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

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

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

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

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

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

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

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

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

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

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.

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

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)

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

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

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

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)

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)

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.

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.

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)

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

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

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.

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):1227-242

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

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

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

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

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

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)

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

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

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

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

LEFT LOWER QUADRANT PAIN Diverticulitis Fecalith-conteining diverticulum

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

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

DIFFUSE ABDOMINAL PAIN Bowel obstruction Intussusception Crohn’s disease

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

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)

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)

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

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

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

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

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)

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

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) RIGHT LEFT