Abstract
SUMMARY
Antibiotic prophylaxis is being commonly used in mesh repair of inguinal hernia but its role has been questioned in a recent Cochrane analysis performed in 2003. Routine use of antibiotic prophylaxis in mesh repair of inguinal hernia can lead to bacterial resistance and increase in cost. In a present double-blind placebo controlled trial involving 120 patients undergoing inguinal hernia repair using prolene hernia system, we did not find any benefit of the routine use of antibiotic prophylaxis in terms of wound infection rate.
Introduction
Inguinal hernia repair is one of the most common operations performed by general surgeons in India and tension-free mesh repair has emerged as one of the most popular techniques used. 1,2 Although the Lichtenstein repair is a popular mesh repair technique, 3 the prolene hernia system (PHS), which is a combination of inlay and onlay mesh, has gained in popularity in last five years. 4,5
The Cochrane meta-analysis in 2003 concluded that routine use of prophylactic antibiotics in mesh repairs of inguinal hernia can neither be recommended nor condemned – further studies are needed. 6 Postoperative wound infection occurs in 0%– 9% of patients after hernia repair. 7 However, the risk of developing possible bacterial resistance 8 and super infections can be reduced if the routine use of antibiotic prophylaxis in hernia repairs is avoided. In addition, withholding the routine use of antibiotics can reduce operation costs by approximately 500 rupees (US$ 12.7) per patient.
To find out if the systemic use of antibiotic prophylaxis can prevent wound infection in PHS repair of inguinal hernia, a randomized double-blind placebo controlled trail was performed.
Methods
Patients
In a period of one year, 120 consecutive patients with primary unilateral inguinal hernia who attended the surgical clinic for mesh repair were selected for this study. Informed consent was obtained from all patients. Patients with recurrent, bilateral, irreducible or strangulated hernia were excluded from the study. Also excluded were: patients with systemic and advanced diseases (e.g. liver failure, chronic renal failure, diabetes); immune-compromized patients; patients with ASA (American Society of Anaesthesiologists) scores higher than 11; patients receiving steroids for any reason; patients younger than 18 or older than 60; patients with local skin infections or disease at the site of incision; and patients allergic to antibiotics or who had received antibiotics less than a week before surgery.
Randomization was performed by a computer-generated code by a junior resident who was not involved in the surgery, data compilation or patient follow up. The same resident also prepared the antibiotic or the placebo syringes containing normal saline.
All patients received either1.2 g amoxicillin and clavulinic acid (AC) or an equal volume sterile saline (placebo) by intravenous bolus route before the incision. AC was selected because of its broad spectrum of activity ranging from Gram positive, Gram negative and anaerobic organisms.
Surgical procedure
The skin was prepared using povidone-iodine and alcohol. Local anaesthesia with sedation under pulse-oximeter monitoring was our preferred technique, but spinal anaesthesia was used on patient's demand or on the failure of local anaesthesia. All were PHS mesh repair (combination of inlay and outlay mesh) and were carried out by the authors. Onlay mesh was fixed using 2-0 monofilament polypropylene interrupted sutures (Prolene, Ethicon Ltd., India). The skin was closed using 3-0 interrupted nylon sutures. A drain was not used in any patient and all were discharged the day after surgery.
Follow up
All wounds were inspected before discharge and all incisions were carefully re-examined at the time of suture removal (7–9 days after operation), two weeks after discharge and four weeks after discharge. Patients were asked to report to the surgical outpatient clinic in cases of any wound discharge, pain or redness, after the fourth week. In order to remove any personal bias, the surgeon who performed the operation was not allowed to follow up their patient. Wound infections were categorized as superficial incision surgical site infection (SSSI) and deep incision surgical site infection (DSSI) according to definition of the Center for Disease Control and Prevention criteria. 9 Superficial infection was defined as an infection occurring within 30 days after surgery involving only the skin or subcutaneous tissue. Deep infection was defined as an infection occurring within one year after surgery involving fascia/muscle layers and the graft. DSSI is a potentially serious complication and often needs re-exploration with the removal of any infected mesh.
Statistical analysis
Data for all the patients who entered trial and were operated upon were analysed on an intention-to-treat basis. Data were analysed using Fisher's exact test, student's t test or χ2 analysis as appropriate. All analysis was made under the guidance of an epidemiologist.
Results
A total of 120 patients were included in this trail over a period of one year with strict adherence to the exclusion criteria. Sixty patients represented the study group (antibiotic given) and the remaining 60 represented the control group (placebo given). There was no protocol violation. Groups were well matched for age, gender, ASA class, type of hernia, type of anaesthesia and duration of operation (Table 1). Postoperative complications shown in Table 2 were evenly distributed between the placebo and the antibiotic groups. No complication related to the involvement of nerves was observed. Seromas were diagnosed on the aspiration of clear serous fluid, which was found to be sterile on culture. All seromas were treated conservatively by aspiration without any sequel. One patient developed retention of urine; none had DSSI; one of the placebo group and one in the antibiotic group developed SSSI. The infection rate was 1.7% for both groups. Staphylococcus aureus was grown from the pus of all infected patients and they were treated with the appropriate antibiotics and drainage. We noted no adverse effects from the use of antibiotics. There was no recurrence during one year of follow up. Ischaemic orchitis was not seen in any of the patients. Postoperative hydrocele was noted in one patient in the placebo group and it was treated by eversion of the sac.
Patient characteristics
Postoperative complications
Discussion
More than one million inguinal hernia repairs are being performed annually in the USA and Europe, 10 and figure is likely to be same for India. Tension-free mesh repair (open flat mesh repair) is the most popular technique. 1,9 However, PHS, a technique using a combination of inlay and onlay mesh-like prolene is becoming more popular because of its zero recurrence rates, less postoperative complications 4,5 and its the ability to protect all three weaknesses (i.e. direct, indirect and femoral) described as ‘3 in 1 system’ according to the principles of Rives and Stoppa (inlay) and Lichtenstein (onlay mesh). 11
Antibiotic prophylaxis is being commonly used in mesh repairs of inguinal hernia but a Cochrane meta-analysis published in 20034 has shown no proven benefits of this procedure. Infection rates in hernia operations has been found to range from 3.3% to 14%. 12,13 Gilbert and Felton, in 1993, reported a 0.34% infection rate without antibiotic prophylaxis and 0.98% with antibiotics in mesh repair of inguinal hernia. 14
In a prospective randomized double-blind multicentre trial involving 619 patients who had undergone inguinal hernia repair, Taylor et al. (1997) did not find any difference in the infection rate between antibiotic group and the placebo group 15
The wound infection rate was found to decrease to 0.7% from 9% in a prospective randomized controlled trial of mesh repair of inguinal hernia using a single dose of an ampicillin and sulbactum combination. 16 This data is open to question because of the unexpectedly high rate of wound infection in the control group and the wide use of drains, which might explain the high rate of wound infection in the control group.
In another prospective double-blind controlled trial in 2004 by Celedran et al. 17 of intravenous antibiotic prophylaxis in mesh repair of inguinal hernia, there was a significantly higher infection rate in the placebo controlled group.
In a multicentre double-blind randomized controlled trial involving 1040 patients, Aufenacker et al. 18 had an infection rate of 1.6% in the antibiotic prophylaxis group and 1.8% in the placebo group without any statistical difference. Drains were used in a very small percentage (2.2% in antibiotic group and 0.8% in placebo group).
In a recent randomized double-blind, placebo controlled trial by Perez et al. 19 involving 360 patients, the authors found that the preoperative administration of a single-dose antibiotic for tension-free inguinal mesh herniorrhaphy did not markedly decrease the risk of wound infection. The infection rate was found to be low, i.e. 1.7% in the antibiotic group and 3.3% in the placebo group. Drains were not used in any patient.
The present series seems to be the first to study the role of antibiotic prophylaxis in repairs of inguinal hernia using PHS. The infection rate was found to be low (1.7%) – comparable to Perez et al. 19 and Aufenacker et al. 18 . We did not use drains in any of our patients. The use of drains appears to increase the incidence of infection in inguinal hernia repairs, as shown in a series by Yerdel et al. 16 and Taylor et al. 15 None of our patient developed DSSI.
Our study did not show any benefit from antibiotic prophylaxis in patients undergoing inguinal hernia repairs using PHS (1.7% in each group, P value <0.05). We have modified our practice by not giving antibiotics in inguinal hernia repair. We believe that this practice can be applied to any type of mesh repair in inguinal hernia but we do not recommend it for mesh repair of ventral hernia as that involves extensive dissection. The sample size of our study is small and we recommend future studies using larger sample sizes to confirm the results and to avoid any type I error.