Abstract
The purpose of this study was to elaborate on the anastomoses between the paraumbilical and systemic veins, particularly the ensiform veins. The connections with the ensiform veins have received little attention in the anatomical and radiological literature, and remain incompletely described. Too small to be reliably traced in normal CT scans, the paraumbilical veins can dilate in response to increased blood flow from systemic veins in superior vena cava obstruction (SVCO), allowing a study of their arrangement and connections. Collateral paraumbilical veins were therefore analyzed retrospectively in 28 patients with SVCO using CT. We observed inferior and superior groups of collateral vessels in 23/28 (82%) and 17/28 (61%) patients, respectively. Inferior veins ascended towards the liver and drained into portal veins (19/28, 68%) or the umbilical vein (8/28, 29%); superior veins descended and drained into portal veins. The inferior veins (N = 27) could be traced to ensiform veins in almost all of the cases (26/27, 96%), and a little over half (14/27, 52%) were also traceable to subcutaneous and deep epigastric veins. They were opacified by ensiform (25/27, 93%), deep epigastric (4/27, 15%) and subcutaneous (4/27, 15%) veins. The superior veins (N = 17) were supplied by diaphragmatic (13/17, 76%) and ensiform veins (4/17, 24%); the diaphragmatic veins were branches of collateral internal thoracic, left pericardiacophrenic and anterior mediastinal veins. Collateral ensiform veins were observed in 22 patients and anastomosed with internal thoracic (19/22, 86%), superior epigastric (9/22, 41%), diaphragmatic (4/22, 18%), subcutaneous (3/22, 14%) and anterior mediastinal veins (1/22, 5%). These observations show that the paraumbilical veins communicate with ensiform, deep epigastric, subcutaneous and diaphragmatic veins, joining the liver to the properitoneal fat pad, anterior trunk, diaphragm and mediastinum. In SVCO, the most common sources of collateral flow to the paraumbilical veins are the ensiform and diaphragmatic branches of the internal thoracic veins.
Highlights
The paraumbilical veins are small accessory portal veins confined between the layers of the falciform ligament
One or two inferior veins had become dilated in 23 patients (23/28, 82%), and a dilated superior vein was found in 17 patients (17/28, 61%)
The inferior veins communicated directly with portal veins (19/28, 68%) or drained into the umbilical vein (8/28, 29%), and the superior veins communicated with portal veins
Summary
The paraumbilical veins are small accessory portal veins confined between the layers of the falciform ligament. Braune observed anastomoses between Sappey’s inferior veins and tributaries of the left superior epigastric vein that ascended deep to the rectus sheath These vessels were named the venae paraumbilicalis xyphoidea by Braune (Fig 1A) and bear a resemblance to the ensiform (latin equivalent for xiphoid) veins, which Nordenson et al [9] and Merklin [10] later described in their investigations on the properitoneal fat pad (Fig 1B). Sappey’s superior veins drain the median diaphragm and communicate with the diaphragmatic and internal thoracic veins [1, 3, 4, 8] They traverse the upper part of the falciform ligament to terminate at the convex surface of the liver where they anastomose with peripheral branches of the left portal vein (LPV). Sappey [3, 4], and Martin & Tudor [1] described a main channel that drains into the LPV, the quadrate lobe directly or uncommonly into the umbilical vein [1, 5], and receives multiple tributaries that communicate with the inferior epigastric and subcutaneous veins
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