Since its inception, Enhanced Recovery After Surgery (ERAS) protocols have steadily gained traction and acceptance. ERAS protocols are evidence-based multi-modal and multidisciplinary protocols focused on enhancing post-operative recovery and decreasing complication rates [1]. While traditionally applied to inpatient admissions, potential benefits exist with application in an ambulatory setting. When implemented correctly they have been demonstrated to reduce recovery time and post-operative complication rates [1]. Several prominent randomized trials and meta-analyses have demonstrated that the implementation of ERAS in colorectal surgery patients improved post-operative recovery and decreased morbidity rates and hospital length of stay [2,3,4]. However, despite the demonstrated success in colorectal surgery and other surgical disciplines the application to ambulatory procedures has been debated.

Inguinal hernia repairs are one of the most common outpatient procedures performed by general surgeons, with over 20 million operations performed annually around the world [5]. Patient outcomes after elective hernia repair have been favorable with a low mortality rate for elective operations [6] and recurrence rates between 0.5 and 15% dependent on the type of repair [5, 7]. Two of the more frequent events adding morbidity include uncontrolled post-operative pain and post-operative urinary retention (POUR). We applied ERAS principles to our ambulatory MIS inguinal hernia repair practice, with a key component of no longer prescribing outpatient narcotic prescriptions for the vast majority of patient. We aim to study POUR and uncontrolled post-op pain using these protocols compared to historic laparoscopic inguinal hernia repair controls.

Materials/methods

A retrospective review of a prospectively maintained, IRB-approved database was performed. All patients who underwent minimally invasive inguinal hernia repair with either a laparoscopic or robotic-assisted approach were identified. All operations were performed by 4 MIS faculty surgeons with trainee (resident/fellow) assistance.

Recorded patient demographics included age, sex, American Society of Anesthesiologists (ASA) score, date of surgery, and ERAS protocol application. Recorded operative data included hernia laterality, history of prior repair, surgical approach, total operative time, intra-operative, post-operative, total narcotic dosage, fluid administration, intra-operative adjunct medication usage, and discharge with or without a narcotic prescription. All narcotic dosage was converted and reported as an oral morphine equivalent dose.

Primary outcomes included POUR and post-operative pain complications. POUR was defined as the need for an indwelling urethral catheter on discharge for urinary retention, post-operative admission for retention, or return to the emergency department or primary care physician for treatment of retention. Post-operative pain complications were defined as patients whose post-operative pain required an additional narcotic prescription, admission for pain control, or emergency department visit for pain control. Secondary outcomes included other post-operative morbidities.

Patients were then divided into 2 groups based on participation in our institution’s ambulatory ERAS protocol. All patients whose surgery occurred in the year 2018 and onward were stratified as part of the ERAS cohort.

Our institution’s ERAS protocol encompassed pre-operative, intra-operative, and post-operative components. A patient’s journey through our ERAS protocol started with their pre-operative clinic visits. There, education regarding their surgery and post-operative management were performed, with special attention on post-operative pain control. Specific education was applied toward utilization of non-narcotic methods of pain control (acetaminophen, ibuprofen, ice packs) and setting expectations for no written narcotic prescriptions for home usage.

Intra-operative components included a multi-modal approach from surgery, anesthesia, and nursing staff. Surgical aspects included subcutaneous administration of a bupivacaine–epinephrine mixture at incision sites and clear communication with the anesthesia and nursing teams. Anesthesia components focused active warming, optimal pain and nausea management with minimal narcotic usage, and goal-directed fluid administration. A standard pre-operative cocktail of non-narcotic adjuncts including either oral or parenteral acetaminophen with or without gabapentin, pregabalin, and/or celecoxib were administered when not contraindicated. Intra-operative adjuncts included parenteral lidocaine and ketorolac for pain control and parenteral dexamethasone and sugammadex for prevention of POUR when appropriate. When using narcotic medications, shorter acting agents such as fentanyl were preferred. Foley catheters were not routinely placed preoperatively for bladder decompression. Patients were encouraged to urinate prior to the operation and decompressed with one-time catheterization if they were unable to or noted to have a full bladder intraoperatively. As a Foley catheter was not routinely placed, goals for fluid administration were set at a maximum of 500 cc of crystalloid should the patient’s hemodynamic status allow. Subgroup analysis of intra-operative and post-anesthesia care unit (PACU) medications and fluid administration was performed only for patients whom data were available; patients whose operation were performed prior to wide spread use of the electronic health system at our institution were not included in this subgroup analysis as their intra-operative and PACU data were not available.

Post-operative components once again focused on minimizing narcotic medication usage and minimizing fluid administration. Shorter agents such as fentanyl were again preferred with parenteral hydromorphone or oral narcotics used should pain remain uncontrolled within the PACU. Patients were discharged without a narcotic prescription per protocol. Patients were encouraged to ambulate early and when able. Patients were discharged after they had recovered from anesthesia, controlled their pain, and had help returning home. The need to urinate prior to discharge was individually assessed per attending surgeon guidance.

Surgical technique

All laparoscopic repairs were performed with either a transabdominal preperitoneal (TAPP) or a totally extraperitoneal approach (TEP) based on surgeon preference and patient factors. Mesh fixation tack use was minimized and peritoneal incisions were closed with running PDS suture.

Statistical analysis

All statistical analysis was performed with GraphPad Prism version 9.2.0. The appropriate statistical analyses were chosen based on the number and type of dependent and independent variables. A two-tailed student’s T test or Mann Whitney U test was performed to compare two groups of numerical variables. A Chi-Squared or Fischer’s Exact test was performed to evaluate groups of categorical variables. Univariable logistic regression was performed to evaluate predictor effects on POUR. Multivariable logistic regression was not performed due to an inadequate size of the POUR group. Analysis of intra-operative data including narcotic usage, fluid administration, and adjunct medication usage was performed only for patient’s whose data were available. The level of significance was set as an alpha value equal to or less than 0.05 for all test except the univariable logistic regression which was set at an alpha value of equal to or less than 0.1.

Results

1097 patients were identified between January 2008 and March 2021 who underwent minimally invasive inguinal hernia repair. The average age was 57.4 (16–91) years, 93% of the patients were male. The average American Society of Anesthesiologists (ASA) score was 2.06 (1–4). 91.3% of cases were performed laparoscopically with the remainder performed with robotic assistance. Left-sided hernias comprised 33.4%, while right sided and bilateral hernias made up 43.9% and 22.7%, respectively. The average follow-up period was 43.7 (1–1827) days. Further demographic information can be found in Table 1.

Table 1 Demographics
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Primary outcomes included POUR and post-operative pain complication rates. A total of 33 patients with POUR were identified, comprising 3.0% of the total patient population. 25 patients were identified to have post-operative pain complications, comprising 2.2% of the total patient population. Secondary outcomes included rates of post-operative morbidity. 94 (9.0%) patients in total acquired a post-operative morbidity. 36 (3.0%) patients acquired a seroma, 3 (0.2%) a superficial surgical site infection, and 1 (0.09%) patient was readmitted for a small bowel obstruction. Results can be found in Table 2.

Table 2 Primary outcomes
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Outcomes were then compared between ERAS and non-ERAS groups. There were a total of 479 ERAS patients comprising 43.7% of the total patient population. Among primary outcomes there was a lower incidence of POUR among the ERAS group (1.4%/4.2%, p value 0.01) without a significant difference in post-operative pain complication rates (1.4%/4.2%, p value 0.07). There were no significant differences among secondary outcomes. Significant differences were also found between groups in ASA score (2.02/2.14, p value 0.03), intra-operative narcotic dosage (18.3 mg/23.2 mg, p value 0.0001), PACU narcotic dosage (16.8 mg/22.8 mg, p value 0.002), total narcotic dosage (28.7 mg/37.7 mg, p value 0.0001), and intra-operative fluid amount (622.2 cc/897.6 cc, p value 0.0001). No differences were found between age (57.3/57.4 years) and operative time (64.2/63.9 min) (Table 3).

Table 3 ERAS vs non-ERAS
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Analysis was similarly performed between the totally extraperitoneal (TEP) and transabdominal preperitoneal (TAPP) approaches. There was no significant difference in POUR rates between the TEP (3.4%) and TAPP (2.9%) approach (p 0.77). These results can be found in Table 4.

Table 4 TEP vs TAPP
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Sub-analysis was also performed between patients discharged with and without a narcotic prescription. 929 (84.6%) of patients were discharged with a narcotic prescription and 168 (15.4%) of patients were not. The rate of patients discharged without a narcotic script required an adjustment period after initiation. Our institution demonstrated an 18% compliance with our ERAS protocol in 2018 which steadily improved to a 78% compliance in 2021 (Fig. 1). Patients who were discharged without a narcotic prescription had a 0% POUR rate compared to 3.5% rate for those with a prescription (p = 0.005). There were no differences between post-operative pain complication rates (2.3%/1.7%, p value 0.99) (Table 5).

Fig. 1
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Rates of narcotic-free discharge vs POUR

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Table 5 Narcotic vs narcotic-free discharge
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Analysis was performed to evaluate for differences between rates of POUR with certain intra-operative adjuncts, primarily sugammadex and dexamethasone. 650 patients had available intra-operative anesthesia data after implantation in the electronic health system record. 293 (45%) patients were found to have been administered Sugammadex. A significant difference was found between POUR rates with sugammadex versus without (0.6%/5.6%, p value 0.0003). 494 (76%) of patients were administered dexamethasone with 2.4% having POUR compared to a 6.4% POUR rate without dexamethasone (p = 0.02).

Further analysis was performed evaluating patients who received both sugammadex and dexamethasone, sugammadex only, dexamethasone only, and neither. The combination of both medications had a POUR rate of 0.7%, sugammadex and dexamethasone alone demonstrated rates of 0% and 4.2%, respectively, and giving neither medication resulted in a POUR rate of 8.3%. Significant differences were found between giving both medications versus either dexamethasone only or neither medication (p value 0.01 and 0.0003, respectively). We then evaluated for differences between ERAS and non-ERAS patients who received intra-operative adjuncts. 2% of non-ERAS patients received sugammadex, while 55% of non-ERAS patients received dexamethasone. No difference was found between ERAS and non-ERAS POUR rates among sugammadex patients (0.5% vs 0%, p 0.99). A higher rate of POUR was discovered among non-ERAS dexamethasone patients compared to ERAS dexamethasone patients (5.5% vs 1.5%, p 0.02). These results can be found in Table 6.

Table 6 Intra-operative adjuncts
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Table 7 Pain analysis
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Regarding post-operative pain complications, analysis was performed between patients with and without uncontrolled post-operative pain. Patients who were found to have uncontrolled post-operative pain received higher intra-operative, PACU, and total narcotic doses (29.1 mg/37.7 mg/64.6 mg) compared to patients without uncontrolled post-operative pain (19.5 mg/17.8 mg/30.5 mg, p values 0.0003, 0.0001, 0.0001). Administration of intra-operative or PACU ketorolac was also evaluated with no significant difference in pain rates (Table 7).

Finally, a univariable analysis of possible POUR predictors was performed. Predictors included age, participation in the ERAS protocol, operative time, fluid volume administered, intra-operative, post-operative, total narcotic dose, sugammadex usage, and dexamethasone usage. Significant risk factors included age (OR 1.06, p value 0.0001), increased fluid volume (OR 1.001, p value 0.04), increased PACU narcotics (OR 1.01, p value 0.01), and increased total narcotics (OR 1.01, p value 0.03). Significant protective factors included ERAS (OR 0.33, p value 0.01), use of sugammadex (OR 0.11, p value 0.003), and use of dexamethasone (OR 0.35, p value 0.01) (Table 8).

Table 8 POUR predictors
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Discussion

Since its introduction, ERAS has challenged traditional peri-operative doctrine in order to minimize metabolic stress and promote an enhanced return to function [1, 8]. One of the first major successes with ERAS protocols occurred within the field of colorectal surgery. Vlug et al. were able to demonstrate in their randomized trial a reduction in length of hospital stay [2], and several meta-analyses have demonstrated a lower rate of morbidity and shorter hospital stay with colorectal surgery [3, 4]. Similar improvements in outcomes have been demonstrated in urology, gynecology–oncology, spinal procedures, bariatrics, and major oncologic resections [8,9,10,11,12,13,14]. However, application of ERAS protocols to ambulatory surgery has not been as extensive [15, 16]. We were able to demonstrate reductions in post-operative morbidity, specifically urinary retention, with the application of an ERAS protocol in the ambulatory surgery setting. In addition, the application of an ambulatory ERAS protocol was found to be a protective factor on univariable analysis (OR 0.33). However, acceptance and widespread application of these protocols take time. In our own institution, compliance the first couple of years after introduction was low. However, after the ambulatory ERAS protocol became widely used POUR rates decreased. This reduction in POUR was likely due to inherent multimodality approach associated with ERAS, including decreased administration and prescription of narcotics, decreased fluid administration, and use of adjunct medications to combat POUR.

Narcotic administration and post-operative urinary retention have been well described in the literature [17,18,19,20]. Koch et al. in their review of 153 minimally invasive inguinal hernia repairs found an increase in POUR rates among patients who received post-operative narcotics [21]. Narcotic administration is thought to contribute to and be a risk factor for POUR via parasympathetic inhibition, reducing the sensation of bladder fullness and sympathetic overstimulation, increasing bladder outflow resistance [17, 22, 23]. We demonstrated a significant decrease in intra-operative, PACU, and total narcotic doses alongside a lower POUR rate between our ERAS and non-ERAS groups. This in turn aligns with univariable analysis describing higher PACU and total narcotic doses as predictive risk factors for POUR.

Alongside decreased intra-operative and PACU narcotic administration, a key component of our ambulatory ERAS protocol involved discharging patients home without a narcotic prescription. In our study no POUR patients were discovered in the narcotic prescription-free group and there was no difference in the rate of uncontrolled post-operative pain between the narcotic prescription versus the no-narcotic prescription groups. The ability to effectively treat post-operative pain and reduce morbidity without a narcotic prescription has significant implications, especially in regards to the current opioid epidemic. Since the late 1990’s the rate of opioid overdoses has tripled, while opioid prescription has nearly quadrupled [24, 25], costing 78.5 billion dollars annually due to health care, abuse treatment, and lost productivity [26, 27]. Surgeons and surgical patients play a unique role, as narcotic pain control remains the standard of care despite intra- and post-operative narcotic administration being recognized as significant risk factors for chronic opioid use and addiction [24, 28]. Alongside direct risk for the patient, narcotic prescriptions can further exacerbate the epidemic as up to 60% of opioid tablets remain unused [29]. These unused pills then become potential diversion sources for non-medical use, as up to 66% of non-medical opioid users report their source as family and friends [30]. Thus, the ability to treat post-operative pain with a multi-modal non-narcotic method can help reduce the opioid epidemic by reducing both direct patient risks and decreasing potential sources of narcotic diversion.

Fluid administration is another commonly cited risk factor for POUR due to over distention of the bladder [31,32,33]. In the randomized trial by Keita et al. with 313 patients evaluating for predictive factors of POUR, an intra-operative fluid administration of greater than 750 cc was found to have an odds ratio of 2.3 for early retention [34]. Similarly Kwaan et al. demonstrated a 20% risk increase for each liter of intra-operative fluid given in their retrospective review of 205 patients undergoing rectal resection [35]. Koch et al. suggested in their review that peri-operative fluid administration may be more important than intra-operative administration [21]. In our review we found a significant association between the amount of intra-operative fluid administration and POUR rates. Both ERAS and Non-POUR groups had significantly lower volumes of intra-operative fluid compared to their counterparts and intra-operative fluid administration was a significant risk factor on univariable analysis with an odds ratio of 1.001.

In order to provide optimal operating conditions, neuromuscular paralysis is often induced with reversal typically performed using neostigmine and glycopyrrolate. However, both neuromuscular blockade and reversal with glycopyrrolate are potential risk factors for POUR due to decreased contractility of the bladder detrusor muscle [36, 37]. Sugammadex, a modified y-cyclodextrin reversal agent, is able to minimize these risks as it does not exhibit muscarinic side effects [36, 38]. In addition, dexamethasone has been postulated to help decrease POUR rates by decreasing inflammation around the bladder [39]. We demonstrated a decrease in POUR rates with the administration of sugammadex and dexamethasone. In addition, both sugammadex and dexamethasone were found to be protective factors against POUR (OR 0.11 and 0.35, respectively). These results are similar to reviews performed by Morales et al. and Denham et al. studying the effects of sugammadex and dexamethasone on POUR rates in inguinal hernia patients, respectively [40, 41].

Several limitations to this study include its inclusion of only minimally invasive inguinal hernia repairs, less than total availability of intra-operative parameters in the medical record, and inability to do multivariable analysis due to the total number of patients with POUR. During the beginning of our ambulatory ERAS protocol, we decided to focus on minimally invasive repair versus open due to the better post-operative pain profile associated with minimally invasive repair. This allowed us for easier application of our no-narcotic prescription protocol and permitted increased patient buy-in and adherence. Minimally invasive inguinal hernia repair has also been thought to be more closely associated with POUR when compared to open approaches given the proximity of dissection to the bladder [21, 42]. However, further study to include the open cohort may add further insight we have begun the inclusion of open repair to our ambulatory ERAS protocol. Regarding the intra-operative parameters, our institution fully transitioned all medical records to the electronic system in 2014. Intra-operative parameters such as narcotic, adjunct medication, and fluid administration were difficult to obtain prior to that date. Analysis of intra-operative parameters were only performed on patients whose data were fully available (650 patients in total). In a similar vein, our institution’s yearly POUR rates increased after 2014. This is most likely due to more inclusive data collection after implementation of the electronic medical record, suggesting that the currently reported rates of POUR is underreported for the years prior to 2014. Should we exclude those years, the difference in POUR rates between the ERAS and non-ERAS groups would likely become even more dramatic. Finally, we were unable to perform a multivariable logistic regression regarding POUR and various predictors given our lower number of patients with POUR and were only able to perform univariable analysis. A multivariable analysis in the future with a greater number of POUR patients can potentially shed further insight into risk and protective factors for POUR in this patient population.

In conclusion, implementation of an ambulatory ERAS protocol can significantly decrease urinary retention and narcotic usage rates after minimally invasive inguinal hernia repair. Pre-, intra-, and post-operative adjuncts each likely play a major role in improving outcomes and a multidisciplinary approach is critical for success.