Anterior approaches to the spinal column are most commonly performed with the assistance of an access surgeon. The approach surgeon is most commonly a vascular surgeon, but cardiac, urologic, gynecologic, and general surgeons also can serve in this role. Regardless of their subspecialty, the access surgeon is typically well-versed in five skill sets that spinal surgeons typically have less experience with. These skill sets include (1) access through the potential retroperitoneal space without entry into the peritoneal sac; (2) mobilization of the large retroperitoneal vascular structures; (3) repair of any damaged structures, including the major blood vessels, bowel, ureter, and kidney; (4) management of entry into the thoracic cavity, including postoperative chest tube management; and (5) wound closure techniques that minimize the risk of hernia formation.

Because the retroperitoneal corridor created with the lateral approach is typically performed by the spinal surgeon, there is the potential that injuries in this area are unfamiliar to the surgeon. Complications can thus occur from numerous causes. These include the failure to properly identify critical anatomical structures that spinal surgeons are less familiar. An example is the failure to see or know the likely location of the ureters. The surgeon may also fail to recognize that a complication has already occurred, missing the opportunity to quickly and effectively manage that problem before it becomes amplified. An example would be failure to detect a bowel perforation, which should be managed with direct repair or colostomy creation, thus avoiding the potentially fatal complication of sepsis. Finally, the surgeon may not be well-versed in the skill sets needed to manage a recognized complication. An example would be the inability to repair a major vascular injury, which can result in death within minutes from exsanguination. The inability to control bleeding quickly can be the result of not having a surgeon available within minutes for this rare but catastrophic problem.

As is typical, reporting of disastrous complications of this nature is initially uncommon and likely leads to an underestimation of their true prevalence. Underreporting is the result of lack of awareness of their occurrence (treatment at another facility than the index operation), surgeon fear and embarrassment, restrictions due to active litigation, and lack of follow-up. However, reports of these complications are beginning to emerge, even if only as case reports.

While covered in a separate chapter, vascular injuries can be particularly problematic. This was highlighted recently in a case report by Heary and colleagues [35] that despite the advantage of bypassing the direct encounter of the great vessels as in the anterior approach, fatal outcome can still occur through XLIF. In this report, a patient underwent an XLIF procedure at outside hospital and suffered from extensive vascular injury presumably from the detachable retractor blade. A salvage operation was carried out after the patient was transferred, and the authors found that these injuries were distinctly recognized at distal posterior inferior vena cava, right common iliac vein, right internal iliac vein, right external iliac vein, and left common iliac vein. Even though hemostasis was obtained and the patient was discharged to acute rehabilitation facility, the surgery still resulted in retroperitoneal abscess 7 days after being discharged with subsequently fatal multiple organ failure. This event demonstrated the danger of great vessels from such approach despite of the advantage of bypassing them as opposed to the direct encounter in the anterior approach. It also demonstrates that multiple sites of vascular injury can occur when a less invasive approach is used with retractors which are not necessarily designed to retract blood vessels.

Another potentially catastrophic complication is bowel injury. In an earlier series in which Kanter et al. [4] utilized XLIF to treat patients with scoliosis, they encountered a bowel perforation in one out of eight patients in the study. The 11 % bowel perforation rate in the study was suggestive of the risk, especially when the procedure was performed in the setting of scoliosis. Malham et al. [24] also reported a patient with bowel perforation in a retrospective study of their first 30-case experience of XLIF. A similar scenario can also been seen in a recent case report by Balsano et al. Thus, it is critical for the surgeons to be alert of such risk, especially in patients with previous abdominal surgery and/or intestinal adhesion, and to take caution during and after the surgery.

The retroperitoneal space itself is a common source of complications, mainly from the manipulation of abdominal wall and thoracolumbar structures, insufficient closure of the deep fascia, and inadequate hemostasis in the corridor. Anand et al. [30] conducted a retrospective review of 28 patients in 2010, and one of the patients suffered from sustained retrocapsular kidney bleeding. This patient suffered 2,000 ml of blood loss from renal bleeding and luckily was salvaged by tamponade without sequelae. Renal laceration was also reported in another series of 107 patients by Isaacs et al. [7]. Wang et al. [11] reported a patient suffering from pneumothorax, which was identified after the surgery. The authors suspected that the event might be resulted from the exposure at T12. Compromise of the pleura occurred during the surgery, and it led to a prolonged stay in the hospital up to 20 days due to the placement of the chest tube. Manipulation of the pleural structures and the organ within might cause pleural effusion as described by Kanter et al. and Isaacs et al. [4, 7].