The purpose of this pilot study is to assess the analgesic efficacy of Erector Spinae Plane block (ESPB) with liposomal bupivacaine in women undergoing cesarean delivery and receiving a postoperative multimodal analgesic regimen as assessed by the dose of rescue postoperative opioids compared to a historical control group of women receiving the same multimodal regimen but with no truncal blocks. This will be a case control study with a prospective and a retrospective component. Women undergoing elective cesarean delivery under spinal or combined spinal epidural anesthesia will be approached to participate in the prospective open label component of the study. Cases will be matched in a 1:4 ratio by age, race, history of prior cesarean delivery, and insurance status with historical controls who received the same multimodal analgesic regimen but no truncal blocks. We plan to enroll 30 subjects for the prospective arm of the study and 120 for the retrospective arm.

This will be a case control study with a prospective and a retrospective component. Women undergoing elective cesarean delivery under spinal or combined spinal epidural anesthesia will be approached to participate in the prospective open label component of the study. Those women will receive the standard of care intraoperative and postoperative analgesic regimen used at Duke university incorporating 100 mcg intrathecal morphine, intraoperative acetaminophen 975 mg PR and ketorolac 15 mg IV and postoperative scheduled oral acetaminophen 975 mg every 6 hours, scheduled 15 mg IV ketorolac for 3 doses every 6 hours followed by oral ibuprofen 600 mg every 6 hours. At the end of surgery, a bilateral ESPB will be performed under ultrasound guidance using 133 mg liposomal bupivacaine and 20 ml bupivacaine 0.25% per side.

Cases will be matched in a 1:4 ratio by age, race, history of prior cesarean delivery, and insurance status with historical controls who received the same multimodal analgesic regimen but no truncal blocks.

Inclusion Criteria:

• Patients ≥18 years of age with a term pregnancy of 37 to 42 weeks and American Society of Anesthesiologists Physical Status Classification II or III scheduled to undergo elective CD.

Exclusion Criteria:

• ≥3 prior CDs, pre-pregnancy body mass index >40 kg/m2, planned concurrent surgical procedure other than tubal ligation, chronic pain or chronic opioid therapy, any clinically significant event or condition uncovered during surgery (eg, excessive bleeding, acute sepsis) that might render the patient medically unstable or complicate the patient's postsurgical course, or allergy or contraindication to any component of the multimodal analgesic regimen.

Up to 48 hours