Ultrasound is an imaging modality that has been in clinical use for approximately 50 years. Sokolov first described the potential for using this technology to produce low-resolution images in 1939. Later understanding of the piezoelectric effect and further technological refinements have resulted in machine advancements. We have seen the machine sizes dramatically decrease; some of the earliest machines were the size of refrigerators while recently we have seen the introduction of transducers that are compatible with smartphones. Although ultrasound technology can be utilized in a variety of different settings and body locations, the focus of this article will be on transabdominal ultrasound, its definition, indications and diagnostic pearls and pitfalls. Transabdominal ultrasound was initially utilized in its most colloquial setting of pregnancy in the 1960s. It is now utilized for visualization of multiple abdominal organs, both intraperitoneal and retroperitoneal. By definition, any evaluation with an ultrasound transducer overlying the abdominal wall can be considered a transabdominal ultrasound. Transabdominal ultrasound can be applied to visualize the liver, gallbladder, kidneys, pancreas, small and large intestine, appendix, bladder, uterus, adnexa, spleen, stomach, aorta, and IVC. In the setting of obstetrics and gynecology (OBGYN), the transabdominal approach is usually performed to evaluate for possible pelvic pathology or pregnancy in a less invasive manner. In the emergency department (ED) a transabdominal ultrasound is most commonly utilized to evaluate for intrauterine pregnancy, cholelithiasis, intraabdominal free fluid, abdominal aortic aneurysm, and hydronephrosis. Emergency physicians (EPs) perform a limited point-of-care ultrasound (POCUS) in comparison to formal radiology transabdominal ultrasounds. The EP performs the former compared to the latter, and a trained sonographer performs a thorough and complete examination of the organ. ED POCUS is focused on binary questions that are rapidly evaluated at the bedside and direct patient care immediately. For example: “Is there an intrauterine pregnancy?” In most cases when an intrauterine pregnancy is identified, the examination is complete. While both EPs and sonographers perform a transabdominal ultrasound, the performance characteristics and goals vary.
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