Drainage pattern of the splenic flexure vein and its accompanying arteries using three-dimensional computed tomography angiography: a single-centre study of 600 patients

AIM

The splenic flexure has variable vascular anatomy, and the details of the venous forms are not known. In this study, we report the flow pattern of the splenic flexure vein (SFV) and the positional relationship between the SFV and arteries such as the accessory middle colic artery (AMCA).

METHODS

This was a single-centre study using preoperative enhanced CT colonography images of 600 colorectal surgery patients. CT images were reconstructed into 3D angiography. SFV was defined as a vein flowing centrally from the marginal vein of the splenic flexure visible on CT. AMCA was defined as the artery feeding the left side of the transverse colon, separate from the left branch of the middle colic artery.

RESULTS

The SFV returned to the inferior mesenteric vein (IMV) in 494 cases (82.3%), the superior mesenteric vein in 51 cases (8.5%) and the splenic vein in seven cases (1.2%). The AMCA was present in 244 cases (40.7%). The AMCA branched from the superior mesenteric artery or its branches in 227 cases (93.0% of cases with existing AMCA). In the 552 cases in which the SFV returned to the IMV, superior mesenteric vein or splenic vein, the left colic artery was the most frequent artery accompanying the SFV (42.2%), followed by the AMCA (38.1%) and the left branch of the middle colic artery (14.3%).

CONCLUSIONS

The most common flow pattern of the vein in the splenic flexure is from the SFV to IMV. The SFV is frequently accompanied by the left colic artery or AMCA.

Vascular anatomy of the splenic flexure, focusing on the accessory middle colic artery and vein

AIM

Recently, the accessory middle colic artery (AMCA) has been recognized as the vessel that supplies blood to the splenic flexure. However, the positional relationship between the AMCA and inferior mesenteric vein (IMV) has not been evaluated. Herein, we aimed to evaluate the anatomy of the AMCA and the splenic flexure vein (SFV).

METHOD

Two hundred and five patients with colorectal cancer who underwent enhanced CT preoperatively were enrolled in the present study. The locations of the AMCA and IMV were evaluated, focusing on the positional relationship between the vessels and pancreas - below the pancreas or to the dorsal side of the pancreas.

RESULTS

The AMCA was observed in 74 (36.1%) patients whereas the SFV was found in 177 (86.3%) patients. The left colic artery (LCA) was the major artery accompanying the SFV in 87 (42.4%) of patients. The AMCA accompanied the SFV in 65 (32.7%) patients. In 15 (7.8%) patients, no artery accompanied the SFV. The origin of the AMCA was located on the dorsal side of the pancreas in 15 (20.3%) of these 74 patients. Similarly, the destination of the IMV was located on the dorsal side of the pancreas in 65 (31.7%) of patients.

CONCLUSION

The SFV was observed in most patients, and the LCA or AMCA was the common accompanying artery. In some patients these vessels were located on the dorsal side of the pancreas and not below it. Preoperative evaluation of this anatomy may be beneficial for lymph node dissection during left-sided hemicolectomy.

Evaluation of the venous drainage pattern of the splenic flexure by preoperative three-dimensional computed tomography

INTRODUCTION

Anatomical evaluation of the splenic flexure vein is essential for complete mesocolic excision with central vascular ligation when treating patients with splenic flexure cancer. Although there have been several studies relating to the arterial branches of the splenic flexure, very limited data are available regarding the variation in venous anatomy in this region.

METHODS

Sixty-six patients with colorectal cancer who underwent preoperative 3-D CT between April 2016 and April 2017 were included in this retrospective study. The pattern of the venous drainage of the splenic flexure and its association with the inferior border of the pancreas were evaluated.

RESULTS

The inferior mesenteric vein flowed into the splenic vein in 32 patients (48.5%), into the superior mesenteric vein in 27 patients (40.9%), and into the confluence of splenic vein and superior mesenteric vein in 7 patients (10.6%). The splenic flexure vein joined the inferior mesenteric vein in 62 patients (93.9%), the splenic vein in 2 patients (3.0%), and the middle colic vein in 2 patients (3.0%). The splenic flexure vein flowed into the inferior mesenteric vein below the level of the inferior border of the pancreas in 58 patients (90.6%) and above it in 4 patients (6.3%).

CONCLUSION

Preoperative evaluation of the venous pattern of the splenic flexure on 3-D CT is useful before complete mesocolic excision with central vascular ligation to avoid intraoperative bleeding during splenic flexure cancer surgery.