Here, our study is able to provide new data on API in neonates, both controls and ARM from a developing country and different populations from previous reports [6, 7, 10,11,12,13,14]. We included the ARM patients with associated anomalies, including the vertebral anomaly, as the novelty of our study (vs. a normal sacrum was the inclusion criteria [12]). In addition, there are still variations in the API among studies [14]. These API variations might be due to different methods for API measurement and ethnic populations [15]. The measurement of API is suggested to determine the neonates' age to minimize the impact of ethnic variations on the API. However, a recent systematic review concluded that ethnic variations did not affect the API [8].
Our study shows that the API is affected by the associated anomalies in neonates with ARM, particularly in males. The associated anomalies have been associated with the functional outcomes of ARM patients after definitive surgery [2,3,4,5]. Therefore, it is suggested that a pediatric surgeon find any associated anomalies in neonates with ARM to ensure appropriate management and counseling for the parents [16].
Another novelty of our study is that we included all ARM neonates with and without associated anomaly vs. ARM neonates without sacral anomaly [12]. In addition, they suggested not using the anal dimple as the proposed neoanus since it might be anterior to the normal anus position [12]. A previous report also suggested that the API should not be used as the only parameter for surgical intervention [13] because the API measurement might be inaccurate, particularly in patients with constipation. Constipation might result in perineal elongation due to the fecal impaction in the rectum [8]. The association between API and constipation is controversial. While some studies noted their association [10, 16], other reports were not [7, 15, 18]. Notably, our study aimed to compare the API between neonates with ARM and controls and determine the impact of associated anomalies on the API in neonates with ARM. Therefore, we did not associate the API with ARM patients' prognosis after definitive surgery. Our study focused on the associated anomalies in ARM patients that affected the API.
Interestingly, our subgroup analysis revealed that the API in ARM males with associated anomalies was significantly lower than in control males (Table 2). Our study is the first report that analyzed the impact of sex and associated anomalies in ARM neonates on the API to the best of our knowledge. In addition, although it was not statistically significant, the ARM group with associated anomalies also had a lower birth weight. Therefore, studying the association between API and birth weight is interesting.
Among associated anomalies, only vertebral anomaly showed a significant association with the API, revealing that ARM neonates with vertebral anomaly have lower API than ARM neonates without vertebral anomaly (Table 3). These findings were also another novelty of our study. However, we did not determine the sacral ratio in our patients. It is known that patients with a lower sacral ratio may have an influence on the API. Furthermore, the most common associated anomalies in our patients were congenital heart disorder (63.6%), followed by Down syndrome (54.5%), vertebral (27.3%), trachea-oesophageal (27.3%), and limb anomaly (18.2%). In contrast, a previous study showed that the most common associated anomalies in ARM patients were genitourinary (39.7%), spinal anomaly (33.3%), and congenital heart disorder (16.1%) [19].
