Anatomical variation in the internal jugular vein: potential risk factors for central venous catheterization – a case report

Central venous catheterization (CVC) is an invasive medical procedure used to measure central venous pressure and provides a stable route for continuous drug administration. CVC is widely used in the emergency department and intensive care units. It is typically performed by inserting a catheter through the internal jugular vein (IJV) into the superior vena cava near the right atrium.[1, 2] While catheterization is a fundamental skill proficiently performed by healthcare professionals, lethal complications may occasionally occur because of undesirable positioning, depth and diameter.[3, 4]

Typically, the IJV is located approximately 1 cm beneath the neck skin. It can be accessed through a central approach by puncturing the apex of Sedillot’s triangle, formed by the sternal and clavicular heads of the sternocleidomastoid muscle and clavicle, toward the nipple on the same side. The anatomy of the IJV is generally stable. However, variations of the IJV, have been reported in the incidence between 0.4% and 3.3%.[5,6] In 2007, Downie et al[7] defined two types of variations: duplication and fenestration. For a more standardized approach, Mumtaz et al[6] proposed distinguishing bifurcation from duplication depending on the branching position and presented two new types: trifurcation and posterior tributary.

In addition to the risk of carotid artery puncture, this variation can also lead to injury to the accessory nerve. The bifurcated variations create extra space, sometimes allowing the accessory nerve to pass through. Furthermore, variational vessels are associated with turbulence,[8] differing from a normal hemodynamical laminar.[9] Consequently, the altered blood flow dynamics may affect surface projection, diameter, and adjacent structures. This increases the risk of complications resulting from injury to the surrounding structures. Moreover, when measuring central venous pressure using an IJV catheter, complex variations within the IJV may cause changes in blood flow and pressure within the vein (Figure 1).

Figure 1.

Anatomical variation of the IJV and altered blood flow. A: normal IJV, which leads to laminar flow; B: duplication; C: fenestration; D: posterior tributary; E: trifurcation. B, C, D, and E may raise a turbulent blood flow due to the stenosis of the vessel theoretically. IJV: internal jugular vein.

In this study, we present three cases of IJV variations, including duplication and fenestration. The clinical features of the published cases were also summarized and analyzed.

Patient 1, a 53-year-old male presented with a T2N0M0 squamous cell carcinoma on the right floor of the mouth. The patient underwent a right functional neck dissection for cancer. A 5-cm long, fenestrated left IJV with a smaller lateral branch was found during the operation. The right side appeared normal (Figure 2A).

Figure 2.

Intraoperative findings of case 1–3. A: patient 1, fenestration of the left IJV; B: patient 2, duplication of the right IJV; C: patient 3, fenestration of the right IJV. IJV: internal jugular vein. SCM: sternocleidomastoid; black arrows show IJV; white arrow shows accessory nerve.

Patient 2, a 42-year-old male presented with a T3N0M0 squamous cell carcinoma of the right floor of the mouth. Right radical neck dissection was performed due to the disease. During the procedure, a duplication of the right IJV was observed. The bifurcation was approximately 6 cm above the clavicle (Figure 2B).

Patient 3, a 49-year-old male presented with a T3N0M0 squamous cell carcinoma of the right buccal mucosa. Radical neck dissection of the right side was performed, and a 4.5-cm long, fenestrated right IJV was found during the procedure, with the accessory nerve passing through the space (Figure 2C).

The IJV develops from the anterior cardinal vein. Rossi et al[10] suggested that variations mainly occur during weeks 3–6 of pregnancy when disturbances in the development of the anterior cardinal vein lead to variations. Three proposed theories seek to explain these variations: venous ring stage theory, neural theory, and osseous theory. Venous ring stage theory suggests that the formation of a venous ring around the accessory nerve during IJV development contributes to variations. Neural theory proposes that changes in the position of the accessory nerve can alter IJV development. Osseous theory attributes variations to the presence of variable bony bridges in the jugular foramen. These variations can impact the success rate and accuracy of CVC, highlighting the importance of pre-procedure ultrasound (US) guidance to mitigate complications.

We conducted a comprehensive literature search on IJV variations, and 51 papers with a total of 65 cases were identified. The proportions of duplications (30/65) and fenestrations (30/65) were found to be similar, whereas the occurrences of trifurcation and posterior tributary types were lower (5/65). Among the cases, 12 patients (18%) presented with a spinal accessory nerve passing through this branch. It was observed that cases reported by anatomists and surgeons was 69% (45/65), while those detected through radiological and US examinations accounted for 31% (20/65) of the cases. Furthermore, cases reported from European and American countries constituted 69% (45/65), while cases reported from India and East Asian countries accounted for 21% (14/65) and 9% (6/65) respectively. Analysis of the clinical features of these variations revealed a predominance among male patients (75%), those older than 45 years of age (84%), and those with variations predominantly on the left side (69%) (Supplementary Table 1). Similarly, our report on three cases of fenestration and duplication showed the same characteristics. Additionally, there were fewer cases reported by researchers from East Asian countries than from Europe, America and India, suggesting a potential ethnic difference in these variations.

Although the surgical variation of the IJV is well-known among anatomists and surgeons, and the current guidelines suggest the use of US-guided catheterization, a lack of data has shown how this variation affects IJV-related measurements and diagnosis. However, in some emergency circumstances, US may not be available, and the complexity of variations may lead to a difficulty even when using US. Considering the significance of the IJV shape and blood flow in CVC, we propose these variations as potential interference factors and further understanding is needed.

In conclusion, both anatomists and surgeons have acknowledged anatomical variations of the IJV. However, the potential risks posed by these variations in CVC have not been extensively reported, especially for specific ethic groups. The focus of our case series has been expanding our knowledge, reducing complications, and furthering our understanding of these anatomical variations.