A neonate at 48 hours of bih with a history of non passage of meconium. Next step in evaluation will be ?

Delayed meconium passage(generally defined as non-passage within the first 48 hours after bih) is mainly a condition of preterm infants and is repoed in up to one third of preterm and low bih weight infants due to factors such as delayed maturation of colorectal motility mechanisms, composition of meconium,. Hence, lower GI study rule out the cause . Reference: GHAI Essential pediatrics, 8th edition