Endoscopic profile of anorectal and colorectal lesions at the University Clinic of hepatogastroenterology in Cotonou, Benin: a retrospective descriptive study from 2022 to 2024

¹University Clinic of Hepatology and Gastroenterology of Hubert Koutoukou Maga, University Hospital Centre, Cotonou, Benin, ²Faculty of Health Sciences, University of Abomey-Calavi, Cotonou, Benin, ³Hepatology and Gastroenterology Department, Calavi International Hospital Centre, Cotonou, Benin

^&Corresponding author
Fidele Desire Semassa, University Clinic of Hepatology and Gastroenterology of Hubert Koutoukou Maga, University Hospital Centre, Cotonou, Benin

Introduction    

One of the main activities of the University Hepatology and Gastroenterology Clinic (CUHGE) at CNHU-HKM is digestive endoscopy, which is an essential diagnostic and therapeutic tool in gastroenterology. Digestive endoscopy is an essential technique that not only allows direct visualization of the digestive mucosa, but also enables targeted biopsies to be performed, thereby contributing to accurate diagnosis and appropriate treatment [1]. One such endoscopic examination is total colonoscopy, considered to be the gold standard for the diagnosis and prevention of colorectal cancer. It not only enables the early detection of adenomatous polyps, but also their removal, significantly reducing the incidence and mortality associated with colorectal cancer [2]. Recent advances in endoscopic technology, such as high-definition endoscopy, chromoendoscopy, and artificial intelligence assistance systems, have significantly improved the detection of early lesions [3].

However, despite these advances, little local data is available on the diagnostic yield and epidemiological characteristics of lesions found during lower digestive endoscopies performed at the CUHGE of the CNHU-HKM. This study aimed to describe the epidemiological characteristics of lesions identified during lower gastrointestinal endoscopies performed at the CUHGE from 2022 to 2024.

Methods     

Study design and setting: this was a retrospective descriptive study that included all patients who underwent lower gastrointestinal endoscopy between January 1, 2022, and August 31, 2024, in the endoscopy unit of the University Hepatology and Gastroenterology Clinic at CNHU-HKM in Cotonou.

Study population: patient records were identified from the endoscopy unit database. Eligible records were required to contain: a complete endoscopy report; patient age and sex; documented indication for examination; interpretable description of endoscopic findings. The records lacking one of these essential variables were excluded from the analysis.

Data collection: for each patient, data collected included age, sex, occupation, place of residence, indication for examination, and endoscopic findings. Colonoscopy was performed after a standardized bowel preparation consisting of a low-residue diet excluding fruits and vegetables on the day preceding the procedure, combined with the administration of an osmotic laxative based on either magnesium sulfate or polyethene glycol to ensure adequate bowel cleansing. The preparation protocol involved dissolving two 30-g sachets of magnesium sulfate or 64 g of polyethene glycol in two litres of water, with patients instructed to ingest 250 mL every 15 minutes; the first dose was taken at 6:00 p.m. on the day before the examination and the second dose at 4:00 a.m. the day of the procedure. Endoscopic examinations were performed using either an OLYMPUS CF H-190L/I video colonoscope coupled with an OLYMPUS EVIS EXERA III system, including a CLV-190 light source, CV-190 PLUS processor, LCD monitor, and OFP-2 irrigation pump, incorporating Dual Focus, Pre-Freeze, and Narrow Band Imaging (NBI) technologies for enhanced lesion visualization, or an AOHUA VCC-Q30JL video endoscope connected to an AOHUA LLS-2800 light source, VME-2800 processor, monitor, and AFP-1 washing pump.

Definitions: endoscopic lesions were classified based on their macroscopic appearance as documented by the endoscopist. Proctological lesions included haemorrhoids, marisks, anal fissures, and anal fistulas, while neoplastic lesions included endoscopically suspicious colorectal masses and benign-appearing polyps. Since histopathological results were not routinely available, the classification of lesions was based exclusively on endoscopic characteristics, which precluded any definitive diagnosis of colorectal neoplasia. Furthermore, due to the retrospective nature of the study and the absence of a standardized surgical report protocol, established classifications —such as the Paris classification for superficial colorectal lesions and histopathological classifications— could not be applied.

Data analysis: the information was collected using a standardized form developed in KoboCollect, and the data was then entered and analyzed using Epi Info 3.1 and Microsoft Office Excel 2019 software.

Ethical considerations: the entire process of data collection, processing, and analysis was conducted in strict compliance with personal information confidentiality and in accordance with the principles of security, ethics, and data protection.

Results     

A total of 817 lower gastrointestinal endoscopy reports were collected, including 685 colonoscopies and 132 anorectosigmoidoscopies. Each patient underwent a single lower gastrointestinal endoscopy session. The examination was well tolerated by all, and no major incidents were reported. Colonic preparation was considered good, with a Boston score between 7 and 9 in 495 (60.5%) of cases.

Socio-demographic characteristics: the most represented age group was 36 to 45 years old, with an average age of 40.5 years, and a predominance of males (458; 56%). Retired people were the most represented in the study population (13.6%), followed by office workers (12.2%). The colonoscopies were mainly prescribed by specialists in hepatology and gastroenterology (80.6%), followed by general surgeons (8.9%).

Distribution of the various lesions encountered following lower digestive endoscopies: the main indications (Table 1) were constipation (260; 31.8%), gastrointestinal bleeding, particularly hematochezia (159; 19.5%); and proctalgia (156; 19.1%). Proctological lesions ranked first among anorectal disorders, accounting for 47.98%, dominated by internal hemorrhoidal disease (247; 30.2%), marisks (90; 11%), and anal fissures (46; 5.6%). Colo-rectal tumors were significantly more common in males, with a marked predominance in the 56-65 age group, with an average age of 60.5 years. This trend applied to both benign lesions, particularly polyps, and malignant colonic tumors. Macroscopically suspicious tumors accounted for 9.4%, with a predominance in the rectum. Among these, there were budding lesions (55.8%), ulcerative-budding lesions (27.2%), stenotic lesions (9.1%), ulcerated lesions (6.5%), and a single infiltrating lesion (1.3%). Benign-looking polyps were identified in 10.9% of patients. Colonic diverticulosis was found in 10.3% of cases, predominantly in the right colon (44%), followed by the left colon (26%) and sigmoid colon (23%). In addition, 8 cases (1%) of vascular ectasia and 21 cases (2.6%) of dolichocolon were observed. Table 2 shows the distribution of the various lesions encountered following lower digestive endoscopies.

Discussion     

The objective of this study was to describe the epidemiological characteristics of lesions identified during lower gastrointestinal endoscopies performed at the CUHGE from 2022 to 2024.

A total of 817 lower gastrointestinal endoscopies were analyzed, primarily involving patients aged 36 to 45 years (mean age: 40.5 years), with men accounting for 56% of the cases. The most common indications were constipation (31.8%), followed by hematochezia (19.5%) and proctalgia (19.1%). The abnormalities observed were dominated by anorectal lesions, notably internal haemorrhoids (30.2%), skin tags (11%), and anal fissures (5.6%), while colonic diverticulosis was present in 10.3% of patients. Macroscopically suspicious rectocolonic tumors were identified in 9.4% of cases, with a predominance in the rectum; benign-appearing polyps were found in 10.9% of cases; and a satisfactory colonic preparation (BBPS ≥ 7) was achieved in 60.6% of patients.

Of the 817 colonoscopies performed, the colonoscopy was pathological in 777 patients (95.1%). No macroscopic lesions were found in 40 patients (4.9%). In terms of age and gender, the most represented age group was 36 to 45 years old, with an average age of 40.5 years and a predominance of males. This result is similar to those reported by some authors [4,5], but differs from studies that found an average age of 51.1 ± 17.6 years [6,7]. However, the majority of studies report a male predominance.

The main indications were constipation (31.8%), followed by gastrointestinal bleeding, particularly hematochezia (19.4%), and proctalgia (19.1%). These results differ from the majority of African data, where gastrointestinal bleeding is the primary reason for endoscopy [4,5,8]. Proctological lesions accounted for 47.9% of conditions, with internal haemorrhoids (30.2%) being the most common. This is consistent with data from Africa [4,5,8-10]. Proctological conditions are a very common reason for consulting a gastroenterologist. It has been shown that 40% of a representative sample of the French population aged over 15 had experienced anorectal symptoms [11]. The frequency of this disease is difficult to assess, as the results of epidemiological studies are disparate and report highly variable figures [10,12].

Hemorrhoidal disease appears around the third decade of life, increases with age, and peaks between 45 and 65 years of age, with constipation as the main risk factor [10]. Internal haemorrhoids most often cause prolapse and/or easily recognizable bleeding. Physical examination always confirms the diagnosis, and a colonoscopy is necessary after age 40 or 45 to rule out colorectal cancer [12]. With regard to parietal anomalies, colonic diverticulosis was present in 10.2% of cases. The exact prevalence of colonic diverticulosis is unknown; its asymptomatic nature is most likely responsible for its underestimation. Its prevalence increases with age and is estimated at 50% in individuals over 60 years of age, rising to over 70% in those over 80 years of age. These values apply to Western populations in industrialized countries. Diverticulosis is rare in Asia (China and Korea), occurring in between 0.5% and 1.7% of the population, and has long been considered exceptional in Africa. However, recent data from Africa show an increase in its prevalence from 3.5% to 9.7% over the last decade [13,14]. In this series, diverticula are predominantly found in descending order in the right colon, left colon, and sigmoid colon, which contrasts with data in the literature where the majority of diverticulosis cases (37% to 90%) involve the left colon and sigmoid colon. Pancolic involvement or involvement limited to the right colon is much rarer (15%). Right colon involvement is more common in Asian patients [14,15]. This geographical variation suggests the combined influence of environmental and genetic factors. Traditional models attributed diverticulosis, particularly on the left side, to low fibre intake leading to increased intra-colonic pressure in a narrow sigmoid colon. However, this mechanism is less effective in explaining right-sided diverticulosis, where the larger diameter and liquid content of the colon limit hyperpressure. Recent data thus challenge the strict right/left dichotomy and support a multifactorial mechanism, incorporating connective tissue alterations, parietal fragility, and individual susceptibility. In Asian populations, the identification of polymorphisms in the WNT4, RHOU, and OAS1/3 genes further supports the hypothesis of a more pronounced genetic contribution in right-sided diverticulosis [15,16].

Tumors were the second most common cause of anorectal diseases recorded, with an overall frequency of 20.3%, divided between 9.4% of rectal tumors macroscopically suspected of malignancy and 10.9% of benign-looking polyps. These results are broadly consistent with the data reported in several studies conducted in tertiary hospitals in sub-Saharan Africa. Indeed, the proportions of tumor lesions reported in patients with symptoms of colorectal diseases varied between 2.18% and 25.2% depending on the country [17-20]. These data confirm the general trend observed in the region, marked by a gradual increase in the incidence of colorectal cancer over the last decade [21].

Morphologically, the lesions were budding (55.8%), ulcerative-budding (27.2%), stenosing (9.1%), ulcerated (6.5%), and a single infiltrating lesion (1.3%). However, other African studies have reported a predominance of ulcerative-budding forms over budding forms [17,22]. Topographically, the lesions were mainly located in the rectum, a trend also found in several African studies, suggesting a rectal preponderance of colorectal tumor locations [7,17]. Finally, available regional analyses indicate that age-standardised incidence rates for colorectal cancer, although higher in high-income countries, are trending upward across all African populations. This epidemiological trend appears to be closely linked to the gradual westernization of lifestyles, marked by rapid urbanization, sedentary lifestyles, weight gain, and increased consumption of red meat, refined sugars, and alcohol, all of which are recognized factors in colorectal carcinogenesis [21].

About structural abnormalities, dolichocolon was identified in 2.6% of our series. Dolichocolon can be suspected during colonoscopy, but its exact prevalence is unknown. Its asymptomatic nature is most likely responsible for its underestimation. The incidence ranges from 1.9% to 28.5% in certain patient series [23]. The quality of bowel preparation was deemed satisfactory in 60.5% of cases, with a Boston Bowel Preparation Scale score between 7 and 9, indicating good mucosal visibility. The most commonly used laxative in our series was magnesium sulfate. According to the literature, several factors predictive of inadequate colonic preparation have been identified, including advanced age, male gender, history of colorectal surgery, diabetes mellitus, cirrhosis, and chronic constipation [24-26]. These factors must be taken into account when planning preparation, as inadequate preparation significantly reduces the detection rate of adenomas and compromises the diagnostic quality of colonoscopy.

International recommendations state that a good preparation rate of over 85% is the minimum target for each endoscopy unit in order to optimize the diagnostic yield of the examination. Improving this rate requires an individualized approach to colonic preparation. It must be tailored to the clinical characteristics of each patient. The quality of preparation must also be systematically assessed using the Boston score, which is mentioned in all colonoscopy reports. This approach is all the more crucial in the African context, where many endoscopy centres do not yet have artificial intelligence assistance systems for adenoma detection [27].

The results of this study should be interpreted in light of certain methodological limitations. Conducted at a tertiary referral hospital and based on the inclusion of medical records containing sufficiently detailed endoscopic reports, the study may be subject to selection bias. The study population, consisting mainly of symptomatic patients or those referred for specialized care, is therefore not necessarily representative of the general population, which limits the generalizability of the results. The lack of systematic histological confirmation of lesions is also a major limitation, as their characterization relied primarily on their endoscopic appearance. Furthermore, the non-systematic use of standardized endoscopic classifications may have reduced the reproducibility of the findings and complicated comparisons with data from the literature. The inadequate quality of bowel preparation in a significant proportion of the examinations may also have compromised the detection of certain lesions —particularly the smallest ones— leading to an underestimation of their actual frequency. Finally, the lack of systematic collection of several recognized quality indicators for colonoscopy —notably the adenoma detection rate and the cecal intubation rate— prevents a full assessment of the quality and diagnostic performance of the procedures performed.

Conclusion     

At the end of this study, the data collected highlight a high prevalence of anorectal lesions in a young adult population, predominantly male. The main indications, particularly constipation and hematochezia, are consistent with the lesion spectrum reported in the literature, which is characterized by a high frequency of internal haemorrhoids. The detection of polyps in more than 10% of patients, as well as the detection of rectal tumors with a malignant endoscopic appearance in 9.4% of cases, highlights the crucial role of endoscopy in the early identification of potentially progressive lesions. Overall, this study confirms the essential contribution of lower digestive endoscopy to the diagnosis of colorectal pathologies. It also highlights its major role in the early detection of pre-neoplastic lesions. Furthermore, it reaffirms the central role of this examination in the prevention and management of colorectal diseases.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Conception, study design, data analysis and interpretation: Fidele Desire Semassa, Olawoumi Faridath Aboudou and Aboudou Raïmi Kpossou. Data collection: Fidele Desire Semassa, Akotchaye Marcel Kakpo, Noume Bella Doumbouya, Olawoumi Faridath Aboudou and Fifame Larissa Sodjinou. Manuscript drafting: Fidele Desire Semassa. Manuscript revision: Comlan N'dehougea Martin Sokpon, Rodolph Koffi Vignon, Aboudou Raïmi Kpossou, Jean Sehonou. Guarantor of the study: Fidele Desire Semassa. All authors approved final version of the manuscript. The author read and approved the final version of this manuscript.

Tables      

Table 1: indications for lower gastrointestinal endoscopies, University Clinic of Hepatology and Gastroenterology Cotonou, 2022 to 2024 (N=817)
Table 2: distribution of the various lesions encountered following lower digestive endoscopies at the University Clinic of Hepatology and Gastroenterology Cotonou, 2022 to 2024 (N=817)

References