Fig 1.
Anatomical depictions of the paraumbilical and ensiform veins.
(A) Detail of Braune’s 1884 color lithograph of the veins of the anterior trunk, Tafel (plate) IV. The muscles were partially removed to uncover the internal thoracic (14) and epigastric veins. The superior (11) and inferior epigastric (2) veins, and their deep tributaries (6) lie superficial to the posterior layer of the rectus sheath. Also exposed are the subaponeurotic obliterated umbilical vein (9) and adjacent inferior Sappey veins (8) ascending from the umbilicus (7) before disappearing in the falciform ligament. A pair of venae paraumbilicalis xyphoidae (10) enter the left superior epigastric vein after piercing the rectus sheath next to the linea alba (a). There are also two unnamed vessels that enter a transverse vein (12) bridging the internal thoracic veins at the xiphoid process. These vessels are likely ensiform veins ascended from the properitoneal fat pad deep to the rectus sheath except at the very top. (Courtesy US National Library of Medicine) (B) Illustration of the properitoneal fat pad and the ensiform branches of the left internal thoracic vessels in a specimen, posterior view. The parietal peritoneum was opened and turned aside, and the xiphoid process was resected. (From Nordenson et al. (1930), by permission of Springer).
Table 1.
Clinical features of 28 patients with superior vena cava (SVC) or left brachiocephalic vein (LBCV) obstruction and collateral paraumbilical veins.
Fig 2.
CT venogram of chest in a 56-year-old woman with SVC obstruction. (A) Slightly oblique 7.5-mm coronal maximum-intensity-projection (MIP) shows an inferior paraumbilical vein (arrowhead) terminating at the umbilical notch of the liver (asterisk). It is predominantly opacified by two tributaries continuous with ensiform vessels (right-left arrow). A third tributary (curved arrow) joins a subcutaneous vein (not shown). The apparent discontinuity in the right ensiform vessel is due to tortuosity. Also shown is the umbilical vein (straight arrow). X, xiphoid process. (B) Oblique transverse 7-mm MIP demonstrates the inferior vein (arrowhead) joining dilated terminal portal vessels in segments IV and III at the margin of the liver. The terminal vessels in segment IV drain into an expanded second- or third-order portal branch that empties into the distal left portal vein (LPVu) resulting in antegrade opacification of an adjacent second- or third-order portal branch (curved arrow) in segment IV and of portal branches in segments III and IV posteriorly. The collateral ensiform veins (straight arrows) are shown in the properitoneal fat pad.
Fig 3.
Routine contrast-enhanced CT scans of chest in three patients with SVC obstruction. (A) 58-year-old woman. Coronal 10-mm maximum-intensity-projection (MIP) shows an inferior paraumbilical vein (arrowhead) terminating at the umbilical notch. It joins subcutaneous veins (not shown), but its only source of collateral flow is an ensiform vein (long arrow) descended from a transverse vessel (curved arrow) between the internal thoracic veins at the xiphoid process. The inferior vein communicates with segments IV and III. The left superior epigastric vein (short arrow) is also shown. (B) 70-year-old woman. Coronal 20-mm MIP shows the confluence of two inferior paraumbilical veins (arrowheads) at the free edge of segment IV. One vessel (black arrowhead) communicates with deep epigastric veins (not shown); the other (white arrowhead) receives two tributaries continuous with ensiform vessels (right-left arrow). The ensiform veins are opacified by the right internal thoracic vein via a transverse branch (curved arrow) across the xiphoid process, and also communicate with left diaphragmatic veins (long arrow). Short arrows point to superior epigastric veins. (C) 76-year-old woman. Sagittal 10-mm MIP shows an inferior paraumbilical vein (arrowhead) destined for segment III. It communicates with a collateral subcutaneous vein (short arrow) across the linea alba and with an ensiform vessel (long arrow). The subcutaneous and ensiform veins both join a transverse vein (not shown) bridging the internal thoracic veins at the xiphoid process (X).
Table 2.
Sources of collateral flow to the paraumbilical veins.
Table 3.
Distribution of the portal segments opacified by collateral paraumbilical veins.
Fig 4.
Routine contrast-enhanced CT of abdomen in a 69-year-old woman with SVC obstruction. (A, B) Oblique sagittal 7-mm maximum-intensity-projections in different planes show an inferior paraumbilical vein (arrowheads), fed by an ensiform vessel (long arrow, A), draining into the umbilical vein (short arrows) just before the liver (asterisk, A). The opacified umbilical vein (black arrow, B) enters the recessus umbilicalis (curved arrow, B) of the left portal vein (LPVu). The umbilical vein below the union (short white arrows) is smaller and not opacified. Also shown is a collateral subcutaneous vein (curved arrow, A).
Fig 5.
Inferior and superior paraumbilical veins.
CT venogram of chest and abdomen in a 53-year-old man with SVC obstruction. (A) Oblique sagittal 10-mm maximum-intensity-projection (MIP) through the umbilical fissure shows an inferior paraumbilical channel (white arrowhead) ascending from deep epigastric veins (curved white arrow). It receives an ensiform vein (straight white arrow) and terminates in the left portal vein (LPVu). Note antegrade filling of a second-order portal branch (curved black arrow) and its territory in segment IV. Also shown are tiny superior paraumbilical veins destined for segment III, which form a tiny venous arch (black arrowhead) and are supplied by the ensiform vein. Straight black arrows point to hepatic veins. (B) Slightly oblique transverse 7-mm MIP shows the collateral channel (short white arrow) in the umbilical fissure and the opacification of segment IV. The tiny superior veins (arrowheads) opacify segment III. The long white arrow points to the ensiform vein; black arrows indicate hepatic veins.
Fig 6.
Routine contrast-enhanced CT of chest in a 56-year-old woman with anatomic compression of the left brachiocephalic vein. Slightly oblique coronal 15-mm maximum-intensity-projection (MIP) shows a superior vein (arrowheads) emptying into segment IV at the top of the liver. It communicates with a medial mediastinal branch (long arrow) of the left internal thoracic vein (short arrow) that traverses Morgagni’s foramen and supplies right diaphragmatic veins (curved arrows) as well. (B) Delayed phase contrast-enhanced CT of chest and abdomen in a 57-year-old man with SVC obstruction. Slightly oblique transverse 7-mm MIP shows a superior vein (arrowhead) along the dome of the liver terminating in segment IV. It receives collateral flow from diaphragmatic branches of a left anterior mediastinal vein (straight arrow) in the cardiophrenic fat pad and the left pericardiacophrenic vein (curved arrow). The mediastinal vein descended in the anterior mediastinum from the left brachiocephalic vein.
Table 4.
Systemic connections of collateral ensiform veins (N = 22 patients).
Fig 7.
Visual model of the arrangement and systemic anastomoses of collateral paraumbilical veins.
The potential collateral pathways between the systemic and paraumbilical veins are shown. Only the left epigastric and subcutaneous vessels are included. An inferior vessel (arrowhead) terminates at the umbilical notch and receives tributaries continuous with ensiform veins, and deep epigastric and subcutaneous veins, which cross the rectus sheath or linea alba (not shown). The ensiform veins descend from a transverse branch of the internal thoracic veins at the xiphoid process. The patent part (arrow) of the umbilical vein (UV) also receives an inferior vein with its tributaries. The obliterated umbilical vein joins the umbilicus. The superior veins communicate with diaphragmatic branches of the internal thoracic, anterior mediastinal and pericardiacophrenic veins. (Visual model created by MUHC Patient Education Office).