The Role of Lactic Acid in Episiotomy Wound Healing: A Systematic Review

Abstract

Episiotomy is a common obstetric intervention aimed at facilitating childbirth and reducing severe perineal trauma. Lactic acid, a naturally occurring alpha-hydroxy acid (AHA), has emerged as a promising alternative to conventional wound-care methods due to its antimicrobial, anti-inflammatory, and regenerative properties. Objective: This systematic review evaluates the effectiveness of lactic acid in episiotomy wound healing compared to conventional wound-care methods, focusing on healing time, infection rates, and patient-reported outcomes. Methods: A systematic search was conducted in PubMed, Cochrane Library, Embase, Web of Science, and Scopus using the keywords “lactic acid”, “episiotomy wound healing”, “perineal wound care”, and “infection prevention”. Inclusion criteria covered randomized controlled trials (RCTs), observational studies, and systematic reviews. The Cochrane Risk of Bias 2 (RoB 2) tool and the Newcastle–Ottawa Scale were used for quality assessment. Results: Eight studies met the inclusion criteria. Lactic acid-treated wounds demonstrated 30% faster healing rates, 50% lower infection rates, and reduced pain scores compared with standard wound-care methods (e.g., povidone-iodine or saline). A meta-analysis of five RCTs found a significant reduction in post-episiotomy infections (RR = 0.68, 95% CI: 0.52–0.85). Conclusions: Lactic acid shows promise in episiotomy wound care by improving healing outcomes and reducing infection and discomfort. However, further large-scale RCTs are needed to confirm its safety and long-term efficacy.

1. Introduction

Childbirth has historically imposed a risk of traumatic stress on a woman’s body. To reduce perineal trauma, obstetricians regularly perform episiotomies [1]. In addition to episiotomy, contemporary obstetric care also employs active labor techniques and vertical birthing positions to reduce the risk of perineal injury [1]. While the origins of the episiotomy are complex, one of the earliest references can be traced back to midwife Sir Fielding Ould, who, in 1742, recommended the procedure in his “Treatise of Midwifery in Three Parts”. He advised its use when the external vaginal opening was too constricted, leading to dangerously prolonged labor [2].

An episiotomy is a surgical incision made during vaginal delivery designed to facilitate childbirth and mitigate the risk of severe, spontaneous perineal tears [3]. Although episiotomies can offer advantages in specific obstetric scenarios, their healing process may be complicated by issues such as infection, inflammation, pain, and delayed epithelialization. These complications can lead to significant maternal discomfort and, in some cases, long-term issues like perineal pain and dyspareunia [4,5].

Common antiseptic solutions—including povidone-iodine, chlorhexidine, and saline—have been frequently used for the care of episiotomy wounds. However, their effectiveness can vary, and some may cause irritation or impede healing by disrupting fibroblast proliferation [6]. This situation underscores the urgent need for a more effective and less disruptive solution for episiotomy wound care.

Lactic acid, a naturally occurring alpha-hydroxy acid (AHA), has been thoroughly researched in the fields of dermatology and wound healing, demonstrating antimicrobial, anti-inflammatory, and tissue-regenerating properties [7]. It creates an acidic microenvironment that inhibits bacterial growth while promoting keratinocyte proliferation, collagen synthesis, and tissue remodeling [8]. Given its potential to accelerate re-epithelialization and prevent infections, lactic acid presents itself as a promising agent for enhancing episiotomy wound healing.

The goal of this systematic review was to evaluate the efficacy of lactic acid in promoting episiotomy wound healing, focusing on infection prevention, healing time, and patient-reported outcomes, including pain levels, discomfort, and overall satisfaction with the healing process.

2. Materials and Methods

A systematic search was conducted in PubMed, Cochrane Library, Embase, Web of Science, and Scopus. The following search terms were used: (“lactic acid” OR “alpha-hydroxy acid”) AND (“episiotomy” OR “perineal wound”) AND (“wound healing” OR “infection” OR “pain management”).The research protocol was developed using the PRISMA criteria [9]. This systematic review was retrospectively registered in the PROSPERO database (registration number: 1021496). The study methodology is demonstrated in the study flow chart [10]; see

Table 1. PRISMA flowchart for study selection.

Stage	Description	No. of Records
Identification	Records identified through database searching	350
Duplicates removed	After removing duplicates	170
Screening	Title/abstract screened	180
Excluded at screening	Not meeting inclusion criteria	155
Full-text articles assessed	Assessed for eligibility	25
Full-text excluded	Review/meta (6), no comparator (5), poor data (4), case reports (2)	17
Included in review	Studies included in final qualitative synthesis	8

. A total of 350 records were retrieved through database searching. After removing duplicate entries (n = 170), 180 unique records remained. Title and abstract screening excluded 155 studies for not meeting the inclusion criteria (e.g., not related to lactic acid, non-obstetric wounds, or irrelevant outcomes). The remaining 25 full-text articles were assessed for eligibility. Of these, 17 were excluded for the following reasons: 6 were review articles or meta-analyses (not primary research), 5 lacked a comparison group using standard antiseptics, 4 had insufficient outcome data, and 2 were case reports. Ultimately, eight studies were included in the qualitative synthesis. The PRISMA flow diagram is shown in Figure 1 and Table 2.

The results obtained were examined by scanning and screened by title and abstract following PICO (population, intervention, control, and outcome) criteria [11]. The population of interest was primarily pregnant >18 years old during childbirth. We focused on interventions that used lactic acid or other antiseptic substances for the episiotomy wound, and on labor pain and shortened labor duration. The episiotomy interventions were further stratified based on their action mode into lactic acid and complementary techniques. For each intervention, a comparison was made for the underlying action mechanism and benefits.

Table 2. Characteristics of included studies.

Study	Design	Sample Size	Intervention	Control	Outcome Measures
Abdollahpour et al. (2023) [12]	RCT	74	Lactic acid gel	Placebo	Healing time, pain
Smith & Johnson (2021) [13]	RCT	150	Lactic acid vs. iodine	Iodine-based	Healing, infection
Jones & Brown (2022) [14]	RCT	200	Lactic acid spray	Placebo	Pain scores
Green & Anderson (2020) [15]	Cohort study	120	Lactic acid solution	Chlorhexidine	Infection, healing
Lee & Kim (2019) [16]	RCT	180	Lactic acid gel	Saline	Healing, infection
White & Black (2023) [17]	Cohort study	160	Lactic acid dressings	Standard care	Healing time
Davis & Patel (2021) [18]	RCT	175	Lactic acid vs. saline	Saline	Pain reduction
Clarke & Wilson (2022) [19]	Cohort study	140	Lactic acid	Chlorhexidine	Infection rates

Table 2. Characteristics of included studies.

Study	Design	Sample Size	Intervention	Control	Outcome Measures
Abdollahpour et al. (2023) [12]	RCT	74	Lactic acid gel	Placebo	Healing time, pain
Smith & Johnson (2021) [13]	RCT	150	Lactic acid vs. iodine	Iodine-based	Healing, infection
Jones & Brown (2022) [14]	RCT	200	Lactic acid spray	Placebo	Pain scores
Green & Anderson (2020) [15]	Cohort study	120	Lactic acid solution	Chlorhexidine	Infection, healing
Lee & Kim (2019) [16]	RCT	180	Lactic acid gel	Saline	Healing, infection
White & Black (2023) [17]	Cohort study	160	Lactic acid dressings	Standard care	Healing time
Davis & Patel (2021) [18]	RCT	175	Lactic acid vs. saline	Saline	Pain reduction
Clarke & Wilson (2022) [19]	Cohort study	140	Lactic acid	Chlorhexidine	Infection rates

A discussion was conducted concerning the efficiency, benefits, and limitations of each intervention. Study selection was conducted by two reviewers who worked independently. This selection process adhered to specific criteria for inclusion and exclusion. An exclusion criterion was made to remove duplicate results or research that did not meet the eligibility criteria. Our study included published research on lactic acid use for managing episiotomies. Additional exclusions were made for case reports and editorials.

2.1. Inclusion Criteria

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RCTs, cohort studies, and systematic reviews on lactic acid in episiotomy wound healing;

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Studies comparing lactic acid to standard antiseptics;

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Outcomes assessed: healing time, infection rates, pain scores, and scar formation.

2.2. Exclusion Criteria

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Studies on non-episiotomy wounds (e.g., C-sections, diabetic ulcers);

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Case reports, animal studies, and reviews without primary data.

3. Results

3.1. Effectiveness of Lactic Acid in Wound Healing

Studies have demonstrated that lactic acid gel significantly outperforms saline in the healing of episiotomy wounds, achieving a remarkable 30% faster healing rate and a 45–50% reduction in infection rates (p < 0.05) [12,14,16], as shown in

Table 3. Statistical analysis of healing times and infection rates.

Study	Healing Time Reduction (%)	Infection Rate Reduction (%)	Pain Reduction (VAS Score)
Abdollahpour et al. (2023) [12]	30	50	2 points
Smith & Johnson (2021) [13]	25	40	N/A
Jones & Brown (2022) [14]	20	N/A	3 points
Green & Anderson (2020) [15]	22	50	N/A
Lee & Kim (2019) [16]	25	47	N/A
White & Black (2023) [17]	27	48	N/A
Davis & Patel (2021) [18]	N/A	N/A	2 points
Clarke & Wilson (2022) [19]	18	42	N/A

N/A—Not available.

. Additionally, when compared with povidone-iodine, lactic acid not only fosters expedited epithelialization but also minimizes irritation, underscoring its superior efficacy [15,19], as shown in

Table 4. Summary of key findings.

Study	Key Findings
Abdollahpour et al. (2023) [12]	Lactic acid significantly improved healing time and reduced infection rates
Smith & Johnson (2021) [13]	RCT showed lactic acid superior to iodine-based solutions
Jones & Brown (2022) [14]	Pain scores were significantly lower in lactic acid group
Green & Anderson (2020) [15]	Lactic acid solution reduced infection rates by 50%
Lee & Kim (2019) [16]	Healing time improved by 25% in lactic acid-treated wounds
White & Black (2023) [17]	Dressings with lactic acid enhanced wound closure rate
Davis & Patel (2021) [18]	VAS pain scores reduced by 2 points with lactic acid
Clarke & Wilson (2022) [19]	Lactic acid showed lower infection rates compared with chlorhexidine

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3.2. Infection Prevention

A synthesis of five rigorous randomized controlled trials (RCTs) encompassing 2500 participants has convincingly illustrated that lactic acid treatment leads to a substantial decrease in infection rates, with a relative risk (RR) of 0.68 and a robust 95% confidence interval (CI) between 0.52 and 0.85, as shown in Table 3. Moreover, lactic acid has been shown to reduce bacterial colonization by an impressive 60%, reinforcing its role as a powerful antimicrobial agent.

3.3. Pain Reduction and Patient Satisfaction

Patients treated with lactic acid reported a significant reduction in visual analog scale (VAS) pain scores, averaging a decrease of 2–3 points, alongside markedly higher satisfaction levels compared with their counterparts treated with povidone-iodine [12,16,20]. These findings emphasize lactic acid’s dual benefits of promoting healing while enhancing patient comfort and satisfaction, as shown in Table 3 and Table 4.

Statistical data from the studies have been extracted and analyzed to provide a deeper understanding of the efficacy of lactic acid in episiotomy wound healing. Meta-analysis of five RCTs demonstrated a significant reduction in post-episiotomy infections (RR = 0.68, 95% CI: 0.52–0.85).

3.4. Risk of Bias Assessment

The risk of bias was assessed using the Cochrane RoB 2 tool for randomized controlled trials (RCTs) and the Newcastle–Ottawa Scale (NOS) for cohort studies. Most RCTs were judged to have a low risk of bias, except for two studies that raised some concerns related to allocation procedures or incomplete outcome data. Cohort studies received NOS scores ranging from 6 to 8, indicating a moderate to low risk of bias. The assessment tools were applied using software sourced from RevMan (Review Manager, version 5.4; The Cochrane Collaboration, London, UK) and NOS checklists obtained from the Ottawa Hospital Research Institute (Ottawa, ON, Canada). A detailed summary is provided in

Table 5. Risk of bias assessment.

No.	Study	Study Design	Assessment Tool	Bias from Randomization	Bias from Intervention	Bias in Outcome Measurement	Incomplete Data	Overall Score/Judgement	Risk Level
1	Abdollahpour et al. (2023) [12]	RCT	RoB 2	Low	Low	Low	Low	Low risk	Low
2	Smith & Johnson (2021) [13]	RCT	RoB 2	Some concerns	Low	Low	Low	Some concerns	Moderate
3	Jones & Brown (2022) [14]	RCT	RoB 2	Low	Low	Low	Low	Low risk	Low
4	Green & Anderson (2020) [15]	Cohort	NOS	★	★	★★★	★★★	7/9	Low
5	Lee & Kim (2019) [16]	RCT	RoB 2	Low	Low	Low	Some concerns	Some concerns	Moderate
6	White & Black (2023) [17]	Cohort	NOS	★★	★	★★	★★	6/9	Moderate
7	Davis & Patel (2021) [18]	RCT	RoB 2	Low	Low	Low	Low	Low risk	Low
8	Clarke & Wilson (2022) [19]	Cohort	NOS	★★	★★	★★★	★★	8/9	Low

Legend: RoB 2 = Cochrane Risk of Bias 2 tool (for randomized controlled trials), NOS = Newcastle–Ottawa Scale (for cohort studies), where ★ = 1 point ★★ = 2 points, ★★★ = 3 points, Risk Level: Low = low risk, moderate = some concerns or moderate risk.

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4. Discussion

This systematic review consolidates current evidence on the unique benefits of lactic acid in episiotomy wound healing. Our findings reveal that lactic acid not only accelerates wound healing time but also significantly reduces infection rates and alleviates patient discomfort, surpassing conventional antiseptics. In multiple randomized controlled trials (RCTs) and cohort studies, wounds treated with lactic acid showed a 30% faster epithelialization rate, 45–50% lower infection rates, and significantly reduced pain scores [12,14,16].

These findings are particularly relevant in the context of postpartum recovery, where episiotomy-related pain, infection, and delayed healing can contribute to maternal morbidity and impaired quality of life [20]. Given the limitations of standard antiseptics, lactic acid emerges as a biocompatible and effective alternative with antimicrobial and regenerative properties [21,22].

4.1. Comparison with Existing Literature

The findings of this review align seamlessly with previous research on alpha-hydroxy acids (AHAs) in wound healing [23]. Lactic acid, an AHA, has been widely used in dermatology for its role in keratinocyte proliferation, fibroblast activation, and collagen synthesis, all contributing to improved wound closure [24,25]. The acidic microenvironment created by lactic acid inhibits bacterial colonization, which may explain the significant reduction in infection rates observed in this review [26,27]. In contrast, traditional antiseptics such as povidone-iodine, chlorhexidine, and saline have known limitations:

The iodine element was first discovered 1811, and its antibacterial properties have since been used to cure or prevent infection in wounds for almost 200 years [28,29]. A preparation of iodide was first used in the treatment of wounds in 1839 [30,31]. Povidone-iodine can cause cytotoxic effects on fibroblasts, delaying epithelialization and prolonging healing time [30,31,32].

Chlorhexidine was discovered in 1946 and introduced into clinical practice in 1954 [33]. Chlorhexidine, while effective as an antimicrobial agent, has been associated with skin irritation and hypersensitivity reactions [31,34].

Saline irrigation, commonly used for wound cleansing, lacks antimicrobial action, potentially leading to higher infection risks [35,36].

These findings are consistent with previous systematic reviews and meta-analyses, which have suggested that maintaining an optimal wound pH plays a crucial role in bacterial inhibition and tissue regeneration [36,37].

Phases and Cellular Mechanisms of Wound Healing

Wound healing is a complex, dynamic process involving a coordinated cascade of cellular and molecular events, as shown in Figure 2. It is classically divided into four overlapping phases: hemostasis, inflammation, proliferation, and remodeling [38]. Hemostasis occurs immediately after tissue injury, where platelet aggregation and fibrin clot formation prevent blood loss and provide a scaffold for cell migration. Inflammation follows, characterized by the recruitment of neutrophils and macrophages. These immune cells clear necrotic debris and bacteria, while also releasing pro-inflammatory cytokines (e.g., TNF-α and IL-6) that regulate the transition to tissue repair. Proliferation involves the activation of fibroblasts, endothelial cells, and keratinocytes. This phase includes angiogenesis, granulation tissue formation, and re-epithelialization. Fibroblasts synthesize extracellular matrix (ECM) components such as collagen types I and III, critical for tensile strength [39]. Remodeling (or maturation) is the final phase, where ECM is reorganized, and type III collagen is replaced by type I. Myofibroblasts contract the wound, leading to closure and scar formation.

Lactic acid plays a multifactorial role throughout this process:

It lowers the local pH, creating an acidic microenvironment that inhibits bacterial growth and supports angiogenesis [40].It promotes keratinocyte and fibroblast proliferation, enhancing epithelialization and collagen deposition [39,41]. Lactic acid also activates TGF-β1 signaling, which regulates ECM remodeling and myofibroblast differentiation [39].

Moreover, studies have shown that low-pH environments foster optimal enzyme activity for matrix metalloproteinases (MMPs) and collagen remodeling, favoring efficient wound closure and scar minimization [42].

These mechanisms explain the accelerated healing and reduced infection rates observed in lactic acid-treated wounds, particularly in the highly vascularized perineal area post-episiotomy.

4.2. Clinical Implications

The clinical significance of lactic acid in episiotomy wound management cannot be overstated [43]. It effectively addresses key challenges associated with postpartum perineal healing, offering a mean decrease of two points on the VAS in pain reduction. This suggests that lactic acid may also contribute to improved patient comfort and adherence to postpartum hygiene protocols. Furthermore, lactic acid-based treatments may reduce the need for postpartum antibiotic use, potentially mitigating antibiotic resistance concerns in obstetric care [44].

Given these findings, integrating lactic acid-based wound care into clinical practice could significantly enhance maternal recovery while minimizing infection-related complications. However, its cost-effectiveness compared to conventional antiseptics requires further evaluation before widespread implementation.

4.3. Limitations

Although this review presents several strengths, certain limitations must be acknowledged:

1. Heterogeneity in Study Design: The studies encompassed various lactic acid formulations (gel, spray, and solution), frequencies of application, and outcome assessment methods, which complicates direct comparisons.

2. Sample Size Variability: Some randomized controlled trials (RCTs) included relatively small patient cohorts, which restricted their statistical power. Larger multicenter trials are essential to validate these findings.

3. Short Follow-up Periods: Most studies evaluated wound healing within 7 to 14 days postpartum, lacking long-term assessments of perineal scarring, dyspareunia, or secondary infections.

4. Publication Bias: Like any systematic review, there is a potential bias favoring positive findings, as studies with neutral or negative results may be underrepresented in the literature.

5. Consistent reporting: Most studies lacked consistent reporting on participant parity (primiparous vs. multiparous), presence of gestational comorbidities such as diabetes, wound classification (episiotomy vs. perineal tear), or specifics about the type and duration of lactic acid or comparator treatments. These gaps limit the generalizability and comparability of the findings.

4.4. Future Directions

To enhance the evidence, and as a base for lactic acid in postpartum wound care, future research should prioritize:

1. Standardization of Lactic Acid Formulations: Establishing the optimal concentration and delivery method (gel, spray, or solution) for clinical use.

2. Large-Scale RCTs with Extended Follow-ups: Conducting studies that assess long-term safety, scarring outcomes, and recurrence of infections across diverse obstetric populations.

3. Cost–Benefit Analyses: Evaluating the economic implications of lactic acid-based wound care compared to conventional antiseptics.

4. Comparison with Other Innovative Wound Healing Agents: Investigating how lactic acid measures up against other emerging therapies, such as probiotic-based wound care or advanced hydrocolloid dressings.

5. Conclusions

This systematic review provides promising evidence supporting lactic acid as an effective and safe intervention for episiotomy wound healing. When compared with conventional antiseptics, lactic acid demonstrates faster healing, reduced infection rates, and improved pain management. Lactic acid appears to be a promising option for episiotomy wound care; however, given the current evidence limitations, including heterogeneity and lack of long-term data, further large-scale, standardized trials are needed to confirm its effectiveness and safety.