Ultrasound-guided Transversus Abdominis Plane Block After Abdominal Hysterectomy: a Prospective Randomized Controlled Trial

Patients undergoing abdominal hysterectomy (n=75) at Parkland Hospital will be randomized into one of three groups to receive either ultrasound-guided bilateral TAP block with or without NSAIDs and acetaminophen (Groups 1 and 2) or the conventional analgesic regimen (Group 3) for postoperative pain management. The remaining aspect of perioperative care, including the general anesthetic technique, will be standardized and similar for all patients. The duration of the involvement in the study will be until 48 hours postoperatively. The pre-anesthesia care unit personnel will identify patients during their preoperative clinic visit. There will be no incentive or payment to the patients.

Patients in Group 1 and 2 will receive ultrasound-guided bilateral TAP block after surgery. In the first 24-h postoperative period, patients in Groups 1 and 3 will receive acetaminophen 650 mg every 6 h orally, ketorolac 30 mg every 6 h, and morphine via an intravenous patient controlled analgesia (IV-PCA) system to maintain adequate pain control. Patients in Group 2 will receive IV-PCA morphine for the first 24 hours in addition to the ultrasound-guided bilateral block. In the 24-48 h study period, all patients will receive oral ibuprofen 800 mg three times a day and a combination of hydrocodone/acetaminophen 5mg/500 mg 1-2 tablets every 6h, prn. The postoperative analgesia will be documented using the visual analog score (0=no pain,10=worst pain). In addition, total opioid dose over the 48-h study period will be documented. Postoperative nausea will be measured using a categorical scoring system (none=0, mild=1, moderate=2, severe=3) and episodes of vomiting will be documented. Rescue antiemetics will be given to any patient who complains of nausea or vomiting. All variables will be assessed at 2, 6, 12, 24, and 48 hours, postoperatively by an investigator blinded to group allocation.

Primary endpoint will be in about 24 hours after surgery morphine consumption. The secondary endpoints will include the VAS pain score at 6, 12, 24 and 48 hours after surgery and side effects associated with morphine use.