The Power Law of Learning in Transumbilical Single-Port Laparoscopic Subtotal Hysterectomy

To analyze the surgical outcomes and learning curve of transumbilical single-port laparoscopic subtotal hysterectomy, which requires sutures of the cervical stump.

A prospective observational study (Canadian Task Force classification II-2).

A university-affiliated center.

From the first (July 2012) and consecutive patients of benign uterine disease scheduled for subtotal hysterectomy until October 2013.

All single-port laparoscopies were performed using straight instruments by 1 gynecologist. An ancillary port was added whenever technical difficulties could endanger surgical quality.

Seventy-five patients were recruited for intention-to-treat analysis with a mean (±SD) age of 44.7 ± 3.8 years and a body mass index of 24.2 ± 3.7 kg/m². No major complication was noted. The mean uterine weight was 432.5 ± 344.0 g with 24 (32%) uteri ≧500 g. The patients' sequential order, or gradually increasing experience, was the determining factor in progressively decreasing operative time. Furthermore, most cases that required an additional ancillary port (67%) were clustered in the first 20 cases, whereas 4 were scattered after the 47th patient because of severe pelvic adhesion. The mean operative time decreased in the power law function of the patients' sequential order with a plateau achieved at the 20th patient.

The patients' sequential order was identified as an independent factor of achieving purely single-port access, and the trend of decreasing operative time delineated the existence of a learning curve. Approximately 20 patients were needed for an experienced multiport laparoscopist to reach technical competency in the current series.