BackgroundMany patients complain of pain following laparoscopic surgery. Clinicians have used ultrasound-guided posterior transversus abdominis plane block (TAPB) and rectus sheath block (RSB) for multimodal analgesia after surgery. We investigated the analgesic effects of US-guided posterior TAPB with RSB on postoperative pain following laparoscopy-assisted radical resection of early-stage rectal cancer.MethodsSeventy-eight adults scheduled for laparoscopy-assisted radical resection of rectal cancer were enrolled in this double-blind placebo-controlled trial. Patients were randomized into 3 groups: the TR Group underwent US-guided bilateral posterior TAPB (40 mL 0.33% ropivacaine) with RSB (20 mL 0.33% ropivacaine); the T Group underwent US-guided bilateral posterior TAPB alone; and the Control Group received saline alone. All patients also had access to patient-controlled intravenous analgesia (PCIA) with sufentanil. The primary outcome was postoperative sufentanil consumption at 0–24, 24–48, and 48–72 h. The secondary outcomes were postoperative pain intensity and functional activity score at rest and while coughing for the same three time periods, intraoperative medication dosage, use of rescue analgesia, recovery parameters, and adverse effects.ResultsThe three groups had no significant differences in baseline demographic and perioperative data, use of intraoperative medications, recovery parameters, and adverse effects. The TR group had significantly lower postoperative use of PCIA and rescue analgesic than in the other two groups (P < 0.05), but the Control Group and T Group had no significant differences in these outcomes.ConclusionsPostoperative US-guided posterior TAPB with RSB reduced postoperative opioid use in patients following laparoscopy-assisted radical resection of rectal cancer.Trial registrationThe trial was registered with chictr.org (ChiCTR2000029326) on January 25, 2020.