https://en.wikipedia.org/wiki/Veress_needle

The first and most critical step in any laparoscopic procedure is the establishment of pneumoperitoneum via Veress needle insertion. A substantial body of clinical data indicates that complications related to Veress needle and primary trocar insertion account for more than half​ of all laparoscopic surgery–related adverse events. The reason behind this striking figure is a hard anatomical reality: this is the only step in the entire laparoscopic operation that cannot be performed under direct laparoscopic visualization - it is a blind puncture.​ Therefore, a thorough mastery of every detail involved in Veress needle insertion is of irreplaceable value in enhancing surgical safety.

I. Structure and Ingenious Design of the Veress Needle

The Veress needle is a specialized spring-loaded needle device consisting of a slender inner stylet housed within an outer cannula. The proximal end of the stylet is fitted with a valve-equipped hub - the key interface for connecting the carbon dioxide (CO₂) insufflation tubing.

The most commendable feature is its blunt-tipped, spring-activated design.​ Unlike conventional sharp trocars, the Veress needle tip remains blunt in its resting state. The ingenuity of this design lies in several aspects:

Safety protection: The blunt tip minimizes the risk of accidental needlestick injuries to the surgeon, scrub nurse, or circulating nurse during handling and instrument passing.

Smart deployment mechanism: When axial pressure is applied against tissue, the internal spring is compressed, and the sharp piercing segment of the stylet protrudes from the blunt outer sheath, generating effective penetrating force.

Automatic retraction upon entry: Once the needle penetrates the peritoneum and enters the abdominal cavity, the sudden loss of resistance allows the spring to recoil, retracting the sharp stylet back into the blunt outer sheath - this mechanism fundamentally reduces the risk of injury to intra-abdominal viscera (such as bowel, major vessels, and bladder) caused by over-penetration.

In essence, the Veress needle is a classic surgical instrument that achieves a remarkable fusion of penetrating efficiencyand inherent safety.

II. Strategies for Selecting the Insertion Site

The choice of insertion site is by no means one-size-fits-all; it requires a comprehensive assessment of multiple factors: uterine size, the planned extent of surgery, abdominal wall thickness, the distribution of previous surgical scars, and the patient's body habitus.

Practical Tip: Leveraging the "Thin-Wall Effect" of the Umbilicus

The Veress needle insertion site is often, though not always, the same location where the primary trocar will be placed. In patients with a thick abdominal wall and loose skin, if the surgical plan requires placing the camera trocar at a higher supraumbilical position, the Veress needle may be fully inserted yet still fail to reach the peritoneal cavity. Two应对策略 (counter-strategies) are available:

Use an extended-length Veress needle;

The "Umbilical Insufflation + High Trocar" strategy: Perform Veress insertion at the umbilicus - where the abdominal wall is thinnest with virtually no fat tissue - to achieve rapid entry into the peritoneal cavity. Once pneumoperitoneum is established at the target pressure, insert the camera trocar at the planned supraumbilical location. By this point, intra-abdominal pressure has pushed the abdominal wall fat outward, significantly reducing trocar insertion resistance.

III. Standardized Technique for Veress Needle Insertion

3.1 Preoperative Preparation Must Not Be Skipped

Before marking the insertion site and making the skin incision, the umbilicus must be thoroughly disinfected.​ Clinical experience has shown that neglecting umbilical cleaning can lead to poor wound healing or even purulent infection at the incision site. It is recommended to use small cotton swabs soaked in povidone-iodine to thoroughly clean the umbilical fossa with 2–3 rotations, removing all accumulated sebum and debris.

3.2 A "Muscle-Memory" Action Before Insertion

The first step​ after picking up the Veress needle - check that the spring mechanism functions properly.​ Make this an indispensable, automatic habit before every insertion.

3.3 Insertion Angle and Depth Control

Special Note: In patients with a history of abdominal surgery, the primary insertion site need not be confined to the midline. It should be placed at least 3 cm away from the original surgical scar. When necessary, a laparoscope may be inserted through an accessory port first to visually assess the presence of adhesions at the planned primary trocar site before safe insertion.

3.4 Influence of Patient Positioning and Body Habitus

Placing the patient in the supine position​ significantly reduces the risk of vascular injury during insertion. Furthermore, the patient's body habitus directly affects the projected position of the umbilicus on the abdominal wall, the optimal insertion angle, and the distance from the insertion trajectory to critical retroperitoneal structures (such as the abdominal aorta and inferior vena cava). A thorough preoperative assessment is essential.

IV. Confirming Successful Entry of the Veress Needle into the Peritoneal Cavity

This is the most critical judgment step​ in the entire procedure. Even when the insertion "feels right," confirmation must be obtained through the following methods.

4.1 Tactile Confirmation: Loss of Resistance

As the needle penetrates the anterior rectus sheath and peritoneum, the surgeon will feel a distinct "pop" or loss of resistance​ - a sudden disappearance of resistance, as if passing through a thin membrane. This is the most intuitive indicator, though it is also the one most dependent on experience.

4.2 Saline Drop Test (Syringe Method)

After the Veress needle is presumed to be in the abdominal cavity, attach a small syringe filled with normal saline to the needle hub. Due to the physiological negative pressure within the peritoneal cavity, the saline will flow passively and steadily into the cavity, and the fluid level in the syringe will drop smoothly.

4.3 CO₂ Pressure Gauge Verification

Connect the Veress needle hub to the CO₂ insufflation tubing. While gently lifting the abdominal wall (to increase intra-abdominal volume), observe the pressure gauge on the insufflator - if it reads within the negative pressure range, this suggests that the needle tip is inside the peritoneal cavity.

4.4 Advanced Verification Methods When in Doubt

When the needle has been advanced to a sufficient depth but the loss of resistance is not obvious, or when there is any doubt about the needle tip's location, the following verification procedures must be initiated:

❶ Aspiration Test

Connect a syringe filled with normal saline to the Veress needle.

First, aspirate: If no blood or bowel contents are returned, inject 5–10 ml of saline.

Interpretation:

✅ Injection is smooth and aspiration yields nothing (or only a minimal amount of saline) → Needle tip is correctly positioned within the peritoneal cavity.

❌ Aspiration returns blood or bowel contents → Bowel or major vessel injury has occurred; immediate assessment for conversion to open laparotomy is required.

❌ Heavy bleeding or pulsatile hemorrhage → Immediate conversion to open surgery is mandatory; no delay is acceptable.

❷ Drop Test

Attach a syringe barrel without a plunger to the Veress needle hub, or simply place a few drops of normal saline directly onto the needle hub. If the liquid is rapidly drawn into the abdomen​ by negative pressure, the needle tip is correctly positioned within the peritoneal cavity.

❸ Early Insufflation Test - A Core Verification Every Beginner Must Master

The above tests only confirm that the Veress needle has entered a "cavity," but cannot definitively confirm that this cavity is the peritoneal cavity​ (it could be an intermuscular space, preperitoneal space, or even a hematoma cavity). Therefore, the early insufflation test is the gold standard for final confirmation:

Connect the insufflation tubing to the insufflator and set the safety pressure limit.

Begin insufflation at a low flow rate of 1 L/min.

Closely observe the combination of pressure curve and flow rate​ on the insufflator:

✅ Normal pattern: Intra-abdominal pressure gradually and steadily rises from the low range to the set value, and the gas flow rate remains stable → The Veress needle has successfully entered the peritoneal cavity. The flow rate may then be gradually increased to continue insufflation.

❌ Abnormal pattern: Pressure remains persistently high with violent fluctuations, and flow rate is extremely low or zero → The needle tip may be embedded in abdominal wall tissue, located in the preperitoneal space, or have penetrated a solid organ or the bowel lumen. Insufflation must be stopped immediately, and the needle tip position must be reassessed.

V. Conclusion

Veress needle insertion is the only step in laparoscopic surgery that cannot be performed under direct laparoscopic visualization, and it is also the step with the highest complication rate. From understanding the mechanical principles of the instrument, to individualized selection of the insertion site, to standardized insertion technique and multi-dimensional position verification - no step can be taken lightly. Especially for beginners, the early insufflation test should become a mandatory standard procedure after every insertion, not an optional "extra step."

Only by internalizing every detail into muscle memory can one build the first and strongest line of defense for the entire procedure - deep within the abdominal cavity, where the surgeon cannot see.