Impact of Anesthetic Technique on Acute Pain, Complications, and Chronic Pain After Inguinal Hernioplasty in a Day Surgery Setting: An Observational Study

Abstract

Background: Inguinal hernia repair is a high-volume procedure frequently performed in Day Surgery settings. While local anesthesia is often considered the gold standard, its feasibility is limited in complex cases or due to patient refusal, necessitating alternatives like general (GA) or spinal anesthesia (SA). This study evaluates the impact of these techniques on acute pain, complications, and chronic postoperative inguinal pain (CPIP). Methods: A retrospective observational study was conducted on 73 adult patients undergoing unilateral Lichtenstein hernioplasty (GA = 24; SA = 49). Pain was assessed using the Numeric Rating Scale (NRS) at discharge (T0), 24 h (T1), 7 days (T2), and 180 days (T3). Postoperative complications, rescue analgesic consumption, and perceived time to recovery were recorded. A multivariable linear regression analysis was performed to adjust pain outcomes for age, sex, and ASA status. Results: GA patients reported significantly lower median NRS scores at T0, T1, and T2 in univariate analysis (p < 0.05). However, the multivariable model did not show statistical significance for anesthetic technique as an independent predictor. Constipation was the most frequent complication (35.6%), while nausea occurred only in the SA group (10.2%). Descriptive data showed a trend toward lower rescue analgesic needs and a faster perceived time to recovery in the GA group compared to SA. CPIP incidence was remarkably low (2.7%). Conclusions: GA is a valid alternative to SA in Day Surgery, showing a clinical trend toward better early pain control, lower analgesic consumption, and improved recovery perception, although multivariable analysis did not reach statistical significance.

1. Introduction

The term “Day Surgery” refers to a diagnostic–therapeutic pathway that allows for surgical interventions, as well as invasive or semi-invasive diagnostic and/or therapeutic procedures, within a hospitalization period limited to daytime hours only; currently, it is estimated that procedures performed in a Day Surgery setting account for 60–70% of all surgeries conducted in developed countries [1]. Inguinal hernias represent a fairly common clinical condition in the general population, and the resulting surgical interest is extensive, with more than 20 million inguinal hernioplasty procedures performed annually [2]. Inguinal hernia repair, being a low-grading surgical procedure with a low risk of bleeding and complications, is one of the most frequently performed surgical procedures worldwide in a Day Surgery setting. The guiding criterion of the surgical pathway lies in an invasiveness calibrated to the type of hospitalization, with the primary objective of ensuring rapid patient discharge [3,4]. Consequently, the choice of anesthetic technique must converge toward this principle, aligning with the expectations of those undergoing surgery: the demand is for an approach that minimizes discomfort, accelerates functional recovery, and, where possible, significantly reduces overall clinical risk. The choice often falls on the local anesthesia (LA) technique, considered the gold standard [5] by major surgical societies, but it is not applicable in all clinical cases (e.g., large inguinal hernias, patient refusal); therefore, valid alternatives must be provided, such as subarachnoid anesthesia, general anesthesia, and analgo-sedation, with varying degrees of depth, as a supplement to the LA itself. Every year, millions of patients undergo inguinal hernia repair treatment, making them potentially exposed to complications that, although small in percentage terms, can collectively represent a significant issue. While in the past the greatest fear was the possibility of recurrence, today the real challenge is preventing the onset of chronic postoperative pain, which is reported in the literature with an incidence ranging from 10% to 17% [6,7]. This figure reflects the evolution in the perception of pain: increasing patient awareness and the search for high-quality standards have transformed postoperative expectations; in this context, it is likely that symptoms are perceived with greater intensity or emphasized more than in the past, placing well-being and quality of life as absolute priorities [7]. The eleventh revision of the International Classification of Diseases (ICD-11) defines chronic postoperative pain (CPSP) as pain that develops or increases in intensity after a surgical procedure at the surgical site, persisting beyond the healing process (i.e., at least 90 days) and not explained by other causes [8]. Studies regarding CPIP (Chronic Postoperative Inguinal Pain) focus primarily on different surgical choices or various prosthetic types [9]. Scientific literature identifies the main risk factors for the onset of CPIP (Chronic Post-Herniotomy Inguinal Pain) as female biological sex, young age, and high pain intensity in both the preoperative and early postoperative phases; additional factors include a prior history of non-specific chronic pain, the use of open repair techniques, and the recurrent nature of the hernia [10]. Given the clinical incidence of this complication, it is essential to plan structured evaluation and follow-up protocols aimed at ensuring timely and targeted therapeutic intervention [6]. This study aimed to evaluate if and how the choice of anesthetic technique can influence the incidence of acute and chronic postoperative pain (CPD) in patients undergoing unilateral inguinal hernioplasty (Lichtenstein technique) in a Day Surgery setting and evaluate the incidence of complications in the immediate postoperative period.

2. Materials and Methods

The study was conducted as a non-randomized retrospective observational study involving adult patients who underwent unilateral inguinal hernioplasty in a Day Surgery setting at the Corporate Multidisciplinary Day Surgery Service of the POU Umberto I in Rome. Patients operated on between June 2024 and January 2025 were selected by examining clinical documentation from the electronic archive. Data such as age, ASA physical status, gender, and the anesthetic technique used were collected from the operative reports within the patients’ electronic medical records; the investigation into postoperative well-being was conducted via telephone interviews with the patients, concomitantly with the acquisition of informed consent for study participation via telephone, followed by confirmation via email.

Inclusion Criteria

• Age > 18 years;
• Surgical repair of unilateral inguinal hernia;
• BMI between 18 and 35;
• ASA Class I–II;
• ASA Class III, provided the condition is compensated;
• Ability and willingness to understand the objectives and procedures of the day surgery regimen.

Exclusion Criteria

• Surgical and/or anesthetic ineligibility for the Day Surgery regimen;
• Deceased before the start of the study;
• Pregnancy;
• Failure to answer the call after a maximum of 3 attempts;
• Overnight stay (conversion of the Day Surgery regimen due to inability to discharge).

Primary Endpoint

The study aims to estimate the incidence of acute and chronic postoperative pain (CPD) in patients undergoing unilateral inguinal hernioplasty (Lichtenstein technique-Medtronic ProGrip^TM Self-Gripping Polypropylene Mesh-Medtronic Sofradim Production-France) in a Day Surgery setting. Pain assessment is performed using the NRS (Numeric Rating Scale) at the following time intervals:

• At the time of discharge (T0);
• 24 h after surgery (T1);
• At 7 days (T2);
• At 90 days (T3).

Secondary Endpoints

The study also aims to evaluate the incidence of complications in the immediate postoperative period, such as:

• Urinary retention;
• Post-dural puncture headache (PDPH);
• Constipation;
• Nausea and vomiting (PONV).

These parameters will also be analyzed in relation to the anesthetic technique adopted to highlight any correlations between the type of anesthesia and the occurrence of these adverse effects. Finally, the average “time to recovery” perceived by the patient within 90 days of the intervention was evaluated and correlated with the type of anesthesia performed.

2.1. Patient Selection and Evaluation

Sample Size

The sample size was calculated to estimate the prevalence of chronic pain in patients undergoing inguinal hernioplasty. In the absence of local data, an expected prevalence of 9% was hypothesized, consistent with values reported in the literature. An acceptable margin of error (precision) was set at 5%, with a 95% confidence interval. Applying the formula for minimum sample size estimation, a requirement of 100 subjects was determined.

A total of 95 patients were identified as eligible according to the aforementioned inclusion and exclusion criteria; of these, twenty patients did not respond to the telephone interview (each patient was contacted up to three times, at different time slots, before being considered unreachable), while an additional two patients were excluded as they underwent surgery under local anesthesia; 73 patients were successfully contacted at least three months after the intervention via a structured telephone interview.

Pain was assessed using the NRS scale; NRS is recommended as the preferred tool in the literature due to its higher compliance rates, superior responsiveness, ease of use, and better applicability compared to verbal scales (such as VAS or Likert scales) [11]. The numerical score from 0 to 10 was further divided into 4 subcategories [12]:

• 0: No pain;
• 1–3: Mild pain;
• 4–6: Moderate pain;
• 7–10: Severe pain.

The other sections of the interview included:

• Perceived time for complete recovery;
• Possible persistence of pain after 90 days (CPD).

2.2. Anesthetic Techniques

The anesthetic technique used was classified into two types, which determined a posteriori division of patients into two cohorts:

Subarachnoid Anesthesia (SA): Performed with a standard dose of 2% hyperbaric Prilocaine2 (3 mL)—60 mg total single shot (Prilotekal^®—Prilocaina cloridrato 20 mg/mL soluzione iniettabile iperbarica—B. Braun Melsungen, Germania)—using a 25 G needle equipped with an introducer (Pencan® New Hub, Pencil-point atraumatic spinal needle, B. Braun Melsungen—Melsungen (Germania)

• Balanced General Anesthesia (GA).

In both groups, surgical wound infiltration was performed at the end of the procedure by the operator using a mixture of local anesthetics (1% Mepivacaine (Mepivacaina Cloridrato SALF 20 mg/mL soluzione iniettabile-SALF spa Laboratorio Farmacologico-Italia) + 0.375% Ropivacaine (Ropivacaina Cloridrato SALF 7.5 mg/mL soluzione iniettabile—SALF spa Laboratorio Farmacologico-Italia)) in a total volume of 10 mL. Postoperative analgesia (until discharge, before 24 h) was standardized: 1 g IV Paracetamol (Paracetamolo 10 mg/mL SALF soluzione per infusione endovenosa- SALF spa Laboratorio Farmacologico-Italia) and potential “rescue” administration of 30 mg IV Ketorolac (Tora-dol^® 30 mg/mL Ketorolac trometamina soluzione iniettabile-Recordati Industria Chimica e Farmaceutica spa-Italia). The choice of technique was not randomized but based on clinical indications or operator preferences (such as the use of anticoagulants, risk of urinary retention due to a history of prostatic hypertrophy, or patient refusal of the spinal technique).

2.3. Statistical Analysis

Continuous variables, specifically the NRS scores relating to pain intensity, were summarized using median and interquartile range (IQR), a choice deemed most suitable for representing ordinal data not necessarily distributed according to a normal curve. For the comparison between the two main groups (General vs. Spinal anesthesia), the Mann–Whitney U test was employed—a non-parametric test suitable for comparing two independent samples in the presence of non-Gaussian distributions. For secondary endpoints (incidence of complications), Fisher’s exact test was used. All statistical analyses were performed with a significance threshold set at p < 0.05.

3. Results

• Initial Eligible Patients (June 2024–January 2025): n = 95.
• Excluded from follow-up: n = 22 (Failed to respond after 3 telephone attempts).

Final Analysis Cohort: n = 73

• General Anesthesia Group (GA): n = 24;
• Spinal Anesthesia Group (SA): n = 49.

3.1. Sample Analysis and Demographic Characteristics

Of the 95 patients initially enrolled, 73 (76.8%) were included in the final analysis, having completed the telephone follow-up three months after surgery. The sample was divided into two cohorts based on the anesthetic technique administered: 24 patients received general anesthesia (GA), while 49 patients underwent spinal anesthesia (SA). Regarding demographic and clinical characteristics:

• Gender: The male component was prevalent, with 67 subjects (91.8%) compared to 6 female patients (8.2%).
• Clinical Status (ASA Class): The distribution of classes showed that the majority of the sample belonged to ASA Class II (57 patients, 78.1%), followed by ASA Class I (14 patients, 19.2%) and, to a lesser extent, ASA Class III (2 patients, 2.7%).
• Age: The mean age in the general anesthesia group was 61.3 years (range 17–82; SD ± 13.0), while in the spinal anesthesia group, the mean value was 54.9 years (range 27–80; SD ± 13.5).

3.2. Postoperative Pain Trends

Pain was measured using the NRS scale (0–10) at four time points: the day of surgery (Day 0), at 24 h (Day 1), at 7 days, and at 3 months. Overall, median scores showed a progressive reduction over time. At three months, 72 out of 73 patients (98.6%) reported a score of 0, and only 1 patient (GA group) reported a value of 1.

When breaking down the data by cohort, significant differences were observed in the first three assessments, favoring the general anesthesia group:

• (T0) Post-intervention/Discharge:

  ○

  GA: median NRS = 3; IQR = 1–5.5;

  ○

  SA: median NRS = 6; IQR = 3.5–7;

  ○

  p = 0.0046.

• (T1) 24 h:

  ○

  GA: median NRS = 3; IQR = 1–5l

  ○

  SA: median NRS = 6; IQR = 3.5–7l

  ○

  p = 0.0109.

• (T2) 7 days:

  ○

  GA: median NRS = 0; IQR = 0–1.5;

  ○

  SA: median NRS = 2; IQR = 0–4.5;

  ○

  p = 0.0180.

• (T3) 90 days:

  ○

  GA: median NRS = 0; IQR = 0–0;

  ○

  SA: median NRS = 0; IQR = 0–0;

  ○

  p = 0.1346.

3.3. Multivariable Analysis

To account for potential confounding factors, a multivariable linear regression model was performed, adjusting for age, sex, and ASA physical status. After adjustment, general anesthesia remained associated with lower pain scores at all early time points; however, these differences did not reach statistical significance:

• Day 0: β = −1.02 (95% CI −2.52 to 0.48; p = 0.183)
• 24 h: β = −0.72 (95% CI −2.16 to 0.72; p = 0.325)
• 7 days: β = −0.75 (95% CI −2.26 to 0.77; p = 0.333)
• 3 months: β = 0.05 (95% CI −0.05 to 0.14; p = 0.329)

Operative time was not included in the model due to unavailability in the dataset. These results indicate a consistent, although non-significant, trend toward lower pain scores with general anesthesia.

3.4. Descriptive Pain Trends

A descriptive analysis confirmed a consistent pattern of lower mean pain scores in the GA group across all time points.

3.5. Analysis of Postoperative Complications

The assessment of complications was conducted based on the data collected during the telephone follow-up. The following adverse events were examined: nausea and vomiting (PONV), headache, urinary retention (requiring straight catheterization), and constipation. The absolute frequency distribution for each complication, stratified by the anesthetic technique administered, is reported below:

Within the overall sample, the incidence of postoperative complications was low. Specifically, the following were recorded:

• Constipation: 26 cases (35.6%)
• Nausea and Vomiting (PONV): 5 cases (6.8%)
• Headache: 2 cases (2.7%)
• Urinary Retention: 1 case (1.4%), requiring straight catheterization

Constipation emerged as the most frequent complication. From a pathophysiological perspective, the high incidence of postoperative constipation can be directly linked to the surgical manipulation inherent in “open” technique hernioplasty. Although this procedure does not involve laparoscopic access, the management of the peritoneal sac and the herniated viscera involves significant mechanical stimulation. Particularly in the treatment of large or longstanding hernias, characterized by tenacious adhesions along the inguinal canal, the dissection and traction of the peritoneal layers can trigger a neurogenic inhibitory reflex. This reflex mechanism leads to a transient reduction in intestinal motility (sympathetic hypertonia), explaining the slowing of peristalsis and the subsequent constipation reported by patients postoperatively. In all observed cases, the symptoms were mild and reversible: bowel function was restored through spontaneous resolution or short cycles of symptomatic therapy, with complete remission of the disorder by the end of the scheduled follow-up period.

3.6. Perceived Time to Recovery

The subjective perception of the time required for complete healing was evaluated in days, highlighting that the majority of the cohort (90.4%) reported a full recovery within the first month. Two patients (2.7%), both belonging to the SA group, did not report a subjective restitutio ad integrum at the end of the follow-up period (90 days).

Comparing the two populations, the mean recovery time in the GA group was 28.5 days (SD ± 24.56), while in the SA group (49 patients) it was 34.43 days (SD ± 22.48); however, the comparison between the two groups did not reach statistical significance (p-value = 0.140).

3.7. Postoperative Analgesic Consumption

The use of analgesic drugs was monitored at different follow-up intervals to evaluate the requirements for pain management in both groups:

• (T1) 24 h:

  ○

  GA Group: 9 patients used paracetamol, 3 patients used NSAIDs, and 12 patients did not require any analgesics.

  ○

  SA Group: 22 patients used paracetamol, 8 patients used NSAIDs, and 19 patients did not require any analgesics.

• (T2) 7 days:

  ○

  GA Group: 3 patients used paracetamol, 2 patients used NSAIDs, and 19 patients did not require any analgesics.

  ○

  SA Group: 10 patients used paracetamol, 5 patients used NSAIDs, and 34 patients did not require any analgesics.

• (T3) 90 days:

  ○

  GA Group: No patients required analgesics at 90 days.

  ○

  SA Group: No patients required analgesics at 90 days.

4. Discussion

The primary objective of this study is to evaluate the impact of anesthetic technique on the onset of postoperative pain and complications in patients undergoing unilateral inguinal hernioplasty using the Lichtenstein technique. The results obtained highlight statistically significant differences in the course of acute pain between the two analyzed cohorts, suggesting a reflection on the clinical choice of the anesthetic regimen in an ambulatory setting. The most relevant finding lies in pain control during the early phases (T0, T1, and T2). Patients undergoing general anesthesia (GA) reported significantly lower median NRS scores compared to those treated with spinal anesthesia (SA), with statistical significance persisting from discharge up to 7 days post-surgery (p < 0.05). In the context of day surgery utilizing short-acting local anesthetics such as prilocaine, general anesthesia could theoretically offer advantages in postoperative pain management compared to spinal anesthesia. This is primarily due to the phenomenon of ‘rebound pain,’ which can occur upon the resolution of the spinal block [13]. Rebound pain is defined as a transient, acute postoperative pain that manifests following the offset of sensory blockade, characterized by clinical significance in terms of intensity or its impact on psychological well-being and recovery. While literature often indicates local anesthesia as the gold standard to minimize systemic risks [14], our data suggest that, when the local option is not feasible, general anesthesia may offer a superior immediate postoperative comfort profile compared to the subarachnoid technique.

An extremely positive result is the very low incidence of chronic postoperative inguinal pain (CPIP), detected in only 2.7% of the sample at 90 days (NRS = 1). This value falls within the lower limit of the range reported in literature (10–17%). Such evidence suggests that the adoption of standardized surgical techniques and effective control of the acute algetic phase—a known risk factor for chronicity [15]—contributed to preventing nervous system sensitization. A relevant aspect of the analyzed sample concerns the gender distribution, characterized by a clear male prevalence (91.8%). Although this data faithfully reflects the epidemiology of inguinal hernia in the general population [16], it deserves careful evaluation in relation to the observed pain outcomes. Scientific literature identifies female sex as one of the main independent risk factors for the development of CPIP [10]. The very low incidence of chronic pain found in our study (2.7% at 90 days), significantly lower than the 10–17% range reported in other works, might be partially influenced by this demographic composition (The male component was prevalent, with 67 subjects (91.8%) compared to 6 female patients (8.2%). However, the optimal control of acute pain observed, especially in the general anesthesia group, remains a decisive protective factor, regardless of gender, in preventing nervous system sensitization and the transition toward pain chronicity. Regarding the perceived recovery time, the trend toward faster recovery in the GA group (28.5 days vs. 34.4 days in SA), although not reaching formal statistical significance, indicates a possible correlation between less acute pain and an earlier subjective recovery of autonomy.

The incidence of complications was low and consistent with the low-risk nature of the procedure. Statistical significance (p < 0.05) was not reached in any comparison. Specifically, for PONV, 5 cases were recorded in the SA group (10.2%) and zero in the GA group; however, the recorded p-value and the wide confidence interval indicate an imprecise estimate due to the small size of the groups under examination. Similarly, other complications showed p-values > 0.05 and wide confidence intervals; these data suggest that the observed numerical differences are attributable to sampling variability rather than real safety discrepancies between the two techniques. A finding of particular clinical interest is the incidence of constipation, which was the most frequent adverse event in the examined sample (35.6%). Traditionally, scientific literature correlates the reduction in postoperative intestinal motility mainly with the execution of general anesthesia and the use of opioid drugs [17], known for their direct inhibitory effect on myenteric plexuses. However, the results of our study seem to invert this established trend. Although opioid use is often associated with GA, the distribution of constipation in our sample was almost homogeneous between the two groups, with a slight prevalence in the spinal anesthesia group. This evidence suggests that, in the context of “open” hernioplasty, the genesis of constipation may be attributable not so much to systemic drugs as to the intrinsic nature of the surgical procedure itself. Conversely, nausea and vomiting (PONV) were recorded exclusively in the spinal anesthesia group (10.2%). This data warrants attention, as classical literature often associates PONV more closely with GA [15,18]; however, in the context of our cohort, factors such as SA-induced hypotension or the use of specific pharmacological protocols might have inverted this trend. Although the initial comparison showed significant differences, the multivariable linear regression model—adjusted for age, sex, and ASA status—did not reach statistical significance for pain scores at any time point. This suggests that while a consistent trend toward lower pain scores exists for the GA group, the observed differences may be influenced by the demographic distribution of the cohorts or the limited sample size. The lack of statistical significance in the adjusted model highlights the need for larger, randomized studies to definitively isolate the effect of the anesthetic technique from other clinical variables. Further qualitative support for the trend of improved acute pain control in the GA group is provided by the descriptive analysis of postoperative analgesic consumption. During the first 24 h (T1), a higher proportion of patients in the GA group required no analgesics (50%) compared to the spinal anesthesia (SA) group (38.8%). By the one-week follow-up (T2), this proportion increased to 79.2% for the GA cohort and 69.4% for the SA cohort. Although no formal statistical testing was performed on these specific drug consumption data, the observed frequency distribution aligns with the lower NRS scores reported by GA patients. This descriptive trend suggests that GA might facilitate a more comfortable early recovery phase, reducing the patient’s perceived need for rescue medications in the immediate days following discharge.

Study Limitations

Despite the satisfactory response rate (76.8%), the present study has some methodological limitations that must be considered when interpreting the results.

• Nature of the study: The observational and retrospective design does not allow for certain causal links between anesthetic technique and reported outcomes, as the choice of technique was not randomized but based on clinical indications or operator preferences.
• Recall Bias: The use of telephone follow-up at 90 days introduces a possible recall bias, where the perception of acute pain and recovery times may have been altered or underestimated due to the time elapsed.
• Sample Size and Balance: The cohort presents an unequal numerical distribution between the general anesthesia group (n = 24) and the spinal anesthesia group (n = 49). A larger sample and a more symmetrical balance between groups would increase the statistical power of comparative analyses and the generalizability of the results; this imbalance may also reduce the overall statistical power of the study.
• Subjectivity of data: “Perceived recovery time” is an inherently subjective variable, influenced by psychological and social factors that were not subject to objective measurement (e.g., functional tests or actual return to work).

5. Conclusions

The study confirms that inguinal hernioplasty in a Day Surgery setting represents a safe procedure, characterized by a low incidence of long-term complications and high clinical success. However, analgesia management in the early postoperative phases remains the determining factor for the patient experience and the optimization of the ambulatory pathway, in line with ERAS (Enhanced Recovery After Surgery) protocols [19]. Our results suggest that general anesthesia (GA) offers superior acute pain control compared to spinal anesthesia in the first 48 h. In a day surgery setting where rapid discharge is a priority, general anesthesia utilizing a fast-track technique—characterized by the avoidance of benzodiazepines, minimization of opioids, and a multimodal analgesic approach—may offer a more predictable and manageable pain profile compared to spinal prilocaine. This approach effectively mitigates the risk of significant rebound pain, which might otherwise occur following patient discharge once the spinal block subsides [20]

Although HerniaSurge Group guidelines indicate local anesthesia as the preferred technique to minimize systemic risks [21], GA proved to be a valid alternative in our sample to ensure faster perceived functional recovery and prompt discharge. Furthermore, the low incidence of chronic postoperative pain (2.7%) found in the 90-day follow-up is a finding of clinical importance, positioning itself at the lower limit of the range reported in literature [6,8]. This result suggests that effective acute pain management and the adoption of standardized surgical techniques are fundamental to preventing nervous system sensitization and the transition to pain chronicity [9].

In conclusion, the personalization of the anesthetic technique and the adoption of multimodal analgesic protocols are essential pillars for the success of abdominal wall surgery. Further prospective and randomized studies on larger samples will be necessary to validate the superiority of GA in terms of cost-effectiveness and to further standardize patient-centered care pathways. The Day Surgery approach is confirmed to be effective and safe. However, analgesia management in the first 48 h remains the critical factor for optimizing the patient journey. The results of this study support the use of general anesthesia as a valid alternative to spinal anesthesia, capable of ensuring more effective pain control and a smoother transition toward complete restitutio ad integrum.