Over the past 25 years, abdominal sonography has become increasingly utilized as a diagnostic tool for surveying hepatobiliary, vascular, urologic, or gynecologic disorders. With progress in the resolution of scanning devices, abdominal sonography has also been used for the evaluation of various acute gastrointestinal abnormalities. The operator-dependent nature of ultrasonography, however, may limit the application of the examination in the emergency setting. In the United States, ultrasonography has been a domain of radiology and, subsequently, the application of the examination for the acute abdomen in the emergency department has been somewhat limited. In most hospitals, the difficulty in providing 24 hour service by expert sonographers has been a major factor in preventing ultrasonography from becoming a primary imaging modality in the emergency or acute care setting. It is quite important, however, to utilize the advantages of ultrasonography to improve patient evaluation in the emergency or acute care setting.
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 computed tomography (CT) and ultrasonography has greatly facilitated the identification of pathology in many patients with an acute abdomen.
CT scanning is an excellent imaging modality to evaluate not only intraperitoneal disorders but also retroperitoneal abnormalities. CT scanning has a greater specificity than plain radiography but has not been used as a routine screening tool for the acute abdomen because it is expensive and not immediately available in many hospitals. Both plain radiography and CT are noninvasive, but are contraindicated in pregnant patients.
In contrast, sonography does not expose patients to ionizing radiation and is noninvasive, readily available, repeatable at the bedside, and less expensive than CT scan. It has been accepted as a useful imaging modality for hepatobiliary, cardiovascular, urologic, or gynecologic disorders. In addition, recent studies have shown that sonography is applicable and may be accurate for acute gastrointestinal disorders such as acute appendicitis, acute colonic diverticulitis, intussusception, and bowel obstruction. It is also beneficial for patients who are hemodynamically unstable, who have unreliable physical examination findings due to drug intoxication or central nervous system disorders, or who have unexplained shock symptoms and an equivocal physical examination. Abdominal sonography, however, has some disadvantages, such as difficulty in visualizing intraperitoneal or retroperitoneal abnormalities in patients who are obese, or who have excessive bowel gas.
The operator-dependent nature of ultrasonography has been identified as a factor influencing the reliability of emergency ultrasound performed by nonradiologist physicians. Indeed, the clinical applications and results of emergency ultrasound are influenced by the clinical experience, skill, and interest of the sonologist. In several European countries and Japan, however, bedside ultrasound performed by nonradiologist physicians has been accepted as a rapid and useful screening ...