1. MDCT US ACUTE ABDOMINAL PAIN
Multidetector Helical CT (MDCT) is increasingly replacing ultrasonography (US) for the evaluation of patients with acute abdominal pain
MDCT US
Extremely fast, often its time burden is less than that of a US examination
Which is the role of US in the
evaluation of acute abdominal pain
It is not disturbed by gas and bone
Obesity is even an advantage
It is not operator dependent and can be reviewed by others

2. US advantages ACUTE ABDOMINAL PAIN
Does not require ionizing radiation, which is very important especially in children, young patients and pregnant women
The spatial resolution of a high-frequency US image is higher than that of a MDCT image, but only in case the target organ can be approached closely (thin patient, use of graded compression)
It is a dynamic, real-time examination; therefore it is possible to observe, for example, the presence or the absence of peristalsis (as in paralytic ileus)
US allows precise correlation of the area of maximum tenderness or palpable mass with the US findings

3. US allows a direct communication with the patient
ACUTE ABDOMINAL PAIN
US allows a direct communication with the patient
Information provided by the patient specific search for a US finding
Certain US findings specific question to the patient
Correlation of the US findings with the clinical data, the laboratory results, other imaging studies, the information provided by the patient
enables
to give a definitive diagnosis
to address to subsequent imaging studies

4. We can distinguish 8 sites of acute abdominal pain:
Depending on the site of the acute pain,, we can assume which abdominal organs could be most frequently involved.
We can distinguish 8 sites of acute abdominal pain:
Right upper quadrant
Left upper quadrant
Central back pain
Flank pain
Diffuse abdominal pain
Right lower quadrant
Left lower quadrant
Pelvic pain

5. RIGHT UPPER QUADRANT PAIN
Gallbladder (acute cholecystitis and its complications)
Biliary system (biliary duct obstruction)
Liver (abscesses, focal lesions with hemorrhage, acute portal vein and hepatic artery thrombosis)
The differential diagnosis for patients with right upper quadrant pain is extensive and includes pneumonia, appendicitis, omental infarction, peritoneal tumor, primary bowel disease, pancreatitis, peritonitis by bowel or pelvic pathology, such as hemorrhagic adnexal masses. Retroperitoneal processes involving kidney and adrenal gland also can present occasionally with right upper quadrant pain, which mimics acute cholecystitis

6. RIGHT UPPER QUADRANT PAIN
ACUTE CHOLECYSTITIS
US features
Gallstones in 85-90% of cases
Gallbladder wall edema resulting in wall thickening of 3 mm or greater
Distension of the gallbladder with a transverse diameter of more than 5 cm
Pericholecystic fluid
Positive sonographic Murphy’s sign (tenderness when pressure is applied to the gallbladder with the ultrasound probe). This sign may not be present if analgesics have been administered to the patient
Increased arterial flow to the gallblader wall may be seen with Doppler imaging, although absence of this sign does not exclude cholecystitis

7. RIGHT UPPER QUADRANT PAIN
Acute cholecystitis
Yellow arrow: wall edema
Yellow arrow: gallstone
White arrow: biliary sludge

8. RIGHT UPPER QUADRANT PAIN
Acute cholecystitis
Gallbladder wall edema and thickening
A distended gallbladder
Pericholecystic fluid

9. RIGHT UPPER QUADRANT PAIN
Acute cholecystitis
Differential Diagnosis
Adenomyomatosis in gallbladder wall diverticula
Gallbladder wall thickening due to cholesterol deposits with the comet-tail artifact within wall diverticula (yellow arrows).
There is no distension of the gallbladder.
- White arrow: gallstone

10. RIGHT UPPER QUADRANT PAIN
Complications of acute cholecystitis
Hemorrhagic cholecystitis
Hemorrhage appears as amorphous, heterogeneous, hyperechoic (more than biliary sludge) and partly cystic material within the gallbladder lumen

11. RIGHT UPPER QUADRANT PAIN
Complications of acute cholecystitis
Emphysematous cholecystitis
Antidependent gas echoes within the lumen and in the wall. The type of shadowing (“clean” vs “dirty”) does not differentiate between calcium and air: the location of the echoes does. This complication, although rare, is very common in diabetic patients.

12. RIGHT UPPER QUADRANT PAIN
ACUTE BILIARY OBSTRUCTION
Choledocholithiasis
Neoplasms of biliary, pacreatic, ampullary origin
Cholangitis
Sonography is highly sensitive for the detection of biliary ductal dilatation but less accurate in identifying the cause of obstruction because overlying bowel gas often prevents visualization of the distal common duct

13. RIGHT UPPER QUADRANT PAIN
Acute biliary obstruction
Intrahepatic ductal dilatation
Distended gallbladder with biliary sludge (white arrow)
Stone in the distal part of the common duct (yellow arrow)

14. LEFT UPPER QUADRANT PAIN
Spleen (infarction, spontaneous hematoma)
Splenic diseases are the most frequent causes of left upper quadrant pain, although, as well as for right upper quadrant pain, pathologies involving pancreas, left kidney or left adrenal gland may determine this type of pain

15. LEFT UPPER QUADRANT PAIN
SPLENIC INFARCTION
US examination shows an area of slight hyperechogenicity (a), with poor flow signal at Color Doppler imaging (b). After e.v. administration of ultrasound contrast agent, this area appears avascular (c), as also shown by contrast-enhanced CT scan (d). a b c d

16. FLANK PAIN
Kidney (obstruction, infarction, hemorrhage, inflammation)
Potential mimickers include appendicitis, pelvic inflammatory disease, ovarian cyst and/or torsion, inflammatory bowel disease and aortic disease

17. FLANK PAIN RENAL OBSTRUCTION
It is the commonest cause of flank pain. Although US has significantly lower sensitivity for ureteric stones because it is unable to depict the entire course of the ureter, stones in the pelvi-ureteric junction, in the proximal tract of the ureter and in the ureterovesical junction are readily visibile at US. In these cases, US can avoid to perform MDCT and therefore to irradiate the patient.
Longitudinal US gray-scale image of left kidney showing hydronephrosis and renal lithiasis (calipers)
The renal obstruction is due to a stone (calipers) located in the lumbar part of the ureter
The stone is about 6 cm far from the pelvi-ureteric junction (calipers)

18. FLANK PAIN Renal obstruction
The same patient as in the previous slide, after 1 month (a) and 2 months (b) of medical treatment
a: the ureteral stone is visible more distally respect to the pelvi-ureteric junction than in the previous US examination (yellow arrow)
b: the stone is close to the ureterovesical junction (yellow arrow)

19. FLANK PAIN RENAL HEMORRHAGE
A female patient with acute left flank pain, one day after percutaneous procedure for renal lithiasis
Transverse US scan of bladder with a large hyperchoic mass in the lumen, consistent with a big clot
Longitudinal US scan shows a perirenal hematoma (yellow arrow) and blood in the renal sinus (white arrow). Kidney (red arrow).
Unenhanced CT scan shows hemorrhage in the renal sinus and parenchyma.

20. CENTRAL BACK PAIN ACUTE PANCREATITIS
Ultrasonography is less sensitive than CT and MR imaging for detecting and grading the severity of acute pancreatitis. In fact, the pancreas may be normal in mild cases; in severe cases it may appear enlarged and hypoechoic. Therefore the primary role of US in acute pancreatitis is not to evaluate the pancreas itself but to look for gallstones in the gallbladder and bile ducts, one of the more common causes of pancreatitis, and to detect fluid collections, mainly peripancreatic and peritoneal fluid collections.

21. CENTRAL BACK PAIN Acute pancreatitis
Pancreatitis can be focal, affecting only part of the pancreas. The affected area will appear swollen and hypoechoic. a b c
A 81 years old woman with suspected acute pancreatitis. a) Oblique subcostal US scan of the liver shows several gallstones b) Transverse US scan of the pancreas shows an hypoechoic focal area (yellow arrow) between the body and the tail of the pancreas. c) Contrast-enhanced CT image during the pancreatic phase better depicts the focal area of pancreatitis (white arrow)

22. ABDOMINAL AORTIC ANEURYSM RUPTURE
CENTRAL BACK PAIN
ABDOMINAL AORTIC ANEURYSM RUPTURE
Ultrasonography is not accurate for detecting aneurysmal rupture and MDCT is the modality of choice if ruptured aortic aneurysm is suspected. But not always a central back pain is referred to abdominal aneurym rupture, especially when the presence of abdominal aneurysm is unknown. Therefore, the knowledge of US findings of abdominal aneurysm rupture can help in suspecting this diagnosis and can suggest to perform MDCT examination. The most important US features of abdominal aneurysm rupture are: large, usually hypoechoic retroperitoneal fluid collection; markedly inhomogeneous mural thrombus with hypoechoic or anechoic areas

23. Abdominal aortic aneurysm rupture
CENTRAL BACK PAIN
Abdominal aortic aneurysm rupture
US transverse scans show a 5 cm abdominal aneurysm with an inhomogeneous thrombus
CT scans, before and after c.m. administration, show the site of the rupture, which is in the anterior wall through the mural thrombus, with a large retroperitoneal fluid collection, missed at US examinaton

24. Diffuse abdominal pain
ACUTE ABDOMINAL PAIN
Right lower quadrant
Left lower quadrant
Diffuse abdominal pain
Acute abdominal pain, arising from these sites, is most commonly caused by bowel diseases. Ultrasonography is not regarded as the first-line imaging modality for suspected intestinal pathology in adults but, when bowel disease is not primarly suspected at the emergency room, ultrasonography is often first performed alone or associated with plain abdominal radiograph. Therefore, familiarity with US findings of bowel disorders causing acute pain is very important to obtain or to suggest a diagnosis.

25. ACUTE ABDOMINAL PAIN US TECHNIQUE
GRADED US COMPRESSION
“MOWING THE LAWN”
Screening of the peritoneal cavity for bowel disease by making 5 or 6 vertical, overlapping lanes over the abdomen: pathologic bowel has a thickened and hypoechoic wall and it is rigid
Fat and bowel are displaced or compressed
Disturbing influence of bowel gas is eliminated
The distance from the transducer to the target organ is reduced, allowing the use of a high-frequency probe with better image quality
Source: Radiol. Clin. N Am 41 (2003):

26. RIGHT LOWER QUADRANT PAIN
Appendicitis
Omental infarction
Crohn’s disease
Infectious and ischemic ileitis
Cecal and ileal diverticulitis
Typhlitis, right sided epiploic appendagitis

27. RIGHT LOWER QUADRANT PAIN
NORMAL APPENDIX + +
Small, compressible, concentrically layered, blind-ending, sausage-like structure with a diameter from outer wall to outer wall < 7 mm

28. RIGHT LOWER QUADRANT PAIN
ACUTE APPENDICITIS
US features
Concentrically layered, non-compressible sausage-like structure demonstrated in a fixed position at the site of maximum tenderness, with maximum diameter > 7 mm (average is 1 cm)
Presence of intraluminal fecalith (30% of cases) obstructing the lumen
Inflammation of the adjacent fat which becomes larger, more hyperechoic and less compressible
Pericecal or periappendiceal fluid collections
Increased vascularization of the appendiceal wall (if there is no concomitant ischemic necrosis) and in the surrounding fatty tissue
Increased volume of mesenteric lymphnodes

29. RIGHT LOWER QUADRANT PAIN
Acute appendicitis
Increased vascularization of the appendiceal wall and of adjacent fat tissue at Color Doppler
Increased diameter of the appendix
Periappendiceal phlegmon

30. RIGHT LOWER QUADRANT PAIN
Acute appendicitis
Enlarged and inflamed appendix with an intraluminal, obstructing fecalith (yellow arrow)
Enlarged mesenteric lymphnode

31. RIGHT LOWER QUADRANT PAIN
Acute appendicitis
The same aspect at
unenhanced CT scan
Inflamed appendix
Inflamed appendix
Enlarged appendix (yellow arrows) with inflammation of surrounding fat tissue which is more echoic (white arrow). Periappendiceal fluid collection (red arrow)

32. RIGHT LOWER QUADRANT PAIN
Stump appendicitis
Post surgical inflammation at the base of the appendiceal remnant
Convex and linear US scans show thickening of the cecal wall with a fecalith at the distal part of the cecum (yellow arrow), intraluminal air (white arrow), pericecal fluid collection (red arrow)
Contrast-enhanced CT scan shows fecalith at the distal part of the thickned cecum (arrow)
US scan performed after medical treatment shows a reduction of cecum wall thickening

33. RIGHT LOWER QUADRANT PAIN
SEGMENTAL OMENTUM INFARCTION
US scan reveals a solid, non-compressible mass of hyperchoic fatty tissue
Unenhanced CT scan better depicts a circumscribed fatty mass ahead of ascending colon, with hyperattenuating streaks

34. LEFT LOWER QUADRANT PAIN
Descending colon or sigmoid diverticulitis
Epiploic appendagitis
Ureteral obstruction

35. LEFT LOWER QUADRANT PAIN
DIVERTICULITIS
US features
Concentrical wall thickening of the colon
Fecalith-containing diverticula appearing as large, strongly reflective, round-ovoid structures casting an acoustic shadow and localized on the outside of the contour of the contracted colon
Paracolic abscess
Hyperechoic, non-compressible tissue which represents the inflamed mesentery and omentum

36. LEFT LOWER QUADRANT PAIN
Diverticulitis
Fecalith-conteining diverticulum

37. LEFT LOWER QUADRANT PAIN
Diverticulitis
Descending colon diverticula (yellow arrows) with inflamed pericolic fat tissue (white arrows)

38. LEFT LOWER QUADRANT PAIN
EPIPLOIC APPENDAGITIS
US scan reveals a solid, non-compressible mass of hyperchoic fatty tissue (white arrow), that abuts the anterior descending colon wall (yellow arrow)
Unenhanced CT scan shows an ovoidal pericolic fatty mass surrounded by a hyperattenuating ring, with a central dot corresponding to thrombosed vessel

39. DIFFUSE ABDOMINAL PAIN
Bowel obstruction
Intussusception
Crohn’s disease

40. DIFFUSE ABDOMINAL PAIN
BOWEL OBSTRUCTION
US information
Bowel wall and content; degree of bowel loops dilatation
Presence or absence of free fluid in the abdominal cavity
When the obstructed bowel segments are dilated and filled with fluid, US is able to recognize not only the level but also the cause of the obstruction
In spite of these capabilities, US is less effective than CT in the evaluation of bowel obstruction

41. DIFFUSE ABDOMINAL PAIN
BOWEL OBSTRUCTION
Bowel obstruction due to sigmoid neoplasm (yellow arrows).
US scan is able to reveal small amount of free fluid between bowel loops (white arrow)

42. DIFFUSE ABDOMINAL PAIN
INTUSSUSCEPTION
US Transverse Scan
• “target or doughnut “lesion
- outer hypoechoic rim (edematous wall of the intussuscipiens)
- central area of increased echogenicity (intussusceptum and its invaginated mesenteric fat)
US Longitudinal Scan
• layering appearance
- alternating hypoechoic and hyperechoic layers
(layers of bowel wall and mesentery)

43. DIFFUSE ABDOMINAL PAIN
INTUSSUSCEPTION
Color Doppler
Free peritoneal fluid
• may be helpful in determining the degree of vascular compromise of the involved bowel segments
• does not necessarily indicate peritonitis
or bowel compromise
Normal vascularized bowel wall of intussuscipiens and intussusceptum segments

44. DIFFUSE ABDOMINAL PAIN
CROHN ‘S DISEASE
US features
Marked mural thickening of the bowel with all layers involved
Decreased or no peristalsis of the bowel involved
Inflammation of the fatty mesentery and omentum

45. DIFFUSE ABDOMINAL PAIN
CROHN ‘S DISEASE COMPLICATIONS
Normal bowel
Pathological bowel
Contrast-enhanced CT scan shows sigmoid fistula as well as US (yellow arrow)
Wall thickening of the sigmoid colon with hypoechoic streaks within the hyperechoic fat tissue, indicating fistula formation
Free fluid between bowel loops

46. ACUTE PELVIC PAIN
Acute pelvic pain usually affects women; in fact it may be the manifestation of various gynecologic conditions that can range from less alarming rupture of the hemorrhagic cyst to life-threatening conditions such as rupture of ectopic pregnancy. The most common gynecological causes are:
Hemorrhagic cyst
Ectopic pregnancy
PID (Pelvic Inflammatory Disease)
Ovarian torsion
Fibroid degeneration
Other causes of acute pelvic pain may include gastrointestinal, urological, neurological and abdominal wall diseases

47. ACUTE PELVIC PAIN a b Source: Radiology 2007; 245(2):385
Hemorrhagic corpus luteal cyst (a) with the characteristic wall hypervascularization, the so called “ring of fire”. It is not easily distinguishable from ectopic pregnancy (b)

48. ACUTE PELVIC PAIN HEMORRHAGIC CYST
A hemorrhagic cyst with a retracting blood clot (arrow), which is lenticular in shape and often adhers to the cyst wall
Classic reticular pattern of a hemorrhagic cyst. The cyst wall is smooth and regular
There is no internal color flow in the hemorrhagic cyst

49. ACUTE PELVIC PAIN PYOSALPINX
Transabdominal pelvic US reveals bilateral dilatation of fallopian tubes which show characteristic tubular shape and low-level echoes in the lumen
Contrast-enhanced axial and coronal CT images show the classic folded configuration of both fluid-filled fallopian tubes (arrows), associated to stranding of the surrounding fat tissue (arrow head)
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LEFT