Choanal atresia is a rare birth defect of the nasal cavity characterized by the complete or partial obstruction of the choana [1] .

Choanal atresia has been extensively studied in both pediatric and adult populations, with an incidence ranging between 1/5000 and 1/10,000 live births [2] [3] . It can be unilateral or bilateral. Previous studies reported that 90% of atresias were purely bony and 10% were purely membranous [3] . In more recent studies, some authors have reported that choanal atresia is mixed in 70% of cases and purely bony in 30% of cases [4] . Regardless of the feature, the treatment of atresia involves surgical resection of the stenosis. Our surgical approach has evolved over the years. For 12 years, we performed blind dilations followed by calibration. Since 2011, with the acquisition of endoscopic equipment, patients have been treated by endonasal endoscopic approach. This study aimed at investigating the clinical characteristics and the types of atresia, as well as to compare the anatomical outcomes between dilation and the endoscopic approach.

We conducted a retrospective and descriptive study ranging from 1^st January 2000 to 31^st December 2023 at the Oto-Rhino-Laryngology Department of FANN Teaching Hospital in Dakar, Senegal. In this study, we included all patients who underwent a treatment for unilateral or bilateral choanal atresia.

During our study period, 37 patients were consulted for choanal atresia. The mean age at the moment of diagnosis was 1 year, with extremes of 1 day and 14 years; 91% of the patients were less than 6 months. The sex ratio was 1.

The incidence of choanal atresia is estimated at 1 case per 5000 to 8000 live births [5] . However, the actual incidence might be slightly higher if we consider that some neonatal deaths due to asphyxia could be attributed to the unrecognized presence of this anomaly. This is especially true in our countries where the death of a newborn does not systematically lead to an autopsy. The 37 cases collected over 22 years probably do not reflect the reality. The average age of patients at the time of diagnosis varies from one series to another, ranging from 11 weeks to 10 years [6] - [9] . This wide variability is related to the inclusion criteria of study populations in different series. Indeed, the average age at diagnosis in predominantly pediatric series is earlier than in mixed series consisting of adults and children. Most authors report a predominance of atresia in females [5] [7] [9] - [11] . However, in our series, the sex ratio was 1, without any explanatory argument for this finding.

Regarding laterality, the unilateral pattern is more common than the bilateral pattern in almost all studies [6] - [11] . However, in our series, bilateral atresia was more significantly found, representing 63.63% of cases. These results do not align with the literature, which can be explained by the fact that unilateral atresias are well tolerated and rarely motivate a consultation. Therefore, the diagnosis is often unrecognized, especially in our limited setting context and a lack of ORL specialists. It is often only considered in cases of neonatal respiratory distress, which constituted 78.79% of our circumstances of discovery. Concerning the diagnosis, CT scan plays a key role. It confirms choanal atresia, assesses its characteristics, nature, whether it is unilateral or bilateral, the extent of bony obstruction, its thickness, and the bony anomalies that constitute it (inclination of the pterygoid processes, thickening of the vomer). In 71% of cases, CT scan reveal mixed atresia, and it is purely bony in 29% [12] [13] . Knowing whether the atresia is bony or mixed helps plan the surgery and anticipate potential difficulties [14] . CT scan was performed in only 27% of cases due to its high cost, the urgency of the situation, and the difficulty of anesthesia in newborns during the procedure. This imaging approach helps rule out a cephalocele or congenital hypertrophy of the inferior turbinates and identify other associated bony anomalies.

Congenital anomalies are associated with choanal atresia in 50% of cases, with CHARGE syndrome being the most common anomaly [15] - [17] . In our series, congenital anomalies were found in 24% of patients. As in the literature, CHARGE syndrome accounted for nearly half of the cases.

The reference treatment for choanal atresia is endonasal endoscopic surgery [18] - [20] . The endoscopic approach offers the advantage of good visualization and allows for extensive resection. It is a short-duration and low-morbidity intervention that can be proposed at birth for bilateral choanal atresias, whether mixed or bony. This surgical technique was introduced into our practice in 2011. Before this date, our patients underwent blind dilation of the stenosed choana. With this blind dilation technique, the postoperative stenosis rate was 50%. Compared to the literature, the endoscopic technique gave better results with good choanal patency in 73% of cases. Dumaz et al. reported a success rate of 85.3% in a total of 238 operated patients [20] . I Achour et al. found a rate of 76.2% after the first surgery and 95% after surgical revision [21] . Despite these good results, endonasal endoscopic surgery is difficult in newborns. This difficulty is related to the narrowness of the nasal cavities, which makes it difficult to pass the endoscope and instruments. Sometimes, we use otological instruments in the absence of pediatric endonasal instrumentation. Besides instrumental and anatomical constraints, there are difficulties with anesthesia in newborns in this emergency context.

Endonasal endoscopic surgery has revolutionized the surgical management of choanal atresia. It represents the treatment of choice and yields better results than blind dilation. There is no consensus on the use of calibration devices or the application of topical agents at the site of the reopened choana. However, extensive resection of the stenosis reduces the risk of recurrence.

Informed consent was obtained from the patient to report this case.