Learning objectives
The retrocrural space is a small triangular region that serves as a communicating conduit between the thoracic and abdominal cavities
Our aim is to facilitate a better understanding and improved recognition of the normal anatomy,
variants and disease processes of this easily overlooked region
Background
Embryology of the diaphragm
The diaphragm is formed through the fusion of tissue from four different sources
The septum transversum,
a thick mass of mesoderm between the primitive heart tube and the developing liver,
gives rise to most of the central tendon
The paired pleuroperitoneal membranes are sheets of somatic mesoderm that develop from the dorsal and dorsolateral body wall
The dorsal mesentery of the oesophagus is invaded by myoblasts and forms the crura of the diaphragm
The body wall contributes muscle to the peripheral...
Imaging findings OR Procedure details
Normal variants of the azygos system
Azygos continuation of the IVC
Also known as absence of the hepatic segment of the IVC with azygos continuation
The causative embryonic event is thought to be failure of formation of the right subcardinal–hepatic anastomosis with atrophy of the right subcardinal vein
As a result,
blood is shunted from the suprasubcardinal anastomosis through an enlarged retrocrural azygos vein,
which is partially derived from the thoracic segment of the right supracardinal vein
This was previously thought to be associated with...
Conclusion
With such a vast array of variant anatomy and disease processes occurring within this region,
a better understanding of the normal and abnormal findings is crucial for the accurate diagnosis of the myriad of both benign and pathological conditions affecting this easily disregarded inter-cavity compartment
References
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Development of the diaphragm.
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ShinMS,
Berland LL.
Computed tomography of retrocrural spaces: normal,
anatomic variants,
and pathologic conditions.AJR Am J Roentgenol1985;145:81–86.
BassJE,
Redwine MD,
Kramer LA,
Harris JH Jr.
Absence of the infrarenal inferior vena cava with preservation of the suprarenal segment as revealed by CT and MR venography.AJR Am J Roentgenol1999;172:1610–1612.
Restrepo CS,
Eraso A,
Ocazionez D,...