Twenty studies (854 patients) were included in the review: 14 case series, three case-control studies, two comparative non-randomised studies, and one retrospective analysis of prospectively collected data. One of the case series studies compared robotic-assisted surgery with laparoscopic surgery. Sample sizes ranged from 10 to 131 patients. The mean follow-up ranged from 10 to 36 months (where reported).
Complication rates: Complication rates ranged from 0 to 42.7% across 20 studies; the overall rate of complications was 15.5%. The major complications reported were anastomotic leak (27 cases), postoperative bleeding (10 cases) and surgical site infection (14 cases). Other complications were ileus, urinary retention, cystitis, pulmonary and cardiac complications, hernia, deep vein thrombosis and pneumonia.
Mortality: Thirteen studies reported mortality outcomes. There was no intra-operative or 30-day mortality reported in these studies, although one patient died from pneumonia three months post-surgery and another patient died of metastases at one-year post-surgery.
Conversion rate: The overall conversion rate to laparoscopic or open surgery procedures was 3.7% (19 studies, range 0 to 12.5%, where reported). Reasons for conversion were obesity with heavy mesentery, inability to identify vascular structures, vascular injury, adhesions, narrow pelvis and technical difficulties (stapler mis-firings and robotic malfunction).
Length of hospital stay: Postoperative length of hospital stay was a mean of 5.9 days (+ 2.1; 18 studies).
Operative time: The mean operative time reported in all 20 studies was 236 minutes (+ 66.5; range 154 to 383.8). Two comparative studies found no differences in operative time between robotic-assisted surgery and the laparoscopic study groups. One study found a significant difference in operative time between robotic-assisted and laparoscopic surgery, although the length of surgery decreased with increased experience. One case series study found that operative time decreased as the number of cases of robotic-assisted surgery increased.
Nineteen studies included surgery performed for malignant disease and more than 12 lymph nodes were retrieved in eleven studies for oncological staging.
In the three studies that reported on total mesorectal excisions, complete resections were achieved in 78%, 84% and 93% of cases.