluid collections
Positive sonographic Murphy’s sign
Hyperemic gallbladder wall on Doppler
interrogation
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26. 26
Impacted gallstone
Thickened wall
Sludge
Post acoustic shadowing

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Distended
lumen
Pockets of odema fluid

28. 28
Sloughed
Membrane
Perforation

29. Bowel obstruction:
 Intestinal obstruction (IO) is a common cause of
acute abdominal pain.
 Sonography in patients with suspected MBO is
usually not helpful because adhesions, the most
common cause of intestinal obstruction, are not
visible on the sonogram.
 Also, the presence of abundant gas in the intestinal
tract, characteristic of most patients with
obstruction frequently produces sonograms of
nondiagnostic quality.
However, in the minority of patients with MBO who do
not have significant gaseous distention, sonography
may be helpful.
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30.  Diagnosis of bowel obstruction is usually made on the basis of the clinical picture
confirmed by plain radiography of the abdomen as the initial investigation.
 Point-of-care ultrasound can answer specific questions related to IO like cause and location
of the obstruction that assist the acute care physician in critical decision making.
 The peritoneal cavity is screened for
bowel pathology with five to six
vertically oriented, overlapping lanes
using a broad based, high frequency
probe.
 This is referred to as 'mowing the lawn‘

This form of screening is facilitated by
the use of thin-liquid US-gel.
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31. Mechanical bowel obstruction is characterized by:
 Dilation of the GI tract proximal to the site of luminal
occlusion.
 Accumulation of large quantities of fluid and gas.
 Hyper peristalsis as the gut attempts to pass the luminal
content beyond the obstruction.
Sonographic study should include:
 Gastrointestinal tract caliber from the stomach to the
rectum.
 Content of any dilated loops.
 Peristaltic activity within the dilated loops.
 Site of obstruction.
.
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32. 32
Gangrenous small
bowel loop as a result of
single fibrous band.

33. Interloop fluid
Sagittal image
Transverse image

34. 34
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35. Acute flank pain and abdominal pain with haematuria
are relatively common presenting complaints in the
emergency department.
 The structural impediment to the flow of urine is termed
obstructive uropathy.
 When obstruction develops suddenly then It results in renal colic. The most
common cause is kidney stone dislodged into ureter.
 Urine flow is blocked by the ureter leading to backup and dilatation of the
pelvicalyceal system, termed hydronephrosis.
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ACUTE RENAL COLIC

36. The diagnosis of acute renal colic has three major components:
1. The patient’s clinical presentation.
2. The presence of blood on urinalysis. 89% of patients with
ureterolithiasis have > 0 RBC per high power field on urine
microscopy.
3. Diagnostic imaging, which may include intravenous
pyelogram (IVP), CT scan or ultrasound.
The goal of bedside renal ultrasonography is to answer a few basic questions:
Is there hydronephrosis?
Unilateral or bilateral?
Is there fluid around the kidney?
Is the bladder distended?
Are stones seen?
Is the aorta normal ?
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37. 37HYDRONEPHROSIS

38. 38
Stones

40. Acute diverticulitis:
 Diverticula of the colon are usually acquired
deformities and are found most frequently in
Western urban populations.
 Diverticula are usually multiple, and their most
common location is the sigmoid and left colon.
Acute diverticulitis and spastic diverticulosis
may both be associated with a classic triad of
presentation:
 LLQ pain
 Fever and
 Leukocytosis.
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41. 41

42. ECTOPIC PREGNANCY:
One in every thirteen women presenting to the
emergency department (ED) in their first trimester of
pregnancy with abdominal or pelvic pain or vaginal
bleeding will eventually be diagnosed with an ectopic
pregnancy
Because the history and physical exam are unreliable
for detecting or excluding the presence of an ectopic
pregnancy, ultrasound has become more than just an
adjunctive diagnostic tool.

45. The most definitive sonographic sign of ectopic
pregnancy is the visualization of an extrauterine
gestational sac containing a yolk sac, embryo or fetal
heart beat.
Sonographic findings in ruptured ectopic pregnancy:
Inhomogenous mass in the adnexa
Free fluid in the morrisons pouch or pouch of douglas.
Empty gestational sac.
“Ring of fire” – mass in adnexa surrounded by hypervascular
Flow on doppler.

46. Ovarian torsion:
Torsion of the ovary is an acute abdominal condition
requiring prompt surgical intervention.
 It is caused by partial or complete rotation of the
ovarian pedicle on its axis.
 Congestion and odema.
Clinically,
 Severe pelvic pain, nausea, and vomiting.
 A palpable mass may be present.
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47.  Enlarged ovary due to ovarian edema,
 Peripherally pushed follicles
 Abnormal ovarian blood flow. Absence of arterial
and venous flow .
 Relative enlargement of ipsilateral ovary,
 Free fluid around ovary or in Douglas pouch
 Underlying ovarian lesion like ovarian cyst.
 Abnormal ovarian location.
Sonographic Features of torsion ovary:
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Peripherally pushed
follicles

48. Abdominal aortic aneursymal rupture:
 A ruptured AAA is a vascular catastrophe.
 Mortality rate after rupture approaches 90%.
 The physical exam is often unreliable in detecting
the presence of an AAA and should never be used
to rule it out.
Indications for ultrasound according to ACEP:
Syncope, shock, hypotension, abdominal pain,
abdominal mass, flank pain, or back pain
especially in the older population.

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Technique for ultrasound scanning of the aorta
A 3.5 MHz transducer is adequate for most abdominal scanning, including
imaging of the aorta. A lower frequency may be needed in large patients,
and a higher frequency will give more detail in thin ones.
Orientation.
Start in the transverse plane, high in the epigastrium, using the
liver as a sonic “window”. Identify the vertebral.
Identify the aorta on the patient’s left, and the IVC (patient’s right)
“above” the vertebral body on the ultrasound image.
Maximum diameter of the abdominal aorta is approx.
2cms.
>3cms suggests aneursym.
If an AAA is identified...
Does probe pressure reproduce symptoms?
Is there free fluid?

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CONCLUSION

51. REFERENCES:
1. DIAGNOSTIC ULTRASOUND 4th Edition by Carol M. Rumack, MD, Stephanie R. Wilson, MD, FRCPC
2. Radiologyassistant.nl Acute Abdomen - Role of Ultrasound by Julien Puylaert, Department of Radiology, MCH
Westeinde Hospital, The Hague, The Netherlands
3. AAPM/RSNA Physics Tutorial for Residents: Topics in US B-mode US: Basic Concepts and New Technology1
Nicholas J. Hangiandreou, PhD
4. J Emerg Trauma Shock. 2012 Jan-Mar; 5(1): 84–86.doi: 10.4103/0974-2700.93109
5. http://www.sonoguide.com/renal.html , Barbara K. Blok, M.D, Beatrice Hoffmann, M.D., Ph.D., RDMS
6. http://radiopaedia.org/articles/ovarian-torsion Dr Yuranga Weerakkody and Dr Andrew Dixon et al.
7. www.adameducation.com/adam_images.aspx
8. www.google.com
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52. Thank you.