Aneurysm of the abdominal aorta (AAA) is a localized dilation of the abdominal aorta by at least half its normal diameter resulting in permanent loss of edge parallelism, turbulence of blood flow, and thrombus formation 1. These aneurysms can be saccular or fusiform 2. AAA is a serious condition that has a decisive impact on the vital prognosis 3. The prevalence is higher in men and increases with age. It is estimated between 2 and 6% of subjects over 65 years old in the USA 4.

In Africa, a study conducted on a population at risk of AAA in Benin in 2014 noted 1 case of AAA out of 245 patients selected, i.e. 0.41% of the population screened 5. As AAA is usually an asymptomatic pathology in 80% of cases, its discovery is most often fortuitous, during a paraclinical examination 6. Apart from inflammatory aneurysms, the occurrence of abdominal pain marks a turning point in the evolution of AAA. It is a sign of significant fissuring or compression and, above all, raises the fear of rupture leading to sudden death 78. The overall mortality rate for patients with ruptured abdominal aortic aneurysms is 80 to 95% 7. Thus, in France, the French National Authority for Health (HAS) recommends targeted, opportunistic screening in patients with risk factors for atherosclerosis. Ultrasound allows the screening and diagnosis of AAAs 9 because of its non-invasive, inexpensive, non-irradiating nature and its hemodynamic advantages 10. In order to overcome the paucity of literature on AAAs in Togo and to determine the interest of early detection by arterial Doppler ultrasound of AAAs, we proposed to carry out this study, the main objective of which was to describe the epidemiological, clinical, and sonographic aspects of abdominal aortic aneurysms. The specific objectives were: to describe the sociodemographic characteristics of patients with AAA; to describe the circumstances of discovery of AAA in Togo; to describe the cardiovascular risk factors of AAA in Togo; to describe the Doppler ultrasound lesions of AAA.

The cardiovascular exploration center (CEC) "Saint-Esprit" of the Association of People's Physicians for Research on Cardiovascular Diseases (AMP-MCV) in Lomé, the clinic "Le Printemps à Lomé" and the cardiology department of the CHU-Kara (located 450 km from Lomé) served as the setting for our study. There were no vascular exploration activities as such in the two cardiology departments of the two university hospitals of Lomé.

This was a prospective study with descriptive and analytical purposes that took place from January 2019 to March 2022 (3 years 2 months).

We included all patients who had undergone arterial Doppler ultrasound of the lower limbs, regardless of the reason, age, and sex in the centers selected for the study and during the study period.

AAA and its characteristics had to be confirmed on arterial Doppler ultrasound by the physician-cardiologist specialized in vascular Doppler explorations.

The performance of abdominal aortic angioscan was not essential for the inclusion of patients in this study.

Patients referred for suspected AAA in whom we did not have confirmation on arterial Doppler ultrasound were not́ retained in the study.

The same applies to patients with abdominal aortic dilatation less than 30 mm. Nonconsent to participate in the survey was also eliminatory.

In accordance with the technique for performing lower extremity arterial ultrasound, we always started and systematically explored the aorto-iliac axes in all patients.

AAA was defined as a rounded arterial vascular structure in cross section with a diameter greater than or equal to 30 millimeters that may have an anechogenic image corresponding to the aortic lumen and a more echogenic image corresponding to the thrombus. Longitudinal sections allowed us to identify the shapes of these AAAs, their location and extension. Extension to the visceral and iliac arteries was defined by an increase of one and a half times the normal size of these arteries. Arterial stenoses were defined as high peak systolic velocity with spectral dispersion and significant downstream pressure drop with flow demodulation. Occlusions were defined by 2-dimensional visualization of total or >90% obstruction (subocclusion) of the artery associated with an absence of pulsed or color Doppler at the artery or the presence of abutting flow.

Patients or accompanying persons were asked to answer questions on a predeveloped survey form.

Arterial Doppler ultrasounds were performed or confirmed by a cardiologist certified in vascular Doppler ultrasound.

Ultrasound checks were scheduled for 3 months with the possibility of a telephone link at any time.

For each patient, we were interested in sociodemographic data (age, sex); medical history, particularly cardiovascular and family AAA; and arterial Doppler ultrasound data.

All data were initially collected on a predefined survey form. Data were analyzed by Rstudio software version 4.1.0. We performed a descriptive and then univariate and multivariate analytical analysis. The qualitative variables were presented as numbers and frequencies, the quantitative variables as mean, standard deviation and extremes. The statistical tests used were the Pearson Chi-square test for qualitative variables and the Mann-Whitney test for quantitative variables. The significance level was set at 0.05. Univariate and multivariate logistic regression was performed to search for factors associated with aneurysm location, size, and shape.

Because ethical and deontological rules govern scientific research, we kept the patients anonymous in the evaluation forms to respect medical confidentiality.

Abdominal aortic aneurysms are serious and fatal pathologies. They are often asymptomatic, poorly detected and poorly documented, even in populations at risk in Africa. In this study, the circumstances of discovery of AAAs are dominated by downstream complications such as ischemia at the gangrene stage most often. The clinical picture is confused with stage III and IV PIA. These patients could be qualified as incidental findings in our context. Because the dreaded complication of AAA remains rupture with sudden death. This is why early detection is necessary, especially in populations at risk.

Aorto-iliac Doppler ultrasonography is a very important, inexpensive, non-invasive, and reproducible tool for the positive and lesion diagnosis of abdominal aortic aneurysms with a sensitivity and specificity close to 100% in well-trained operators. It is also the tool of recommendation for early detection in order to institute early management or monitoring to avoid sudden rupture of very poor prognosis even in developed countries.

The site of AAA predominate in the subrenal aorta. Aneurysms are fusiform, thrombosed and present extensions to other arteries.

The prevention of aortic aneurysm in patients at risk requires a good control of cardiovascular risk factors and a systematic screening from 60 years old as well as the systematic realization of autopsies. Other studies could focus on mass screening for AAA throughout the Togolese territory in at-risk populations.