a b s t r a c t

Background: Ultrasound-guided paracentesis is commonly performed in the emergency department (ED) setting. Injury to the inferior epiGastric artery (IEA) is an uncommon but potentially Life-threatening complication of paracentesis. Use of anatomic landmarks has been recommended to avoid this structure. If feasible, sonographic localization of the IEA before ultrasound-guided paracentesis may provide the operator with anatomic mapping of this vascular structure.

Case reports: We present 5 cases demonstrating the feasibility of identifying the IEA in ED patients with ascites. Why should an emergency physician be aware of this? Sonographic localization of the IEA before ultrasound- guided paracentesis may provide a more reliable means of avoiding iatrogenic injury to this vessel. Further study is warranted to determine whether routine IEA visualization before paracentesis results in a decreased complication rate.

(C) 2015

Introduction

Needle aspiration of ascites fluid from the peritoneal cavity or paracentesis is routinely performed in the emergency department (ED) setting for both diagnostic and therapeutic purposes. Complications in- clude infection and injury to anatomic structures such as solid organs and the Inferior epigastric artery (IEA) [1-4]. This latter complication can have devastating consequences including hemorrhage, pseudoaneurysm formation, and death [5-7]. Prior investigation has shown that the use of ultrasound-guidance confers a greater success rate during paracentesis than a traditional landmark approach [8]. The use of sonography also reduces complications and may in turn decrease costs [9].

To date, no known studies or case descriptions exist for use of ultra- sound to identify the IEA in ED patients with ascites. Although a stan- dard emergency medicine procedure textbook recommends use of ultrasound to identify ascites, no mention is made of sonography for IEA identification [10]. Rather, the recommendation is to use a tradition- al avoid-by-landmarks approach, staying lateral to the rectus sheath to avoid the IEA [10]. Some authorities recommend using ultrasound to identify fluid pockets amenable to paracentesis, with the goal of im- proving paracentesis success rates and minimizing complications;

? Sources of support: none.

?? Presented: Second World Congerss on Ultrasound in Medical Education, September

28, 2013.

? Conflicts of interest: none.

* Corresponding author at: 1517 W Trindle Rd, Carlisle, PA, 17015. Tel.: +1 717 982

0208.

E-mail address: [email protected] (J.C. Stone).

¹ Send reprints to: James H. Moak MD, PO Box 800699, Charlottesville, VA 22908.

however, we are unaware of standard recommendations for identifying the IEA [8,9,11,12].

Two locations for performing needle insertion in paracentesis have been described, at the avascular midline lower abdomen and the lateral, lower quadrant [11]. The lateral lower quadrant is generally preferred, as it offers a thinner abdominal wall with less collateral vessels and a larger pool of ascites fluid. In addition, rising obesity has caused in- creases in midline wall thickness, which can decrease ease of use of the midline site for large volume paracentesis [11,13].

The IEA typically arises from the external iliac artery just superior to the inguinal ligament. The artery then courses superiorly and medially to enter the rectus sheath. Several studies have attempted to define the usual anatomic location of the IEA [14-16]. These studies, however, did not focus on patients with ascites who may have altered anatomy due to abdominal distension. We reviewed charts over a 13-month period from November 2011 to December 2012 to identify patients on whom we documented visualization of the IEA during paracentesis performed in the ED. In this retrospective case series, we describe 5 cases of ED pa- tients with ascites in whom the use of ultrasound to identify the IEA was feasible. We also describe the sonographic technique for identifying this important structure. This study was approved by the medical center institutional review board (IRB) and was not part of any other study.

Case reports

Case 1

A 65-year-old man with a history of Hepatitis C and alcoholic liver disease presented to the ED with abdominal pain and distension. He

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Case 3

A 36-year-old man with a history of hepatitis B presented as a walk- in with complaints of fluid retention and swelling of the abdomen, scro- tum, and bilateral lower extremities. He also noted occasional hematemesis, epistaxis, shortness of breath, and Urinary retention. He noted hemorrhoids and was taking furosemide 20 mg daily. Examina- tion revealed an afebrile male with abdominal protuberance, shifting dullness, a positive fluid wave, and anasarca. Diagnostic and therapeutic ultrasound-guided paracentesis was performed. The left IEA was identi- fied in the lower quadrant, and needle insertion was performed lateral to that site. Two liters of cloudy yellow fluid was removed, and fluid analysis was negative for Spontaneous bacterial peritonitis. He was discharged with increased doses of diuretics after a 2-day admission (Video 1).

Case 4

Fig. 1. sonographic appearance of the IEA (red) flanked by 2 accompanying inferior epigastric veins (blue). Hypoechoic fluid can be seen deep to the abdominal wall.

appeared jaundiced and had diffuse abdominal tenderness without re- bound. Bedside ultrasound was positive for ascites. The IEA was visual- ized sonographically before performing ultrasound-guided paracentesis (Fig. 1). Five liters of ascites fluid were removed without complication. The patient experienced symptomatic improvement and was admitted to the gastroenterology service for further care.

Case 2

A 62-year-old man with a history of alcoholic liver disease and bleeding gastric varices presented with abdominal pain and shortness of breath. Physical examination revealed a tense, grossly distended abdomen. Using bedside ultrasonography, the location of the right IEA was marked (Fig. 2). Large volume paracentesis was then performed in the ED with removal of 5 L of peritoneal fluid. There were no complications. The patient reported improved symptoms and was subsequently admitted.

Fig. 2. Photograph demonstrating the location of the inferior epigastric vessels in a patient with ascites.

A 57-year-old man with a history including hepatitis C, cirrhosis, and Hepatic encephalopathy was transferred to the ED for evaluation of Liver failure and altered mental status. He had undergone a therapeutic paracentesis 4 days prior. Jaundice, bibasilar crackles, abdominal fluid wave, right upper quadrant tenderness, and asterixis were noted on ex- amination. Bedside ultrasonography was used to identify the IEA and mark an optimal site for paracentesis, which was conducted without complication. He required 2 additional therapeutic paracenteses during a 2-week admission and was treated for spontaneous bacterial peritoni- tis and hepatic encephalopathy.

Case 5

A 40-year-old woman with a history of cirrhosis, hepatitis C, alcohol dependence, and transjugular intrahepatic portosystemic shunt was transferred to the ED from an outlying hospital for abdominal pain, vomiting, and worsening transaminitis. Of note, paracentesis had been performed 4 times in the 6 weeks before presentation, most recently a large volume (5 L) of paracentesis just before transfer. On evaluation, she was afebrile and tachycardic with a distended, tight, diffusely tender abdomen. The IEA was identified. Right lower quadrant diagnostic and therapeutic paracentesis were performed, obtaining 2 L of fluid. The patient was subsequently admitted to the gastroenterology service. She improved to discharge with lactulose, a short antibiotic regimen, and diuresis.

Sonographic technique for identifying the IEAs

In each of the cases described, a Sonosite M Turbo with a 6- to 13- MHz 25-mm linear array transducer was used. All procedures were done with static ultrasound guidance by junior-level resident physi- cians under the supervision of a single ED attending physician with more than 10 years of experience in the use of ultrasound. The attending also has experience as an emergency ultrasound fellowship director. In all cases, the IEA was identified. There were no complications from the procedure in any case.

Technique

The IEA is identified along its course in the lower abdomen by scan- ning with a high-frequency transducer, beginning at the mid-inguinal ligament and proceeding superomedially toward the umbilicus. Com- monly, the IEA may be seen as a round, pulsatile, hypoechoic structure flanked by 2 inferior epigastric veins (see Fig. 1). In patients with a par- ticularly large amount of ascites, a more lateral starting point may be re- quired. If the IEA is not visualized just above the inguinal ligament or if this area is difficult to access due to the patient’s body habitus, an alter- nate approach may be used. First, place the transducer in a transverse

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plane in the anterior axillary line over the patient’s pannus or distended abdomen. Next, slowly slide the transducer medially, maintaining a transverse plane. If the IEA is not visualized initially, repeat this lateral-to-medial approach from a more cephalad starting position. Applying increasing amounts of pressure may allow improved visuali- zation of the artery and the peritoneal-ascites interface but may also compress the flanking veins. Of note, other small vessels may also be seen during these maneuvers. These structures may be collateral or branch vessels, and, if seen, their positions should also be noted and avoided during paracentesis.

Discussion

Use of ultrasound to identify the IEA in ED patients with ascites be- fore paracentesis has not been described previously. We present a series of cases that show feasibility of use of ultrasound for this purpose. Ultra- sound guidance and visualization of anatomy are more frequently being incorporated as standard of care for procedures. Although ultrasonogra- phy has long been recommended to avoid injury of anatomic structures, visualization of the IEA has not been routinely discussed [12]. Tirado et al noted that the IEA may be identified and avoided during paracentesis in their review of ultrasound-guided procedures in the ED [17]. Our study expands on this concept by describing the feasibility of IEA identification in the context of actual ED patients with ascites.

Abdominal wall vessel anatomy may be more variable in patients with ascites, causing these vessels to lie outside the boundaries of rec- ommended anatomic landmarks. Murthy et al [6] suggested that, in pa- tients with ascites, the IEA is displaced laterally due to abdominal wall distension and stretching and is therefore more likely to be injured dur- ing paracentesis. Several investigators have attempted to define the an- atomic location of the IEA [14-16]. One study used Doppler ultrasonography to approximate the ideal location of the IEAs among a random sample of patients in an attempt to define optimal sites for laparoscopic port placement to minimize risk of Vascular injury. At the levels of the umbilicus and the anterior superior iliac spine, they found that the IEA did not lie in excess of 6 cm from midline on either side, with a median distance less than 5 cm [14].

Additional studies have been performed with computed tomograph- ic scan and Cadaveric dissection. One study using abdominal and pelvic computed tomographic scan to map the epigastric vessels for laparo- scopic “safety zones” described the mean distance from the midline to the epigastric vessels as 5.88 cm at the level of the umbilicus, 5.32 cm midway between the umbilicus and pubic symphysis, and 7.47 cm at the level of the pubic symphysis. Although this study excluded condi- tions such as ascites that may alter the location of the epigastric vessels, it demonstrated that the IEA was significantly more lateral to the mid- line in patients with a body mass index greater than 26.3 m²/kg. Specif- ically, in this group, the mean distances were 6.9 cm at the umbilical level, 6 cm at the midway level, and 8.1 cm at the pubis [15]. Epstein et al [16] performed cadaveric dissections of the IEA to determine the optimal site for laparoscopic trocar placement. These authors recom- mended insertion more than two-thirds of the way from the midline to the anterior superior iliac spine. They noted that IEA branch positions are highly variable but may also be injured. These branches are less like- ly to be encountered inferiorly and lateral to the IEA itself [16]. The value of these studies’ findings in patients with ascites is unknown. It is not clear how the course of the IEA varies in patients with abdominal dis- tention due to ascites.

The precise incidence of IEA injury is unknown and may be underreported. Several studies have attempted to establish the incidence of hemorrhagic complications from paracentesis. Runyon [18] suggested a rate of approximately 1%. Mercaldi and Lanes [9] showed an overall hem- orrhagic complication rate of 0.8% (0.27% with ultrasound guidance and 1.25% without). Pache and Bilodeau [7] reported an incidence of 0.2% for severe hemorrhagic complications and 0.02% for death (n = 4729) in their retrospective study. De Gottardi et al [4] performed a prospective

study on complication rates from paracentesis in 515 patients with cirrho- sis, finding a 1.6% rate of major complications. To date, there are very few prospective studies of complication rates from paracentesis.

Although rare, potentially serious complications of paracentesis are well documented [1-3]. Sobkin et al [1] described IEA injury in 8 pa- tients (40% of their study group) that resulted in massive abdominal wall hemorrhage. Mulpuru et al [2] described a case of life- threatening, large rectus sheath hematoma from IEA branch bleeding. Several other case studies have described IEA pseudoaneurysms as complications of paracentesis in patients with ascites [6,19]. Preprocedural external skin mapping of the IEA using ultrasound has been described for procedures other than paracentesis, such as transabdominal lymph node biopsy, from which hemorrhagic compli- cations are also rare [20]. In addition, use of ultrasound to evaluate the IEA before harvesting of the internal mammary artery for coronary re- vascularization procedures has been described [21].

Use of ultrasound to identify the IEA during paracentesis appears fea- sible and has little or no added risk or cost. Based on the feasibility dem- onstrated in this small number of cases, the authors have adopted IEA identification as a routine and easily incorporated step in ED paracentesis for patients with ascites. The precise time to obtain images of the IEA was not recorded or recoverable from time stamps for these cases. Our anec- dotal experience suggests that little extra time is required, and we esti- mate that this structure can be identified in less than a minute by even novice scanners. Further study to determine precise image acquisition times among providers of varied experience may be warranted.

Conclusion

Complications involving injury to the IEA are well documented. Cur- rent landmark techniques do not allow for visualization of the IEAs dur- ing paracentesis, and the anatomic course of the IEA may vary in patients with ascites. The feasibility of IEA identification with ultra- sound makes this technique a valuable preparatory step for paracentesis in the ED setting. Additional larger studies may demonstrate a decrease in complication rates from paracentesis by routine incorporation of sonographic IEA visualization.

Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.ajem.2015.06.067.

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