Donʼt Be Fooled: Take Serial FAST Scans in Blunt Flank Trauma

Abstract

ImageA 38-year-old man presented to the emergency department after a horse kicked him in the left flank. He denied chest and abdominal pain. His heart rate was 85 bpm, blood pressure was 139/93 mm Hg, and oxygen saturation was 99%. He had tenderness over a 4 cm contusion on his left flank at the 10th posterior rib. His abdomen was not tender. The assessment was otherwise unremarkable. The initial focused assessment for sonography in trauma (FAST) scan was negative. (Image 1: Right upper quadrant.) A computed tomography (CT) scan illustrated a grade 3 splenic laceration without active extravasation, perisplenic hematoma, small hemoperitoneum, and left 9th and 10th rib fractures. (Image 2.) A repeat FAST scan 10 minutes later was positive in the right upper quadrant only. (Image 3: Right upper quadrant.) The patient was admitted to the intensive care unit where his hematocrit fell to a nadir of 36.4 % (normal 35.0-47.0%). He was discharged on hospital day three. Patients can present after blunt torso trauma with solid organ injury without abdominal tenderness or hypotension. The spleen is the most commonly injured organ, comprising one-third of such injuries. Splenic injury management includes observation, angiography and embolization, or laparotomy depending on the degree of injury and hemodynamic stability. The FAST scan is an accepted screening tool for trauma evaluation. (Curr Opin Crit Care 2007;13[4]:399.) The right upper quadrant view is the most sensitive in a supine patient no matter the location of injury due to the anatominal attachment of the posterior mesentery. In experienced hands, 250 ml of fluid can be detected with an overall sensitivity and specificity of 86% and 98%, respectively. (J Trauma 2001;50[1]: 108.) As this case illustrates, it is imperative to perform repeat FAST scans to increase sensitivity. (J Trauma 2004;57[5]:934; J Emerg Med 2000;18[1]:79.) In hemodynamically stable patients with a positive FAST, CT can diagnose the specific injury and evaluate the retroperitoneal space because FAST scans only evaluate the intraperitoneal space. When the physician has a high degree of suspicion for intra-abdominal injury but does not have access to CT or surgical services, the FAST scan should be repeated as to avoid missing life-threatening injury.Initial ultrasound of Morrison's pouch, right upper quadrantComputed tomography of abdomen. Arrow indicates a grade 3 splenic laceration without active extravasation. Asterisks indicate large perisplenic hematoma.Repeat ultrasound of Morrison's pouch demonstrating intraperitoneal fluid (arrow).Drs. Rossi and Gharahbaghian are emergency physicians in the department of surgery, division of emergency medicine, at Stanford University Medical Center. Dr. Gharahbaghian is also the associate director of Emergency Ultrasound and a director of the Emergency Ultrasound Fellowship at Stanford. Return to EM-News.com