Properitoneal fat

Last revised by Dr Joshua Yap on 27 Jul 2022

The properitoneal fat, also known as the preperitoneal space, is a fat-containing space in the abdomen.

Posteriorly it lies deep to the transversalis fascia and fills the posterior pararenal space. Laterally it thickens and forms the properitoneal fat pad, which is the anterior extension of posterior pararenal space. It communicates superiorly with the falciform ligament and intersegmental fissure of the liver. Supero-medially it can communicate with extrapleural fat (via spaces of Larrey) 4. Inferiorly it is continuous with the pelvic extension of the posterior pararenal space which terminates as a potential space between the perivesical peritoneal folds 5.

Spread of hemorrhage or infection throughout this space can result in the clinical appearances of Cullen's sign and Grey Turner's sign 6.

The properitoneal fat pad is known as a plane in surgical anatomy, and as a line or stripe when seen on imaging. It is also referred to frequently as the flank stripe

  • fat
  • ensiform veins

Loss of the properitoneal fat line is associated with:

A potential pitfall is that the properitoneal fat line can mimic pneumoperitoneum or pneumoretroperitoneum.

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Cases and figures

  • Case 1: x-ray - properitoneal fat
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  • Case 2: red arrows
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  • Case 3: annotated image
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  • Case 4: properitoneal gas
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