The trocar serves as the "gateway" of minimally invasive surgery, and its successful insertion marks the first step toward a smooth operation, yet it also carries inherent risks. Mastering standardized insertion techniques, gaining in‑depth understanding of relevant anatomy, and being well‑versed in complication prevention and management are compulsory courses for every laparoscopic surgeon. From the classic closed (blind) insertion method to the safer open Hasson technique and visual puncture, technological advances have consistently centered on the core goal of reducing puncture‑related complications.

Insertion Techniques: Evolution from Blind Puncture to Direct Visualization

   Closed Method (Insertion after Veress Needle Puncture)This is the most traditional technique. First, a Veress needle is punctured at the umbilicus or a predetermined site to establish a pneumoperitoneum, separating the abdominal wall from internal organs to create an operative space. The Veress needle is then withdrawn, and the first trocar (primary cannula) is inserted at the same puncture site. Regarded as blind insertion, this step entails the highest risk and requires extensive clinical experience and refined tactile feedback from the surgeon.

   Open Method (Hasson Technique)To avoid risks of blind puncture, especially for patients with prior abdominal surgery and potential intra‑abdominal adhesions, the open method offers superior safety. A small incision is made directly at the selected site, with layered dissection down to the peritoneum. A blunt‑tipped cannula such as the Hasson trocar is placed into the abdominal cavity under direct visualization, sutured and secured, followed by connection to a pneumoperitoneum insufflator. While blind insertion is avoided, this method takes slightly longer and involves a marginally larger incision.

   Visual PunctureWith the widespread use of optical trocars, a novel approach combining advantages of both closed and open techniques has become mainstream. After pneumoperitoneum establishment, a transparent trocar equipped with an endoscope is slowly rotated and advanced under direct visualization, penetrating abdominal wall tissues layer by layer until entering the peritoneal cavity. Delivering the highest safety level, this method is gradually becoming the first choice in many surgical centers.

Key Operational Principles and the Transillumination Test

   Puncture angle: The trocar is generally inserted perpendicular to the abdominal wall rather than at an oblique angle, to prevent injury to retroperitoneal major blood vessels such as the common iliac vessels.

   Force control: Insertion should be steady, slow and rotational, with tissue penetration relying on the instrument's sharpness or blunt dissection force. Excessive force must never be applied. A sensation of "give‑way" indicates entry into the abdominal cavity.

   Transillumination test: After inserting the primary observation trocar and placing the laparoscope, subsequent working trocars should be inserted under laparoscopic light illumination. The abdominal wall is inspected externally to avoid visible blood vessels including the inferior epigastric vessels, with puncture performed in avascular zones, effectively preventing abdominal wall vascular injuries.

Common Complications and Their Prevention & Management

Despite continuous technological improvements, trocar‑related complications still occur at an incidence rate of 0.2%–6%. Major types are listed below:

Vascular injury: The most severe and potentially life‑threatening complication

Major vessel injury: Damage to the abdominal aorta, inferior vena cava or iliac vessels, mostly caused by overly deep puncture, improper angles or an extremely lean patient physique. Immediate conversion to open laparotomy for hemostasis is required once injury occurs.

Abdominal wall vessel injury: Most commonly involving the inferior epigastric artery, preventable via the transillumination test. Manifested as active bleeding from the puncture site after injury, management includes external compression, intra‑abdominal electrocoagulation or suturing. A Foley catheter may also be inserted through the trocar port, with balloon inflation and outward traction for compression hemostasis.

   Visceral injury: Potential damage to the bowel, urinary bladder, liver and other organs, prevalent in patients with intra‑abdominal adhesions. Injuries identified intraoperatively require immediate repair; delayed postoperative bowel perforation typically presents with peritonitis and necessitates emergency exploratory laparotomy.

   Trocar Site Hernia (TSH): Protrusion of intra‑abdominal contents through fascial defects at trocar ports ≥10 mm in diameter. Reported incidence in domestic gynecological laparoscopy is approximately 0.013%, yet higher in single‑port laparoscopy. Prevention is paramount: fascial layers must be sutured at the end of surgery for ports 10 mm or larger. Blunt‑dissection trocars also lower hernia risks by producing more regular and smaller fascial defects.

   Trocar‑site tumor seeding: Rare yet critical in surgeries for malignant tumors such as ovarian cancer and gallbladder cancer, possibly associated with repeated instrument passage‑induced contamination, tumor cell aerosolization and CO₂ pneumoperitoneum effects. Tumor‑free principles are essential: tumor‑contaminated instruments should avoid repeated withdrawal through trocars; resected specimens, especially lymph nodes, must be extracted inside specimen retrieval bags rather than directly via trocar ports.

   Gas‑related complications: Including subcutaneous emphysema and pneumothorax, mostly linked to improper pneumoperitoneum establishment rather than trocar insertion itself.

Conclusion

Trocar insertion is a technically demanding and high‑risk key step in laparoscopic surgery. The application of new technologies such as optical trocars has greatly improved puncture safety. Nevertheless, even state‑of‑the‑art instruments cannot fully replace solid anatomical knowledge, standardized operational techniques and rigorous awareness of complication prevention. Adhering to clinical guidelines, proficiently mastering diverse puncture methods, and maintaining high vigilance against potential risks are fundamental to ensuring minimally invasive surgery achieves both minimal trauma and safety.