Does massive irrigation reduce the risk of intra-abdominal abscess after laparoscopic appendectomy for perforated appendicitis?

doi:10.21203/rs.3.rs-5217597/v1

Purpose

This study aimed to determine if massive intra-abdominal irrigation reduced the risk of postoperative intra-abdominal abscess (PO-IAA) after laparoscopic appendectomy (LA) for perforated appendicitis in pediatric patients.

Methods

A case-control study was conducted at Saitama Prefectural Children’s Medical Center from January 2014 to December 2023. Sixty-nine pediatric patients with perforated appendicitis who underwent LA were included. Patients were divided into PO-IAA and PO-IAA-free groups. We compared the irrigation volume (IV), ratio of IV to body weight (IV/BW), and ratio of IV to body surface area (IV/BSA) between the two groups. Statistical analyses were performed to identify significant differences and optimal cutoff values.

Results

The PO-IAA-free group had a significantly higher IV (median 8000 mL vs. 6000 mL, p= 0.014), IV/BW (270.9 mL/kg vs. 159.2 mL/kg, p = 0.009), and IV/BSA (7500.6 mL/m² vs. 4890.6 mL/m², p = 0.008) than the PO-IAA group. Receiver operating characteristic curve analysis identified cutoff values of 6000 mL for IV, 234.6 mL/kg for IV/BW, and 6352.2 mL/m² for IV/BSA.

Conclusion

Massive intra-abdominal irrigation during LA for perforated appendicitis in children may be effective in preventing PO-IAA.

irrigation

postoperative intra-abdominal abscess

laparoscopic appendectomy

perforated appendicitis

Perforated appendicitis accounts for 15–20% of all cases of pediatric appendicitis [1, 2]. Perforated appendicitis is in turn a significant risk factor for postoperative intra-abdominal abscess (PO-IAA), which occurs in 5–10% of pediatric patients with perforated appendicitis [2–5]. PO-IAA prolongs hospitalization due to long-term antibiotic use, drainage, and reoperation [6, 7]. Many surgeons have therefore attempted to improve the surgical technique and perioperative management of appendectomy to prevent PO-IAA, and intraperitoneal irrigation has been the subject of much discussion [1, 6, 8–13].

Intraperitoneal irrigation for peritonitis was first reported in 1906, since when it has been performed by many surgeons [1, 9, 14], with only 7% of pediatric surgeons in North America in 2004 not performing intraperitoneal irrigation during appendectomy [15]. We also irrigate the abdominal cavity with a large volume of saline solution during laparoscopic appendectomy (LA) for perforated appendicitis. Several studies have compared irrigation with suction alone, most of which supported the suction-alone approach and indicated that irrigation was ineffective in preventing PO-IAA [8, 10, 16]; however, most studies that supported the suction-alone approach reported irrigation volumes (IV) of 500–1000 mL [1, 6, 9, 11–13, 17]. We have irrigated until the irrigation solution was clear, with an empiric IV of 500–1000 mL, which is insufficient. In contrast, few reports have examined the effects of a large IV on PO-IAA, and although several reports have compared irrigation versus suction alone and massive irrigation versus suction alone [1, 6, 8–13, 16, 17], no reports have examined the effect of the IV.

This study aimed to compare the IV between patients with and without PO-IAA. As a secondary objective, we also compared the IV to body weight (IV/BW) and IV to body surface area (IV/BSA) ratios between the PO-IAA and PO-IAA-free groups to identify the parameters determining the IV.

1.1. Study Design and Setting

This case-control study was conducted at a single institution (Saitama Prefectural Children’s Medical Center) between January 2014 and December 2023. The study conforms to the STROBE reporting guidelines [18]. Data were collected retrospectively from medical records at Saitama Prefectural Children’s Medical Center.

1.2. Inclusion and Exclusion Criteria

The study population consisted of pediatric patients diagnosed with perforated appendicitis who underwent LA. Perforation was defined as an intraoperative finding of a hole in the appendix. Patients with simple appendicitis, without perforation, interval appendectomy, or those who underwent percutaneous drainage were excluded, because extensive irrigation was not typically performed in such cases.

Not all patients underwent postoperative imaging studies. Patients with postoperative fever, abdominal pain, and elevated inflammatory response who underwent computed tomography or abdominal echocardiography and had intra-abdominal abscesses were classified as the PO-IAA group.

2.3. Variables and Measurements

Preoperative patient characteristics (age, sex, height, BW, body mass index (BMI), BSA), days until surgery after symptom onset, highest perioperative serum leukocyte count, highest perioperative serum C-reactive protein (CRP) level, duration of antibiotic use, presence of PO-IAA, and IV were collected. The primary outcome was the difference in IV between patients with and without PO-IAA. The secondary outcomes were differences in IV/BW, IV/BSA, operation time, and intraoperative blood loss between the PO-IAA- and PO-IAA-free groups.

For perforated appendicitis, we selected antibiotics that primarily target Gram-negative rods and anaerobic bacteria, and administered antibiotics until the inflammatory response became negative.

2.4. Sample Size

Our sample size calculation was based on the study by Melanie et al. [16], who examined the relationship between the amount of intraperitoneal lavage during appendectomy and residual abscess. In this study, the incidence of residual abscess was 0% (0/140) in the high intraperitoneal washout group and 6.2% (18/292) in the other groups. A correlation coefficient of 0.5, alpha of 0.05, and power of 0.9 determined the required sample size as 68.

2.5. Statistical Analysis

Statistical analyses were performed using appropriate software (EZR version 1.67) [19]. Descriptive statistics were calculated for all variables. Categorical variables were compared with Fisher’s exact tests, continuous variables with a normal distribution with t-tests, and continuous variables with a non-normal distribution with Mann-Whitney U tests. Statistical significance was set at p < 0.05. Receiver operating characteristic (ROC) curves were applied to obtain the area under the curve (AUC) and to determine ideal cutoffs.

2.6. Ethical Considerations

The study protocol was reviewed and approved by the Institutional Review Board of Saitama Prefectural Children’s Medical Center. Informed consent was obtained from the parents or guardians of all participants. Data confidentiality was maintained in accordance with the institutional guidelines and regulations.

A total of 1136 patients were hospitalized and treated for appendicitis between January 2014 and December 2023, and 369 patients underwent LA. Of these, 69 patients were enrolled based on the operative findings (Fig. 1). 49 patients were assigned to the PO-IAA-free group and 20 to the PO-IAA group.

3.1. Patients

The patient characteristics are shown in Table 1. There were no significant differences in demographics (age, sex, height, BW, BMI, BSA), highest perioperative serum CRP, days until surgery after symptom onset, and duration of antibiotic use between the groups; however, the highest perioperative serum leukocyte level was significantly higher in the PO-IAA group.

3.2. Outcomes

The results are presented in Table 2. The median IV in the PO-IAA-free group was 8000 mL compared with 6000 mL in the PO-IAA group (p = 0.014). We created a ROC curve showing the relationship between sensitivity and 1−specificity for different thresholds of IV, to determine the IV required for PO-IAA prevention (Fig. 2). The curves help to determine the optimal cutoff values for the assessed parameters in predicting the prevention of PO-IAA. The Youden index was used as the cutoff value [20]. The cutoff value for IV was 6000 mL and the AUC was 0.688. The median IV/BW was significantly higher in the PO-IAA-free group (270.9 mL/kg) compared with the PO-IAA group (159.2 mL/kg) (p = 0.009). The cutoff value for IV/BW was 234.6 mL/kg, with an AUC of 0.702 (Fig. 2). The median IV/BSA was significantly higher in the PO-IAA-free group (7500.6 mL/m²) compared with the PO-IAA group (4890.6 mL/m²) (p = 0.008). The ROC curve for IV/BSA indicated a cutoff value of 6352.2 ml/m², with an AUC of 0.702 (Fig. 2). There were no significant differences in operative time or intraoperative blood loss between the two groups. The outcomes were compared using the Mann-Whitney U test, because both datasets were non-normally distributed according to the Shapiro-Wilk normality test.

The results of this study showed that patients without PO-IAA had a significantly larger IV than those who developed PO-IAA. In terms of the secondary outcomes, IV/BW and IV/BSA were also significantly higher in the PO-IAA-free group. The lack of any significant difference in operative time or intraoperative blood loss between the PO-IAA and PO-IAA-free groups indicated that massive intraoperative rinsing could be performed safely. We also generated ROC curves to determine if IV was effective for preventing PO-IAA, and the AUC values suggested that cutoff values of IV/BW 234.6 mL/kg and IV/BSA 6352.2 mL/m² may be effective.

Several previous studies have reviewed the use of intraoperative irrigation in patients undergoing surgery for perforated appendicitis. Shawn et al. reported no significant differences between pediatric patients treated with intraoperative irrigation and suction alone for perforated appendicitis in terms of the incidence of PO-IAA (19.1% and 18.3%, respectively, p = 1.0) and length of hospital stay (5.5 ± 3.0 and 5.4 ± 2.7 days, respectively, p = 0.93) [9]. Zhou et al. reviewed a randomized controlled study that examined the amounts of intraperitoneal washings for intraperitoneal infections. They found no advantages between intraperitoneal lavage compared with suction alone in terms of mortality (0% and 1.1%, respectively; relative risk [RR] 0.31, 95% confidence interval [CI] 0.02–6.39], intra-abdominal abscess (12.3% vs. 11.8%, respectively; RR 1.02, 95% CI 0.70–1.48; I² = 24%), incisional surgical site infections (3.3% vs. 3.8%, respectively; RR 0.72, 95% CI 0.18–2.86; I² = 50%), postoperative complications (11.0% vs. 13.2%, respectively; RR 0.74, 95% CI 0.39–1.41; I² = 64%), reoperation (2.9% vs. 1.7%, respectively; RR1.71, 95% CI 0.74–3.93; I² = 0%), and readmission (5.2% vs. 6.6%, respectively; RR 0.95, 95% CI 0.48–1.87; I² = 7%) [13]. Several other studies found that irrigation did not produce superior results in terms of PO-IAA prophylaxis compared with suction alone [1, 3, 6, 12, 17]. However, similar to the current results, Fengbo et al. and Melanie et al. studied intraoperative massive irrigation in patients with perforated appendicitis (> 2 L and 3–12 L, respectively) and found that both were effective in preventing PO-IAA [10, 16].

Intraperitoneal lavage has been considered to be ineffective for several possible reasons: (1) bacteria may adhere to the peritoneal mesothelial cells, such that irrigation cannot decrease the microorganism load on the peritoneum; (2) irrigation may cause bacterial dislocation and diffuse or remote inoculation, leading to pollution by spreading microorganisms; and (3) irrigation may dilute mediators of phagocytosis, such as opsonic proteins and immunoglobulins [13]. However, IV in the previous studies that recommended suction alone rather than irrigation was 500–1000 mL in each case, which is insufficient compared to our IV, and we assume that insufficient IV was the reason why irrigation was found to be ineffective [1, 6, 9, 11–13, 17]. The current results, however, suggest that massive irrigation may be effective in preventing PO-IAA, at least by physically reducing intraperitoneal bacteria.

The strength of this study lies in its finding that massive irrigation may effectively help to prevent PO-IAA, as a major complication of perforated appendicitis, and the generated ROC curve can estimate the amount of IV required. Because pediatric appendicitis can occur at various ages, from infants to adolescents, the definition of massive irrigation may vary depending on the patient’s size. Additionally, the AUC values for IV/BW and IV/BSA may also help to determine the amount of washing required to prevent PO-IAA.

One limitation of this study was its retrospective design. In addition, the study did not compare the results with the outcomes of suction alone, which has been the standard procedure in many studies. Further studies are therefore required to compare suction alone with massive irrigation.

Massive intra-abdominal irrigation may help to prevent PO-IAA in children undergoing LA for perforated appendicitis.

Ethics approval and consent to participate

The study protocol was reviewed and approved by the Institutional Review Board of Saitama Prefectural Children’s Medical Center. Informed consent was obtained from the parents or guardians of all participants. Data confidentiality was maintained in accordance with the institutional guidelines and regulations.

Consent for publication

Not applicable.

Availability of data and materials

The data generated and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Conflict of Interest Statement

Not applicable

Funding

The authors received no specific funding for this study.

Authors' contributions

The research design was designed by S.T. and T.T.

S.T. wrote the main manuscript text. All authors reviewed the manuscript.

Acknowledgments

We thank Susan Furness, PhD, from Edanz (https://jp.edanz.com/ac) for editing a draft of this manuscript.

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Table 1 Patient characteristics

	PO-IAA-free n=49	PO-IAA n=20	p-value
Age, years, median (IQR)	10 (0–15)	9 (4–13)	0.477*
Sex, n (%) Female Male	21 (42.9) 28 (57.1)	8 (40.0) 12 (60.0)	0.551^†
Height, cm, median (IQR)	142.2 (64–167)	133.0 (104–163)	0.771*
Body weight, kg, mean±SD	31.94±12.89	33.52±12.22	0.640^‡
Body mass index, kg/m², median (IQR)	16.40 (12.35–22.95)	17.15 (13.18–25.6)	0.061*
Body surface area, m², mean±SD	1.09±0.31	1.11±0.28	0.826^‡
Days until surgery after symptoms, median (IQR)	2 (0–12)	2 (1–10)	0.285*
Highest perioperative serum leukocyte count, /μL, mean±SD	16530.8±4583.3	18896.5±4076.6	0.049^‡
Highest perioperative serum C-reactive protein, mg/dL, mean±SD	17.1±6.9	18.6±7.5	0.417^‡
Duration of antibiotic use, days, median (IQR)	11 (3–33)	17.5 (5–38)	0.771*

PO-IAA, postoperative intra-abdominal abscess; IQR, interquartile range; N, number; SD, standard deviation

*Mann-Whitney U test; ^†Fisher’s exact test; ^‡t-test

Table 2 Outcome data

	PO-IAA-free n=49	PO-IAA n=20	p-value
IV, mL, median (IQR)	8000 (6000–10000)	6000 (4000–7250)	0.014
IV/BW, mL/kg, median (IQR)	270.9 (176.0–409.4)	159.2 (128.0–223.0)	0.009
IV/BSA, mL/m², median (IQR)	7500.6 (5048.4–9656.6)	4890.6 (3742.8–6446.9)	0.008
Operation time, min, median (IQR)	107 (53–242)	138 (60–261)	0.146
Intraoperative blood loss, mL, median (IQR)	1.0 (1.0–200.0)	1.0 (1.0–200.0)	0.915

PO–IAA, postoperative intra–abdominal abscess; IQR, interquartile range; IV, irrigation volume; BW, body weight; BSA, body surface area

No competing interests reported.

Does massive irrigation reduce the risk of intra-abdominal abscess after laparoscopic appendectomy for perforated appendicitis?

Status:

Version 1

Abstract

Figures

Introduction

1. Methods

1.1. Study Design and Setting

1.2. Inclusion and Exclusion Criteria

2.3. Variables and Measurements

2.4. Sample Size

2.5. Statistical Analysis

2.6. Ethical Considerations

3. Results

4. Discussion

5. Conclusion

Declarations

References

Tables

Additional Declarations

Status:

Version 1