A Revisit into Blunt-Tip Coaxial Introducer Technique

Abstract

Biopsy procedures, especially those guided by computed tomography, pose significant challenges when vital structures are present along the needle path. The advent of the blunt-tip coaxial introducer has improved the safety and efficacy of these procedures by facilitating controlled needle advancement while minimizing the risk of injury to critical structures. Initially introduced for procedures such as nephrostomy, biliary drainage, and abscess drainage, the blunt-tip coaxial introducer has proven to be an effective tool in navigating complex anatomical regions.

 

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Keywords

blunt-tip coaxial introducer - CT-guided biopsy - intervention biopsy

Introduction

Biopsies can often pose challenges due to the presence of critical structures along the needle path. Computed tomography (CT) is the preferred imaging modality in such cases, as it facilitates the selection of an optimal trajectory to minimize the risk of injury to vital structures.[1]

The combined use of a coaxial biopsy system and automatic or semiautomatic biopsy guns of various lengths and sizes has significantly enhanced the quality of biopsy samples. An advancement in the coaxial technique for safer access to hard-to-reach lesions is the use of a blunt-tip coaxial introducer.[1] [2] [3]

The initial application of blunt-tip introducers for abdominal procedures, including nephrostomy, biliary drainage, and abscess drainage, was documented in 1989.[1] [2] Various other methods, such as the saline instillation technique or adjusting the patient's position, have been implemented to displace critical structures away from the needle path.[1] [3] [4] [5] Additionally, the combination of saline instillation with a soft-tip stylet has further improved the safety of these procedures.[6]

In this context, we present the blunt-tip coaxial introducer technique as a guiding tool for accessing CT-guided biopsies and performing percutaneous drainage, supported by illustrative cases.

 

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Technique

The “THREE P's”—Planning for a successful biopsy, Positioning the patient to achieve the optimal biopsy plane, and Protection of vital vascular and neural structures along the needle path—are essential considerations in biopsy procedures.

In our cases, as presented in this exhibit, percutaneous CT-guided biopsies were performed using an 18-gauge coaxial biopsy set (Bard Max-Core Biopsy Instrument, BARD, Switzerland) ([Fig. 1]). The introducer cannula, equipped with a sharp-tip stylet ([Fig. 2A]), is used for puncturing the skin, muscle, and fascia. For added safety, a soft-tip stylet ([Fig. 2B]) may be employed to prevent injury to structures such as the lungs, blood vessels, and bowel loops, particularly when advancing the cannula through adipose tissue or between fascial planes. The soft-tip stylet serves to gently displace or slide over vital structures rather than cause damage. Representative images are added ([Figs. 3] [4] [5] [6]).

Fig. 1 Yellow arrow: sharp-tip stylet, and orange arrow: blunt-tip stylet.

Fig. 2 (A and B) Panel A showing a sharp-tip stylet is fitted with introducer cannula for piercing the skin, muscle, and fascia. Panel B showing soft-tip stylet may be used for avoiding injury to structures like vessels and bowel loops especially while advancing the cannula through fatty tissue or between fascial planes.

Fig. 3 (A) Anterior mediastinal mass (anterior parasternal approach) histopathological examination (HPE): thymoma. (B) Posterior mediastinal mass (posterior paravertebral approach) HPE: ganglioneuroma. (C) Para-aortic lymph node (posterior paraspinal approach) HPE: tuberculosis. (D) Left iliac lymph node encasing the iliac artery (anterior abdominal approach) HPE: metastasis. Note: Mass is delineated with yellow color, major vascular structures—arteries and veins—are referred with red and blue colors, respectively.

Fig. 4 (A and B) Initially, coaxial introducer fitted with the sharp-tip stylet is introduced, abdominal wall and paraspinal muscles are crossed and entered into retroperitoneum. Sharp stylet is replaced with blunt-tip needle and via posterior pararenal space vital structures like the inferior vena cava (IVC) and ureter are negotiated and biopsy taken from pancreatic mass. No complications occurred. Histopathological examination (HPE) showed benign serous cystadenoma of pancreas.

Fig. 5 (A) Showing blunt-tip coaxial introducer technique used to access peripancreatic collection along the posterior border of the spleen by avoiding injury to the spleen. (B) Showing blunt-tip coaxial introducer technique used to access peripancreatic collection between the anterior border of the spleen and splenic flexure by avoiding injury to the spleen and bowel loops. Note: The collection is delineated with yellow color, splenic margin with blue color, and bowel outline with green color.

Fig. 6 (A and B) Initially, coaxial introducer fitted with the sharp-tip stylet is introduced, abdominal wall and paraspinal/psoas muscles are crossed and entered into the retroperitoneum. Sharp stylet is replaced with blunt-tip needle and vital structures like the inferior vena cava (IVC), ureter, and gonadal vein are negotiated and biopsy taken from the retroperitoneal lymph node. No complications occurred. Histopathological examination (HPE) showed necrotizing granulomatous lymphadenopathy.

 

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Advantages

• (1) The primary advantage of this technique lies in the blunt tip's ability to glide over major vessels and organ capsules, thereby avoiding penetration of muscle tissue.[1]

• (2) The use of larger blunt tips distributes the applied force across a broader surface area, which reduces pressure and minimizes the risk of unintentional perforation.

• (3) Unlike standard introducers, which typically require a direct path from the entry site to the target, the blunt-tip introducer allows the radiologist to navigate safely through adipose tissue, circumventing critical structures.[7]

 

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Limitations

• (1) The soft-tip stylet is not suitable for piercing dense tissues such as the skin, fascia, or muscle.[6]

• (2) The tissue yield may be suboptimal for lesions smaller than 1 cm in size.[7]

 

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Conclusion

The blunt-tip coaxial introducer technique represents a significant advancement in the field of interventional radiology, offering enhanced safety and precision during CT-guided biopsies and percutaneous drainage procedures. Despite being documented in medical literature, the blunt-tip coaxial introducer remains underutilized by many radiologists. This technique is safe, well-tolerated by patients, and can be incorporated into routine practice by interventional radiologists seeking to access complex targets.

 

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Conflict of Interest

None declared.

• References

• 1 de Bazelaire C, Farges C, Mathieu O. et al. Blunt-tip coaxial introducer: a revisited tool for difficult CT-guided biopsy in the chest and abdomen. AJR Am J Roentgenol 2009; 193 (02) W144-8
• 2 Akins EW, Hawkins Jr IF, Mladinich C, Tupler R, Siragusa RJ, Pry R. The blunt needle: a new percutaneous access device. AJR Am J Roentgenol 1989; 152 (01) 181-182
• 3 Goodacre BW, Savage C, Zwischenberger JB, Wittich GR, vanSonnenberg E. Salinoma window technique for mediastinal lymph node biopsy. Ann Thorac Surg 2002; 74 (01) 276-277
• 4 Karampekios S, Hatjidakis AA, Drositis J, Gourtsoyiannis N. Artificial paravertebral widening for percutaneous CT-guided adrenal biopsy. J Comput Assist Tomogr 1998; 22 (02) 308-310
• 5 Zwischenberger JB, Savage C, Alpard SK, Anderson CM, Marroquin S, Goodacre BW. Mediastinal transthoracic needle and core lymph node biopsy: should it replace mediastinoscopy?. Chest 2002; 121 (04) 1165-1170
• 6 Neyaz Z. Soft-tip stylet and saline instillation technique: making difficult percutaneous CT-guided biopsies possible. Indian J Radiol Imaging 2022; 31 (04) 956-960
• 7 Cazzato RL, Garnon J, Shaygi B. et al. Performance of a new blunt-tip coaxial needle for percutaneous biopsy and drainage of “hard-to-reach” targets. Cardiovasc Intervent Radiol 2017; 40 (09) 1431-1439

Publication History

Article published online:
29 July 2025