Sharon, when you are asking this question are you looking at any specific codes? Specific codes may have details / rules that determine the answer to your question.
Without any additional information as to which codes you have in mind, I looked in a good reference book for clarification on this. In
Medical Terminology & Anatomy for ICD - 10 Coding, Betsy J. Shiland states: "The pelvis is composed of two coxal (hip) bones that are connected in the front at the pubic symphysis and in the back at the sacrum."
That is, the pelvis refers to the hip area.
By the way, Shiland's book is used as a textbook for
CodingCertification.Org's MTA course.
HTH