Etiology and Embryogenesis

The exact embryogenesis of CPC is not known. In 1959, Trusler proposed that the dilatation was the result of chronic obstruction, but this theory was discarded as the pouch fails to decrease in size even after colostomy [2]. Another theory proposed was aborted hindgut development following obliteration of the inferior mesenteric artery early in fetal life [18]. Chatterjee proposed that the cecum and right colon develop normally from the postaxial midgut when this portion of the midgut is stimulated by normally developing hindgut [12]. Thus improper development of the postaxial midgut or presplenic gut is due to a primary disorder of the proximal end of the hindgut or postsplenic gut.

Wu Yuejie suggested that faulty rotation and fixation of the colon leads consequently to a disturbed longitudinal growth [10]. Chadha et al. proposed that varying extents of vascular insult at the time of the partitioning of the cloaca by the urorectal septum could explain the different types of the malformation [17]. Wakhlu et al. have postulated that CPC represents a stage in the development of cloacal exstrophy and is the combined effect of defective development of the splanchnic layer of the caudal fold and failure of rotation of the gut, causing defective longitudinal growth of the colon [19].

In the authors' view, the high density of cases in the northern belt of the Indian subcontinent points toward environmental factors, with deficiency of iodine or vitamin B as some of the possible factors contributing to this anomaly. In the recently conducted survey on this anomaly from various pediatric surgical centers in India, Pakistan, Bangladesh, Nepal, Sri Lanka, Italy, Sweden, and Japan, the incidence was reported to be the highest in north India (Kashmir, Chandigarh, Delhi, Lucknow, Varanasi), but decreased as we proceeded toward the east. It was uncommon in Bangladesh (1.07%); however, in Pakistan, the incidence was as high as 8% of all ARM. Only sporadic cases have been seen from Sweden, Japan, and Italy, and were reported merely as curiosities (personal communications).

As the blood supply is always abnormal to the pouch in these patients, an early vascular insult cannot be ruled out. It is only the superior mesenteric artery that is prominent and supplies the whole distal bowel. The inferior mesenteric artery is present in only 50% of cases of distal CPC, and it is also quite insignificant. A genetic predisposition also needs to be ruled out.

The north Indian belt is also known as the stone belt (due to the deficient nutritional factors in the diet) and also for the iodine deficiency in the water there. The land is very fertile and the pesticides are used liberally in the fields. The population is mainly vegetarian and consume lot of fresh vegetables in the diet. In addition, most of the population with ARM in this region have a low socioeconomic status. All of these factors suggest environmental factors affecting or precipitating the anomaly at a window time after conception when the hindgut is developing and differentiating into urinary and intestinal tracts.

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