Objectives Surgical site infiltration (SSI) and transversus abdominis plane (TAP) block are postoperative analgesic techniques. Liposomal bupivacaine may prolong analgesic effects. We hypothesize that surgical site infiltration of liposomal bupivacaine will reduce opioid consumption in the 48-hour postoperative period compared to TAP block.

Methods A single blind randomized controlled trial comparing surgical site infiltration of liposomal bupivacaine versus TAP block with liposomal bupivacaine after midline vertical laparotomy in patients with suspected or known gynecologic malignancy. Negative binomial regression was used to estimate the differences in total morphine milligram equivalent (MME) use between groups. Multivariable linear regression of pain scores on visual analog scale 0–10 was used at each time interval (2, 6, 12, 24, and 48 hours postoperatively) while controlling for medication use and age.

Results Of 43 patients, 22 received SSI and 21 received TAP block. Mean age was 57.8 (SD = 11.50). There were no significant differences in demographics, incision length, surgery duration or pathology between groups. After controlling for age and BMI, there was not a statistically significant difference in total MME between the treatment groups (β = -0.17, 95% CI = -0.77, 0.43, p = 0.59). There were no statistically significant differences in pain scores (both resting and exertion) at all time points after controlling for age and pain medication utilization.

Conclusions Surgical site infiltration of liposomal bupivacaine did not reduce opioid use and did not decrease pain scores within 48 hours after surgery compared to TAP block after midline vertical laparotomy for gynecologic cancer.