Diagnostic Imaging of the Acute Abdomen

1 Clinical Examination and Symptoms.- 2 Imaging Techniques and Systematic Image Analysis (in Adults).- 2.1 Plain Abdominal Radiography.- 2.2 Real-Time Ultrasonography.- 2.3 Computed Tomography.- 2.4 Angiography.- 3 Radiographic, Sonographic, and Computed Tomographic Findings.- 3.1 Pathologic Gaseous Distension of the Intestinal Tract.- 3.1.1 Pathologic Gastric Distension.- 3.1.2 Duodenal Distension.- 3.1.3 Distension Limited to the Small Bowel.- 3.1.4 Distension Limited to the Colon.- 3.1.5 Combined Distension of the Small and Large Bowel.- 3.2 Pathologic Thickening of the Bowel Wall - Separation of Gas-Filled Bowel Loops - Mucosal Alterations.- 3.3 Intraperitoneal Fluid Collections.- 3.4 Extraperitoneal Fluid Collections.- 3.5 Pathologic Gas Collections.- 3.5.1 Free Intraperitoneal Gas (Pneumoperitoneum).- 3.5.2 Extraperitoneal Gas Collections.- 3.5.3 Pathologie Gas Collections in Organ Parenchyma.- 3.5.4 Intraluminal and Intramural Gas Collections in Canalicular Structures and Hollow Viscera.- 3.6 Intra-abdominal Masses.- 3.7 Calcifications.- 3.8 Foreign Bodies.- 4 Major Diseases Associated with Acute Abdomen and Their Accessibility to Diagnostic Imaging.- 4.1 Acute Inflammatory Abdominal Diseases.- 4.1.2 Acute Pancreatitis.- 4.1.3 Diffuse Peritonitis.- 4.1.4 Acute Appendicitis.- 4.1.5 Absces.- 4.1.5.1 Intraperitoneal Abscesses.- 4.1.5.2 Extraperitoneal Abscesses.- 4.2 Acute Bowel Diseases.- 4.2.1 Mechanical Obstruction of the Small Bowel.- 4.2.2 Mechanical Obstruction of the Large Bowel.- 4.2.3 Intestinal Pseudo-Obstruction (Atonic, Adynamic, Paralytic, Functional Ileus).- 4.2.4 Acute Intestinal Ischemia - Mesenteric Infarction.- 4.2.5 Toxic Megacolon.- 4.3 Acute Hemorrhage.- 4.3.1 Upper Gastrointestinal Hemorrhage.- 4.3.2 Lower Gastrointestinal Hemorrhage.- 4.3.3 Intramural Intestinal Hemorrhage.- 4.3.4 Acute Intraperitoneal Hemorrhage (of Nontraumatic Cause).- 4.4 Acute Retroperitoneal Disorders.- 4.5 Acute Abdominal Trauma.- 4.6 Soft-Tissue Lesions of the