“Acute abdomen” is a term used to encompass a spectrum of surgical, medical and gynecological conditions (intra-abdominal process), ranging from the trivial to the life threatening, which require hospital admission, investigation and treatment

Assesing the patient with an acute abdomen need many investigation including laboratory test and imaging studiesplain photo, US, CT and contrast study .

Plain abdominal films: erect chest film, supine, and upright (optional:left lateral decubitus)

Abdominal US Abdominal CT

Erect Chest Supine Abdomen Erect AbdomenLeft Lateral Decubitus Abdomen

Best for free air under right diaphragm

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

For air-fluid levels and little else

For free air and air-fluid levels

Plain abdominal film

Table 1 Plain abdominal film

Looking for› Gas pattern› Calcifications› Soft tissue masses

Substitute – none

Looking for› Free air› Air-fluid levels

Substitute – left lateral decubitus

Hemorrhage GI perforation Bowel obstruction Inflammatory disorder Circulatory impairment

Intraperitoneal hemorrhage› Rupture:

hepatoma aortic anuerysm ectopic pregnancy ovarian bleeding

Gastrointestinal hemorrhage› Upper GI hemorrhage

Duodenal ulcer Gastric ulcer Hemorrhagic gastritis Esophageal or gastric varices ect.

› Lower GI hemorrhage Bleeding of colon cancer Ischemic colitis ect.

US finding› Free peritoneal fluid accumulation on the

Morison’s pouch, the rectovesical pouch, the pouch of Douglas, and the bilateral subphrenic space

Abdominal CT› CTgold standars for specific intraabdominal

pathology

Gastrointestinal perforation are serious disorder requiring rapid diagnosis and treatment

Since they may be severe enough to produce septic or hypovolemic shockrapid decision-making for urgent laparotomy is crucially important

● Radiological appearances:

Plain abdominal film: - Oval/linear collection of gas: ♠ Subhepatic space ♠ Morison’s pouch ♠ Beneath the diaphragm (the cupola sign) ♠ In the centre of the abdomen over a fluid collection (the football sign) ♠ Fissure for ligamentum teres

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Rigler’s signFissure for ligamentum teres

The first investigation when bowel obstruction is suspected is the supine plain abdominal X-ray, together with an erect chest film if perforation is a possibility

Occasionally, all the dilated bowel may be fluid fill and not visible on a plain X-ray and further imaging with contrast studies, CT or US may be needed to demonstrate dilated bowel

Imaging aims: to confirm the presence of bowel obstruction, define the level obstruction, identify the cause and detect complications such as perforation

Extrinsic Bowel wall IntraluminalAdhesions Neoplasia Intussusception

Hernia Strictures:inflammatory, radiation,chemical

Foreign body

Volvulus Intestinal ischaemia

Gallstone ileus

Inflammation/abscess

Malignant infiltration (e.g. peritoenal deposits)

Etiology: - Adhesions due to previous surgery - Strangulated hernias - Volvulus - Gallstone ileus - Intussusception - Neoplastic, etc.

Plain filmprimary investigation of choice Plain film of SBO:

Dilated small bowel loops:› Tend to the central› Numerous› 2.5-5.0 cm diameter› Have a small radius of curvature› Valvulae conniventes: thin, numerous, and

extend right across the bowel› Do not contain solid faeces

Multiple fluid levels on the erect film String of beads sign on the erect film Absent or little air in the large bowel

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US:SBO

CT sign of SBO› Small bowel loops measuring>2.5 cm in diameter› Identifiable focal transition zone from prestenotic

dilated bowel to post-stenotic collapsed bowel loops

Fluid-filled loops Bowel calibre change

Etiology:

- Neoplastic (benign & malignant)

- Volvulus (caecal & sigmoid), etc.

Radiological appearances:

Depends on the state of competence

of the ileocaecal valve:

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Plain-film signs of LBO:› Dilated large bowel loops which:

Tend to be peripheral Few in number Large: above 5.0 cm diameter Wide radius of curvature Haustra: thick and widely separated and may or

may not extend right across the bowel (compare these features with the valvulae conniventes found in the small bowel

Contain solid faeces

› Caecum maybe dilated› Small bowel may be dilated

Contrast enema maybe helpful:› To differentiate pseudo-obstruction and may be

indistinguishable on plain film from mechanical of obstruction

› To localized the point of obstruction› To diagnose the cause of obstruction e.g.

tumour, inflamatory mass

coffee bean sign

Plain film:Sigmoid volvulus

Generalised paralytic ileus: ●Etiology: - Peritonitis - Post-operative - Hypokalaemia - General debility or infection - Drugs: morphine - Congestive cardiac failure, renal colic, etc.

●Radiological appearances: - Both small & large-bowel dilatation - Horizontal-ray films: multiple fluid levels

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Acute appendicitis Acute pancreatitis Acute cholecystitis Abdominal absces Peritonitis

Abdominal x-ray (AXR)› Non-specific finding› Approximately 10%a calcified appendicolith

US› Generally, the normal cannot be defined with US,

clear visualization of the appendix is suggestif of inflammation

› Swollen, non compressible appendix greater than 7 mm in diameter with a target or bulls-eye configuration is produced by the hypoechoic dilated appendiceal lumen

› Assymetrical wall thickening due to phlegmonous infiltration, an appendicolith with acoustic shadowing

US finding› Echogenic hallo form by omental tissues draped

over the appendix› Free fluid in the culdesac› Atony in the terminal ileum with compression US

CT finding› 90% diagnostic accuracy to detect acute appendicitis› With the good contrastfilling of the terminal ileum

and the cecum (oral contrast given 1 hour before examination)

› Tubular structure 4 mm to 20 mm in diameter with a thickened wall that enhance after administration IV contrast medium

› Pericecal fluid collection and calcified appendicolith

Plain film:apendicolith

Severity of acute pancreatitis rangesmild edema with minimal symptoms to a severe necrotizing process that culminates in multiple organ failure

US and CT most precisely define the anatomic extent of the lesions and the detect local complications

Plain filmsno significant plain film findings in up to two-thirds of patients wih acute pancreatitis

Plain-film signs may include:› Paralytic ileus in the left upper quadrant› Generalized ileus› Loss of left psoas outline› Separation of greater curve of stomach

from tranverse colon

CXR signs that may be seen include:› Left pleura effusion› Atelectasis of left lower lobe› Elevated left hemidiaphragm

US finding:› The acutely inflamed pancreasenlarged with

decreased echogenicity and blurred irregular margin

› Fluid collection are seen as hypoechoic areas› US can be used to guide aspiration and the

drainage procedures, and for follow up

CTimaging investigation of choice for acute pancreatitis, and is particularly useful for the following:

› Confirmation of the diagnosis› Identification of necrotic gland tissue› Diagnosis of complication› Guidance of interventional procedures

CT signs of acute pancreatitis include:› Diffuse or focal pancreatic enlargement with

decreased density and indistinct gland margins› Thickening of surrounding fascial planes e.g. left

paranephric fascia

› Acute fluid collections, most commonly related to pancreas though also in the lesser sac and in the left pararenal space

› Phlegmon appears as an irregular mass spreading along fascial planes and can be quite extensive

› Abscess› Pseudocyst

Approximately 85%-90% of cases with acute cholecystitis (AC) develop as a complication of cholelithiasis

Conversely, approximately 10%-20% of patients with gallstone will require surgery for complication, usually cholecystitis, within 15 years after their stone disease is diagnosed

Acalculous cholecystitis account for 5%-15% of cases of acute cholecystitis (immunocompromize, critically ill,iatrogenic, congenital etc)

Plain filmsinsensitive for acute cholecystitis

Plain films signnonspesific and include:› Gallstone (only seen in 10%)› Soft tissue mass in the right upper

quadrant due to distended gallbladeer› Paralytic ileus in the right upper quadrant

USinvestigation of choice for suspected acute cholecystitis

US signs of acute cholecystitis include:› Gallstones:hyperechoic lesions with acoustic

shadowing which are mobile› Thickening of gallbladder wall to greater than

4 mm› Hypoechoic gallblader wall due to oedema› Surrounding fluid or localized fluid collection› Distended gallbladder› Localized tenderness to direct probe pressure

CTscanning contribute little to diagnosis of cholecystitis

CTinvestigation of complicatiosbiliary or pericholecystic abscess

Peritonitisan inflammatory or suppurative reaction of the peritoneum to direct irritation

Cause:› Inflammatory› Infectious› Ischemic

Exudation,Hematogenous,

Contiguous extension,Iatrogenic manipulation

Plain abdominal radiograph: cannot provide specific› Air-fluid Levels› Stones› Ascites› Eggshell calcification › Air in Biliary tree.› Obliteration of psoas-shadow in retro-

peritoneal disease› Right lower quadrant sentinel loops in acute

appendicitis

USnonspecific Abdominal CT

› CT signs Ascites (free or encapsulated) Infiltration of the omentum and/or mesentery Thickening of the parietal peritoneum

Angiography for ischaemia, hemorrhage

• Acute inflammatory colitis• Toxic megacolon• Pseudomembranous colitis• Ischaemic colitis

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Plain film can assess : ♠ the extent of the colitis ♠ the state of mucosa: It can be assessed from : - the faecal residue: In left-sided disease, the proximal limit of faecal residue will indicate the extent of active mucosal lesion. - the width of the bowel lumen - the mucosal edge - the haustral pattern

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A fulminating form of colitis with transmural inflammation, extensive & deep ulceration & neuromuscular degeneration.

Involve the transverse colon Ro. Findings: Mucosal islands (=pseudopolyps) & dilatation (8

cm) Common complication: Perforation in the sigmoid & peritonitis

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Etiology: Vascular insufficiency & bleeding into the wall of the colon. Sudden onset of severe abd.pain in the early

hours of the morning, followed by bloody diarrhoea.

In middle-aged & elderly patients. The wall of splenic flexure & descending colon is

greatly thickened→ thumb printing (plain films). The right side of colon is frequently distended.

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thumb printing