Lesser Sac Borders

Foramen Winslow Borders

Fig. 3-21. The foramen ofWinslow.

(a) Sagittal ultrasonography. The foramen of Winslow is indicated by the triangular zone (white arrow) between the portal vein (double arrows) and the inferior vena cava (C).

(Reproduced from Weill.22)

(b) Sagittal ultrasonography. In a patient with ascites, a small amount of fluid enters the foramen (open arrow) between the portal vein (arrow) and the vena cava (arrowheads).

(Reproduced from Weill and Manco-Johnson.23)

Fig. 3-21. The foramen ofWinslow.

(a) Sagittal ultrasonography. The foramen of Winslow is indicated by the triangular zone (white arrow) between the portal vein (double arrows) and the inferior vena cava (C).

(Reproduced from Weill.22)

(b) Sagittal ultrasonography. In a patient with ascites, a small amount of fluid enters the foramen (open arrow) between the portal vein (arrow) and the vena cava (arrowheads).

(Reproduced from Weill and Manco-Johnson.23)

Lesser Sac Epiploic Foramen Axial

Fig. 3-22. The lesser sac and its relationships.

The foramen of Winslow is generally only large enough to admit the introduction of one to two fingers, but in vivo it represents merely a potential communication between the greater and lesser peritoneal cavities.

Fig. 3-22. The lesser sac and its relationships.

The foramen of Winslow is generally only large enough to admit the introduction of one to two fingers, but in vivo it represents merely a potential communication between the greater and lesser peritoneal cavities.

Lesser Sac Borders

Fig. 3-23. The lesser sac and its relationships, shown with the stomach upraised.

Foramen of Winslow (see arrow).

Fig. 3-23. The lesser sac and its relationships, shown with the stomach upraised.

Foramen of Winslow (see arrow).

Fig. 3—24. Lesser sac anatomy illustrated by sagittal sections of the upper abdomen through the inferior vena cava (a), midline (b), and left kidney (c).

(a) The epiploic foramen is well demonstrated between the inferior vena cava and hepatoduo-denal ligament. A small portion of the lesser sac is seen anterior to the pancreas. In this section, the greater omentum and transverse mesocolon are relatively short. Note fusion of the inner two layers of the greater omental peritoneum and adhesion of the posterior layer of the greater omentum with the anterior layer of the transverse mesocolon.

(b) The lesser omentum extends from the stomach to the fissure for the ligamentum venosum. The posterior peritoneal layer of the lesser omentum reflects back to the caudate lobe. In this section, the greater omentum and the transverse mesocolon are elongated. The anterior boundaries of the lesser sac are the lesser omentum, stomach, and gastrocolic ligament. The posterior ones are posterior parietal peritoneum and the transverse mesocolon with greater omen-tum. The inferior one is fused greater omentum.

(c) The lesser sac is bounded by the stomach and the gastrocolic ligament anteriorly, the gastro-splenic ligament superiorly, and transverse mesocolon posteriorly. The lesser sac is separated from the posterior left subphrenic space and left subhepatic space (gastrohepatic space) by the stomach and gastrosplenic ligament.

(Courtesy of Yong Ho Auh, M.D., Asan Medical Center, Seoul, Korea)

Subphrenic RecessThe Lesser Sac AbdomenSubhepatic SpaceMri Omentum

Fig. 3-25. The lesser sac (LS) seen on sagittal MRI at level of the left kidney (K).

T2-weighted MRI in presence of ascites shows boundaries of the lesser sac. LL = left lobe of liver; LO = lesser omentum; ST = stomach; SP = spleen; GSL = gastrosplenic ligament; GO = greater omentum; TM = transverse mesocolon. (Courtesy of Yong Ho Auh, M.D., Asan Medical Center, Seoul, Korea)

Sagittal Section The Mesocolon

Fig. 3-26. Extent of lesser sac within greater omentum.

Lesser omentum and stomach cut and section removed from greater omentum and transverse colon. Drawing shows potential inferior extension of lesser sac between the layers of the greater omentum.

Fig. 3-26. Extent of lesser sac within greater omentum.

Lesser omentum and stomach cut and section removed from greater omentum and transverse colon. Drawing shows potential inferior extension of lesser sac between the layers of the greater omentum.

Lesser Sac

Fig. 3—27. Ascites between the leaves of the greater omen turn.

In a patient with metastatic adenocarcinoma, ascitic fluid has dissected into the inferior recess of the lesser sac (ILS) between the unfused anterior and posterior leaves of the omentum. These are each evident by virtue of their fat-laden nature. Marked ascites is also present in the greater peritoneal cavity.

(Courtesy of Robert Mindelzun, M.D., Stanford University, Palo Alto, CA.)

Fig. 3—27. Ascites between the leaves of the greater omen turn.

In a patient with metastatic adenocarcinoma, ascitic fluid has dissected into the inferior recess of the lesser sac (ILS) between the unfused anterior and posterior leaves of the omentum. These are each evident by virtue of their fat-laden nature. Marked ascites is also present in the greater peritoneal cavity.

(Courtesy of Robert Mindelzun, M.D., Stanford University, Palo Alto, CA.)

Greater Sac Peritoneal Cavity

Fig. 3—28. Opacification of the lesser sac in vivo.

Following percutaneous puncture before a drainage procedure and contrast injection, the anatomic extent of the vestibule and the upper recess (UR) of the lesser sac is clearly depicted.

(Courtesy of Jacques Pringot, M.D., Brussels, Belgium.)

The base of the fold can be identified indirectly by virtue of its typical location and associated vessels (Fig. 3-31) and directly in the presence of fluid collections on both sides (Figs. 3-32 through 3-34). The fold should not be confused with a minor delicate membrane, termed the gastropancreatic ligament, between the posterior gastric wall and the pancreas, which often remains unnoticed and is not visualized by computed tomography.27,28

On the left, the lesser sac is bounded by the splenic attachments—the gastrosplenic ligament in front and the splenorenal ligament behind (Figs. 3-14a, 3-31a, 3-35, and 3-36). On the right side, the space extends just to the right of the midline, where it communicates, at least potentially, behind the free edge of the lesser omentum with the right subhepatic space via like foramen ofWin-slow (Figs. 3-23, 3-37, 3-38).

The ultrasonographic features of the lesser sac have been described,2,30, 1 but it is computed tomography that clearly demonstrates the anatomic characteristics in vivo32-34(Figs. 3-31 to 3-33, 3-35, 3-36, 3-39, 3-40). Lesser sac collections can be easily distinguished from loculated fluid collections in perihepatic spaces and hepatic fissures19 (Figs. 3-41 and 3-42). Details are also identifiable by MR imaging (Fig. 3-43).35

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Fluid Superior Recess Lesser Sac

Fig. 3—29. Boundaries of superior recess of the lesser sac.

The borders of this cul-de-sac include the diaphragm posteriorly, the caudate lobe of the liver anteriorly, the intraabdominal segment of the esophagus to the left, and the inferior vena cava (IVC) to the right. Ao = aorta.

(After Sauerland EK, Grant's Dissector, 10th ed. Williams & Wilkins, Baltimore, 1991.)

Fig. 3—30. The caudate lobe of the liver (CL) projects into the upper recess of the lesser sac.

It is discretely outlined by air and contrast medium from a perforated gastric ulcer studied by an upper GI series. Contrast also outlines the lateral border of the lesser sac (arrows). A small amount has escaped through the foramen of Winslow into the subhepatic space (arrowhead).

Fig. 3—31. Anatomy of the lesser sac and the gastropan-creatic plica.

(a) Anatomic specimen with spaces injected. The gastropan-creatic plica (white arrowheads), within which courses the left gastric artery (black arrowhead), is a structure of some dimension. It separates the vestibule (Vb) in relationship to the caudate lobe (CL) from the larger lateral recess of the lesser sac (LS). The latter is separated by the gastro-splenic ligament (open arrow) from the gastrosplenic recess (GSR) and by the splenorenal ligament (white arrow) from the splenorenal recess (SRR). The vestibule is separated by the gas-trohepatic ligament (curved arrow) from the gastrohepatic recess (GHR). Ao = aorta; C = inferior vena cava; Sp = spleen. (Reproduced from Kumpan.27) (This figure also appears in the color insert.)

(b) In a case of ascites, CT demonstrates the gastropancreatic plica through which the left gastric artery courses (curved arrow) separates the fluid collections within the two recesses of the lesser sac (LS). This is bounded anteriorly by the gastrohepatic ligament (small arrows) from fluid in the gastrohepatic recess (GHR) and laterally and posteriorly by the gastrosplenic and splenorenal ligaments from fluid in the gastrosplenic (GSR) and splenorenal recesses, respectively. Ao = aorta; C = inferior vena cava; cl = papillary process of caudate lobe; St = stomach;

Caudate Lobe ArteryIntraperitoeal Compartments

Identification of landmarks enhanced by intraperitoneal fluid. The lesser sac (LS) is divided into two compartments by a peritoneal fold (white arrow) enclosing the left gastric artery as it passes from the posterior abdominal wall to reach the lesser curvature of the stomach (ST). Differentiation between ascites fluid (A) and intrapleural fluid (PL) is clear. CL = caudate lobe of liver; HA = hepatic artery; SA = splenic artery; SP = spleen; VC = vena cava.

(Reprinted by permission from Feldberg MAM; Computed Tomography of the Retroperitoneum. Martinus Nijhoff, Boston, 1983.)

Identification of landmarks enhanced by intraperitoneal fluid. The lesser sac (LS) is divided into two compartments by a peritoneal fold (white arrow) enclosing the left gastric artery as it passes from the posterior abdominal wall to reach the lesser curvature of the stomach (ST). Differentiation between ascites fluid (A) and intrapleural fluid (PL) is clear. CL = caudate lobe of liver; HA = hepatic artery; SA = splenic artery; SP = spleen; VC = vena cava.

(Reprinted by permission from Feldberg MAM; Computed Tomography of the Retroperitoneum. Martinus Nijhoff, Boston, 1983.)

Lesser Sac

Fig. 3-33. CT anatomy of the lesser sac.

The lesser sac (LS), distended with ascites, is traversed by the stretched peritoneal fold (arrows) in which the left gastric artery courses to reach the lesser curvature of the stomach (ST).

Based on this anatomic feature, the potential clinical loculation of fluid to one or the other compartment can be anticipated. The extraperitoneal fat near the base of origin within the gastropancreatic plica is identifiable (open arrow).

On the left, note the posterior extent of the lesser sac bounded by the splenorenal ligament within which distal splenic vessels course (arrowhead).

Ascites within the right (RSP) and left (LSP) subphrenic spaces is separated by the falciform ligament.

Fig. 3-33. CT anatomy of the lesser sac.

The lesser sac (LS), distended with ascites, is traversed by the stretched peritoneal fold (arrows) in which the left gastric artery courses to reach the lesser curvature of the stomach (ST).

Based on this anatomic feature, the potential clinical loculation of fluid to one or the other compartment can be anticipated. The extraperitoneal fat near the base of origin within the gastropancreatic plica is identifiable (open arrow).

On the left, note the posterior extent of the lesser sac bounded by the splenorenal ligament within which distal splenic vessels course (arrowhead).

Ascites within the right (RSP) and left (LSP) subphrenic spaces is separated by the falciform ligament.

Fig. 3—34. The gastropan-creatic fold seen on axial CT (a) and coronal MRI (b).

The gastropancreatic fold (arrows) is seen as a fat-containing pleat in the lesser sac. It divides the lesser sac into the small superior (medial) (one asterisk) and large inferior (lateral) (two asterisks) recess. In MRI, the caudate lobe occupies the superior recess of lesser sac. LO = lesser omen-tum; GSL = gastrosplenic ligament; SRL = splenorenal ligament; GSR = gastrosplenic recess; SRR = splenorenal recess; ST = stomach; CL = caudate lobe; PV = portal vein; LL = left lobe of liver. (Courtesy of Yong Ho Auh, M.D., Asan Medical Center, Seoul, Korea)

Lesser SacGreater Sac Lesser Sac

Fluid in the lesser sac (LS) behind the stomach (ST) is bounded anteriorly by the gas-trocolic ligament (white arrows) and communicates via the epi-ploic foramen (curved arrow) between the inferior vena cava (vc) and portal vein (pv) with ascitic fluid (A) in the greater peritoneal cavity. Deep to the splenic artery (sa) and pancreatic tail (PT) there is associated fluid within the anterior pararenal space (aps) extending to the angle of the spleen (SP).

Splenorenal Angle

Ascites is present in the greater peritoneal cavity (A) and in the lesser sac (LS) between the pancreas (P) and stomach (ST), where it is distinctly demarcated laterally by the gastrosplenic ligament (arrows). SP = spleen.

Foramen Winslow Normal

Fig. 3—37. CT anatomy of the foramen of Winslow entrance into the lesser sac.

(a and b) CT scans of the abdomen following intraperitoneal injection of contrast show communication of the greater peritoneal cavity with the lesser sac (LS) via the epiploic foramen of Winslow (curved arrow), between the inferior vena cava (C) and portal vein (PV).

Perihepatic contrast is limited anteriorly by the falciform ligament (FAL), where some tracks along the ligamentum teres (LT), and posteriorly at the level of the bare area of the liver (BAL). LP = left perisplenic space. (Courtesy of Hiromu Mori, M.D., Oita Medical University, Oka, Japan.)

Fig. 3—37. CT anatomy of the foramen of Winslow entrance into the lesser sac.

(a and b) CT scans of the abdomen following intraperitoneal injection of contrast show communication of the greater peritoneal cavity with the lesser sac (LS) via the epiploic foramen of Winslow (curved arrow), between the inferior vena cava (C) and portal vein (PV).

Perihepatic contrast is limited anteriorly by the falciform ligament (FAL), where some tracks along the ligamentum teres (LT), and posteriorly at the level of the bare area of the liver (BAL). LP = left perisplenic space. (Courtesy of Hiromu Mori, M.D., Oita Medical University, Oka, Japan.)

Fig. 3—38. CT anatomy of the foramen of Winslow entrance into the lesser sac.

Contrast-enhanced CT shows that ascites in the greater peritoneal cavity (P) gains entrance through a widened foramen of Winslow (asterisk) in the portacaval space to the lesser sac (LS). Visualization of the hepatoduodenal ligament (arrowhead) is achieved by virtue of fluid on both sides.

(Reproduced from DeMeo et al.29)

Images Portacaval SpaceLesser Sack

Fig. 3-39. Fluid in the herniated lesser sac.

Umbilical herniation containing fluid in the lesser sac (LS), the middle portion of the transverse colon (TC) and a segment of the distal transverse mesocolon, as well as the greater omentum (GO) in a patient with gastric carcinoma. The gastrosplenic ligament (arrows) is bowed toward the ascites in the general peritoneal cavity (A). (Courtesy of César Pedrosa, M.D., Hospital Universitario San Carlos, Madrid, Spain.)

Anatomy Distended Abdominal Cavity

Fig. 3—40. CT anatomy of the lesser sac. Fluid in lesser sac.

(a) Direct coronal image demonstrates extent of right (RLS) and left (LLS) compartments of the lesser sac. LSS is larger and its inferior recess (black and white arrows) may extend between anterior and posterior leaves of greater omentum. Superiorly the left part of the lesser sac extends to a level below the apex of the diaphragm (black arrows). The greater omentum (arrowheads) is compressed between the lesser sac and the spleen (SP). A = ascites around liver; SI = opacified small intestine.

(b) The lesser sac (LS) communicates with Morison's pouch (MP) through the epiploic foramen of Winslow (black arrow). MT = mesentery of small intestine.

(Reprinted by permission from Feldberg MAM: Computed Tomography of the Retroperitoneum. Martinus Nijhoff, Boston, 1983.)

Fig. 3—40. CT anatomy of the lesser sac. Fluid in lesser sac.

(a) Direct coronal image demonstrates extent of right (RLS) and left (LLS) compartments of the lesser sac. LSS is larger and its inferior recess (black and white arrows) may extend between anterior and posterior leaves of greater omentum. Superiorly the left part of the lesser sac extends to a level below the apex of the diaphragm (black arrows). The greater omentum (arrowheads) is compressed between the lesser sac and the spleen (SP). A = ascites around liver; SI = opacified small intestine.

(b) The lesser sac (LS) communicates with Morison's pouch (MP) through the epiploic foramen of Winslow (black arrow). MT = mesentery of small intestine.

(Reprinted by permission from Feldberg MAM: Computed Tomography of the Retroperitoneum. Martinus Nijhoff, Boston, 1983.)

Retroperitoneal Winslow

Fig. 3—41. Ascitic fluid in gastrohepatic recess simulating fluid in lesser sac.

(a and b) Contrast-enhanced CT in a patient with alcoholic liver disease reveals a large fluid collection (arrows). This is localized in the gastrohepatic recess since the fluid follows the lateral surface of the left lobe lateral segment posteriorly into the fissure for the ligamentum venosum and extends to the left and right portal veins. Fluid does not engulf the caudate lobe (cl) to indicate that this is fluid within the lesser sac.

(Courtesy of James Brink, M.D., Yale University School of Medicine, New Haven, CT.)

Fig. 3—41. Ascitic fluid in gastrohepatic recess simulating fluid in lesser sac.

(a and b) Contrast-enhanced CT in a patient with alcoholic liver disease reveals a large fluid collection (arrows). This is localized in the gastrohepatic recess since the fluid follows the lateral surface of the left lobe lateral segment posteriorly into the fissure for the ligamentum venosum and extends to the left and right portal veins. Fluid does not engulf the caudate lobe (cl) to indicate that this is fluid within the lesser sac.

(Courtesy of James Brink, M.D., Yale University School of Medicine, New Haven, CT.)

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Responses

  • benito
    Is the spleen related to lesser sac?
    7 years ago
  • swen
    Which intraperitoneal space does the lesser sac communicate with via the foramen of winslow?
    7 years ago
  • GUNDOBAD LONGHOLE
    How to open lesser sac?
    6 years ago
  • Gary
    Where is subhepatic recess?
    2 years ago
  • toivo
    Is spleen in direct contact with lesser sac?
    12 months ago
  • sven
    Which space communicates with the lesser sac?
    10 months ago
  • isengrin
    Is the spleen a boundary of the lesser sac?
    6 months ago

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