Exparel PK and Breast Milk Excretion

Inclusion Criteria: 1. Pregnant women \>18 year old, scheduled for elective Cesarean delivery and who desire to have a TAP block performed after delivery. 2. American Society of Anesthesiologists physical status I, II, and III Exclusion Criteria: 1. Patient refusal or inability to cooperate. 2. Allergy, hypersensitivity, intolerance, or contraindication to liposomal bupivacaine. 3. Severely impaired renal or hepatic function (eg, serum creatinine level \>2 mg/dL \[176.8 µmol/L\], blood urea nitrogen level \>50 mg/dL \[17.9 mmol/L\], serum aspartate aminotransferase \[AST\] level \>3 times the upper limit of normal \[ULN\], or serum alanine aminotransferase \[ALT\] level \>3 times the ULN). 4. Participants at an increased risk for bleeding or with any coagulation disorder (defined as platelet count less than 80, 000 × 103/mm3 or international normalized ratio greater than 1.5) (all contraindications to TAP block). 5. Clinically significant medical disease in either the mother or baby that, in the opinion of the investigator, would make participation in a clinical study inappropriate. This includes any psychiatric or other disease in the mother that would constitute a contraindication to participation in the study or cause the mother to be unable to comply with the study requirements. 6. Patient membership in a vulnerable population such as a prisoner, mentally unable to provide direct consent etc. 7. Participant has contraindication to breastfeeding or not planning to breastfeed the first 2-3 days after delivery.