Trocar injuries can occur with laparoscopic and robotic surgery, and trocar placement is similar with both platforms. In a study comparing direct trocar, Veress needle, and open approaches, there were fewer trocar injuries to bowel and blood vessels using the open approach (open 0 %, direct trocar 2.9 %, Veress 0.6 %) [15]. Placement of the first trocar is most likely to cause organ injury as the remaining trocars are placed under laparoscopic vision. Much of the trocar injury literature is from the gynecologic and urologic laparoscopic arena [16, 17]. In a review of 40 litigated cases of laparoscopic bowel injury, it was found that the initial trocar was the most common cause of bowel injury. The Hasson open technique did not eliminate this complication. Delayed recognition of the injury was the major consideration with regard to liability [16].

Some modify trocar placement in obese individuals. Schwartz recommended initial placement of the Veress needle in the left upper quadrant in morbidly obese patients to decrease the risk for trocar injury to viscera [18]. Others have recommended optical-tip trocars [19]. An approach to trocar placement that eliminates the risk of enterotomy and other visceral injuries has not yet evolved.

Trocars sites are at risk for herniation. The incidence varies from 0.65 to 5.4 % and reports on the clinical impact of this complication vary throughout the literature [19, 20]. The incidence of trocar-site hernias may be underestimated because many are asymptomatic hernias and may remain undetected. Reported risk factors for trocar-site hernia include chronic obstructive pulmonary disease, smoking, obesity, large trocar size, midline trocar sites, incomplete fascial closure, lengthy operations, and bladed trocars. However, none of these risk factors have been conclusively demonstrated to cause trocar-site hernias on multivariate analysis. Eighty-six percent of hernias occur at trocar sites ≥10 mm, while only 2.7 % occur at sites ≤8 mm. Patients presenting with symptomatic trocar-site hernias may have incarcerated or strangulated small bowel and operative repair may require small bowel resection with the attendant risks [19].

In a review of 624 obese patients who underwent laparoscopic bariatric surgery without closure of any trocar-site fascia, 1.6 % developed trocar-site hernias at a mean of 15 months. None had intestinal obstruction or other complications related to the hernias [20]. A retrospective review of 647 laparoscopic colorectal procedures over 3 years revealed that 1.23 % of patients developed trocar-site hernias, all of which were symptomatic and all of which required operative repair. These authors recommended primary closure of trocar-site defects ≥10 mm [19]. A Medline search of 11,699 laparoscopic procedures that included 477 colorectal operations demonstrated that 1.47 % developed trocar-site hernias at a mean follow-up of 71.5 months. These authors also recommended primary closure of fascial defects ≥10 mm [21].

Others have reported higher rates of trocar-site hernias when following patients with imaging studies. In a study of 102 laparoscopic and 48 robotic Roux-en-Y gastric bypasses for morbid obesity, 39.3 % of laparoscopic and 47.9 % of robotic procedures developed trocar-site hernias, most of which were identified by ultrasonic rather than by physical examination or clinical presentation. Only two patients with hernias required operative intervention, both in the laparoscopic group [22]. In a review of 498 robotic prostatectomies, two port-site hernias were identified, both of which were located at the 12 mm supraumbilical trocar site. In this study, routine port placement included two 12 mm, three 8 mm, and one 5 mm port. Only the midline 12 mm supraumbilical trocar-site fascia was closed.

The risk for incisional hernias in midline wounds, especially at the umbilicus, is reported to be up to 10–15 %. These midline-wound hernia rates are higher than other locations such as the Pfannenstiel incision and other wounds off the midline, where the risk is less than 5 %. As a result of these data, some authors do not close 12 mm trocar-site fascial defects off the midline [23, 24]. There are conflicting reports, though, with respect to hernia size and location as reflected by case reports of hernias at 8 mm robotic trocar sites [25]. Though the literature varies with regard to conclusions about the incidence and prevention of trocar-site hernias, most surgeons close trocar-site fascial incisions greater than 8 mm at every location. And it is important to keep in mind that hernias may occur even after trocar-site fascial closure [23].

Injuries to the intestinal tract during robotic surgery not caused by trocar placement are uncommon. Existing series are largely in the urologic and gynecologic literature [26]. The incidence of rectal injuries during prostatectomy is 0.17 % and compares favorably with open and laparoscopic prostatectomy [27]. Colon and rectal surgeons should be familiar with this complication as they may be consulted for repair. If recognized intraoperatively, simple suture closure of small bowel and colon injuries is usually safe and effective. In patients with ulcerative colitis undergoing robotic proctectomy, an unintentional proctotomy in a diseased rectum deep in the pelvis may be best visualized and suture repaired with the robot, rather than converting to a laparoscopic or an open procedure.

Conversions to open surgery occur less frequently after robotic than after laparoscopic colorectal resection [1, 28–35]. The COLOR II randomized controlled trial comparing laparoscopic and open surgery for rectal cancer was composed of surgeons with considerable laparoscopic expertise. Even so, the conversion rate for laparoscopy was 17 % in this study [36]. In a large national database analysis, the robot was associated with a 59 % reduction in conversion in the abdomen and 90 % reduction in conversion in the pelvis, when compared to laparoscopy [1]. In a study comparing robotic and laparoscopic rectal resection for cancer, Patriti reported a 19 % conversion rate for laparoscopy compared to no conversions with the robot. This difference was remarkable in that the robot group was composed of a majority of patients with previous abdominal surgery and low rectal neoplasms requiring preoperative chemoradiation and total mesorectal excision [28].

A meta-analysis of four randomized controlled trials comparing robotic and laparoscopic colorectal surgery demonstrated that conversion for robotic colorectal procedures was 1.8 % compared to 9.5 % for laparoscopic colorectal operations [33]. In an analysis of a large regional protocol-driven externally audited database characterized by definitions for data entry, Tam et. al. found that conversion in the pelvis for robotic procedures was 7.8 % versus 21.2 % for laparoscopy (p < 0.001), and 9.0 % for the robot in the abdomen compared to 16.9 % for laparoscopy (p = 0.06) [34]. Conversions early in an operation, done to avoid complications, are associated with fewer complications than conversions done in response to intraoperative bleeding or enterotomies [37, 38].

There are rare occasions when conversion is required because of urgent intraoperative complications related to bleeding or enterotomies. Bleeding may occur when dissecting the inferior mesenteric artery during the course of a sigmoid resection or low-anterior resection. This is the time when the art of surgery demands poise and thoughtfulness, deciding between calm and control of bleeding with instruments, versus urgent de-docking and laparotomy. Often the bleeding vessel can be clamped with a fenestrated bipolar grasper or Maryland forceps and a locking clip or vessel sealer applied. If blood loss has not been significant and hemostasis has been obtained, then the procedure may proceed as planned. If bleeding has been temporarily controlled, but definitive hemostasis with clips or energy has not been obtained, a laparoscopic instrument through the assistant port may substitute for the robotic instrument, allowing de-docking and laparotomy in a controlled fashion with hemostasis. Alternatively, the robotic instrument may be left clamped on the vessel, while the other robotic instruments are removed and the respective robotic arms detached from the trocars. Though the robot arm providing hemostasis remains at the operating table in this case, these maneuvers typically leave enough room for laparotomy and open control of the bleeding. A hex wrench attached to the robot is used to release the instrument from the vessel at the appropriate time (D.C. Coffey, M.D., personal communication).

It is critically important that the bleeding vessel is dissected out and visualized well enough to ensure no other structures, like the ureter, are injured while gaining hemostasis. It is also important not to dissect structures not easily visualized because of bleeding, and this may be the critical factor that convinces the operating surgeon to convert to open. Though it is important not to persist to the point of significant blood loss, often blood loss appears more than it is because of the magnified image. If there is any doubt, however, de-docking the robot and laparotomy to control hemorrhage is the prudent choice. It is important to have open instruments readily available for any minimally invasive procedure to address urgent complications like bleeding.

Another important bleeding scenario is presacral hemorrhage during a robotic total mesorectal excision for rectal neoplasia. Though bleeding can sometimes be controlled with energy sources, it is best at times not to persist in this effort and instead place a small sponge and/or hemostatic agent on the bleeding vessel. A robotic instrument or suction device allows pressure to be maintained. It may be worth waiting 5–10 min once the bleeding is controlled before releasing pressure and then assessing for persistent bleeding. If the bleeding vessel, usually a torn vein, is controlled with the sponge, it is sometimes possible to continue with other parts of the procedure and reassess later. Often the bleeding will resolve spontaneously with patience. If the bleeding is not well controlled or persists despite the above maneuvers, conversion may be the prudent option.

Converting to an open procedure requires removing the robotic instruments under direct vision, detaching the robotic arms from the trocars, removing the robot from the patient bedside, providing open instruments, and proceeding with laparotomy. This can be a time-consuming process and if the conversion is for bleeding can lead to considerable blood loss and hemodynamic compromise. Though it may not be practical for every institution to do so, procuring a circulating nurse, scrub nurse or technician, and anesthesia nursing team dedicated to robotics and familiar with preparation, malfunctions, and operative approaches may decrease the risk for morbidity during these urgent and emergent scenarios. A reflective role-playing exercise to include all relevant operating room caregivers and to simulate the emergent need to convert may help prevent morbidity in this situation [5].

Inadequate distention of the abdomen with carbon dioxide (CO₂) gas results in a poorly visualized operative field and can result in organ injury. Several possible explanations for inadequate pneumoperitoneum should be considered including an open port allowing the loss of CO₂ gas, a disconnected gas line, a port that has retracted into the subcutaneous tissue or out of the abdominal wall altogether, an empty gas tank, and rarely, inadequate muscle relaxation. The operation should be temporarily paused when visualization is obscured and inadequate pneumoperitoneum should be considered as the cause. A stepwise progression of consideration of the above etiologies should be performed with expectation that the cause for inadequate pneumoperitoneum will be identified and the operation then safely resumed [5]. In the obese patient, a second gas insufflator utilizing a robotic gas port may resolve the problem. Rarely, a procedure may need to be converted to open because of inadequate visualization of the operative field.

Early in the course of high- and low-anterior resections, and after thorough exploration of the abdomen, it is important to displace the small bowel to the right upper quadrant, allowing visualization of relevant anatomy and allowing the planned operative techniques to proceed. This is usually accomplished by strategic use of the Trendelenburg position and left-to-right rotation of the operating table. Natural fusion planes between the terminal ileum, terminal ileal mesentery, pelvic structures, and pelvic sidewalls, as well as adhesions from previous pelvic surgery or appendectomy, may make this maneuver difficult. Inadequate muscle relaxation may also make this challenging. If the Trendelenburg position and anesthetic muscle relaxation does not keep the small bowel in the right upper quadrant, taking time to divide offending adhesions using laparoscopic techniques will often be the remedy. Alternatively, these adhesions can be divided after docking the robot and using robotic techniques. However, the operating surgeon should be confident that the assistant will be able to deliver the small bowel out of the pelvis without the attached robotic arms impeding progress. Pausing to detach a robotic arm to assist in this maneuver is also an option.