Yes, this reference in Act 5 to Macduff's birth is a reference to a Cesarian section.  In Act 4, the witches' prophesy states that Macbeth shall not be harmed by one born from a woman.  Macbeth narrowly interprets this advice by assuming that by nature, every person is born from a woman.  However, he does not consider that the prophesy may mean a "natural" birth through the birth canal.  As stated in the previous response, C-sections were not common at the time and were only used as a last resort in the case of emergency.  In Act 5, Macduff says that he was "untimely ripped" from his mother's womb, suggesting that he was also born prematurely.  It is possible that his mother was ill or had gotten into some type of accident that endangered her life, causing a local practitioner to take the baby from her womb earlier than planned to save his life.