Comparison of Intra-Abdominal Abscess Formation Following Laparoscopic and Open Appendicectomy in Children

Introduction

Appendicitis is a common pathology encountered by the pediatric surgeon. Definitive treatment is appendicectomy and has been performed by using an open approach since the late-19th century. ¹ Laparoscopic appendicectomy (LA) was first described by Karl Semm in 1983 ² and is now widely used.^3–9 The advantages of LA, when compared to the open technique, are the subject of debate. A Cochrane review comparing LA and open appendicectomy (OA) in adults found that although there are decreased rates of wound infection with the laparoscopic technique, there is an increased rate of intra-abdominal abscess formation. ³ Evidence of this association in a pediatric population remains unclear.^4–6 The aim of this study was to compare the techniques of LA and OA in a pediatric population with acute appendicitis. The primary outcome measure was intra-abdominal abscess formation. Secondary outcome measures were the predictive values of various preoperative investigations.

Subjects and Methods

A retrospective data analysis of 200 pediatric patients having undergone appendicectomy at our institution was performed over a 26-month period. Data were collected from medical records, operating theater records, and the hospital coded database. Ethical approval was obtained for the study from the Chelsea and Westminster Hospital Research Department (London, UK). Patients who underwent interval appendicectomy were excluded from the final analysis. The operative technique used was determined by the preferences of the surgical consultant responsible for the admission.

LAs were performed with the standard three-trocar technique. The umbilical port was inserted by using the open Hasson technique. Once a pneumoperitoneum was established, the additional ports were inserted under direct vision. Mesoappendix division was achieved with hook diathermy dissection, two endoloops (1 cm apart) were utilized for the appendicectomy. Appendicectomies via the open technique were performed by using a modified Lanz incision, and the appendiceal base was transfixed with Vicryl. All patients with the presence of intra-abdominal pus received a thorough washout. This consisted of warmed sodium chloride; variable amounts were used, depending on the age of the patient and the degree of peritoneal contamination. An approximate value of 20–40 mL/kg was used for most patients. Care was taken to ensure that both the right and left paracolic gutters, as well as the pelvis, received adequate irrigation. During open surgery, this is performed with a urethral catheter to allow an extension to those areas, though is less accurate than laparoscopy.

All patients with macroscopic appendicitis, irrespective of operative technique, received postoperative antibiotic therapy. Patients with mild appendiceal inflammation received 24 hours of single intravenous (i.v.) coamoxiclav therapy. Patients with complicated appendicitis received 5 days of broad-spectrum i.v. antibiotic therapy with benzylpenicillin, metronidazole, and gentamicin. Patients in both groups were discharged once normal enteral feeds had been established, patients were mobilized appropriately, and pyrexia was not present for more than 24 hours. All wounds were examined prior to discharge, and any postoperative pyrexia after 5 days was investigated with an abdominal ultrasound.

Patient data were analyzed primarily for incidence of an intra-abdominal abscess and operative modality. Secondary parameters included gender, age at operation, length of hospital stay, wound infection, preoperative investigations, conversion rates, microbiologic cultures, and histologic analysis. The grade of the operating surgeon was also recorded. An intra-abdominal abscess was defined as recorded pyrexia, raised inflammatory marker, and a positive radiologic confirmation of an intra-abdominal collection. A wound infection was defined as purulent discharge from the wound, with positive microbiologic analysis associated with localized pain and swelling. Subset analysis was also performed on patients undergoing either an LA or OA with complicated appendicitis. Data analysis comprised a Fisher's exact and Mann-Witney test, as appropriate. A P-value of <0.05 was considered significant.

Results

Two hundred pediatric patients underwent an appendectomy at our institution during this time period. All patients had a minimum follow-up of 4 months, with a median follow-up of 18 months (range, 4–30). Forty patients underwent an LA, 151 an open procedure, and 9 interval appendicectomy. The latter were excluded from the study due to the absence of acute pathology at the time of surgery. There was no significant difference between the baseline demographics of the two groups (Table 1). Conversion rate for the LA group was 1 of 40 (2.5%), the latter due to concern over a caecal perforation, which was excluded following conversion.

Preoperative investigations of the two groups included ultrasonography and serologic analysis. Of the 191 patients (LA and OA), 48 (25.1%) had a preoperative ultrasound (USS) and 3 a computed tomography (CT) scan (1.6%). fourteen (28%) patients undergoing USS and 3 (100%) undergoing CT scan had appendicitis confirmed. The positive predictive values (PPVs) and negative predictive values (NPVs) for preoperative USS were 93 and 27%, respectively. Serologic analysis included white cell count (WCC) and C-reactive protein (CRP). A preoperative leucocytosis was consistent with a confirmed histologic diagnosis of appendicitis in 92% of patients (PPV, 82.2%; NPV, 59.36%), and 95% of patients with a preoperative leucocytosis and elevated CRP had a histologic confirmation of appendicitis (PPV, 75.14%; NPV, 80.07%).

In the laparoscopic appendicectomy group, a consultant was present in the operation (either as primary or secondary surgeon) in 88% of cases. This compared with only 24% of cases in the open group (P = 0.0001). There were no intra-abdominal abscesses observed following a laparoscopic appendicectomy 0 of 40 (0%), whereas 5 developed an intra-abdominal abscess in the OA group (5/151; 3.3%; P = 0.8). The management of intra-abdominal abscesses occurring in the OA group included radiologic guided drainage, surgical intervention (laparoscopic and open) with or without drain placement, and conservative management with the use of broad-spectrum i.v. antibiotics. The median time from operation to the development of intra-abdominal abscess was 9 days (range, 8–11).

Wound infections were observed in both groups: 3 of 40 (7.5%) in the LA group and 7 of 151 (4.6%) in the OA group (P = 1.0). A hydrosaphinx developed in the 1 patient converted from laparoscopic to an open procedure, and a second laparoscopic patient developed postoperative small-bowel obstruction. In the OA group, 3 patients experienced an episode of postoperative urinary retention requiring catheterization, a urinary tract infection, and a conservatively managed small-bowel obstruction.

Complicated appendicitis was defined as the presence of pus at the time of operation or histologic evidence of perforation. In the laparoscopic group, 13 of 40 (33%) patients had complicated appendicitis, compared with 59 of 151 (39%) in the open group. There was no significant difference between the two groups (P = 0.47). In the open group, 4 of 5 (80%) patients who later developed an intra-abdominal abscess had complicated appendicitis (P = 0.02). The subset analysis revealed that 0 of 13 (0%) of the laparoscopic group with complicated appendicitis developed an intra-abdominal abscess, compared with 4 of 59 (6.8%) in the open group. This was also not significant (P = 1.0).

Discussion

Since the introduction of LA, there has been considerable controversy over its advantages, when compared with the open technique. An increased incidence of intra-abdominal abscess following the LA is widely reported as a disadvantage of this technique,^10–13 with increased procedural cost repeatedly demonstrated to be the only highly significant disadvantage of laparoscopic appendicectomy.^3,4 A Cochrane review in adults found the benefits for the laparoscopic technique included a shorter hospital stay, reduced postoperative pain, and a faster return to normal activities. ³ Such findings have also been confirmed by other study groups.^4–6 Sauerland et al. included only five studies in pediatric patients, all of which were comparable to the adult data. ³

The evidence behind an increased incidence of intra-abdominal abscess formation in children following complex appendicitis is conflicting.^7,10,14–17 In our cohort of 200 children, we have demonstrated no statistical difference between the incidence of intra-abdominal abscess in those treated laparoscopically or via the open approach. None of the patients in the laparoscopic group, however, developed an intra-abdominal abscess (0 versus 3.3%; P = 0.8). The open and laparoscopic groups also had a similar incidence of complicated appendicitis (33 versus 39%). The subset analysis also found no significant difference between the two groups (0 versus 6.8%; P = 1.0). In our cohort, we found a significantly increased incidence of intra-abdominal abscess formation following an OA in patients with complicated appendicitis. Our data confirm previous studies, in which no difference exists for intra-abdominal abscess formation as a result of either an LA or an OA regardless of complexity.^14,18 Our study differs from others, in that it found a decreased trend for intra-abdominal abscess formation in complicated LA, when compared with OA. ¹⁴ There was also no significant difference in the incidence of postoperative wound infection between the two procedural groups [3/40 (7.5%) versus 7/151 (11.6%); P = 1.0) or in their median hospital stay. Our findings confirm previously published data. ¹⁵

A surgical consultant was present more often during an LA, appendicectomy compared with an OA (88 versus 24%; P = 0.0001). The absence of intra-abdominal abscesses in the LA group could, therefore, be due to the presence of a more senior operator. If true, this also has significant implications for the management of complex appendicitis in our unit. The primary operator, however, was still a registrar for both procedures.

The diagnostic role of preoperative investigations in pediatric patients with acute appendicitis still remains unclear. A clinical diagnosis of appendicitis can be difficult in children, and investigations continue to augment a clinical diagnosis in many situations.^19,20 In our study, the PPV for preoperative ultrasound investigation was 93%, and the NPV was 27%. This is supported by other published data.^16,17 With a raised WCC, preoperatively, the PPV was 82.2% and the NPV 59.36%. For both a raised WCC and CRP, the PPV was 75.14%, while the NPV was 80.07%. Our data support the finding that appendicitis in children is primarily a clinical diagnosis, although positive ultrasound or serologic findings is useful in some patients. Negative results alone appear to have no place in the diagnosis of appendicitis.

Conclusions

LA is a viable alternative to the open technique in children, irrespective of the presence of complicated appendicitis. There is no significant difference with the incidence of intra-abdominal abscess formation and wound infection rates in children treated with either modality. Intra-abdominal abscesses appear more likely following complicated appendicitis, regardless of technique. There may be a reduced risk following the laparoscopic technique, as no patients in this group developed an intra-abdominal abscess. A multicenter, randomized, controlled study is underway to investigate this finding.