Cite as: Grajales-Reyes JG, Salianski O, Blessing M. ASRA answers: does intrathecal morphine still have a role in modern ERAS pathways?. ASRA Pain Medicine News 2026;51. https://doi.org/10.52211/asra080126.005.

ASRA Answers

Introduction

Intrathecal morphine (ITM) is among the most effective opioid-sparing analgesic techniques in perioperative medicine. While widely accepted as standard of care in obstetric anesthesia, adoption across other surgical subspecialties remains inconsistent despite increasing emphasis on opioid-sparing approaches, such as enhanced recovery after surgery (ERAS) pathways and multimodal analgesia.¹ ERAS protocols, developed in the early 1990s to optimize postoperative recovery through evidence-based and multidisciplinary perioperative care,² emphasize use of multimodal analgesia strategies to reduce opioids, facilitate early mobilization, and shorten hospital length of stay.³ With the proliferation of different multimodal analgesic regimens and peripheral nerve blocks (PNBs) in non-obstetric surgery, the role of ITM remains uncertain. Does it continue to offer clinically meaningful benefits within modern ERAS pathways, and does ITM offer additive benefit beyond what blocks alone can achieve?

Evidence and Literature Review

ITM has consistently demonstrated opioid-sparing efficacy across multiple surgical populations. In laparoscopic colorectal surgery, Kong et al. in a 2002 double blind randomized controlled trial (RCT) of 36 patients showed that ITM (0.2 mg) significantly reduced parenteral opioid requirements for 48 hours postoperatively.⁴ The more precise clinical question, whether ITM adds meaningful benefit on top of PNBs within modern ERAS pathways, is answered by a much smaller body of evidence.

Zheng et al. (2025) conducted a large double-blind RCT (n = 252) within a fully developed ERAS protocol, comparing ITM with liposomal bupivacaine transversus abdominis plane (TAP) blocks to TAP blocks alone; this study demonstrated not only significantly lower opioid consumption but also superior quality of recovery and earlier ambulation with ITM.⁵ The reason for this is likely because TAP blocks cover somatic pain only, and ITM addresses the additional visceral pain as well.

Aside from this study, most of the available literature compares ITM with nerve blocks rather than testing the combination. In open abdominal surgery, Kjølhede et al. (2019) RCT (n = 80) showed that ITM shortened length of stay with lower opioid consumption and equivalent pain control compared to an epidural in gynecologic cancer laparotomy.⁶ In pancreatic surgery, Burchard et al. (2022) used retrospective data to show ITM decreased opioid consumption and accelerated functional recovery after pancreaticoduodenectomy on its own and when combined with a TAP block (n = 233).⁷ When compared with truncal PNBs alone, ITM has been associated with a significant reduction of pain scores and opioid consumption in the immediate post-operative period and even leads to an increased rate of extubation in the operating room.⁸ However, when compared to epidural in a pre-existing ERAS protocol, ITM plus PNBs were found to provide comparable analgesia without further benefit in length of stay or recovery.⁹

The obstetric literature offers an instructive comparison. The established consensus in obstetric anesthesia — supported by multiple RCTs — is that TAP blocks do not add significant analgesic benefit when ITM is used for cesarean section.¹⁰ However, studies that addressed adding ITM to peripheral nerve block (PNB), the scenario we are trying to address in non-obstetric surgery, have found benefit.¹¹

Dosing in ERAS Pathways

Dosing practices have moved toward lower doses to minimize adverse effects, though optimal dosing varies by surgery. Most of the data guiding the use of ITM come from obstetric anesthesia. In obstetrics, the Society of Obstetric Anesthesia and Perinatology suggests little additional analgesic benefit above 75-100 mcg.¹² However, a recent RCT from Borreli and colleagues looked at doses of 50 mcg, 150 mcg, and 250 mcg of ITM and found longer analgesic duration with the higher dose (250 mcg) without any increase in the frequency of adverse effects.¹³ In addition, patients who received 250 mcg of ITM remained opioid free up until 72 hours after cesarean section.¹³

In orthopedics, for hip and knee arthroplasty, a meta-analysis of 29 articles and 1,814 patients suggested 100 mcg as a “ceiling” dose for analgesia, beyond which the frequency of post-operative nausea and vomiting increases without additional analgesic benefit.¹⁴ In a randomized dose-finding study in total hip arthroplasty (THA), Slappendel et al. found that 0.1 mg of ITM provided effective analgesia with fewer adverse effects than higher doses.¹⁵ Higher doses were associated with more pruritus and hypotension, while lower doses provided worse pain control. However, ITM is not recommended for ambulatory procedures, but this study supports 0.1 mg as an effective dose for THA and is worth considering if same-day discharge is not planned. Studies on ITM for THA have focused on comparing it with PNBs as competing strategies rather than evaluating their combined use. Consequently, whether low-dose ITM provides clinically meaningful additional analgesia when incorporated into modern hip ERAS pathways that use fascial plane blocks remains uncertain. The same could be said for total knee arthroplasty, where PNB use is even more common. Teunissen et al performed a meta-analysis of 75 RCTs of ITM use in non-abdominal surgery. For lower extremity arthroplasty, ITM with spinal anesthesia was less effective when local infiltration was also used.¹⁶

In colorectal surgery, doses of 0.2 mg-0.3 mg have been shown to provide meaningful analgesic benefit while minimizing adverse effects.^5,17 Williams et al. found that higher-dose ITM (250 mcg), when used with an aggressive five-drug antiemetic regimen, may extend analgesia to approximately 16 hours compared with roughly 8 hours at lower doses (< 200 mcg), while also reducing reliance on systemic opioid administration.¹⁸

For minimally invasive gynecologic surgery, Russo et al. performed a retrospective, dual-center cohort study that included 100 female patients undergoing robotic-assisted laparoscopic hysterectomy, who received low-dose ITM. The 0.15 mg group demonstrated significantly lower pain scores and reduced supplemental opioid requirements. While no respiratory depression was observed in either dose group, opioid-related effects, such as pruritus and postoperative nausea and vomiting, were present in both. This study supports 0.15 mg as a potential “sweet spot” between efficacy and tolerability in robotic ERAS pathways for surgery associated with moderately intense pain.¹⁹

For major abdominal oncologic procedures, larger doses have been studied and may be beneficial. Fares and colleagues performed an RCT comparing 200 mcg, 500 mcg, and 1,000 mcg in 90 patients undergoing major abdominal cancer surgery. The highest dose (1,000 mcg) provided the highest level of analgesia for the first 48 hours post-operatively, with no differences in side effects except for pruritus, which was more common at the highest dose.²⁰

In summary, determining the appropriate dose of ITM for a specific procedure and patient population should be based on evidence, with the goal of maximizing ITM’s opioid-sparing properties while minimizing the frequency of adverse effects or complications. Also, the dose may vary depending on the invasiveness of a given surgery, while the amount of somatic versus visceral pain may determine the degree to which ITM provides benefits beyond those achieved with local anesthetics administered by the surgeon or in PNBs performed by the anesthesiologist. Dose should not be based on body weight, since cerebrospinal fluid (CSF) volume does not vary by weight in adults. Instead, the pharmacokinetics of intrathecal morphine are influenced by its hydrophilicity, baricity, and CSF dynamics, leading to rostral spread and dose-related pharmacodynamic effects.

Common Side Effects of ITM

Adverse effects of ITM can be differentiated into two categories: pulmonary and non-pulmonary. Fear of delayed respiratory depression — occurring 6-24 hours after administration due to the hydrophilic nature of morphine — is the major reason for provider avoidance of ITM. As a result, it is important to adhere to the American Society of Anesthesiologists and ASRA Pain Medicine recommendations for 24 hours of monitoring following neuraxial opioid administration.²¹

Non-respiratory adverse effects, such as pruritus, nausea, and drowsiness, are typically mild and manageable, though they may negatively affect the patient experience. Rarely, post-dural puncture headache may occur from intrathecal administration. Importantly, these effects are not incidental but reflect the expected pharmacologic profile of ITM: Higher doses increasingly yield more pruritus and postoperative nausea and vomiting with diminishing additional analgesic benefit.²² Pruritus is a meaningful barrier in susceptible patients. This dose-dependent relationship reinforces the principle of using the lowest effective dose and supports incorporating preoperative patient education into ERAS pathways to optimize recovery and facilitate early discharge.

Answers & Future Directions

The literature on ITM reveals a consistent pattern of broad analgesic efficacy limited by dose-dependent adverse effects across a broad range of surgical populations. Based on the evidence discussed here, a strong argument can be made for wider implementation of ITM in ERAS pathways for analgesia for patients who will be admitted for at least 24 hours of postoperative observation. But the more clinically precise question is whether ITM adds meaningful benefit on top of PNBs within modern ERAS pathways, which is addressed by a much smaller body of evidence. For procedures with significant visceral pain, particularly abdominal and pelvic surgery, the mechanistic rationale for ITM within ERAS pathways is sound and directly supported by the Zheng and Boisen trials.^5,8 For somatic-dominant procedures such as orthopedic arthroplasty, the evidence suggests ITM and nerve blocks perform comparably as alternatives without clearly demonstrating additive benefit from combination. The direct combinatorial question of whether ITM plus blocks versus blocks alone is more effective remains formally unanswered in most non-obstetric surgical settings and represents the most important gap for future research to address.

Renewed interest in ITM does not reflect the emergence of a novel technique, but rather the re-evaluation of a well-established analgesic strategy within modern multimodal perioperative care. Current evidence supports low-dose ITM (0.1-0.15 mg) providing the best balance of analgesia and tolerability for appropriately selected patients undergoing surgery associated with moderately intense pain, while doses of 0.2-0.25 mg or higher may be considered for more painful open abdominal procedures.¹⁶ The role of ITM in ambulatory ERAS pathways remains limited by 24-hour monitoring requirements. ITM has been used in many types of non-obstetric surgery (thoracic, abdominal, spine, lower extremity orthopedic, gynecologic, urologic); however, discussing its application and the evidence for all of these types of surgery is beyond the scope of this article.

Ultimately, wider implementation will depend less on questions of efficacy, which the literature has already answered, and more on institutional comfort with postoperative monitoring, workflow integration, and management of predictable opioid-related adverse effects.²¹ The question of the direct combination of ITM plus PNBs remains formally unanswered in most non-obstetric surgical settings and represents the most important gap for future research to answer.

References

1. Karamese M, Akda O, Tosun Z. The Comparison of intrathecal morphine and IV morphine PCA on Pain control, patient satisfaction, morphine consumption, and adverse effects in patients undergoing reduction mammoplasty. Eplasty 2015;15:e15
2. Taurchini M, Del Naja C, Tancredi A. Enhanced recovery after surgery: a patient centered process. J Vis Surg 2018;4:40. https://doi.org/10.21037/jovs.2018.01.20
3. Simpson J, Bao X, Agarwala A. Pain management in enhanced recovery after surgery (ERAS) protocols. Clin Colon Rectal Surg 2019;32(2):121-8. https://doi.org/10.1055/s-0038-1676477
4. Kong S, Onsiong SMK, Chiu WKY, et al. Use of intrathecal morphine for postoperative pain relief after elective laparoscopic colorectal surgery. Anaesthesia 2002;57(12):1168-73. https://doi.org/10.1046/j.1365-2044.2002.02873.x
5. Zheng L et al. Intrathecal morphine for enhanced recovery after laparoscopic colorectal surgery: a randomized clinical trial. JAMA Surg 2026;161(2):124-31. https://doi.org/10.1001/jamasurg.2025.5699
6. Kjølhede P, Bergdahl O, Borendal Wodlin N, et al. Effect of intrathecal morphine and epidural analgesia on postoperative recovery after abdominal surgery for gynecologic malignancy: an open-label randomised trial. BMJ Open 2019;9(3):e024484. https://doi.org/10.1136/bmjopen-2018-024484
7. Burchard PR, Melucci AD, Lynch O, et al. Intrathecal morphine and effect on opioid consumption and functional recovery after pancreaticoduodenectomy. J Am Coll Surg 2022;235(3):392-400. https://doi.org/10.1097/XCS.0000000000000261
8. Boisen ML et al. Intrathecal morphine versus nerve blocks in an enhanced recovery pathway for pancreatic surgery. J Surg Res 2019;244:15-22. https://doi.org/10.1016/j.jss.2019.05.049
9. El-Mallah JC, Greene AC, Clegg TJ, et al. Comparison of epidural infusion versus intrathecal morphine block as part of enhanced recovery after open pancreatoduodenectomy. J Surg Oncol 2024;129(5):869-75. https://doi.org/10.1002/jso.27574
10. Mishriky BM, George RB, Habib AS. Transversus abdominis plane block for analgesia after Cesarean delivery: a systematic review and meta-analysis. Can J Anaesth 2012;59(8):766-78. https://doi.org/10.1007/s12630-012-9729-1
11. Hutchins JL et al. The addition of intrathecal morphine to a transversus abdominis plane block with liposome bupivacaine provides more effective analgesia than transversus abdominis plane block with liposome bupivacaine alone: a retrospective study. Local Reg Anesth 2019;12:7-13. https://doi.org/10.2147/LRA.S190225
12. Bauchat JR et al. Society for Obstetric Anesthesia and Perinatology consensus statement: monitoring recommendations for prevention and detection of respiratory depression associated with administration of neuraxial morphine for cesarean delivery. Anesth Analg 2019;129(2):458-74. https://doi.org/110.1213/ANE.0000000000004195
13. Borrelli MC, Sprowell AJ, Moldysz A, et al. A randomized controlled trial of spinal morphine with an enhanced recovery pathway and its effect on duration of analgesia after cesarean delivery. Anaesth Crit Care Pain Med 2024;43(1):101309. https://doi.org/10.1016/j.accpm.2023.101309
14. Gonvers E, El-Boghdadly K, Grape S, et al. Efficacy and safety of intrathecal morphine for analgesia after lower joint arthroplasty: a systematic review and meta-analysis with meta-regression and trial sequential analysis. Anaesthesia 2021;76(12):1648-58. https://doi.org/10.1111/anae.15569
15. Slappendel R, Weber EW, Dirksen R, et al. Optimization of the dose of intrathecal morphine in total hip surgery: a dose-finding study. Anesth Analg 1999;88(4):822-6. https://doi.org/10.1097/00000539-199904000-00026
16. Teunissen AJW, Van Gastel L, Stolker RJ, et al. The use of intrathecal morphine in non-abdominal surgery: a scoping review. BJA Open 2025;14:100387. https://doi.org/10.1016/j.bjao.2025.100387
17. Koning MV, Teunissen AJW, Van Der Harst E, et al. Intrathecal morphine for laparoscopic segmental colonic resection as part of an enhanced recovery protocol: a randomized controlled trial. Reg. Anesth. Pain Med 2018;43(2):166-73 https://doi.org/10.1097/AAP.0000000000000703
18. Williams BA, Hall DE, Dalessandro C, et al. Patient-centered intrathecal morphine dose response in major abdominal surgeries when augmented by innovative five-drug antiemetic prophylaxis. Front Anesthesiol 2025;4:1521409
19. Russo A, Perelli F, Aceto P, et al. Intrathecal morphine dose optimization in robotic-assisted laparoscopic hysterectomy: a dual-center cohort study. J Robot Surg 2026;20(1):481. https://doi.org/10.1007/s11701-026-03445-y
20. Fares KM, Mohamed SA-B, Abdel-Ghaffar HS. High dose intrathecal morphine for major abdominal cancer surgery: a prospective double-blind, dose-finding clinical study. Pain Physician 2014;17(3):255-64.
21. Practice Guidelines for the Prevention, Detection, and Management of Respiratory Depression Associated with Neuraxial Opioid Administration: An Updated Report by the American Society of Anesthesiologists Task Force on Neuraxial Opioids and the American Society of Regional Anesthesia and Pain Medicine. Anesthesiology 2016;124(3):535-52. https://doi.org/10.1097/ALN.0000000000000975
22. El‐Boghdadly K. et al. Pulmonary complications after intrathecal morphine administration: a systematic review and meta‐analysis with meta‐regression and trial sequential analysis. Anaesthesia 2025;80(8):959-72. https://doi.org/10.1111/anae.16606