|Year : 2022 | Volume
| Issue : 1 | Page : 11-17
Level of variations of the aortic bifurcation and distance measurements between the aortic bifurcation and the common iliac bifurcations
Arzu Ekingen1, Mehmet Güli Çetinçakmak2
1 Vocational High School of Health Services, Batman University, Batman, Turkey
2 Associate Professor, MD, Department of Radiology, Medical School, Dicle University, Diyarbakir, Turkey
|Date of Submission||10-Mar-2021|
|Date of Acceptance||31-Oct-2021|
|Date of Web Publication||17-Mar-2022|
Dr. Arzu Ekingen
Vocational School of Health Services, Batman University, Batman
Source of Support: None, Conflict of Interest: None
Introduction: The purpose of the present study was to investigate the vertebral levels of the aortic bifurcation (AB) in patients with and without the abdominal aorta (AA) deviation and to measure the distances between the AB and the right-left common iliac bifurcations (CIBs) which are crucial anatomical information, especially for anterior lumbar interbody fusion surgery. Additionally, we made comparisons levels of the AB according to sex and examined whether the results were statistically significant, which we could not find other studies comparing gender in literature. Material and Methods: The images of 721 patients, undergoing angiography with multidetector computed tomography between January 2016 and October 2019, were reviewed retrospectively. The AB levels of the patients with and without the AA deviation were classified and evaluated separately. It was measured the distances between the level of the AB and the right and left CIBs with the 3-dimensional ruler technique in only 207 of 721 patients. Results: It was detected seven different vertebral levels of the AB among patients (116 patients) with the AA deviation, in which is the highest L4-upper (27.59%), and 11 different vertebral levels of the AB among patients (605 patients) without the AA deviation, in which is the highest L4-upper (22.48%). When comparing cases with and without AA deviation, a statistically significant difference was found between the sexes (P < 0.05). Discussion and Conclusion: The presented study demonstrates that there is a significant relationship between the genders at some levels. The preoperative information of the morphological variations of the AB may be very useful for laparoscopic, invasive procedures, and spinal surgery procedures. At the same time, these variation information reveals new information for anatomy.
Keywords: Abdominal aorta, anatomic variation, aortic bifurcation, common iliac artery, lumbar vertebrae, multidetector computed tomography
|How to cite this article:|
Ekingen A, Çetinçakmak MG. Level of variations of the aortic bifurcation and distance measurements between the aortic bifurcation and the common iliac bifurcations. J Anat Soc India 2022;71:11-7
|How to cite this URL:|
Ekingen A, Çetinçakmak MG. Level of variations of the aortic bifurcation and distance measurements between the aortic bifurcation and the common iliac bifurcations. J Anat Soc India [serial online] 2022 [cited 2022 Aug 17];71:11-7. Available from: https://www.jasi.org.in/text.asp?2022/71/1/11/339881
| Introduction|| |
The abdominal aorta (AA) is the part of the aorta in the abdomen, the largest artery in the abdomen. The thoracic aorta, which is a part of the aorta in the thorax, takes the name AA after passing in the diaphragm at the level of the 12th thoracic vertebra. As described generally in anatomy books, the AA ends with a bifurcation, which is called aortic bifurcation (AB), at the slightly left side of the midline on the body of L4 and divides into the right and left common iliac arteries (CIAs) which are approximately 5 cm. Each common iliac artery runs toward in the pelvis, then divides into the external iliac and internal iliac arteries on both sides at the anteromedial of the sacroiliac joint. This point where it splits into two is the common iliac bifurcation (CIB).,,, Although the AB level and the CIAs are described as described above, various studies have shown that there may be various level variations related to the AB.,
The AB and CIAs anatomy is very important for anterior lumbar interbody fusion surgery, which is generally preferred for spinal problems such as segmental lordosis, spondylolisthesis, foraminal stenosis, spinal trauma, and scoliosis. In addition, knowledge of the variations of these structures is useful for invasive procedures such as laparoscopic lumbar discectomy, lumbosacral total disc arthroplasty and some cardiovascular diseases such as abdominal aortic aneurysm, aortic stenosis, calcified atherosclerosis of the bifurcation region.,,,,,,, Furthermore, the anatomy of the AB and the CIB are very crucial for kissing stent reconstruction which is used for aortoiliac disease and external beam radiotherapy which is preferred in the treatment of carcinoma of the cervix.,,,, critical complications like vascular injuries can happen in diagnosis and treatment interventions involving the AB and lumbar region. Retroperitoneal major blood vessel injury may cause hypovolemic shock, this can result in shock-related deaths or serious illness. Anatomical information of the AB and the CIB on both sides may reduce the risk of these complications.,,
Advances in radiology such as digital subtraction angiography, magnetic resonance imaging (MRI), and later developed multidetector computed tomography (MDCT) angiography have enabled more reliable images of vascular structures. Especially, the images obtained with the MDCT technique can convert into 3-dimensional (3D) volumetric images and so on it can be make a clearer interpretation of the anatomical structures.,,,,, Variations related to the localization of the AB were mostly investigated by associating lumbar vertebrae and various techniques such as cadaver dissection, pelvic angiography, and computed tomography (CT) were used in these studies. However, the AB and the CIB studies that used MDCT are very few.
Aims and objectives
In this study, we aimed to determine the vertebral levels of the origin of the AB among patients with AA deviation and without AA deviation and to measure the distance between the AB and the bifurcations of the CIAs via MDCT angiography.
| Material and Methods|| |
This study was approved by the Dicle University Medical School Noninterventional Clinical Research Ethics Committee (Meeting date, November 14, 2019; Decision no, 52).
In our study, a total of the image records of 721 patients, undergoing angiography with MDCT between 2017 and 2019 at the Department of Radiology of the Dicle University and range 18–85 years, were included in the study. All patients with AA aneurysms, spinal anomalies, and undergoing major abdominal surgery and having poor image quality were excluded. Our study population comprised 339 women and 382 men, the median age of the patients was 49.2 years old.
The MDCT angiography was performed using 64-detector computed tomography (CT) (Brilliance CT System, Philips Medical Systems, Cleveland, OH, USA). Approximately 75-120 mL of nonionic contrast material was injected through a superficial vein located in the forearm region of patients with the supine position at a rate of 3–4 mL/s using an automatic power injector and shooting process started with a delay of 28 s after the start of the injection. Applied CT parameters: Slice collimation, 0.5 mm; gantry rotation, 0.34 s; section thickness, 0.9 mm; tube current, 200–250 mAs; the tube potential, 120 kV. Images obtained in the arterial phase after angiography were sent to a separate workstation (Philips Medical Systems, Philips Extended Brilliance Workspace, Best, The Netherlands). In this workstation, 3D volumetric images were created using the volume rendering (VR) technique. All determinations and measurements of the present study were made on these 3D images obtained.
For determining the level of the AB, 3D images of patients were divided into two groups: patients with AA deviation and patients without AA deviation. Then, the central point of the AB was defined for each case in both groups and the vertebra level matching this central point was determined. To determine the level of the spine where the AB is located, 4 planes including the lumbar vertebrae and intervertebral disc structure were determined: Upper (above the level of the pedicle vertebra), middle (at the level of pedicle vertebra), lower (below level of the pedicle vertebra) and disc level (located at the level of the intervertebral disc) [Figure 1]a. In the images, the plane corresponding to the AB was accepted as the vertebral level of the AB.
|Figure 1: (a) The four planes including the lumbar vertebrae and intervertebral disc to determine levels of the aortic bifurcation; (b) The distance measurements between the aortic bifurcation and the bifurcations of the right-left common iliac artery by the 3-dimensional ruler technique; Abdominal aorta; Aortic bifurcation; common iliac artery; common iliac bifurcation|
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For the distance measurements, we were able to evaluate the AB and the bifurcations of the CIAs together in only 207 patients because most of the right-left CIB were out of 3D images and poor image clarity which affects the precise measurement. Firstly, we marked separately the centers of the AB and the bifurcations of the right-left CIAs, second, we measured the distances between the level of the AB and the right and left CIB via the 3D ruler technique [Figure 1]b.
The obtained data from the radiological images were transferred to the computer environment and all statistical analyzes were performed using the SPSS (IBM SPSS Statistics for Windows, Version 21.0. Armonk, New York, USA). The summary of the data was expressed as mean ± standard deviation, percentage, and frequency. The Independent-Samples t-test and Chi-square test were used to compare between the groups according to gender. P values with P < 0.05 were accepted statistically significant.
| Results|| |
The comparison of patients with the AA deviation and without the AA deviation by gender is given in [Table 1]. The prevalence of women with the AA deviation (58.62%) is higher than men with the AA deviation (41.38%), whereas the percentage of men without the AA deviation (55.20%) is higher than women without the AA deviation (44.80%). These results are statistically significant (P < 0.05) [Table 1].
|Table 1: Comparison of the patients with AA deviation and without abdominal aorta deviation|
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Considering the results of the AB levels among patients without the AA deviation in [Figure 2] and [Table 2], the total prevalence of the AB located in above and middle levels of the L3 in women (3.32%) was higher than the total AB prevalence located at the same levels in men (1.80%). The AB prevalence located at the L3 lower (8.86%), the L3-L4 disc levels (24.72%), L4 middle (21.03%) were higher in females. However, the AB prevalence located at the L4 upper (24.25%), L4 lower (17.07%), and L4-L5 disc levels (14.97%) were higher in males. A total percentage of the AB located in the L5 upper and middle levels were higher in women (2.21%) than men (1.80%). When the data were evaluated statistically in this way, a significant difference was found between the genders (P < 0.05) [Table 2]. It was found that the L2-L3 intervertebral disc level which was the highest AB level we found, was (0.50%) in 3 of the patients without the AA deviation in total [Figure 3]. However, the highest AB level of patients with the deviation AA was the L3 lower level (2.59%) [Figure 4]. The most common levels of the AB for both patient groups without the AA deviation and with the AA deviation were the L4 upper levels as 22.48% and 27.59%, respectively [Figure 5]a and [Figure 5]b.
|Figure 2: Distribution of the aortic bifurcation levels by gender in patients without the abdominal aorta deviation|
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|Table 2: The levels of the aortic bifurcation in patients without abdominal aorta deviation|
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|Figure 3: The aortic bifurcation locating at the L2-L3 intervertebral disc level of a patient without abdominal aorta deviation (38 years, male); Abdominal aorta; Aortic bifurcation|
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|Figure 4: The aortic bifurcation was locating at the L3 lower level of a patient with the abdominal aorta deviation (53 years, female), the abdominal aorta shows deviation to the right at the L2-L3 level (star); Abdominal aorta; Aortic bifurcation|
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|Figure 5: (a) The aortic bifurcation locating at the L4 upper level of a patient without abdominal aorta deviation (49 years, female); (b) The aortic bifurcation locating at the L4 upper level of a patient with abdominal aorta deviation, the abdominal aorta shows deviation to the right at the L2-L3 level (star), (63 years, male); Abdominal aorta; Aortic bifurcation|
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The AB locating at the L5 middle level, lowest vertebral level detected in this study, was (0.50%) in three patients without AA deviation. The AB locating at the L5 upper level, lowest vertebral level detected in patient without AA deviation for this study, was 4 (3.45%) [Figure 6]a and [Figure 6]b.
|Figure 6: (a) The aortic bifurcation locating at the L5 middle level of a patient without abdominal aorta deviation (75 years, male); (b) The aortic bifurcation locating at the L5 upper level of a patient with abdominal aorta deviation, the abdominal aorta shows deviation to the right at the L3 level (star) (68 years, female); Abdominal aorta; Aortic bifurcation|
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In the disc levels, the L3-L4 disc level was observed as 19.67% in the patients without the AA deviation and 9.48% in the cases with the AA deviation [Figure 7]a and [Figure 7]b. The L4-L5 disc level was observed as 11.40% in the patients without the AA deviation and 17.24% in the cases with the AA deviation [Figure 8]a and [Figure 8]b.
|Figure 7: (a) The aortic bifurcation was locating at the L3-L4 intervertebral disc level of a patient without the abdominal aorta deviation (32 years, female); (b) The aortic bifurcation was locating at the L3-L4 intervertebral disc level in a patient with the abdominal aorta deviation which shows deviation to the left at the L3 level (star) (43 years, female); Abdominal aorta; Aortic bifurcation|
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|Figure 8: (a) The aortic bifurcation was locating at the L4-L5 intervertebral disc level of a patient without the abdominal aorta deviation (38 years, male); (b) The aortic bifurcation was locating at the L4-L5 intervertebral disc level in a patient with the abdominal aorta deviation which shows deviation to the right at the L4 level (star) (61 years, female); Abdominal aorta; Aortic bifurcation|
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When the comparison is made between men and women in the patients with the AA deviation, no significant difference was found between the genders (P > 0.05) [Figure 9] and [Table 3].
|Figure 9: Distribution of the aortic bifurcation levels by gender in patients with the abdominal aorta deviation|
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|Table 3: The levels of the aortic bifurcation in patients with abdominal aorta deviation|
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In the distance measurements between the bifurcations of the CIAs and the AA, we founded that the mean value was 57.82 mm in females, 61.09 mm in males on the right side and was 60.41 mm in females, 63.79 mm in males on the left side, these results were statistically insignificant [Table 4].
|Table 4: Measurement distances between the aortic bifurcation and the bifurcations of the right-left common iliac arteries and distribution according to the sex|
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| Discussion|| |
Basic anatomy books describe the level of the AB where the AA is divided into right and left CIAs as the level of the 4th lumbar vertebrae. In the following years, the problems preventing blood flow such as atherosclerosis showed that this region should be examined better, because it may have a variety of variations.,, The difficulties encountered in laparoscopic approaches, especially for the L4-L5 intervertebral disc and the increasing morbidity rates have made more important the anatomy of the prevertebral vascular structures in this region and especially, anatomy of the AB and the CIBs.,,
In our study, the total AB rate at the L3 levels was found to be 8.11% (49 cases) in patients without the AA deviation. Huang et al. explained a high-positioned bifurcation of the AA at the level of the upper L2 body in one case by CT technique. In our study, the L2-L3 intervertebral disc level in 3 (0.50%) patients without the AA deviation and the L3 lower level in 3 (2.59%) patients with the deviation AA were determined as the closest level to the L2 level. Chithriki et al. reported that the AB prevalence corresponding to the L3 levels was determined as 9.30% (41 cases) by MRI.
Ponni et al. examined the images of 26 patients with cervical cancer and radiotherapy and said that the division of the AA into CIAs occurred at the level of L3-L4 intervertebral space, the body of L4 vertebra and L4-L5 intervertebral space in 53.84%, 30.76% and 15.40% of the patients, respectively. In our study, these prevalences are as follows; 19.67% (L3-L4 disc level), 58.35% (L4 level), 11.40% (L4-L5 disc level). Lakchayapakorn and Siriprakarn and Deswal et al. found the L4 levels as the highest level of the AB in 63% and 64%, respectively. Khamanarong et al. explained that the AA bifurcated into the CIAs at the level of the L4 vertebra in 131 cases (70.10%), at L4-L5 intervertebral disc in 23 cases (12.30%), and at the level of the L5 vertebra in 33 cases (17.60%) of 187 cadavers. Pirro et al., Chithriki et al., and our current study also showed that the most common levels of the AB were the L4 vertebrae levels [Table 5]. These studies mentioned above showed that the AB is mostly at L4 levels and the results of the level of the studies with CT and MR techniques are lower than the results of the level determined by the cadaver dissection. The reason for that may be due to the fact that the CT technique is more sensitive and reliable as well as enables research in a wider population. The AB prevalence localized at L5 levels was found as 2.50% in the study of Chithriki et al. 1.99% in our study, the lowest level detected in our study was the levels of the L5 vertebrae.
|Table 5: Comparison of the different studies and the present study related to the aortic bifurcation levels|
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When we compared the intervertebral disc levels of the AB in our study, the AB was the most common at the L3-L4 disc level (19.67%) and the least at the L2-L3 disc level (0.50%), and 11.40% at the L4-L5 disc space in patients without the AA deviation and it was 11 cases (9.48%) at the L3-L4 disc level, 20 cases (17.24%) at the L4-L5 disc level in the cases of the AA deviation. But, Deswal et al. said that the rate of the AB was 16% at the L4-L5 intervertebral disc and 4% at the L3-L4 disc space. This difference among these studies may be due to the research method.
The difference of our study from other studies, we evaluated the AB data of patients with the deviation AA and with nondeviation AA separately, made comparisons according to sex, and examined whether the results were statistically significant. We did not find studies evaluating patients having the AB with AA deviation separately. Accordingly, a significant difference was found between patients with AA deviation and without the AA deviation, and between patients without AA deviation when comparing among genders in our study (P < 0.05) [Table 1] and [Table 2]. These meaningful results may be related to the genetic and height of women and men.
Deswal et al. said that the mean values of length of the CIAs were 56.49 mm on the right side and 53.75 mm on the left side on 25 cadavers and no statistically significant difference was observed. Panagouli et al. found that the mean length of the left CIA was 61.2 mm and that of the right one was 60.3 mm in 76 cadavers. In our study, the general mean of the length of the CIAs was 59.43 mm on the right side and 62.07 mm on the left side which these lengths were longer than the lengths written in classical anatomy texts.
| Conclusion|| |
The anatomical knowledge of the levels of the AB and the CIB is particularly beneficial during surgical and laparoscopic procedures which are used for both diagnostic and treatment for diseases such as vertebral, spinal cord and disc problems, aortic-iliac atherosclerosis, aortic aneurysm. Knowing the AB levels before these procedures makes a great contribution both to prevent unwanted injuries during surgery and to prevent various complications after surgery.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]