Unexpected Metachronous Hernia Development in Children Following Laparoscopic Unilateral Hernia Repair with Negative Evaluation for Contralateral Patent Processus Vaginalis

Introduction

Inguinal hernia is estimated to affect 1%–4% of children. ¹ Although variations in the techniques of open inguinal approach and more recently of laparoscopic repair have been described, the fundamental principle of high ligation of the neck of the sac at the deep ring has changed little over decades. The management of the contralateral side in a child presenting with clinically apparent unilateral inguinal hernia, however, has been debated for several decades since the early reports of the frequent findings of contralateral patent processus vaginalis (CPPV) and its potential risk of metachronous hernia development.^2–4

Pediatric surgeons have long been divided on the practice of routine contralateral groin exploration to detect CPPV.^5,6 The introduction of transinguinal laparoscopy through the open hernia sac to evaluate CPPV in the early 1990s and the accumulating evidence of its effectiveness in the following decade have eliminated much of the grounds for routine contralateral groin exploration.^4,7–9 Unexpected metachronous hernia development, however, has recently been reported in 2.5% of children following negative evaluation for CPPV by transinguinal laparoscopy in a major center pioneering this procedure. ¹⁰

Data are scarce in the literature regarding false-negative evaluation of CPPV by transumbilical laparoscopy. A more direct visualization of the deep ring to evaluate CPPV by transumbilical laparoscopy has been proposed to be one of the advantages of laparoscopic hernia repair in children. ¹¹ Previous meta-analysis found that in children after unilateral hernia repair without any CPPV evaluation, 90% develop metachronous hernia within 5 years. ¹² The aim of the present study was to investigate metachronous inguinal hernia development in children who had undergone laparoscopic unilateral hernia repair 5 or more years ago with negative findings for CPPV in the initial transumbilical laparoscopy.

Patients and Methods

We conducted a retrospective chart review of consecutive children who presented with clinically apparent unilateral inguinal hernia and underwent laparoscopic unilateral hernia repair with negative findings for CPPV in transumbilical laparoscopy from July 2004 to June 2007. The study subjects were recruited from the cohort that we had studied previously when we investigated the early outcomes of our patients after laparoscopic hernia repair. ¹³ The laparoscopic hernia repairs were performed by four attending surgeons, each of whom had performed 74–130 such procedures during the 3-year study period. ¹³ These children with their latest follow-up progress were reviewed again in the present study to investigate metachronous hernia development. Children who had had contralateral groin surgery before the laparoscopic hernia repair or those who had not returned to the outpatient clinic for follow-up after surgery were excluded.

Our technique of laparoscopic hernia repair in children was reported previously. ¹³ A 5-mm telescope, a 3-mm grasper, and the hernia hook were our standard instruments for transumbilical laparoscopy. CPPV was evaluated by laparoscopic inspection during the study period and was defined by an open tunnel without identifiable termination to the peritoneal sac in the inguinal canal. Metachronous hernia development was defined in the present study by a clinically detected inguinal hernia on the side with negative findings of CPPV in the initial laparoscopy and subsequent confirmation of patent processus vaginalis in the second surgery. The inter-hospital electronic patient records system was used to review each study subject in addition to the medical records of our institution. The system provided access to the retrieval of any outpatient consultation notes and operative records of our study subjects in other general surgical and pediatric surgical centers of the whole territory. The system allowed us to capture the required clinical data if the study subjects presented with metachronous hernia to other institutions and had the surgical repair done by others.

The study protocol was approved by the joint ethical committee of the University and the Hospital.

Results

Two hundred ninety-three children were recruited for review in the present study. There were 246 boys and 47 girls, 1 month to 15 years old at the time of laparoscopic unilateral hernia repair. There were 116 left-sided and 177 right-sided hernias in the initial clinical presentation. The median follow-up was 48 months (range, 12–93 months) from the time of initial laparoscopy. In total, 9 children (3.1%) developed metachronous inguinal hernia. The negative CPPV evaluation during the initial laparoscopic hernia repairs involved all four attending surgeons. The 9 children underwent the second laparoscopic repair in our institution, and the presence of CPPV resulting in clinically indirect metachronous hernias was confirmed in all cases. All the metachronous hernias were found in boys, who were 1 month to 7 years old at the time of the first surgery for left-sided hernia in 4 and right-sided hernia in 5. Metachronous hernia developed at 6–42 months (median, 24 months) from the time of negative CPPV evaluation by transumbilical laparoscopy. There was no difference in the incidence with regard to the laterality of the hernia in the initial presentation (P=.76).

Discussion

The best way to detect CPPV in children presenting with unilateral inguinal hernia has been a subject of debate for decades. Laparoscopic evaluation for CPPV was introduced in 1992, and in the first report the laparoscopy was performed by a separate umbilical incision when the clinically apparent inguinal hernia was repaired by the open inguinal approach. ¹⁴ Transinguinal laparoscopy through the hernia sac was then reported in the following years with initial promising results.^7,15,16 Over the last decade the accumulating evidence has unquestionably supported transinguinal laparoscopy as the diagnostic tool of choice to investigate CPPV during open inguinal hernia repair.^4,9,17–20

In recent years laparoscopic hernia repair in children has gained increasing popularity among pediatric surgeons, and different techniques have been described.^13,21–26 CPPV evaluation by transumbilical laparoscopy has then become a routine in children who undergo laparoscopic repair for clinically apparent unilateral hernia. Despite the incidence of CPPV conversion to clinical inguinal hernia and although factors that determine the conversion are not fully understood, CPPV closure is routine should it be detected whether by transinguinal or transumbilical laparoscopy.

Nevertheless, metachronous hernia development following negative laparoscopic evaluation for CPPV has continued to be a real but uncommon phenomenon. A pooled analysis of nine early studies found 1 case of metachronous hernia development in 526 children (0.2%) with negative laparoscopic evaluation for CPPV at follow-up from 1 month to 3 years. ⁸ With the availability of more long-term results, Saad et al. ¹⁷ and Juang et al. ¹⁰ have recently reported an incidence of 0.6% and 2.5%, respectively, of metachronous hernia development in children following negative CPPV evaluation by transinguinal laparoscopy over study periods spanning 8–10 years.

Data are scarce in the pediatric literature regarding metachronous hernia development following false-negative CPPV evaluation during laparoscopic unilateral hernia repair. A more direct view at the deep ring to examine for CPPV provided by transumbilical laparoscopy has been proposed as one of the advantages of laparoscopic repair. ¹¹ Most of the investigators interested in laparoscopic hernia repair in children did not report the observation of metachronous hernia development.^{21,22,24–26} Endo et al. ²³ have reported recently that 0.8% of Japanese children developed metachronous hernia following laparoscopic unilateral hernia repair and negative laparoscopic findings for CPPV.

In the present study we recruited for analysis only those children who had been found negative for CPPV by transumbilical laparoscopy for 5 or more years ago. Meta-analysis found that 90% of metachronous hernias developed within 5 years from the time of initial unilateral hernia repair. ¹² Our findings that 3.1% of children developed unexpected metachronous hernia as a result of false-negative laparoscopic evaluation is the highest ever reported in the pediatric literature, whether by transinguinal or by transumbilical laparoscopy.^10,17,20,23 As not every CPPV will develop into clinically apparent hernia, more CPPV cases might have been missed in our patients than the incidence of metachronous hernia can tell. Our inclusion criteria of an extended period of 5–8 years from the time of laparoscopy in our study patients may explain our higher incidence rate than those reported by others. The incidence of metachronous hernia was reported to be as high as 29% in a study with extended follow-up to 20 years. ²⁷ It is possible that some of our study subjects might develop a metachronous hernia after they reach their adulthood. The overall development of metachronous hernia following false-negative evaluation for CPPV by transumibilical or transinguinal laparoscopy might have been underreported in the pediatric literature.

Our finding that all nine metachronous hernias developed in boys is in agreement with the findings of others. Juang et al. ¹⁰ reported that 32 out of 1291 children who developed metachronous hernia following negative CPPV evaluation by transinguinal laparoscopy were all male. Among the 6 cases reported by Saad et al., ¹⁷ there were 5 boys and 1 girl, whereas the male-to-female ratio in the whole group of study subjects was only 3:1. It is interesting that male gender was not found to be a risk factor in meta-analysis for metachronus hernia development after unilateral inguinal hernia repair without any CPPV evaluation. ¹² Our observation of male predominance in unexpected metachronus hernia development following negative laparoscopic evaluation of CPPV may reflect a higher likelihood of missing a CPPV in male than female patients during laparoscopy for reasons not fully understood. The lack of association between laterality of the initial hernia and metachronous hernia development in our study is consistent with other reports. ¹²

The median of 24 months from negative laparoscopy to the clinical presentation of metachronous inguinal hernia noted in our children is longer than the range of 4–9 months and the median of 12.2 months reported by others.^10,20 An even longer median period might result if late metachronous hernia development were to be seen. One of the postulations for false-negative CPPV evaluation during laparoscopy is the closure of the opening of CPPV by the peritoneal fold during CO₂ insufflation. The deceptive closure may give the surgeon an unequivocal but false finding of absence of CPPV regardless of the route of laparoscopy. Routinely using the grasper by a standard technique to examine for CPPV during laparoscopic hernia repair may prove to have benefit in excluding CPPV, and further studies are warranted to address this issue.

Our study is limited by its retrospective nature with a wide range in the follow-up period of the patients. The way to examine for CPPV was at the discretion of the operating surgeon and was largely by laparoscopic inspection without any standardization in the routine use of the grasper to evaluate CPPV. There was no recording of the initial laparoscopy, and so how the false-negative CPPV evaluation in the initial surgery occurred cannot be adequately analyzed in this study. Despite all these limitations, our findings still alert pediatric surgeons to the possibility of metachronous hernia development in children following negative CPPV evaluation by either transinguinal laparoscopy during open inguinal repair or transumbilical laparoscopy in laparoscopic repair. Although its implication for daily surgical practice may appear trivial, further prospective studies are still warranted to develop cost- and time-effective maneuvers applicable to transinguinal or transumbilical laparoscopy to minimize false-negative evaluation for CPPV.