Inguinal hernia repair is one of the most common procedures performed by a pediatric surgeon, with a reported incidence of 0.8–4.4% [5]. Failure of closure of the processus vaginalis, leads to a persistent canal that allows abdominal contents to protrude through the deep ring. The persistence of the canal carries a risk of incarceration and strangulation of the contents, therefore surgical intervention is indicated in all.

Laparoscopic hernia repair was first described by El-Gohary [1]. It was initially used as an option for inguinal hernia repair in female patients due to concerns about damage to the vas and vessels in males. This was followed by laparoscopic repair in males by Esposito [2] who initially described laparoscopy to treat recurrence following open hernia surgery. Subsequently, laparoscopic repair has become one of the standard approaches to treat inguinal hernias in children, and was adopted by Great Ormond Street Hospital in 2009. A prospectively held database of all patients undergoing the procedure has been maintained since. Laparoscopic repair carries with it several advantages including; improved post-operative pain and cosmesis, faster operative times for bilateral cases, identification of metachronous hernia and less trauma to delicate cord structures [6]. Moreover, in cases of incarceration, the laparoscopic technique appears safer and easier to perform than open repair and can be done without the need to wait after reduction [7].

When discussing minimally invasive surgery and inguinal hernia repair, it is important to firstly recognize that a wide range of techniques exist. These can broadly be divided into intra-corporeal or extra-corporeal depending on the method by which the needle is inserted into the peritoneal cavity and how the deep ring is closed [8]. Our operative approach is similar to that described by Montupet [9]. Most clinicians, in the present series, chose to place a second purse string or Z-stitch [10] on the symptomatic side/s. Treatment of the asymptomatic PPV was with a single purse-string suture only with or without an overlying “Z” stitch.

Controversy exists regarding the assessment and treatment of the asymptomatic (PPV); however, closure is generally recommended to reduce the risk of a metachronous hernia. A recent evidence-based guideline on minimal access approaches to inguinal hernia, published by the International Pediatric Endosurgery Group in 2016, found the incidence of contralateral PPV is 20–30% [6]. In our series, the incidence of asymptomatic PPV was 40%. It was more likely in children presenting with symptomatic left sided hernias, when compared with right, as expected from the embryological descent of the testis and delayed closure of the processus vaginalis on the right [11]. The natural history of the PPV is one of the spontaneous closures.

The incidence of PPV and inguinal hernia in a full-term infant is between 3 and 5%, which increases up to 30% in pre-term infants [12, 13]. Pre-term infants are also considered to be at increased risk of metachronous inguinal hernia [14]. A study by Burgmeier et al. [15] reviewed the findings of a contralateral PPV in term versus pre-term infants, which demonstrated a contralateral PPV rate in the pre-term group of up to 58.8%. This finding is supported by our study, which also demonstrates a significantly higher incidence of contralateral PPV (52%) in pre-term infants. There is no evidence to determine if a PPV seen at laparoscopy will become symptomatic but the risk of a contralateral asymptomatic PPV developing into a metachronous hernia is approximately 25% [6]. Laparoscopic assessment is easy, feasible and closure of the PPV can potentially prevent morbidity associated with a metachronous hernia. It seems to be more important in the pre-term infants, where the risk of a contralateral PPV is above 50%.

We note that laparoscopic assessment of the contralateral PPV is not failsafe. A meta-analysis by Zhong et al. [16] demonstrated 1.31% rate of metachronous hernia development in children with a false-negative finding of a contralateral PPV during laparoscopy. The incidence of false-negative closed ring in our series was 0.08%, with one patient in our cohort developed a metachronous inguinal hernia following laparoscopic inguinal hernia repair, where initial assessment had not demonstrated a contralateral PPV. Overall, the assessment and management of a contralateral PPV are recommended during laparoscopic inguinal hernia repair.

The reported disadvantages of laparoscopic inguinal hernia repair are a potentially higher recurrence rate. The reported recurrence rate after laparoscopic hernia repair is between 0% and 5.5% (mean 1.4%) [3]. Age and weight have previously been reviewed as indicators for recurrence in LIHR [17]. Our cohort of patients included patients from day 1 of life up to 14 years at operation, and these factors did not have an impact on recurrence. Comparing laparoscopic and open approaches, the recurrence rate in a systematic review and meta-analysis on by Bada-Bosch et al. [18] demonstrated no significant differences. Higher recurrence rates (up to 5.5%) quoted in the systematic review by Esposito [3] on LIHR are due to the inclusion of a paper by Koivusalo [19] in which one recurrence was seen after laparoscopic hernia repair in a small cohort (18 patients). This leads to an overestimation of the true population recurrence rate. The recurrence rate in our cohort of 1195 patients was 1.6%. However, this rate reduced to 0.8% when an intra-corporeal second Z-suture stitch was used on the symptomatic side. The use of a Z-stitch was first described by Schier, initially in girls [20], and then in boys [10]. Following early experience with LIHR in our center, a double stitch/Z-stitch was adopted, which resulted in a significant reduction in the rate of recurrence. This paper provides a set of data in which to accurately assess the recurrence rate, in a large cohort of patients with follow-up of up to 12 years [6].

Iatrogenic cryptorchidism is a recognized complication following inguinal hernia repair, which is postulated to occur as a result of adhesions created by dissection of the processus vaginalis (PV), leading to scarring of the cord [21]. Further growth of the pediatric patient can result in a descended testis ascending over time. The laparoscopic approach, in theory, would cause less scarring as there is no disruption to the processus vaginalis. However, persistence of the PV may, in part, impact the rate of testicular ascent. 90% of patients in our cohort with undescended testis pre-herniotomy required a formal orchidopexy. The majority of these were in patients less than 6 months of age at the time of hernia repair. Although spontaneous descent of undescended testis in children < 6 months is reported [22], it is not common. A large proportion of our cohort were born prematurely, which also influences the prevalence of undescended testis. It is not possible to determine if the testes that were undescended prior to LIHR would have undergone spontaneous descent. Twelve testes ascended following LIHR in our cohort. This number may reflect the lack of documentation of pre-operative testicular position, as well as the potential impact of the persistence of the PV. Overall, LIHR is associated with less complications when compared to open repair, with specific reference to the incidence of iatrogenic cryptorchidism [23].

Limitations of this study include its retrospective design resulting in an heterogenous protocol for technique and patient characteristics. However, our statistical analysis suggests differences in technique did not alter the rate of recurrence. The practice of documentation of post-operative testicular position is not standardized; therefore, the observation of iatrogenic cryptorchidism may be overestimated. We also acknowledge that some patients may have developed recurrence that did not present to GOS and, therefore, alter our incidence of recurrence.