Diagnostic Ultrasound - Abdomen and Pelvis

Splenic Infarct
Diagnoses: Spleen
– Emboli to small intraparenchymal arteries → small
infarcts, often multiple, may be asymptomatic
– Emboli to splenic artery/major branches → large or
massive infarcts, acute symptoms
– Cardioembolic: Myocardial infarction, atrial fibrillation
– Atheroembolic: Aorta, celiac artery
– Emboli from aneurysm: Aortic, celiac, SA
○ Infarction due to severe splenomegaly
– Chronic myelogenous leukemia, myelofibrosis
(extramedullary hematopoiesis), lymphoma,
hemoglobinopathies, infections (EBV, CMV, malaria)
– Infiltrative disorders → splenomegaly and increased
oxygen requirement; congestion from intrasplenic
microcirculatory obstruction and possibly anemia;
result: Ischemia that may become critical → infarction
– Hemoglobinopathies → splenomegaly/increased
oxygen demand and direct microcirculatory
obstruction (e.g., sickle cell crisis)
○ Infarction due to splenic artery occlusion
– Atherosclerosis, vasculitis, fibromuscular dysplasia,
complication of liver transplantation/other surgery,
torsion (wandering spleen)
○ Infarction due to SVT or parenchymal small vessel
thrombosis
– Pancreatitis-related SVT
□ Chronic pancreatitis: 10-40% SV thromboses
□ Associated with pseudocysts: (1) edema, cellular
infiltration, fibroinflammatory reaction in vein wall;
(2) direct compression of SV
□ Acute pancreatitis: Less frequent cause than
chronic pancreatitis
– Other etiologies: Hypercoagulable states, direct
neoplastic invasion/compression (usually pancreatic
carcinoma), portal vein thrombosis > SV extension,
abdominal sepsis (SV thrombophlebitis), blunt trauma,
complication of variceal sclerotherapy or surgery
Gross Pathologic & Surgical Features
• Infarction
○ Necrosis/hemorrhage within splenic parenchyma;
possibly splenic pseudocyst chronically
Microscopic Features
• Bright band sign thought to reflect preserved fibrous
trabeculae surrounded by intervening coagulative necrosis
• Infarction may be accompanied by microscopic features of
an underlying infiltrative disorder
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Often asymptomatic, found incidentally by imaging
– Only ~ 10% of infarcts are recognized clinically
– Asymptomatic infarcts are small but may be
sequential and multiple
○ Left upper quadrant abdominal pain;
nausea/vomiting/malaise
○ Splenomegaly, due to congestion, inflammation,
hemorrhage, or underlying disorder
○ If related to chronic SV thrombosis, may see secondary
signs related to varices (such as upper GI bleeding)
Demographics
• Age
○ Related to underlying disorders
• Gender
○ Related to underlying disorders
• Epidemiology
○ Governed by underlying disorders
Natural History & Prognosis
• Small infarcts → parenchymal scarring
○ Multiple infarcts may reduce splenic function
• Large infarcts
○ Resorption of necrotic tissue/hematoma → scar
○ Encapsulation of necrotic tissue/hematoma →
pseudocyst
○ Splenic abscess: Potential complication especially when
infarct caused by septic embolization
○ Splenic rupture
• Acute SA or SV thrombosis
○ May cause infarction and associated pathology, but
collateralization may prevent this outcome
• Chronic SV thrombosis
○ Possible gastroesophageal hemorrhage, depending on
route of major collaterals
○ Can be recurrent, intractable, life threatening
Treatment
• Infarction: Treatment governed by size
○ Small: Self-limiting, no treatment
○ Large: Observation or splenectomy; rupture risk with
massive infarcts
• SA or SV thrombosis: Treatment governed by extent of
infarction and gastroesophageal hemorrhage
○ Gastroesophageal hemorrhage: Endoscopic
sclerotherapy, splenectomy if recurrent/intractable
DIAGNOSTIC CHECKLIST
Image Interpretation Pearls
• Classic appearance of acute splenic infarct: Hypoechoic,
peripheral, wedge shaped, and avascular
○ Non-classic: Rounded or peripheral band morphology;
global infarction; hyperechoic
○ Bright band sign
• Chronic infarction: Atrophic, scarred spleen,± calcification
• Associated findings: Splenomegaly, SV occlusion (with large
perisplenic varices), SA thrombosis
SELECTED REFERENCES
1. Llewellyn ME et al: The sonographic "bright band sign" of splenic infarction. J
Ultrasound Med. 33(6):929-38, 2014
2. Mackenzie DC et al: Identification of splenic infarction by emergency
department ultrasound. J Emerg Med. 44(2):450-2, 2013
3. Benter T et al: Sonography of the spleen. J Ultrasound Med. 30(9):1281-93,
2011
4. Kamaya A et al: Multiple lesions of the spleen: differential diagnosis of cystic
and solid lesions. Semin Ultrasound CT MR. 27(5):389-403, 2006
5. Madoff DC et al: Splenic arterial interventions: anatomy, indications,
technical considerations, and potential complications. Radiographics. 25
Suppl 1:S191-211, 2005
6. Goerg C et al: Splenic infarction: sonographic patterns, diagnosis, follow-up,
and complications. Radiology. 174(3 Pt 1):803-7, 1990
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