Bladder exstrophy-epispadias-cloacal exstrophy complex: characteristics, aetiologies, and epidemiologic findings

Bladder exstrophy-epispadias-cloacal exstrophy complex (BEEC) is a spectrum of congenital urologic anomalies that involve the bladder, urethra, genitalia, and pelvic musculoskeletal system, and can affect urinary continence, sexual health, and fertility. BEEC includes a wide spectrum of anatomical abnormalities with different levels of severity: epispadias represents the mildest phenotype, classic bladder exstrophy (CBE) is the most common defect, and cloacal exstrophy (CE) - often referred to as omphalocele, exstrophy, imperforate anus, and spinal defects (OEIS) complex - is the most severe form. BEEC disorders cause significant health problems and affect the health-related quality of life (QoL) of affected individuals. There have been significant insights into the aetiology of BEEC in the last decade. Specifically, recent genetic studies have suggested that downstream regulator(s) of p63, Isl1, and other genes may play a role in the failure of the lower urinary tract to close. This narrative review outlines the unique anatomy of bladder exstrophy (BE) and epispadias, with a brief mention of the anatomy found in CE. A literature review using PubMed and Google Scholar databases was used to identify relevant articles on the outlined topics without placing any limitations on publication years or study designs. We included full-text English articles published in peer-reviewed journals related to the terms: "exstrophy" & "epispadias" AND "aetiology", "embryology" and "incidence". We summarise the epidemiology of this rare complex - including what is known about its incidence in Africa - before presenting recent advances in comparative genetics from mouse models and human studies that provide insights into BEEC pathogenesis.