Added value of contrast-enhanced ultrasound (CEUS) with Sonovue^® in the diagnosis of inferior epigastric artery pseudoaneurysm: report of a case and review of literature

Abstract

The anatomical position of the inferior epigastric artery (IEA), within the rectus sheath, subjects patients to possible IEA injury during abdominal wall surgical and interventional procedures. Pseudoaneurysm arising from IEA is very uncommon with only 16 cases reported in the literature. We present a case of an IEA false aneurysm resulting from therapeutic paracentesis for ascites in a 71-year-old patient who came to our department for abdominal pain and signs of anemization. To our knowledge, no published reports are currently available describing an IAE pseudoaneurysm successfully diagnosed with contrast-enhanced ultrasound.

Electronic supplementary material

The online version of this article (10.1007/s40477-019-00398-x) contains supplementary material, which is available to authorized users.

Introduction

Pseudoaneurysms of the inferior epigastric artery (PAIEA) are very rare vascular injuries. A systematic review of the literature highlighted that there are only 14 articles about this topic, for a total of 16 cases [1]. PAs have been described following laparoscopic procedures [2], surgical sutures removal [3], evacuative paracentesis [4], surgical removal of peritoneal dialysis catheter [5], and drainage catheter placement/manipulation [5]. A spontaneous PAIEA has also been described [6].

Ultrasonography (US) is widely used in clinical practice for the first level study of traumatic and non-traumatic abdominal urgencies [7, 8]. It detects of effusions in the serous cavities, blood clots and hematomas. However, it is not able to document whether the bleeding is still active or it stopped [9].

The development of low-mechanical-index real-time contrast-enhanced ultrasound (CEUS) techniques performed with the second generation blood-pool US contrast agents has led to an accurate depiction of macrovasculature and microvasculature. The technique yields information about vascular injury almost as computed tomography (CT) and magnetic resonance imaging (MRI) with the added value to be in real time and with no use of ionizing radiation or iodinated organic compounds as contrast media [7–10].

We here-in describe a case of PAIEA subsequent to evacuative paracentesis simulating an active blood extravasation. Despite an extensive literature research, no other case of PAIEA diagnosed with CEUS was found.

Case report

A 71-year-old male patient with a medical history of HCV-related liver disease and congestive heart failure was referred to our observation for left lower quadrant (LLQ) abdominal pain radiating to the ipsilateral flank. The pain started about 2 days prior referral date, immediately following an evacuative paracentesis performed for a conspicuous ascites.

On physical examination, the abdomen was protuberant with ascites. The LLQ was tender showing evidence of a painful and pulsatile mass of the abdominal wall. There was a bruit over the mass. An ecchymosis of the overlying skin was also observed. Vital signs were within normal limits except a blood pressure of 190/100 mm of mercury (mmHg). His chest and cardiac examinations were unremarkable. Apart from a slight anemia (hemoglobin [Hb], 12.2 g/dL), laboratory studies including serum chemistry panel, lipase and liver function tests, were normal.

US was performed with a MyLab 70 XVG GOLD scanner (Esaote, Genoa, Italy) using multifrequency convex (2.5–5 MHz) and linear (7.5–12 MHz) probes. For Doppler imaging, it was used the lowest pulse repetition frequency and Doppler gain settings that did not cause aliasing. The pulse repetition frequency was set at 350–1000 Hz with 70–80% color gain and a 25- to 50-kHz wall filter was used. With a restricted FOV, the color box was maintained in the area of interest. It was as small as possible to keep the frame rate high.

US demonstrated the presence of a conspicuous soft tissue hematoma of the abdominal wall, which showed a round hypo-anechoic area inside (Fig. 1). Real-time US examination allowed also to detect a “smoky swarm” of small–medium-sized echoes with whirling motion (smoke-like effect) within this area (Video 1). The finding, compatible with the “black hole” sign reported in the literature, suggested bleeding (active bleeding or pseudoaneurysm). The color Doppler (CD) integration showed a pulsatile high-flow color jet inside the hypo-anechoic area. There was also a direct communication with the PAAEI (Fig. 2 and Video 2). Thus, the diagnostic hypothesis of bleeding was confirmed.

Fig. 1.

B-mode US image demonstrates the presence of a conspicuous soft tissue hematoma of the abdominal wall, which showed a round hypo-anechoic area inside. However, gray-scale US evaluation does not have diagnostic value due to the low specificity of the finding

Fig. 2.

Color Doppler image shows a linear color jet within the hypo-anechoic area and its direct communication with the AEI

However, due to the lack of further additional useful elements for differential diagnosis, an in-depth analysis would have been necessary by advanced imaging methods (i.e., CTA or angiography). Nevertheless, due to the patient’s reported iodinated organic agents allergy, it was considered appropriate proceeding using CEUS with Sonovue^® (Bracco, Milano, Italy). Sonovue^® was injected into the antecubital vein in a bolus fashion of 2.4 mL, followed by a flush of 10 mL of 0.9% normal saline solution. Continuous scanning began immediately and lasted 4–5 min following contrast injection.

CEUS demonstrated the presence of contained vascular injury with synchronous enhancement to the arterial vessels with no signs of active extravasation of contrast agent (Fig. 3a, b). Moreover, real-time CEUS allowed to observe the pulsating nature of the hyperechoic jets of contrast agent, which began from the communication point with AEI, filled the PA cavity with a “whirling” appearance, up to a complete PA homogenization during the late phase (Video 3).

Fig. 3.

CEUS images at 25 s (a) and at 38 s (b) from the Sonovue^® injection. CEUS confirms the diagnosis of pseudoaneurysm by demonstrating the presence of a contained vascular injury with synchronous enhancement to the arterial vessels with no signs of active extravasation of contrast agent. A round-shaped, hypoechoic, lymph node is also detectable behind the abdominal wall, adjacent to the epigastric vessels

We proceeded with US-guided compression performed with a linear probe for about 30 min obtaining the progressive PA sac exclusion from the blood flow (Fig. 4). The final control, performed 7 days later, showed the complete thrombosed PA sac without arterial supply.

Fig. 4.

Color-Doppler US examination performed 30 min after a US-guided compression maneuver shows the almost complete PA sac exclusion from the blood flow by thrombosis with a small residual vascular spot

Discussion

The IEA arises as a branch of the external iliac artery just above the inguinal ligament. From its origin, it courses upward and medially to enter the rectus sheath. Within the rectus sheath, it runs between the transverse fascia and parietal peritoneum. At the level of the semicircular line, the artery enters the transversal fascia and moves into the thickness of the rectus abdominis muscle with its numerous branches communicating with the superior epigastric artery of the internal mammary artery.

The anatomical IEA position subjects patients to possible injury during abdominal wall procedures and surgery and following percutaneous biopsy [1].

The PA is a perfused sac directly connected with the arterial lumen by a disruption of the vessel wall continuity [10]. PA can be life threatening due to rupture and bleeding. Therefore, PA is considered an emergency disease and requires being diagnosed accurately and quickly [11, 12].

In the presence of pulsating swelling, a careful clinical examination can be sufficient to suspect the presence of a PAIEA, especially in the patients with history of surgery or interventional procedures of the abdominal wall. However, patients may not all be easily evaluated and, not infrequently, complications such as active bleeding need to be ruled out, as in our case [11].

The US finding identified in our case, i.e., presence of a hypo-anechoic area within a hematoma, was first described as a “black hole” sign by our group [12]. It is a highly predictive sign of bleeding. However, the differentiation between active bleeding and pseudoaneurysm is usually not possible with US or Doppler examination. However, in clinical practice, this differentiation is necessary because it underlies relevant clinical and therapeutic implications: active bleeding requires endovascular or surgical treatment, while in selected PA cases a conservative approach can also be used, especially in the presence of hemodynamic stability [11].

Literature reports sensitivity values of 94–95%, specificity values of 94–97% and diagnostic accuracy values of 94–95% in the color Doppler diagnosis of PA [13, 14]. However, results by Doppler techniques in the detection of active blood extravasation were unsatisfactory [15, 16].

CTA [17, 18] and angiography [19] demonstrated a significant higher diagnostic value but are not indicated as first-level imaging methods, except in the acute phase or in the presence of clinical signs of hemodynamic instability. Thus, they should be reserved to those cases to be directly treated, especially angiography [19].

CEUS, an emerging method in recent years [7–10], is gaining reliable results, although the method is not enclosed in standardized vascular imaging protocols yet [20]. CEUS is able to detect the blood signal, even when it is stationary and in an extravascular localization, due to the presence of intravascular US contrast medium [20]. This method has shown the possibility of detecting the contrast agent extravasation as a sign of post-traumatic active hemorrhage, bleeding during the anticoagulant therapy, spontaneous gallbladder hemorrhage, digestive hemorrhage, spontaneous rupture of abdominal masses and rupture of abdominal aortic aneurysms [21, 22].

Similarly, the administration of Sonovue^® microbubbles has been usefully applied to evaluate traumatic and iatrogenic PAs, especially those that occurred following femoral arterial puncture. CEUS, in fact, allows an accurate evaluation of normal or pathological blood flow within vessels. Thus, also the blood flow into the PA cavity and its different pattern of distribution (“swirl” or “fountain-like”) are excellently appreciable with real-time CEUS examination [20].

Conclusions

The possibility of a real-time evaluation of vascular and extravascular findings occurring during the hemorrhage with a rapid and mini-invasive method such as the CEUS represents an added diagnostic value: it allows to exclude an active extravasation in the context of a hematoma, avoiding further more invasive diagnostic investigations or unnecessary therapeutic measures.

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Author contributions

Each author has participated sufficiently in any submission to take public responsibility for its content.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

Written informed consent was obtained from all patients, and the study was approved by the ethics committee of the institution.