Entry complications, which occur before surgery or during trocar insertion and pneumoperitoneum establishment, are common even in simple laparoscopic procedures. Although the absolute rate is low (0.2–0.4 cases per 1000 procedures), entry complications account for over 50% of all laparoscopic complications [15,16,17]. They are the Achilles’ heel of laparoscopic surgery, as trocar insertion is blind and may pose unrecognized risks at the time of injury [18]. Laparoscopic complications are categorized as major and minor. Minor complications, often resulting from incorrect placement, include omental damage, mild bleeding, postoperative infection, subcutaneous emphysema, nerve injury, abdominal wall hematoma, failed port insertion, and extraperitoneal gas insufflation [1]. Major injures, requiring additional laparoscopic or laparotomic intervention, occur in 0.4–0.9 cases per 1000 procedures [19] and include bowel, bladder, ureter and blood vessel injuries, significant bleeding (> 600 mL within 24 h postoperatively), severe infections, and pulmonary edema, although data is limited [18,19,20]. Bowel and large vessels are the most common sites of injury, with the latter potentially being severe and even lethal.

The debate over the safest technique for trocar insertion is ongoing [21, 22]. The literature does not unanimously support a single procedure, and international guidelines do not recommend one method over others [15, 23,24,25], so surgeons must choose the technique they are most familiar with [26]. Table 2 summarizes laparoscopic complications according to severity.

Table 2 Laparoscopic complications: major and minor injures

Key Facts:

50% of laparoscopic complications occur during trocar insertion and pneumoperitoneum establishment.

Major complications (0.4–0.9 per 1000 cases) include bowel, bladder, ureter, and vascular injuries.

Bowel and vascular injuries are the most severe trocar-related complications.

Preoperative imaging and patient history are crucial to assess risks of adhesions and determine safer entry sites.

The umbilicus remains the preferred entry site owing to its predictable anatomy and reduced tissue variability.

Comparing the Techniques

Since the first report on laparoscopic entry complications over 30 years ago [27], significant progress has been made in safety improvements. Optical trocars, radially expanding trocars or retractable-blade trocars are just a few examples of how laparoscopy has evolved during this time frame.

Currently, three main methods are used for inserting the trocar into the abdominal cavity: the conventional closed-entry technique (Veress needle with CO2 pre-insufflation), Hasson’s non-insufflated open entry technique, and the direct trocar or optical entry method [28]. The optical trocar (direct vision) entry, consisting in accessing the peritoneal cavity directly, under monitor guidance without prior umbilical pneumoperitoneum, will not be the subject of our analysis [29].

Below is a brief description of these trocar entry techniques (Table 3).

Table 3 Trocar entry techniquesThe Veress Needle Technique

The Veress needle, designed to prevent organ perforations, features a sharp flute-like outer tip and a retractable inner cannula, retracting to safely engage tissues as it passes through the abdominal wall. Once reaching the peritoneum, a spring mechanism pushes the blunt end beyond the outer cannula tip, protecting internal organs. Typically inserted at the umbilical scar, it can also be placed along the midline (between the umbilicus and a point 5 cm cranially to the pubic symphysis) or at the lateral margin of the rectus abdominis muscle (at McBurney’s point). However, insufflation at these sites can lead to preperitoneal insufflation, as the peritoneum does not perfectly adhere to the abdominal wall. Insufflation through the Veress needle creates a gas cushion above the intestinal loops, facilitating the safe insertion of the first trocar and induction of pneumoperitoneum for surgery [30, 31].

The Open Entry Technique

The Hasson technique (non-insufflated open entry) uses a small infraumbilical incision to access and directly open the peritoneum, reducing the risks of blind instrument insertion. A 3-cm vertical incision is made, preperitoneal adipose tissue is dissected and the fascia is incised transversely, with two sutures piercing the fascial margins to anchor the Hasson trocar. Pneumoperitoneum is then induced. Although it reduces the risk of retroperitoneal vessel injury, intestinal perforation remains a concern. The most common complication is intestinal injury during fascial incision [30].

Direct Entry Technique

A 1–1.5-cm umbilical incision allows perpendicular insertion of the first trocar into the muscular fascia. Subsequently, the abdominal wall is elevated below the umbilical scar, creating a tent-like space between the parietal peritoneum and the internal structures. The trocar is advanced at a 45° angle towards the pelvis until the security system clicks, indicating blade retraction due to pressure changes. Correct trocar positioning within the abdominal cavity is confirmed by the 0° optic [32].

Accessory Trocars

Accessory trocars are placed under direct laparoscopic guidance, with positioning based on pelvic anatomy and surgical needs. Ideally, trocars are inserted at a 90° angle, forming an equilateral triangle. Access points are performed in the avascular lower abdomen, 3 cm medial to the anterior superior iliac spine, for insertion of 5-mm trocars. For additional access, a third 5-mm trocar is inserted on the patient’s left side, approximately 12 cm above the umbilicus [32, 33]. Lateral trocar placement increases the risk of injuring the inferior and superficial epigastric arteries, which run cranially and laterally to the pubic symphysis. Transillumination assists in precisely locating the superficial epigastric artery, to prevent vascular injuries during trocar insertion. Laparoscopic identification of these arteries relies on their anatomical course [30].

Entry Trocar Techniques: Which One Should We Prefer?

Direct entry trocar has recently overtaken the traditional Veress needle and open methods owing to its lower complication risks; previously, the Veress needle was utilized in 90% of cases, compared to 5% for the open technique and just 1% for direct entry [19, 20, 26, 34]. This shift is driven by fewer major and minor complications, including reduced visceral injuries and trocar-site infections [8,9,10]; moreover, direct trocar entry is faster (while the open method is the slowest) [26] and more efficient, minimizing the failure entry rate associated with multiple attempts, extraperitoneal gas insufflation, and omental damage are characteristic of the Veress technique more than the direct entry technique [19, 20]. In clinical practice, and according to our experience, the most frequently used technique is direct entry, with the Veress needle inserted at Palmer’s point representing a preferred option in cases of prior median laparotomic incision, as a result of fewer adhesions encountered in this area [35].

With no consensus on the safest technique, surgeons should use their preferred method [34], while remaining adaptable to alternatives in case of failure.

Radially Expanding Trocars (RET)

The 2019 Cochrane review does not favor any technique [20] but suggests radially expanding trocars (RET) may be safer. RET begins with Veress needle entry, encased in a polymer sleeve, followed by a blunt obturator inserted with a twisting motion. Compared to traditional blunt trocars, RET reduces trocar site bleeding, visceral and vascular injures, postoperative adhesions [36] and pain, while causing a smaller fascial defect due to a narrower incision [37]. However, it requires greater force to insert, leading some authors to recommend using the index finger to prevent uncontrolled entry from sudden resistance loss.

Key Facts:

No single trocar insertion method is universally superior. Surgeons should use the technique they are most proficient in.

Veress needle technique: Creates a protective gas cushion before trocar insertion but carries a risk of preperitoneal insufflation and failed entry if mispositioned. Its insertion at Palmer’s point is a safer alternative in high-risk cases.

Open entry (Hasson technique): Reduces retroperitoneal vascular injury, but is slower and increases the risk of bowel perforation during fascial incision.

Direct entry technique: Faster and associated with lower failure rate and lower risk of visceral injury, but may have a higher risk of vascular injury.

Radially expanding trocars (RET): Minimize tissue trauma, bleeding, and adhesion formation, but require greater insertion force and can be harder to control.

Accessory trocars: Allow flexible placement based on anatomy. Improper positioning increases the risk of injuring epigastric vessels.

General Safety Rules

Bowel and vascular injuries are the most common trocar-related complications, followed by bladder damage. Adhesions from previous surgeries, particularly transverse (6.87%) or longitudinal (31.46%) laparotomy incisions [38], significantly increase bowel injuries risk, though even patients without prior surgery face a 0.68% risk [39]. Therefore, a detailed medical history and preoperative imaging in high-risk patients help identify adhesions and determine safer entry points, such as Palmer’s point when umbilical access is unsuitable.

Gentle lifting of the abdominal wall during Veress needle or trocar insertion reduces bowel perforation risk, while optical trocars provide direct visualization to minimize blind injuries. In complex cases, a rectal probe can help delineate anatomical planes during dissection and prevent inadvertent injuries.

Timely detection of bowel perforation significantly reduces morbidity and mortality. Standardized safety checks, including thorough inspection of the bowel and dissection sites at the end of the surgery, are recommended.

Vascular injuries, particularly to the iliac vessels, aorta, vena cava, and aortic bifurcation, are critical because of their proximity to the umbilicus. The umbilical site remains the preferred entry point due to its consistent anatomy and predictable distance from major vessels. Here, the abdominal wall tissues are fused, and thickness remains constant across patients, including those with obesity. The iliac vessels and aorta are positioned at a fixed proportion (one-third of the total abdominal thickness) providing a stable and safe zone for trocar insertion. However, Trendelenburg positioning and leg stretching should be applied only after the first trocar is placed to minimize vessel exposure (Fig. 1). Similarly, a Foley catheter inserted preoperatively reduces bladder volume, positioning it retropubically to lower the risk of injury.

Fig. 1

Patient position. The picture shows the relationship between the umbilical trocar and the sacrum in a 0° position (left-side) and in Trendelenburg (right-side). The comparison shows that a Trendelenburg position exposes the promontorium and the aortic bifurcation increasing the risk of vascular injuries

To prevent stomach damage, a nasogastric tube should be placed before pneumoperitoneum induction.

Tips and Tricks

Use preoperative imaging and patient history to assess adhesion risk and determine the safest entry site (e.g., Palmer’s point in case of prior midline incisions).

Trendelenburg positioning should be avoided before first trocar placement to reduce vascular exposure.

Employ gentle lifting of the abdominal wall during Veress needle or trocar insertion to minimize bowel perforation risk.

Prefer optical trocars to enhance visualization and minimize blind entry risks.

Insert a Foley catheter and a nasogastric tube before insufflation to reduce bladder and gastric injury risks.

Postpone Trendelenburg positioning and leg extension until after the first trocar is inserted to minimize vascular exposure.

Conduct standardized safety checks at the end of surgery to ensure no undetected injuries remain.

Safety Rules: Veress Needle

Proper technique reduces risks. A stable mid-level grip prevents unintended movements during insertion. The needle, held like a pen, should be inserted at a 45° with stretched skin, directed towards the pelvis for safety, ensuring airflow moves away from the bowel. A 90° angle is recommended [40] for greater vascular clearance and improved port insertion, especially in patients with obesity [41].

Intra-abdominal placement is confirmed using standardized tests. The pressure test is the most reliable method (Azevedo et al.) [42]: intra-abdominal pressure < 10 mmHg within 10 s of insufflation (1.2 L/min) confirms correct positioning. Alternative tests include air aspiration—rather than blood, feces, or other biological fluids or tissue—(aspiration test), and 5 mL saline injection (injection test), where moderate fluid resistance excludes ectopic needle entry. Moreover, the double-click of the valve as the needle passes through layers, along with recovery tests, confirms intraperitoneal entry.

Tips and Tricks

Use a 45° angle with stretched skin for standard insertion or 90° for patients with obesity to enhance vascular clearance.

Confirm intraperitoneal entry with standardized tests:

Pressure test: Intra-abdominal pressure < 10 mmHg within 10 s.

Aspiration test: Air aspiration confirms correct placement.

Injection test: Moderate resistance during saline injection excludes ectopic entry.

Listen for the double-click of the needle’s valve passing abdominal layers.

Avoid excessive needle manipulation to reduce bowel and vascular injury risks.

Be cautious of preperitoneal insufflation, which can lead to failed trocar entry and misplacement.

Safety Rules: Inserting the First Trocar

In direct entry, the skin incision should match trocar size to avoid excessive traction and complication risks. Extending the incision when necessary is advisable.

A palm-grip on the trocar, guided by the index finger and gently rotated during insertion, ensures proper alignment (Fig. 2).

Fig. 2

Introduction of the first trocar. a The surgeon lifts up the inferior margin of the umbilical cushion; b The umbilical skin incision is performed caudocranially starting at the inferior margin on the left side; c Once the skin has been incised the scalpel is moved parallel to the skin plane proceeding on the left side of the scar; d The fusion of the abdominal fascias is then exposed by the assistant and released; e Prior to the insertion of the trocar the air valve should be opened; f The trocar is laid on the fascia, then the surgeons lift up the abdominal wall and the trocar is inserted perpendicular to the fascia. The index finger should be placed along the trocar to avoid sudden uncontrolled trocar entry

Conversely, in the open technique, the trocar is inserted perpendicularly to the muscular fascia, while stretching the abdominal wall to increase vessels clearance. Loss of resistance confirms successful entry.

Tips and Tricks

Ensure the skin incision matches the trocar size; extend it if necessary to avoid excessive traction and tissue damage.

For direct entry:

Handle the trocar with the palm grip, using the index finger at the tip for controlled insertion.

Rotate gently to ensure proper alignment.

For open entry:

Insert the trocar perpendicular to the fascia, stretching the abdominal wall to increase vessel clearance.

Loss of resistance signals successful entry into the peritoneal cavity.

Place lateral trocars in the “safety zone” (2–3 cm above the superior iliac spine) to prevent epigastric vessel injury.

Opt for conical or radially expanding trocars (RET) to minimize fascial trauma and reduce adhesion formation.