Acute Abdomen

Intravenous contrast enhancement is indicated for all CT examinations performed for the evaluation of acute abdomen. Acute abdominal conditions for which CT is commonly performed include appendicitis, diverticulitis, intraabdominal abscess, and bowel obstruction. While intravenous contrast material enhances the visualization of all of these conditions, its role is not as great as in CT for abdominal trauma. For example, mesenteric inflammation is detectable in the absence of intravenous contrast enhancement in the case of appendicitis or diverticulitis. Furthermore, intravenous contrast enhancement is not involved in the detection of the complications of acute gastrointestinal inflammation, such as bowel obstruction, abscess formation, and bowel perforation. One cause of an acute abdomen, bowel ischemia, is an exception, in that intravenous contrast enhancement plays a major role in its detection, especially when strangulation is present.

The role of intravenous contrast enhancement in the detection of intraabdominal abscess is somewhat controversial, and good opacification of bowel loops by an oral contrast agent is arguably more important than the use of intravenous contrast agents in optimal CT evaluation for the diagnosis of intraabdominal abscess. As in other pathologic processes in the female pelvis, radiologic evaluation of intrapelvic abscess in a female should usually begin with transabdominal and endovaginal ultrasound rather than CT. The uterus and ovaries are almost always better visualized by endovaginal ultrasound.

For the diagnosis of appendicitis, ultrasound with graded compression is an accurate alternative to contrast-enhanced CT. 12 The technique is rapid and requires no intravascular contrast material. Its main disadvantage is the requirement of a sonographer skilled in the specific technique of examining the appendix.

Focused helical CT of the appendix without intravenous contrast enhancement has been shown to be a cost-effective method of evaluating patients with clinically suspected appendicitis.13 This examination is performed with both oral and rectal contrast material but without intravenous contrast agents, and images of only the axial levels surrounding the appendix are obtained.14 A focused CT examination of the appendix should be considered only if the primary clinical question is the presence or absence of appendicitis. Evaluation for other intraabdominal pathologic conditions may be limited in this type of focused CT examination.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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