1. Correct Answer: B. Surgical consultation

Rationale: Figure 76.1 shows an abdomen with free air and ascites. Although the patient is at risk for spontaneous bacterial peritonitis, this presentation is much more concerning for perforated viscus and emergent surgical consultation is most appropriate (Choice B is correct). Although the diagnosis of perforated viscus is not commonly made with ultrasound, it is important to recognize air when it is seen. It most often appears as an echogenic stripe representing the peritoneum associated with deep artifactual reverberation echoes with a comet tail appearance. Detection can be operator-dependent and certain patient maneuvers and positions, such as deep breathing and left lateral decubitus position, can be helpful. One study found the sensitivity of ultrasound for free air in acute abdominal pain patients to be 85% and the specificity to be 100%, making it a valuable diagnostic tool. With this finding, paracentesis should not be performed (Choices A and C are incorrect). Although a CT scan would be helpful in confirming the presence of intraperitoneal air and may be able to identify the source of the injury, the decision to perform more diagnostic testing should occur after surgical consultation in an acutely ill patient with generalized peritonitis, as delays in surgery may be associated with worse survival (Choice D is incorrect).

1. Bohnen J, Boulanger M, Meakins JL, McLean APH. Prognosis in generalized peritonitis: relation to cause and risk factors. Arch Surg. 1983;118(3):285-290. doi:10.1001/archsurg.1983.01390030017003.

2. Hefny AF, Abu-Zidan FM. Sonographic diagnosis of intraperitoneal free air. J Emerg Trauma Shock. 2011;4:511-513. doi:10.4103/0974-2700.86649.

3. Moriwaki Y, Sugiyama M, Toyoda H, et al. Ultrasonography for the diagnosis of intraperitoneal free air in chest-abdominal-pelvic blunt trauma and critical acute abdominal pain. Arch Surg. 2009;144(2):137-141. doi:10.1001/archsurg.2008.553.

2. Correct Answer: A. Evaluate different sites for paracentesis

Rationale: Figure 76.2 shows a vessel above the large pocket of ascites. Although placing color on Figure 76.2 could confirm this, it is not necessary (Choice C is incorrect). It is likely that moving your probe a few centimeters would avoid the vessel and the procedure could be performed safely at the bedside (Choice A is correct; Choice D is incorrect). Generally, paracentesis is performed with a low-frequency curvilinear probe, but it is reasonable to use a high-frequency linear probe to help identify superficial vasculature, which could contribute to additional bleeding from the procedure. Blind techniques for paracentesis utilize either the infraumbilical midline or the lower quadrants superior and medial to the anterior superior iliac spine to avoid the inferior epigastric vessels. Ultrasound allows entry sites at other parts of the abdominal wall, provided that vessels are actively avoided. This vessel could easily be punctured with a paracentesis attempt, inadvertently leading to the creation of an abdominal wall hematoma (Choice B is incorrect).

1. Ennis J, Schultz G, Perera P, Williams S, Gharahbaghian L, Mandavia D. Ultrasound for detection of ascites and for guidance of the paracentesis procedure: technique and review of the literature. Int J Clin Med. 2014;05(20):1277-1293. doi:10.4236/ijcm.2014.520163.

2. Nicolaou S, Talsky A, Khashoggi K, Venu V. Ultrasound-guided interventional radiology in critical care. Crit Care Med. 2007;35(5 suppl.). doi:10.1097/01.CCM.0000260630.68855.DF.

3. Runyon MS, Marx JA. Peritoneal procedures. In: Roberts JR, Custalow CB, Thomsen TW, Hedges JR, eds. Roberts & Hedges’ Clinical Procedures in Emergency Medicine. 6th ed. Elsevier/Saunders; 2014:852-872.