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Vascular/Cardiac » Aortoiliac
Ruptured abdominal aortic aneurysm
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Presentation A 62-year-old man presented with spontaneous pneumothorax, lumbar pain and pain in the lower limbs. Biochemical investigations revealed a low hemoglobin and hematocrit. Plain abdominal radiographs revealed prevertebral calcifications at the mid-abdominal level. An abdominal ultrasound was performed which revealed left hydronephrosis and the following findings.
 
 
 
Caption: Transverse image of the central retroperitoneum
Description: A large heterogeneous prevertebral retroperitoneal mass is seen on the left side of the abdomen. This mass was in close proximity to the abdominal aorta and demonstrated pulsations.
 
 
 
Caption: Another scan at the mid-abdomen level
Description: A heterogeneous mixed echogenicity mass is seen again in this view, in the pre-aortic region.
 
 
 
Caption: A magnified view of the abnormality seen
Description: The large, heterogeneous pre-aortic mass is seen again here.
 
 
 
Caption: Another scan at the mid-abdomen level
Description: The pre-aortic mass displays cystic component. Posteriorly, few linear strongly echogenic specs are noted, which show posterior shadowing and possibly represent calcifications.
 
 
 
Caption: Color Doppler ultrasound, transverse image of the central retroperitoneum
Description: The level of the communication of the retroperitoneal mass with aortic dilatation is observed.
 
Differential Diagnosis Large retroperitoneal hematoma with associated aortic abdominal aneurysm rupture
 
Final Diagnosis Large retroperitoneal hematoma with associated aortic abdominal aneurysm rupture
 
Discussion

Abdominal aortic aneurysm is a segmental dilatation of the aortic wall that causes the vessel to be larger than 1.5 times its normal diameter or that causes the distal aorta to exceed 3 cm. This can continue to expand and can rupture spontaneously causing exsanguinations and even death [1].
Abdominal aortic aneurysm rupture is an important cause of unheralded deaths in people older than 55 years. The risk factors for aneurysm rupture are: the increased initial or the rapid growth of the aneurysm diameter, smoking, advanced age, male sex, lower forced expiratory volume, chronic obstructive pulmonary disease, hypertension, and family history. Abdominal aortic aneurysm rupture is more frequently produced in the left side [1, 2].
Clinically abdominal aortic aneurysm rupture may be an incidental discovery or the patient could present with abdominal, back or flank pain [1, 2].
X-Ray findings: A curvilinear calcified rim often to the left of the midline is apparent on some plain abdominal radiographs. Mural calcification can be radiographically unapparent and lead to a false-negative finding in as many as half of small abdominal aortic aneurysm [1, 3].
Unlike most other modalities (aortography, CT, MRI), abdominal ultrasound can be performed expeditiously and at the bedside. With partially encapsulated hematoma, a hypoechoic or anechoic para-aortic space-occupying lesion may be detected. Color-flow Doppler can aid in detecting the site of leak or extravasations, although adjustment to low-velocity scales may be necessary to register leaks with low flow rates [3, 4, 5].
CT findings that indicate possible abdominal aortic aneurysm rupture include soft tissue hyperdensity outside the aortic wall, an indistinct aortic wall, thinning or fracture of a calcified aortic wall segment, penetration of a hematoma into the leaves of the mesentery, or extravasation of contrast into the psoas muscle or retroperitoneum, enlargement or obscuration of the psoas muscle, and anterior displacement of the kidney [1, 5, 6].
MRI is a valuable alternative to CT in patients with renal insufficiency in who contrast material–induced nephropathy is a concern. MRI is also helpful in further delineating the aorta in the context of a large retroperitoneal collection that obscures the borders between adjacent structures, as well as laminated clot or atherosclerotic debris on the aneurismal wall [7].
Angiographically a circumscribed extraluminal contrast enhancement is seen. In case of leaking aneurysm the frank extravasation of contrast material with poor washout is observed. This is rarely demonstrated because the patients are typically in unstable condition and are transported directly to the operating room [1, 3].
Abdominal aortic aneurysm rupture, symptomatic expansion, or sentinel leak is a surgical emergency. Endovascular reparation with graft placement with or without hypo gastric or internal iliac artery embolization represents a surgical option [1, 3]

 
Case References 1. Tan WA, Makaroun MS. Abdominal Aortic Aneurysm, Rupture; http://www.emedicine.com/radio/topic2.htm
2. Frank A. Lederle. Ultrasonographic Screening for Abdominal Aortic Aneurysms; Annals 2003;139:516-522.
3. Radvany MG,  Seguritan V. Abdominal Aortic Aneurysm, Diagnosis; http://www.emedicine.com/radio/topic1.htm
4. Badea RI. Aorta. In: Dudea SM, Badea RI. Ultrasonografie vasculara, Ed. Medicala, Bucuresti 2004, 353-362.
5. Bendick PJ, Zelenock GB, Bove PG, Long GW, Shanley CJ, Brown OW. Duplex ultrasound imaging with an ultrasound contrast agent: the economic alternative to CT angiography for aortic stent graft surveillance. Vasc Endovascular Surg. 2003 May-Jun; 37(3):165-70.
6. Giannoni MF, Palombo G, Sbarigia E, Speziale F, Zaccaria A, Fiorani P. Contrast-enhanced ultrasound imaging for aortic stent-graft surveillance. J Endovasc Ther. 2003 Apr; 10(2):208-17.
7. Tatli S, Lipton MJ, Davison BD, Skorstad RB, Yucel EK, MR Imaging of Aortic and Peripheral Vascular Disease; RadioGraphics 2003; 23:S59–S78.
 
Technical Details

The ultrasound examination was performed using Medison Kretz SonoAce 8800 equipment with 3.5-5 MHz curved transducer.

 
Follow Up The patient was urgently transferred to the Surgical Cardio-Vascular Clinic, where the patient was operated without any further delay. A large abdominal aortic aneurysm with retroperitoneal hematoma and erosion of the adjacent vertebral bodies was revealed at surgical intervention. Dacron #30 termino-terminal prosthesis was placed between the infrarenal aorta and aortic bifurcation.
 
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