Infantile hypertrophic pyloric stenosis: An association in twins?

The etiology of infantile hypertrophic pyloric stenosis (IHPS) remains a mystery. Some suspected risk factors include birth rank, maternal age, sex, family history and monozygosity in twins. Various theories attempt to explain the etiology of IHPS. Scientific research suggests that enteric neuronal damage and nitric oxide synthase dysfunction may be implicated, but the consensus is that environmental modification must exist to account for the variability in its occurrence. Four cases of concordant occurrences of IHPS in twins were examined to determine the history and outcome of IHPS development in twins. Three sets were dizygotic and one was monozygotic. Of the eight infants, three were female, including the one monozygotic pair. In all four cases, a time lag existed between the development of symptomatic onset of IHPS in twin A and twin B. In one set, sonographic confirmation, performed because of IHPS diagnosis in the twin sibling, occurred concurrently with onset of vomiting, leading to early surgery before fluid and electrolyte imbalances developed. Despite the lack of agreement as to whether the cause of IHPS is genetic, environmental or both, the high concordance rate seen in twins is indisputable. Thus, the empirical evidence provides credence to consider examining the asymptomatic co-twin when one of the twins presents with IHPS.