Introduction

Incisional hernia (IH) is one of the frequent postoperative complications of open and laparoscopic surgery. IH may present with swelling, pain due to bowel obstruction or skin problems. Although the incidence rate of IH after open abdominal surgery in adults is reported to be 5–50%, the literature on IH in children is limited [1,2,3,4]. Our study aims to clarify the incidence and analyze the risk factors for IH in children in our hospital group.

Materials and methods

We retrospectively reviewed all patients who underwent pediatric abdominal surgery at the Jikei University Hospitals (Jikei University Hospital, Kashiwa Hospital, Katsushika Medical Center and Daisan Hospital) between January 2001 and December 2016. Pediatric abdominal surgery was defined as open and laparoscopic abdominal surgery in patients ≤15 years old, except open repair for inguinal hernia, umbilical hernia repair, congenital abdominal defect (gastroschisis and omphalocele) repair and open orchiopexy for abdominal testis.

Statistical analyses were performed using a statistical program (StatView software version 5.0, SAS institute, Cary, NC, USA). All data were compared using nonparametric statistical analysis with Chi-square and Fischer’s exact tests for categorical variables. In all analyses, p < 0.05 was considered statistically significant.

Results

Fourteen children (10 males and 4 females) developed IH, among 2049 children who underwent abdominal surgery at our hospitals, and the incidence of IH was 0.68% (14/2049) (Table 1,2). The median age for primary surgical procedure was 2 years and 3 months (range 2 days to 14 years and 4 months) (Table 1). The primary surgical procedure and IH repair were performed under general anesthesia in all patients. All IH patients did not have diabetes, systemic use of steroids, previous abdominal operation, surgical site infection (SSI), malignant tumor, connective tissue disorder and collagen metabolic disorder at the time of primary surgical procedure. The mean age of patients who had IH repair was 3 years and 5 months (range 6 months to 14 years and 7 months) (Table 1). All IH in laparoscopic surgery was rising from 5-mm port site in umbilical portion. According to our records, all IH patients underwent repair surgery for IH at our hospitals.

Table 1 Details of patients of IH
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Table 2 Comparison of patients with or without IH
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The details of primary surgical procedure are as follows: gastroesophageal reflux in four, pyloric stenosis in two, and abdominal testis, inguinal hernia, idiopathic thrombocytopenic purpura (ITP), cystic kidney, duodenal atresia, anal atresia, meconium peritonitis and intestinal atresia in one each (Table 3).

Table 3 Details of primary surgical procedure of patients of IH
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The primary surgical procedure were for laparoscopic fundoplication in three, intestinal anastomosis in two, open supraumbilical pyloromyotomy in two, and open fundoplication, laparoscopy-assisted orchiopexy, laparoscopic percutaneous extraperitoneal closure, laparoscopic splenectomy, laparoscopic nephrectomy, duodenoduodenostomy and stoma creation in one each (Table 3).

The incidence rate of IH was 0.71% (7/986) in laparotomy patients and 0.66% (7/1063) in patients with laparoscopic surgery. There is no significant difference between laparotomy and laparoscopic surgery. Furthermore, we analyzed the age distributions of the patients: neonates 2.42% (4/165), under 1 year 0.88% (6/682), ≤1 year 1.09% (10/915), ≤3 years 1.01% (12/1193) and ≤5 years 0.84% (12/1434). The incidence rate of IH was 2.60% (3/105) in patients laparoscopic fundoplication, and it was 4.26% (2/47) in patients with supraumbilical pyloromyotomy (Table 2). We did not have cases of IH in neonatal patients who underwent laparoscopic surgeries, although we have one IH patient after stoma creation in neonate (Table 2).

The statistically significant variables were operation in neonates, laparoscopic fundoplication and open supraumbilical pyloromyotomy (Table 4). However, there was no statistically significant relationship between IH development and open or laparoscopic surgery (Table 2).

Table 4 Results of multivariate stepwise logistic regression analyses
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All IH repairs were performed by resecting the hernia sac, and absorbable sutures were used to close the peritoneum and fascia separately without artificial mesh. Standard office follow-up for all patients after IH repair was 2 weeks from hospital discharge. Subsequent follow-up was by the referring clinician. In all patients who had IH repair, there was no recurrence during the follow-up period of 50.4 months (range 1 month to 10 years) except two recurrence cases (14.3%) (Table 1). Two recurrent patients do not desire the repair operation.

Discussion

IH is a commonly reported complication following abdominal surgical procedures. The incidence rate of IH in adults after open abdominal surgery 5–50% depends on the type of incision, patient group and closure technique [1, 2]. Previous studies of IH in adults reported various independent risk factors, including sex, advanced age, high body mass index, emergency surgery, SSI, malignant tumor, diabetes, collagen metabolic disorder and chronic obstructive pulmonary disease [1, 2, 5]. Dietz UA et al. [5] reported risk factors, recurrence rating, morphology and hernial gap size, and classified IH in a retrospective study of 330 adult patients (>18 years). It is reported that the incidence of IH in children is lower than that in adults, with an incidence of 2.1–3.2% [1, 4]. However, there is a paucity of data related to IH in children [1, 3, 4].

Our study included over 2000 patients who were investigated for IH after abdominal surgery in four hospitals for the span of 16 years. In this study, the risk factors for IH are neonatal operation, laparoscopic fundoplication and open supraumbilical pyloromyotomy.

Our data indicated that neonatal operation is one of the risk factors for IH. The previous studies report that laparotomies in neonate and younger children were the high risk of IH in children [1, 2]. Talbot et al. [6] reported that IH was a significantly common complication after neonatal stoma creation at low weight. We have one neonate who developed IH after creation of stoma, but it is not statistically significant.

Furthermore, the current study demonstrated that laparoscopic fundoplication is one of the risk factors for IH. The additional reports that followed showed an overall incidence of 0–3%; however, there are few reports of children case [7,8,9,10]. Our three cases of IH after laparoscopic fundoplication were neurologically impaired children. We think that the atrophy of rectus muscles by neurological impairment is related to the risk factor for IH.

In addition, our data revealed that open supraumbilical pyloromyotomy was a high-risk procedure for developing IH. IH is major complications following supraumbilical pyloromyotomy in 1–2% of cases [1, 11, 12]. We suggest that there is relation between high risk factor for IH and malnutrition caused by pyloric stenosis.

The European Hernia Society published guidelines to decrease the incidence of IH.

They recommended utilization of a non-midline approach to a laparotomy whenever possible [1, 13]. Moreover, with regard to method of abdominal closure, they suggested to use slowly absorbable monofilament suture through a single-layer aponeurotic closure technique without separate closure of the peritoneum. For laparoscopic surgery, they suggested to use smallest trocar size suitable for the procedure and closure of the fascial defect if trocars larger or equal to 10 mm are used [1, 9]. However, Mullassery et al. [1] reported two cases of IH from 3-mm port site in pediatric laparoscopy. In children, the abdominal wall is rather thin and the abdominal muscles are weak, and even oblique trocar insertion passes nearly straight through the abdominal wall. To prevent IH of trocar site in children, we recommended fascial closure of all trocar sites even if less than 3 mm and reduced the port in pediatric laparoscopic surgery.

In conclusion, the incidence of IH in children is significantly lower than that in adults. Given the limitations of retrospective study, there is a necessary to conduct a multicenter prospective study to examine the natural history and risk factors for IH in children. Further particulars reports and meta-analyses are necessary to clarify the true role of IH in children. Our study indicated that the risk factors for IH are neonatal operation, laparoscopic fundoplication and open supraumbilical pyloromyotomy. These are completely different risk factors from that of IH in adults. We recommend that the abdomen is sutured closely in these operations. Furthermore, pediatric surgeons should not fail to inform IH and its risk factors when obtaining informed consent for abdominal surgery.