sequence (medicine) sequence (medicine) in medicine, a sequence is a series of ordered consequences due to a single cause. it differs from a syndrome in that seriality is more predictable: if a causes b, and b causes c, and c causes d, then d would not be seen if c is not seen. however, in less formal contexts, the term "syndrome" is sometimes used instead of sequence. examples include: oligohydramnios sequence (also known as potter sequence) pierre robin sequence poland sequence