The present case highlights the usefulness of preoperative examination. Careful preoperative examination showed a rare venous malformation, which reduced the stress of the surgeons and improved operative accuracy.
Retzius reported cases of a short circuit from the duodenum to the IVC and from the left colon to the left renal vein in 1835 . The retroperitoneal intestinal vein-general circulation anastomotic pathway is now called the Retzius vein [2, 3]. The cause of a Retzius venous shunt is not completely understood; however, two major theories have been proposed [3,4,5,6,7]. The first is the congenital origin theory, which suggests persistence of the communication between the portal and caval systems that occurs during embryonal development. The second is the acquired theory, which suggests that the shunt results from trauma, portal hypertension by liver cirrhosis, etc. A Retzius venous shunt usually occurs in patients with portal hypertension and is mainly induced by liver cirrhosis, but it can sometimes occur in patients who do not have liver cirrhosis. In fact, a previous imaging study showed that the veins of Retzius were demonstrated on CT arterial portography in approximately 50% of patients with and 50% of patients without liver cirrhosis . The presently described patient had no liver cirrhosis or history of trauma. Thus, the Retzius venous shunt in the present case was thought to be congenital in origin.
Preoperative risk assessment is an important aspect of surgical planning because it helps surgeons identify patients with an increased risk of a poor postoperative outcome . CT imaging is widely available, and all patients with cancer routinely undergo preoperative CT for staging. Recently, 3D-CT was shown to help in the preoperative assessment of vascular anatomy for laparoscopic lymph node dissection. The 3D-CT is a combined technology of a conventional CT scan with that of traditional angiography to create detailed images of vessels in the body, and noninvasive and provides highly reliable and reproducible vascular anatomy. Furthermore, 3D-CT also allows noninvasive vascular assessment and is used widely in preoperative planning workups for patients requiring laparoscopic surgery and in the evaluation of vascular anomaly and other vascular conditions . When the preoperative 3D-CT is obtained for these purposes, it can simultaneously serve as a tool for preventing a serious situation, such as an unexpected bleeding or conversion to open surgery, during laparoscopic surgery. In fact, several authors reported that imaging of vascular anatomy with 3D-CT facilitates surgery [11,12,13,14,15,16,17,18,19]. We also use 3D-CT constructed from routine contrast CT images to preoperatively evaluate the tumor-feeding artery, drainage vein, and vascular anatomy. In the present case, 3D-CT unexpectedly showed a Retzius venous short circuit between the IMV and IVC. Laparoscopic surgery with a Retzius venous short circuit would have been dangerous without the detailed preoperative examination, but the preoperative information acquired by 3D-CT made the surgery the safest operation possible. Based on this case report, we would like to stress the importance of recognizing the veins of Retzius which, if unrecognized, could lead to significant vascular complications, including hemorrhage. As the resolution of CT increases, the importance of preoperative imaging for patients with vascular malformations will be even greater in the future.