Over the past three decades, abdominal sonography has become increasingly utilized as a diagnostic tool for surveying hepatobiliary, vascular, urologic, or GYN disorders. With progress in the resolution of scanning devices, it has also been used for the evaluation of various acute GI abnormalities. In the emergency setting, the focused assessment with sonography for trauma (FAST) examination has been widely performed by growing numbers of nonradiologist physicians, such as emergency physicians and surgeons, and accepted as a rapid and appropriate screening tool for trauma. In the same way, bedside abdominal sonography has been increasingly utilized for surveying the acute abdomen. The operator-dependent nature of ultrasonography, however, may limit the application of the examination in the emergency or acute care setting. In many hospitals, the difficulty in providing 24-hour ultrasonography service has been a major factor in preventing ultrasound from becoming a primary imaging modality. However, it is quite important to utilize the advantages of sonography to improve patient evaluation in the emergency or acute care setting.
This chapter discusses practical applications of sonography for the acute abdomen, especially for surgical emergencies associated with this presentation.
The evaluation of acute abdominal disorders begins with a careful history and physical examination. When required, the clinical findings may be supplemented by laboratory tests or conventional plain radiographs. Plain radiography may show some significant findings, such as pneumoperitoneum and bowel dilatation, but unsatisfactorily, it shows nonspecific findings in a significant number of patients. The development of high-resolution CT and ultrasonography has greatly facilitated the identification of pathology in many patients with an acute abdomen.
CT is an excellent imaging modality to evaluate not only intraperitoneal disorders but also retroperitoneal abnormalities. CT has a greater specificity than plain radiography. Multiple-detector CT (MDCT), which has taken the place of single-detector CT in recent years, shows three-dimensional, high-quality images of the viscera and presents detailed structures of acute abdominal abnormalities. Both plain radiography and CT are noninvasive, but are contraindicated in pregnant patients. The level of irradiation for CT may be more than a hundred times of that in plain radiography.
In contrast, sonography does not expose patients to ionizing radiation and is noninvasive, readily available, repeatable at the bedside, and less expensive than CT. It has been accepted as a useful imaging modality for hepatobiliary, CV, urologic, or GYN disorders. In addition, it has been demonstrated that sonography is applicable and accurate for acute GI disorders such as acute appendicitis, acute colonic diverticulitis, intussusception, and bowel obstruction. Abdominal sonography, however, has some disadvantages such as difficulty in visualizing abnormalities in patients who are obese or who have excessive bowel gas.
The operator-dependent nature of ultrasonography is one factor influencing the reliability of point-of-care ultrasound performed by nonradiologist physicians. Indeed, the clinical applications and results of point-of-care ultrasound are influenced by the clinical experience, skill, and interest of the clinician. In several European countries and Japan, however, point-of-care ultrasound ...