<prompt> A new born girl not passed meconium for 48 hrs, has abdominal distention and vomiting, Initial investigation of choice would beManometryGenotyping for cystic fibrosisLower GI contrast studySerum trypsin immunoblot  <response>: bowel obstruction with an absent caecal gas shadow in ileocolic cases. A soft tissue opacity is often visible in children. A barium enema may be used to diagnose the presence of an ileocolic intussusception the claw sign Ref: Bailey Love;s Sho Practice of Surgery,E25,Page-1196 