Effect of Preoperative Versus Postoperative Use of Transversus Abdominis Plane Block With Plain 0.25 % Bupivacaine on Postoperative Opioid Use

A Retrospective Study

Richard Kalu; Peter Boateng; Lauren Carrier; Jaime Garzon; Amy Tang; Craig Reickert; Amalia Stefanou


BMC Anesthesiol. 2021;21(114) 

In This Article


Patient Selection

All patients who received TAP blocks during a transabdominal colorectal resection between August 2018 and January 2020 were identified through hospital chart review. The TAP procedure was performed by the regional anesthesiologist on duty that day. The majority of TAP blocks are performed preoperatively in our institution. At times, the TAP block was done at the conclusion of the operation often due to timing issues. All included patients underwent colorectal resection done by colon and rectal surgeons at our tertiary care hospital. We abstracted patient demographics, medical comorbidities, preoperative diagnosis, past medical and surgical history, procedure-related details, and postoperative opioid use after the index operation until discharge. The study was approved by the Henry Ford Health System Institutional Review Board. This manuscript was conducted in accordance with the ethical standards laid down in the amended 1964 Declaration of Helsinki.

Patients were divided in 2 groups based on timing of TAP block procedure: before (preoperative) or immediately after (postoperative) their surgical procedure.

TAP Block Technique

Under ultrasound guidance, TAP blocks were performed by, or under supervision of, the attending anesthesiologist who specializes in acute pain management and regional anesthesia. The blocks were performed either 1 h preoperatively or at the conclusion of the surgery procedure within 30 min of reaching the post-anesthesia care unit. The TAP block consisted of bilateral injection of 20 mL of 0.25 % plain bupivacaine in the fascial plane between the internal oblique and transversus abdominis muscles in the midaxillary line. None of the patients in the 2 groups received additional regional anesthesia, including epidural or spinal anesthesia.

Additional Multimodal Adjuncts

Our postoperative pain management protocol consisted of scheduled acetaminophen, muscle relaxant (methocarbamol or cyclobenzaprine), gabapentin, and ketorolac in the absence of any contraindication. Patient-controlled analgesia (PCAs) were initiated for patients who had inadequate pain control, had pain-related hypertension or tachycardia, or were unable to ambulate or participate in pulmonary toilet. All patients were routinely assessed for their pain levels. However, the use of numerical pain scoring was not consistent amongst the patients and hence, was not included in the study. While there may be minor differences in pain management based on specific surgeon-preference, most of the patients were treated using this protocol. Finally, the decision to prescribe discharge opioid was based on several factors such as surgeon's discretion, the level patient's pain control, and history of chronic opioid use.


The primary outcome of the study was postoperative opioid use. The incidence, type, and total amount of opioid in milligram morphine equivalent (MME) and non-opioid analgesic medications administered after the index procedure were recorded. Secondary outcomes included procedure-related operative details, length of hospital stay, rates of readmission, and reoperation.

Statistical Analysis

Statistical analyses were conducted to compare the baseline characteristics of the patients who received preoperative TAP blocks with those who received postoperative TAP blocks. Continuous variables were described using the mean and standard deviation (SD), and categorical variables were described with the frequency and percentage. Analysis of variance or Kruskal–Wallis tests were used for continuous variables and chi-square tests or Fisher's exact tests were used for categorical variables as appropriate. P < 0.05 was considered statistically significant. All analyses were done in SAS 9.4 (SAS Institute, Cary, NC).