Acute Abdomen Radiological

Approach

Acute Abdomen Radiological

Approach

Prof Dr. Haney A Sami

Acute Abdomen

Bowel Gastric Small Large

Visceral GB Pancreas Kidney

Vascular Aorta Mesenteric

DefinitionAcute 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 appendicitis Acute cholecystitis Bowel obstruction Urinary colic Perforated peptic ulcer Acute pancreatitis Acute diventricular disease

Causes

Imaging techniques

Clinical assessment is often difficult and laboratory investigations are often non specific.

Plain X-ray

Ultra sonography

CT examinations

Contrast studies

Imaging techniques

Plain radiographs of the abdomen, is of significant diagnostic limitations, It is the initial radiological approach.

Two views are usually taken a

supine and an erect.

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. Examining solid organs.

The major obstacle to replace plain abdominal radiography with unenhanced CT appears to be its cost, availability, and radiation dose.

Value of CT

Common causes of acute pain in an abdominal quadrant

Right upper quadrant:

Acute calculous / non calculous Cholecystitis.

Amebic liver abscess. Spontaneous rupture of hepatic

neoplasm. Myocardial infarction.

Common causes of acute pain in an abdominal quadrant

Left upper quadrant:

Splenic infarction.

Splenic abscess.

Gastritis.

Gastric ulcer.

Common causes of acute pain in an abdominal quadrant

Right lower quadrant:

Acute appendicitis. Acute terminal ileitis. Acute typhlitis.

Pelvic inflammatory disease.

Complications of overian cyst.Endometriosis.Ectopic pregnancy.

Common causes of acute pain in an abdominal quadrant

Left lower quadrant:

Diverticulitis. Epiploic appendagitis.

PancreatitisUlcer

Diverticulitis

Cholecystitis

Appendicitis

What to Examine by Plain X-ray

Gas pattern Extraluminal air Soft tissue masses Calcifications Skeletal pathology

Key to densities in AXRs

● Black—gas

● White—calcified structures

● Gray—soft tissues

● Darker gray—fat

● Intense white—metallic objects

The clarity of outlines of structures depends, on the differences between these densities.

Normal Gas Pattern

Stomach Always

Small Bowel Two or three loops of non-distended bowel Normal diameter = 2.5 cm

Large 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

Stomach Always (except supine film)

Small Bowel Two or three levels possible

Large Bowel None normally

Erect Abdomen

Always air/fluid level in stomach

A few air/fluid levels in small bowel

Large vs. Small Bowel

Large Bowel Peripheral Haustral markings don't extend

from wall to wall

Small Bowel Central Valvulae extend across lumen

Haustra films Faecal mottling

Complete AbdomenObstruction Series

Supine Erect or left decubitus Chest - erect or supine Prone or lateral rectum

Complete AbdomenSupine

Looking for Scout film for gas

pattern Calcifications Soft tissue masses

Substitute – none

Complete AbdomenErect

Looking for Free air Air-fluid levels

Substitute – left lateral decubitus

Complete AbdomenErect Chest

Looking for Free air Pneumonia at bases Pleural effusions

Substitute – supine chest

Complete AbdomenProne

Looking for Gas in rectum/sigmoid Gas in ascending and

descending colon

Substitute – lateral rectum

Abnormal Gas Patterns

1. Functional Ileus Localized (Sentinel Loops) Generalized adynamic ileus

2. Mechanical Obstruction SBO LBO

Sentinel Loops

Supine Prone

One or two persistently dilated loops of large or small bowel

Gas in rectum or sigmoid

Localized Ileus Key Features

PancreatitisUlcer

Diverticulitis

Cholecystitis

Appendicitis

Sentinel LoopsLocalized Ileus

Localized IleusPitfalls

May resemble early mechanical SBO

Clinical course Get follow-up

Gas in dilated small bowel and large bowel to rectum Long air-fluid levels Only post-op patients have generalized ileus Other causes:-

Peritonitis Hypokalemia Metabolic disorder as hypothyroidism Vascular occlusion

Generalized IleusKey Features

Generalized Adynamic Ileus

Supine Erect

Is It An Ileus?

Is the patient immediately post-op? Are the bowel sounds absent or hypoactive?

Mechanical SBOKey Features

Dilated small bowel Fighting loops Little gas in colon,

especially rectum Key: disproportionate

dilatation of SB

SBO

Mechanical SBOCauses

Adhesions Hernia* Volvulus Gallstone ileus* Intussusception

*Cause may be visible on plain film

Mechanical SBOPitfalls

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 LBOKey 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

LBO

Supine

Prone

Mechanical LBOCauses

Tumor Volvulus Hernia Diverticulitis Intussusception

Mechanical LBOPitfalls

Incompetent ileocecal valve Large bowel decompresses into small bowel May look like SBO Get BE or follow-up

Carcinoma of Sigmoid – LBO – Decompressed into SB

ProneSupine

The goals of imaging in a patient with suspected intestinal obstruction have been defined and are as follows:

1. To confirm that it is a true obstruction and to differentiate it from an ileus.

2. To determine the level of obstruction.

3. To determine the cause of the obstruction.

4. To look for findings of strangulation.

5. 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

Mesenteric Occlusion

Abnormal Gas PatternsIleus and Obstruction

Localized ileus Generalized ileus Mechanical SBO Mechanical LBO

Conditions causing extraluminalair

Perforated abdominal viscus Abscesses (subphrenic and other) Biliary fistula Cholangitis Pneumatosis coli Necrotising enterocolitis Portal pyaemia

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 AirFree Intraperitoneal Air

Signs of Free Air

Air beneath diaphragm Both sides of bowel wall Falciform ligament sign In the biliary system

Crescent sign

Free Intraperitoneal Air

Free AirCauses

Rupture of a hollow viscus Perforated ulcer Perforated diverticulitis Perforated carcinoma Trauma or instrumentation

Post-op 5–7 days NOT perforated appendix

Extraperitoneal Air

Soft Tissue Masses

Soft Tissue Masses

Hepatosplenomegaly Plain films poor for judging liver size

Tumor or cyst Bowel displacement

Splenomegaly

Myomatous Uterus

Bladder Outlet Obstruction – pre- and post- cath

Hours later

Hours later

Right Renal Cyst

RLQ Abscess

AbdominalCalcifications

AbdominalCalcifications

Normal structures thatcalcify

● Costal cartilage

● Mesenteric lymph nodes

● Pelvic vein clots (phlebolith)

● Prostate gland

Abnormal structures thatcontain calcium

Calcium indicates pathology

● Pancreas

● Renal parenchymal tissue

● Blood vessels and vascular aneurysms

● Gallbladder fibroids (leiomyoma)

Abnormal structures thatcontain calcium

Calcium is pathology● Biliary calculi● Renal calculi● Appendicolith● Bladder calculi● Teratoma

Abdominal CalcificationsPatterns

Rimlike Linear or track-like Lamellar Cloudlike

Renal Cyst Gallbladder Wall

Rimlike Calcification Wall of a hollow viscus

Cysts Renal cyst

Aneurysms Aortic aneurysm

Saccular organs e.g. GB Porcelain Gallbladder

Atherosclerosis Calcification Vas Deferens

Linear or Track-like Walls of a tube

Ureters Arterial walls

Stone in UreterocoeleStaghorn Calculi

Lamellar or Laminar Formed in lumen of a hollow viscus

Renal stones Gallstones Bladder stones

Nephrocalcinosis Myomatous Uterus

Cloudlike, Amorphous, Popcorn

Formed in a solid organ or tumor Leiomyomas of uterus Ovarian cystadenomas

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. Cholelithiasis2. 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 fat2. Peripancreatic fluid collections can often be seen3. 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%.

Pancreatic necrosis

Pancreatic pseudocyst

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) displaysperiappendicial 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 colonand 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

Diverticulitis

Distal ureteral stone lead ing to righthyrdronephrosis in above image

Ureteral junctional stone

Renal Colic

Renal stone right sided hydronephrosis

Renal Colic

Aortic aneurysms

Case give a diagnosis

The End