DR MOSES ACAN DEPARTMENT OF RADIOLOGY The ACUTE ABDOMEN DR MOSES ACAN DEPARTMENT OF RADIOLOGY

Definition Acute abdominal pain Is Pain unrelated to trauma It is one of the most common conditions in patients presenting to the hospital emergency department. It is a syndrome characterized by the sudden onset of severe abdominal pain, requiring early medical or surgical treatment

The Abdominal Series For all acute abdominal complaints where plain film imaging is indicated, get a COMPLETE abdominal series Exceptions: Suspected renal calculus or foreign body, where a single view is OK CT and ultrasound are often performed after plain films

Abdominal Series Indications: Highest yield: Presentations suggestive of free air or obstruction Not very good for masses, ascites, organomegaly, biliary tract disease, GI bleeding and vague abdominal complaints Yield is higher in the elderly

The Abdominal Series Erect chest, AP supine and erect abdomen Or, if patient unable to sit/stand: supine chest, supine and left lateral decubitus abdomen For calculus or foreign body: AP supine abdomen

The Erect Chest Best for free air To evaluate for intrathoracic abnormalities presenting with abdominal complaints, especially pneumonia (more common in kids)

Supine Abdomen Best for abdominal detail: Organs, bones and joints, calcifications, fat and gas pattern

Erect Abdomen For air-fluid levels and little else

Left Lateral Decubitus Abdomen Substitute for erect chest (free air) and erect abdomen (air-fluid levels) in a patient unable to sit or stand

Indications for a single erect abdomen film ONLY NONE None

The Check List Bones and joints Calcifications Organs Fat Gas: In bowel and outside of bowel

A memory aid “First organs, bones, and stones, Then masses, fat, and gas. Don’t forget the corner zones, And you’ll always cover your…subject”

The Normal Abdominal Series Chest Supine abdomen Erect abdomen Left lateral decubitus abdomen

Chest

Supine Abdomen

Erect Abdomen

Left Lateral Decubitus Abdomen

In the gut, and elsewhere GAS In the gut, and elsewhere

FREE AIR: Perforated Gut PNEUMOPERITONEUM FREE AIR: Perforated Gut

Free Air Best views: Erect chest and left lateral decubitus abdomen Erect abdomen is less sensitive Supine abdomen is insensitive

How Sensitive? Plain films are 85% sensitive for free air Theoretical threshold is 2 cc CT is much more sensitive and is the “Gold Standard”

Signs Air beneath diaphragm Both sides of bowel walls (Riglers sign) Falciform ligament , medial and lateral umblical ligaments and the urachus In the biliary system Air in the Morisons pouch Cupula sign Football sign

Free Air: Erect Chest Air under the diaphragm Usually on the right Occasionally only seen on the left

Free Air: Erect Chest

Free Air: Left Lateral Decubitus Right side up, left side down Patient who can’t sit or stand Air under right abdominal wall

Free Air: Left Lateral Decubitus

Free Air: Supine Abdomen Double bowel wall sign

Bile ducts Gall bladder Air in Biliary System Bile ducts Gall bladder

Air in Biliary System Usually secondary to surgery on bile ducts Can be due to biliary-bowel fistula from infection or neoplasm Rarely, can be due to infection

Air in Bile Ducts/gall bladder

A sign of dead or dying bowel Portal Venous Air A sign of dead or dying bowel

Portal Venous Air

Gas and Fluid Too Much and Too Little The GUT Gas and Fluid Too Much and Too Little

The Gas Pattern Can be specific for obstruction Often, nonspecific: General ileus, focal ileus, ischemia, or obstruction A paucity of gas may be due to vomiting or fluid-filled bowel

OBSTRUCTION Small bowel Colon

Small Bowel Obstruction: Causes Small bowel obstruction much more common than colon: 70:30 Causes Adhesions 80% Hernia 15% Tumors, intussusception, midgut volvulus, etc.

Small Bowel Obstruction: Findings Step-ladder dilated bowel loops on supine view Step-ladder air-fluid levels on erect/decubitus views Stretch sign on supine view String-of-pearls sign on erect/decubitus views

Ultrasound Can demonstrate dilated fluid filled loops of small bowel obstruction Assessment of peristalsis can be made at the same time CT scan is increasingly being used It is capable of demonstrating bowel caliber change and the level Fluid filled loops are clearly visible The level of obstruction can be identified

How Big is Big? In an adult, any visible small bowel is abnormal, but small amounts often not significant. Kids normally have small amounts. Jejunum over 3 cm and ileum over 2 cm diameter is very abnormal, but not specific for obstruction

Air, Fluid or Both? Small bowel can be distended by either air or fluid or both Fluid-filled bowel may be more significant than air-filled bowel, but often the significance is the same

Air Filled Small Bowel

Fluid Filled Small Bowel

Air-Fluid Levels Always abnormal in small bowel, but not specific; often normal in colon The height of the fluid levels, same or different, is NOT helpful in distinguishing ileus from obstruction

Small Bowel Air-Fluid Levels

What is Dilated? If small bowel and colon dilated equally, probably not small bowel obstruction: nonspecific ILEUS If small bowel significantly more dilated than colon, suggests SBO Some gas in colon does NOT exclude SBO

Ileus

Classic Small Bowel Obstruction, Supine

Classic Small Bowel Obstruction, Erect

Stretch Sign: Supine

String-of-Pearls Sign: Erect

COLON Obstruction Causes Carcinoma of the colon 80% Volvulus 5% Diverticulitis 5% Fecal impaction 5% Everything else 5%

Colon Obstruction: Carcinoma

Colon Obstruction: Volvulus 5% of total 80% sigmoid 20% cecum

Volulus: Sigmoid Specific signs include: - coffee bean sign - Frimann Dahl's sign - three dense lines converge towards site of obstruction absent rectal gas

Volvulus: Cecum Radiologically Large gas filled and fluid filled viscus situated almost anywhere in the abdomen Identification of an attached gas filled appendix confirms the diagnosis Moderate or severe small bowel distension is found in about ½ of cases The left half of the colon is usually collapsed

Colon Obstruction: Measurements The cecum is the most distensible part of the colon A cecum of 9 cm diameter is cause for concern A cecum of 11 cm is impending perforation

Other Emergency Conditions of the Gut Toxic megacolon: Crohn, UC; 5cm transverse colon is impending perforation Enterocolitis: C. diff. and other microbes Ischemia

A word on Thumbprinting It means thickened bowel wall It can occur acutely in C. diff. or ischemia or hemorrhage Chronically, it can be seen in inflammatory bowel disease and neoplasm and a few other less common diseases

C. diff. Enterocolitis

Ischemic Bowel Disease Arterial emboli Arterial thrombi Venous thrombi: Hypercoag., neoplasm Non-occulsive mesenteric ischemia: Low flow states

Ischemia: Findings Normal gas pattern Non-specific ileus Thumbprinting Gas in bowel wall Gas in portal vein system Free air

Ischemia: Thumbprinting

ACUTE APPENDICITIS

Ultrasound in acute appendicitis; graded compression technique Blind ending tubular structure at the point of tenderness Non compressible Diameter 7mm or greater No peristalsis Appendicolith casting acaustic shadow High echogenicity non compressible surrounding fat Surrounding fluid or abscess Oedema of caecal pole

CT in acute appendicitis – is highly accurate An appendix measuring greater than 6mm in diameter Failure of the appendix to fill with oral contrast or air upto its tip An appendicolith Enhancement of its wall with contrast Surrounding inflammatory changes Increased fat attenuation Fluid Inflammatory phlegmon Caecal thickening Abscess Extraluminal gas Lymphadenopathy The “arrow head sign” Sometimes the lumen of the caecum can be seen pointing towards the obstructed opening to the appendix

Acute Appendicitis: CT

Focal Ileus and appendicolith

Gall Bladder Disease

Acute Cholecystitis Almost all cases are associated with gallstones and most are caused by obstruction of the cystic duct Only about 20% of gall stones contain sufficient calcium to be visible on plain radiographs and only rarely does the wall of the gallbladder itself calcify

Inflammation- Cholecystitis Ultrasound is the preferred imaging method to confirm cholecystitis in the appropriate clinical setting. Hypoechoic margin Indistinct contour of the gallbladder wall and fluid around the fundus of the GB Gallstones which cast acaustic shadows A stone obstructing the cystic duct producing a grossly dilated GB Echogenic sediment seen in the lumen caused by inspissated bile or pus Tenderness of the GB (positive Murphy sign)

Cholelithiasis: Ultrasound

Cholelithiasis

PANCREATITIS Acute

Acute Pancreatitis Clinical diagnosis is extremely difficult in the initial stages with perforated PUD and acute cholecystitis as differentials Alcohol abuse and gallstones are the commonest causes Other causes include trauma, cryptogenic, tumor, infection, hyperlipidemia, and ERCP.

Ultrasound findings Pancreatic enlargement with indistinct boundaries Diminished echogenicity due to oedema Duodenal atony and wall thickening With necrotizing pancreatitis Liquid or semifluid tissue may be identified spreading beyond organ boundaries Pleural effusion and ascites may be detected State of the biliary tree (dilatation if obstruction is present)

Pancreatitis CT Findings typical of pancreatitis include: necrosis, hemorrhage and solid parenchyma that enhance with i.v contrast 1. An enlarged pancreas with infiltration of the surrounding fat 2. Peripancreatic fluid collections can often be seen 3. Pseudocysts, (encapsulated fluid collections containing pancreatic secretions, are later complications of pancreatitis) CT is also useful for assessing patients with complications of acute pancreatitis pseudocysts, abscess, hemorrhage, necrosis and ascites

Notice the peripancreatic stranding (bars) as well as the fluid thickening of the interfascial space

A common complication of pancreatitis is the development of pancreatic necrosis. Lack of gland enhancement following IV contrast administration is diagnostic. When over half the pancreas becomes necrosed, the mortality rate may reach as high as 30%.

Pancreatic pseudocyst

Chronic Pancreatitis

Abdominal Aortic Aneurysm

AAA Plain films are not sensitive, but can be diagnostic Calcified walls of aorta can allow measurement of lumen AAA if over 3 cm AP diameter Ultrasound and CT are much more sensitive

AAA

AAA: CT

The odd and the interesting A few more… The odd and the interesting

Echinococcus cyst

Foreign Body: Battery

Tongue Ornament Misadventure

Body Packer or Mule