Acute Abdomen Radiological Approach Prof Dr. Haney A Sami
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
Acute diventricular disease
Clinical assessment is often difficult and laboratory investigations are often non specific.
Imaging techniques Plain radiographs of the abdomen, is of significant diagnostic limitations, It is the initial radiological approach. Two views are usually taken a
If the patient is unable to stand, a decubitus view
CT is clearly superior to plain radiography :- Confirming the diagnosis (site and level) Revealing the cause of bowel obstruction Detecting pneumoperitoneum Identifying ureteric stones . Value of CT
The major obstacle to replace plain abdominal radiography with unenhanced CT appears to be its cost, availability, and radiation dose.
Common causes of acute pain in an abdominal quadrant Acute calculous / non calculous Cholecystitis.
Spontaneous rupture of hepatic neoplasm.
Common causes of acute pain in an abdominal quadrant
Common causes of acute pain in an abdominal quadrant Pelvic inflammatory disease.
Complications of overian cyst. Endometriosis. Ectopic pregnancy.
Common causes of acute pain in an abdominal quadrant
Pancreatitis Ulcer Diverticulitis Cholecystitis Appendicitis
What to Examine by Plain X-ray
Key to densities in AXRs ● White—calcified structures ● Intense white—metallic objects
The clarity of outlines of structures depends, on the differences between these densities.
Normal Gas Pattern Two or three loops of non-distended bowel
In rectum or sigmoid – almost always
Gas in stomach Gas in a few loops of small bowel Gas in rectum or sigmoid Normal Gas Pattern
Normal Fluid Levels Always (except supine film)
Two or three levels possible
Erect Abdomen Always air/fluid level in stomach A few air/fluid levels in small bowel
Large vs. Small Bowel Haustral markings don't extend from wall to wall
Valvulae extend across lumen
Haustra films Faecal mottling
Complete Abdomen Obstruction Series
Complete Abdomen Supine
Scout film for gas pattern
Complete Abdomen Erect
Substitute – left lateral decubitus
Complete Abdomen Erect Chest
Substitute – supine chest
Complete Abdomen Prone Gas in ascending and descending colon
Substitute – lateral rectum
Abnormal Gas Patterns Localized (Sentinel Loops)
Generalized adynamic ileus
Localized Ileus Key Features Sentinel Loops Supine Prone
One or two persistently dilated loops of large or small bowel
Localized Ileus Pancreatitis Ulcer Diverticulitis Cholecystitis Appendicitis Sentinel Loops
Localized Ileus Pitfalls
May resemble early mechanical SBO
Gas in dilated small bowel and large bowel to rectum Only post-op patients have generalized ileus Generalized Ileus Key Features
Metabolic disorder as hypothyroidism
Generalized Adynamic Ileus Supine Erect
Is It An Ileus? Is the patient immediately post-op?
Are the bowel sounds absent or hypoactive?
Mechanical SBO Key Features Little gas in colon, especially rectum SBO
Key: disproportionate dilatation of SB
Mechanical SBO Causes *Cause may be visible on plain film
Mechanical SBO Pitfalls
Early SBO may resemble localized ileus -get F/O
Differentiation between SBO & ILEUS Obstruction transition of dilated loops Degree of dilatation is greater with obstruction
Spacing between the bowel loops
Mechanical LBO Key Features Dilated colon to point of obstruction Little or no air in rectum/sigmoid Little or no gas in small bowel, if…
Ileocecal valve remains competent
LBO Supine Prone
Mechanical LBO Causes
Mechanical LBO Pitfalls Incompetent ileocecal valve
Large bowel decompresses into small bowel
Carcinoma of Sigmoid – LBO – Decompressed into SB Prone Supine
The goals of imaging in a patient with suspected intestinal obstruction have been defined and are as follows: To confirm that it is a true obstruction and to differentiate it from an ileus. To determine the level of obstruction. To determine the cause of the obstruction. To look for findings of strangulation.
To allow a good management either medically or surgically by laparoscopy or laparoscopy).
Air in biliary tree Gallstone Gallstone Ileus
Post-op C-section Adynamic Ileus
Abnormal Gas Patterns Ileus and Obstruction
Conditions causing extraluminal air Perforated abdominal viscus Abscesses (subphrenic and other)
Chilaiditi’s syndrome Chilaiditi’s syndrome is an important normal variant on the erect chest radiograph,
which must be distinguished from pathological free gas under the diaphragm. (apparent, as haustra are seen within the gas filled structure). This gas is still contained in the bowel loop.
Extraluminal Air Free Intraperitoneal Air
Signs of Free Air Crescent sign Free Intraperitoneal Air
Free Air Causes Rupture of a hollow viscus Perforated diverticulitis
Trauma or instrumentation
Soft Tissue Masses
Soft Tissue Masses
Plain films poor for judging liver size
Bladder Outlet Obstruction – pre- and post- cath Hours later
Right Renal Cyst
Normal structures that calcify
● Pelvic vein clots (phlebolith)
Abnormal structures that contain calcium Calcium indicates pathology ● Renal parenchymal tissue ● Blood vessels and vascular aneurysms
● Gallbladder fibroids (leiomyoma)
Abnormal structures that contain calcium
Abdominal Calcifications Patterns
Rimlike Calcification Renal Cyst Gallbladder Wall
Linear or Track-like Atherosclerosis Calcification Vas Deferens
Lamellar or Laminar Stone in Ureterocoele Staghorn Calculi
Formed in lumen of a hollow viscus
Cloudlike, Amorphous, Popcorn Nephrocalcinosis Myomatous Uterus
Formed in a solid organ or tumor
Visceral Inflammation Colitis Appendicitis Diverticulitis Bowel Inflammation Cholecystitis Pancreatitis
Inflammation - Cholecystitis Acute cholecystitis is inflammation of the gallbladder usually from impaction of a gallstone within the cystic or common bile duct . Ultrasound is the preferred imaging method to confirm cholecystitis in the appropriate clinical setting .
CT findings of cholecystitis include : 1 . Cholelithiasis 2 . Gallbladder wall thickening 3 . Pericholecystic fluid . Complicated cases may reveal perforation or hepatic abscess formation .
Acute calculous cholecystitis: Calculus obstructs the cystic duct The trapped concentrated bile irritates the gallbladder wall, causing increased secretion, which in turn leads to distention and edema of the wall.
Rising intra luminal pressure compresses the vessels, resulting in thrombosis, ischemia, and subsequent necrosis and perforation of the wall.
Thickening of gallbladder wall Cholelithiasis .
Pancreatitis Acute pancreatitis is most often secondary to alcohol abuse or gallstone impaction in the distal common bile duct . Other causes include trauma, cryptogenic, tumor, infection, hyperlipidemia, and ERCP . CT Findings typical of pancreatitis include :
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 )
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% .
Appendicitis Right lower quadrant pain, fever and leukocytosis are the classical clinical findings . CT and US are being used more often to confirm clinical suspicions and reduce the number of unnecessary laporotomies .
General CT findings for acute appendicitis include : 1 . Dilated appendix greater than 6 mm or visualization of an appendicolith with an appendix of any size 2 . Peri - appendicial fat stranding
This image of an acute abdomen ( arrow ) displays periappendicial stranding and dilattion of its terminal portion .
For comparison, this image of a normal appendix can be visualized at the ileocecal junction . Also notethe fat ventralcontaining heria
Inflammation - Colitis Colitis, or inflammation of the colon, is a frequent cause of abdominal pain . Specific entities which produce inflammatory thickening of the colon include:-
Diverticulitis, inflammatory bowel disease, pseudomembranous colitis, and other bacterial infections ( i . e . typhlitis ).
This example of colitis shows thickening of the colon and pericolonic stranding typical of inflammation .
Thickening of sigmoid colon due to pseudomembranous colitis
A case of diverticulitis showing a thickened sigmoid colon and a diverticulum
Distal ureteral stone lead ing to right hyrdronephrosis in above image Ureteral junctional stone Renal Colic
Renal stone right sided hydronephrosis Renal Colic
Case give a diagnosis