Endometriosis is a condition that causes significant pelvic pain and affects 10-15% of reproductive age women. Treatment options area both medical and surgical for pain relief, however with surgical options, past studies have demonstrated a higher risk of surgical complications as well as higher postoperative pain scores in women with endometriosis. Despite attempts to limit narcotic pain medications with enhanced recovery after surgery (ERAS) protocols, persistent opioid use after surgery is a national crisis, and it is important to explore multimodal options for pain relief. Various studies have shown improvement in pain with use of superior hypogastric nerve blocks in gynecologic surgery, but these effects have not yet been examined in the setting of a minimally invasive endometriosis resection. The goal of this clinical trial is to determine if a superior hypogastric nerve plexus block with 0.25% bupivacaine hydrochloride can decrease postoperative pain and opioid requirements in patients undergoing robotic assisted resection of endometriosis for the first week after surgery. Researchers will perform a superior hypogastric nerve plexus block by either injecting 0.25% bupivacaine hydrochloride (investigative treatment) or normal saline (placebo) in subjects who are undergoing a robotic assisted resection of endometriosis. To determine if postoperative pain is reduced, the subject will be asked to rate their pain score on the Visual Analog Scale (VAS) at 0 hours, 2 hours and 4 hours postop while in the Post-anesthesia Care Unit (PACU). They will then document their pain score each day on a form provided to them for 7 days after surgery. To determine the effect of this research study on postoperative opioid requirements, the subject will be asked to fill out a form documenting how many tablets of an opioid medication they took each day for a total of 7 days after surgery.