Insights into Inguinal Hernias in Children

Inguinal hernias are a common condition that requires surgical repair in children. In pediatrics, they are usually indirect and are characterized by the protrusion of intra-abdominal contents through the patent vaginal process (PVP). The incidence of inguinal hernias is approximately 8 to 50 per 1,000 live births in full-term newborns, and increases to almost 20% in extremely low birth weight newborns (less than 1,000 g).1-2

The risk of incarcerated inguinal hernia in children is estimated to be 4%, with the highest risk (8%) seen in infants; Therefore, they are usually repaired soon after diagnosis.3,4

This report reviews the embryology, pathophysiology, and natural history of PVP, as well as the contemporary evaluation and treatment of pediatric hernias, with special attention to the risks of general anesthesia in very young children.

Some controversies in the treatment of inguinal hernias include the optimal timing of repair in premature infants, who should perform these repairs, the optimal approach, the need for contralateral evaluation, the approach to recurrent hernias, and the treatment of asymptomatic PVP. identified during an examination of the abdomen unrelated to hernias.

Complete understanding of the issues related to surgical repair of an inguinal hernia requires knowledge of embryology and the subsequent development of the processus vaginalis.

In males, testicular descent involves 2 phases: intra-abdominal and extra-abdominal.5 The developing testicle is initially attached to the diaphragm by the craniosensory ligament; Regression of this ligament causes transabdominal migration of the testicle. Simultaneously, as the male fetus grows and the abdomen elongates, the testicle becomes essentially anchored by the thickened gubernaculum to the dependent scrotum.6

In the female fetus, the craniosensory ligament is maintained; therefore, the ovary retains its dorsal intra-abdominal (retrocoelomic or retroperitoneal) location. Furthermore, the gubernaculum does not thicken, but rather persists as the round ligament of the ovary.

During the extra-abdominal phase (25-35 weeks of gestation), the testicle descends through the inguinal canal, dragging with it an extension of the peritoneal lining called the processus vaginalis.7 Normally, the processus vaginalis is obliterated and persists as the tunica vaginalis, enveloping the testicle. . Both in vitro human tissue cultures and studies in rodent models imply that genitofemoral innervation is essential for the regulation of gubernacular length, as well as for obliteration of the processus vaginalis.8-10

Incomplete involution results in a PVP which, when fluid-filled, may present clinically as a hydrocele. If the communication is large or intra-abdominal pressures are high, intra-abdominal structures such as the intestine can herniate, resulting in an indirect inguinal hernia. In this work, PVP indicates a communication between the labia/scrotum and the peritoneal cavity, “hydrocele” indicates a fluid-containing PVP, and “inguinal hernia” indicates a PVP containing abdominal contents.

The relationship of the processus vaginalis to testicular descent is believed to explain why more than 90% of pediatric inguinal hernias occur in males.11 Involution of the left processus vaginalis precedes that of the right, which is consistent with the observation that 60% of indirect inguinal hernias occur on the right side.12

The prevalence of PVP is highest during childhood (up to 47% in newborns and 27% in children under 2 years of age) and decreases with age.13 Congenital hydroceles, which are essentially clinically apparent PVP, usually resolve spontaneously in However, these prevalence estimates have generally been extrapolated from findings at the time of contralateral internal ring exploration during inguinal hernia repair and possibly overestimate the true prevalence of PVP. in the general population. Rowe et al reported a 64% rate of contralateral PVP identified at the time of inguinal hernia repair in infants younger than 2 months.

Reported rates of contralateral PVP decrease to between 33% and 50% in children younger than 1 year and are as low as 15% at 5 years.13,17-20 Centeno-Wolf Weaver et al reported that the rate of asymptomatic PVP in children undergoing non-hernia abdominal surgeries was 9.1% and 20%, respectively.16,21

The majority of patients included in the first study were older than 8 years, which could explain the lower estimated point prevalence in that group.17 Not all patients with an asymptomatic PVP subsequently develop an inguinal hernia. In patients undergoing surgery for inguinal pathology, Toki et al estimated that the spontaneous regression rate of PVP after 9 months of age ranged between 67% and 91%.22

Rowe et al reported that the contralateral PVP is obliterated in approximately 40% of patients in the first months of life and in an additional 20% over the next 2 years, with only 40% remaining present after 2 years.17 Among those who develop a PVP after 2 years, approximately half will develop a clinical hernia.23

Among patients without previously known inguinal pathology and an incidentally discovered PVP in the studies by Centeno-Wolf and Weaver et al, a clinically evident inguinal hernia developed in a proportion of 10.5% and 13.5%, respectively, during a mean follow-up period of 10.5 and 8.1 years, respectively.16,21 The incidence of incidentally discovered PVP in adults is similarly estimated at 12%, and the presence of one of them confers a risk of 12% of developing a posterior indirect inguinal hernia.26

Despite being one of the most common operations in premature neonates, the optimal timing for inguinal hernia repair remains controversial, as suggested by the significant variability in practice among pediatric surgical specialists. Sulkowski et al reported that although children treated at hospitals participating in the Pediatric Health Information System were overall more likely (67.1%) to undergo repair before hospital discharge, there were notable variations in practice, since between 3% and 74% of repairs at individual centers were performed on an outpatient basis.27 Additionally, just over half (53%) of pediatric surgery specialists, in a survey conducted by the American Academy of Pediatrics, reported that they repaired inguinal hernias in premature neonates when appropriate.28

Possible motivations for delaying inguinal hernia repair in preterm neonates include technical difficulties, increased recurrence rate, comorbidities associated with prematurity, and concerns related to anesthesia, including the risk of postoperative apnea and dependency. prolonged use of postoperative respirator.29,30

Lautz et al., using the Kids’ Inpatient Database from 2003 and 2006, demonstrated that the inguinal hernia incarceration rate in 49,000 premature newborns reviewed was 16%, with a proportional increase in the incarceration rate with increasing age. corrected gestation at the time of surgery.31 Given this possible higher incidence of incarceration in preterm infants, some pediatric surgeons maintain that delay in repair may increase the frequency of inguinal hernia-related complications, such as intestinal incarceration, strangulation and testicular atrophy.32,33 Furthermore, in case of incarceration, urgent repairs in this group of patients also pose a greater risk of perioperative complications.

Others hypothesize that repeated hernia reductions attributable to intermittent incarceration may potentially lead to scarring of the hernia sac, thereby increasing the complexity of subsequent repair.34 A recent meta-analysis that included 7 retrospective studies with a total of 2,024 patients attempted to identify the optimal timing of repair.30 This analysis included 1,176 patients who underwent repair before discharge from the NICU and 848 patients who underwent repair after discharge from the NICU, with no observed differences in incarceration rates: 18.1% versus 11.3%, respectively.

The rates of recurrence (5.7% vs 1.8%), reintervention (5.7% vs 3.3%), respiratory complications (odds ratio 5 4.9) and duration of surgery were significantly higher in those who underwent repair before NICU discharge. Furthermore, a retrospective study of 263 preterm infants revealed a significantly shorter length of hospital stay after repair in the cohort who underwent repair after discharge from the NICU (11.75 vs. 1.02 days).29

The authors concluded that there was moderate-quality evidence supporting delaying inguinal hernia repair until after discharge from the NICU in preterm infants, because this may reduce the risk of respiratory difficulties without increasing the risk of incarceration and reoperation.30 The Timing of Inguinal Hernia Repair in Premature Infants trial (#NCT01678638) recently completed patient recruitment. The results of this trial are awaited and are expected to help determine whether an early or late repair approach is optimal in preterm infants.35

Several previous studies have shown that the volume of subspecialty training and the volume of pediatric general surgery specialists can lead to better surgical outcomes.36,37 When fellowship-trained pediatric surgical specialists care for certain surgical conditions, such as pyloromyotomy and acute appendicitis, better results have previously been demonstrated.38

Borenstein et al 41 used the Canadian Institute for Health Information to review 20,545 pediatric inguinal hernia repairs and showed that, although pediatric surgical specialists cared for a greater proportion of patients younger than 1 year, the overall risk of recurrence of hernia was 2.4 times higher among patients treated by general surgeons.

Among pediatric surgical specialists, the estimated risk of recurrence was independent of surgical volumes. However, there was a significant inverse relationship between recurrence rates and general surgeon case volume: general surgeons who performed fewer than 10 pediatric inguinal hernias per year had the highest incidence of recurrence, and higher-volume general surgeons achieved Recurrence rates similar to those of pediatric surgery specialists.

Academically trained pediatric surgical specialists have the lowest rate of hernia recurrences. However, if access to a pediatric surgical specialist is difficult due to geographic limitations, general surgeons who perform a reasonable number of pediatric hernia repairs can achieve similar results. Similarly, pediatric urologists have been shown to achieve very low rates of inguinal hernia recurrence.42

Another necessary resource for optimal care of an infant undergoing inguinal hernia repair is care provided under the direction of a pediatric anesthesiologist.43

Pediatric patients seen by a pediatric anesthesiologist versus a general anesthesiologist have been shown to have a lower incidence of perioperative cardiac arrest and respiratory complications.44,45 Similar to the outcome-by-volume ratio discussed above for surgical providers, Anesthesiologists who perform 200 or more pediatric anesthesias per year appear to have lower rates of perianesthetic complications.46

If access to a pediatric anesthesiologist is limited due to geographic restrictions, it would be preferable to have general anesthesiologists with the annual volume described. Additionally, medically complex patients at higher risk for perioperative complications, such as those with uncorrected congenital heart disease, pulmonary hypertension, etc., would likely benefit from the additional expertise of a pediatric anesthesiologist.

The traditional gold standard approach to pediatric inguinal hernia repair has been open high ligation of the hernial sac. However, laparoscopic approaches are increasingly popular, as evidenced by a five-fold increase in the proportion of cases performed laparoscopically between 2009 and 2018.47,48

Initial comparisons of open versus laparoscopic repairs suggested potentially higher recurrence rates with the latter approach, which remains a common criticism of this approach.30 More recent data have not supported these initial findings. Outcomes between open and laparoscopic approaches have been directly compared in 8 randomized controlled trials to date.30

Meta-analysis of these trials comparing 375 patients in each arm demonstrated no differences in complication and recurrence rates. It was observed that the laparoscopic approach was associated with a significantly shorter intervention time in patients with bilateral inguinal hernias compared to the open approach.30

Chong et al.,49 in a retrospective review of 1,697 pediatric inguinal hernias, reported a significantly higher rate of development of metachronous contralateral inguinal hernia in the open approach (10.7 per 1,000 person-years) compared with the laparoscopic approach ( 3.4 per 1,000 person-years). Compared with open surgery, the hazard ratio of needing a second surgical procedure (metachronous contralateral hernia or recurrence) with a laparoscopic approach was 0.3, with a number needed to treat of 33.

This difference is likely explained by the ability to visualize the contralateral internal inguinal ring with the laparoscopic approach, resulting in a significantly higher rate (38% vs. 17%) of bilateral repairs seen in the laparoscopic group compared to the open group.50 Additionally, Shalaby et al.,51 in a randomized controlled trial comparing open versus laparoscopic inguinal hernia repair, reported that 4% of patients’ parents reported an "ugly" scar. in the open repair group compared to none in the laparoscopic group.

They also reported that 3.3% of patients in the open group had a significant reduction in testicular perfusion and size, with no differences observed in pre- and postoperative ultrasound findings in the laparoscopic group. Koivusalo et al 52 reported a significantly greater need for rescue analgesia in patients repaired using the open approach (79% vs. 42%) compared with the laparoscopic approach.

The International Pediatric Endosurgery Group’s evidence-based guidelines on pediatric inguinal hernia repair also favor minimally invasive approaches over open surgery, due to the lower rate of postoperative complications, shorter surgical time in patients requiring bilateral repair and similar recurrence rates.50

Within the realm of laparoscopic approaches, there is considerable variation in specific repair techniques. Speck and Smith, for the American Society of Gastrointestinal Surgeons and Endoscopists, have broadly classified these approaches as intracorporeal and extracorporeal.53 Intracorporeal approaches aim to close the internal ring with a suture placed intracorporeal, while extracorporeal methods use the placement of a suture to close the internal ring in the preperitoneal plane through a separate inguinal incision under laparoscopic guidance.

Three randomized studies have directly compared these minimally invasive repair methods, revealing no differences in recurrence rate. However, surgical times appear to be shorter with the extracorporeal technique.31, 54-56

In summary, extensive evidence suggests that the laparoscopic approach is at least as effective as open high ligation. Among minimally invasive approaches, there is some evidence in favor of the extraperitoneal approach.

Among patients with unilateral inguinal hernia, contralateral exploration has been the subject of considerable debate. Proponents of screening cite a 10% to 15% rate of developing a metachronous hernia. Therefore, routine exploration and, if identified, ligation of a PVP could potentially avoid subsequent anesthesia.30

Detractors contest that not all PVP progress to a clinically significant inguinal hernia, and routine exploration exposes the patient to potentially unnecessary operative complications.

The meta-analysis of 23 retrospective studies with 9,603 patients reported that a contralateral vaginal process was identified in 63.5% of patients undergoing unilateral inguinal hernia repair, with an approximate 1.9% rate of complications with the routine contralateral exploration.30 In this analysis, only 8.4% of patients undergoing unilateral repair without contralateral exploration developed a metachronous hernia. Although these pooled data suggest a reduced rate of development of a metachronous inguinal hernia with systematic contralateral exploration, given the low quality of the data, no firm recommendations can be made.

However, the use of a laparoscopic approach allows inspection of the contralateral side without additional interventions. However, when a contralateral PVP is identified in an otherwise asymptomatic child, there is controversy over whether to perform ligation.

A systematic review of 129 published studies by Kokorowski et al 57 reported that there is a 30% rate of detection of a contralateral PVP with only a 7.3% rate of development of a contralateral metachronous inguinal hernia, implying that It will be necessary to close 3 asymptomatic PVPs to prevent a contralateral metachronous inguinal hernia.

In the absence of better quality data, it remains unclear whether these incidentally identified PPVs should be repaired. A family-centered preoperative discussion encompassing the low but present risk of developing a contralateral hernia, the very low but potentially harmful risk of an incarcerated hernia, and the possible need for another surgical procedure in the future can guide surgical treatment, as Different families may have a variety of perspectives related to risk and benefit.

Recurrence remains a rare complication, with an estimated rate of approximately 1% following elective hernia repairs.58

The recurrence rate can increase up to 24% with certain patient factors, such as incarceration, the presence of ascites, or a ventriculoperitoneal shunt.58

Several technical factors may contribute to the risk of developing a recurrent hernia after an open repair. These include failure to ligate the sac at a sufficient height, repair of an excessively large internal inguinal ring, and excessive dissection causing damage to the inguinal floor leading to a subsequent direct hernia.58 Similarly, after repair laparoscopic surgery, excessive tension and the presence of omission areas (especially near the testicular vessels, vas deferens and epigastric vessels) may cause a higher risk of recurrence.59

Repair of these recurrent hernias by repeat inguinal exploration can be extremely difficult, especially in male patients, due to the difficulty of identifying critical structures, and they are known to be associated with an increased risk of testicular atrophy.60 The laparoscopic approach of these recurrent hernias offers the advantage of a previously unexplored field (if the index approach was open), identification of the underlying cause of recurrence, and the opportunity to identify rare defects, such as a femoral hernia.

Shalaby et al, describing their series of 42 recurrent inguinal hernias, reported that the perceived difficulty of the procedure and operative times for recurrent inguinal hernias treated laparoscopically were the same as those for a primary laparoscopic repair.58

Yildiz et al 61 compared the open versus the laparoscopic approach to recurrent pediatric inguinal hernias and observed a considerably shorter surgical time in the laparoscopic group (32.4 versus 61 minutes), with no postoperative recurrences or testicular atrophy during the 8- to 10-minute follow-up. 16 months. On the basis of retrospective data and intuitively given the advantages listed above, laparoscopy appears to be a feasible option in the treatment of recurrent pediatric inguinal hernias.

Concern regarding the effect of general anesthesia on pediatric neurodevelopment has increased in recent years following the publication of a "Drug Safety Communication" by the US Food and Drug Administration, which included a warning regarding the effects of general anesthesia on neurodevelopment.62

This concern originally arose from animal studies demonstrating the development of learning and behavioral deficits following exposure to general anesthesia in later life.63 Several human studies have also explored the relationship between anesthesia exposure general and subsequent neurodevelopmental deficits in children. As noted in a recent systematic review, 64 human studies have provided conflicting evidence of any association between anesthesia exposure in early childhood and long-term adverse neurodevelopmental outcomes.

Several of these studies are marred by significant variations in study methodology, including the tools used for neurodevelopmental assessment: some have relied on the opinions of teachers or parents through surveys and others still assess exposure to any number of anesthetics. Because young children often undergo general anesthesia for surgical procedures or research studies, it is possible that underlying pathology or other comorbidities are important unadjusted confounders of the risk of later poor neurodevelopmental outcomes.

The 2 most solid studies available to analyze this association are the General Anesthesia Compared with Spinal Anesthesia (GAS) and Neurodevelopmental Evaluation in Pediatric Anesthesia studies. In the GAS trial,65,66 infants up to 60 weeks postmenstrual age scheduled for unilateral or bilateral inguinal hernia repair who were born at more than 26 weeks’ gestation were included in this randomized control trial at 28 participating hospitals on 3 continents. .

Those with risk factors for potential neurological injury or prior exposure to volatile general anesthesia were excluded from the study, and 363 patients were randomly assigned to awake regional anesthesia (spinal, caudal, or combined) and 359 to general anesthesia with sevoflurane. The primary outcome of the trial was full-scale IQ score on the Wechsler Preschool and Primary Intelligence Scale at age 5 years. The secondary outcome was the Bayley Scales of Infant and Toddler Development III composite cognitive score, assessed at 2 years of age.

The mean duration of anesthesia in the general anesthesia group was 54 minutes. At 2 years of age, secondary data from 238 children in the awake regional anesthesia group and 294 children in the general anesthesia group were analyzed. The mean (SD) composite cognitive score in the awake regional anesthesia group and the general anesthesia group was equivalent (98.6 [14.2] vs. 98.2 [14.7]). At 5 years of age, primary data from 205 children in the awake regional anesthesia group and 242 in the general anesthesia group were analyzed.

The mean (SD) full scale IQ was 99.08 (18.35) in the awake regional anesthesia group and 98.97 (19.66) in the general anesthesia group, with a mean difference ( awake regional anesthesia minus general anesthesia) of 0.23 (95% confidence interval, 2.59 to 3.06), providing strong evidence of equivalence.

The Pediatric Anesthesia Neurodevelopment Assessment study67 evaluated neuropsychological functions and behavior between 8 and 15 years of age using a matched sibling cohort design in patients who had undergone a single exposure to general anesthesia during inguinal hernia surgery. before 36 months of age between 2000 and 2010. Global cognitive function (IQ) was the primary outcome, and domain-specific neurocognitive functions and behavior were secondary outcomes.

A total of 105 sibling pairs (exposed vs. unexposed) underwent IQ testing at mean ages of 10.6 and 10.9 years, respectively. All exposed children received inhaled anesthetic agents for a mean duration of 80 minutes. Mean IQ scores between exposed siblings (scores: full scale = 111; performance = 108; verbal = 111) and non-exposed siblings (scores: full scale = 111; performance = 107; verbal = 111) were not statistically significantly different. No statistically significant differences were found in mean scores between sibling pairs in memory/learning, motor/processing speed, visuospatial function, attention, executive function, language, or behavior.

Grabowski et al.,64 in their systematic review of studies analyzing the effect of general anesthesia on neurodevelopmental outcomes, concluded that although it would be reasonable to avoid multiple exposures or prolonged anesthesia for elective surgical procedures, there is no evidence that exposure to a single brief general anesthetic poses a significant risk to neurodevelopment, academic performance, or the risk of attention deficit hyperactivity disorder or autism spectrum disorder.

The American Academy of Pediatrics also noted in its response to the US Food and Drug Administration’s warning on the use of anesthesia in children that controlled human trials and multiple epidemiological studies have not demonstrated any developmental problems in children exposed to a single anesthesia or brief sedation.68

Among preterm infants, the risk of postoperative apnea is an important consideration when deciding on an outpatient setting for repair. Several prospective and retrospective studies have attempted to identify patients at highest risk.69-72 A pooled analysis of 8 prospective studies noted that the risk of postoperative apnea was strongly associated with gestational age, postconceptional age, and anemia.72

Among nonanemic infants without apnea in the recovery room, the risk of postoperative apnea did not decrease below 1% until the postconceptional age was 56 weeks with a gestational age of 32 weeks or the postconceptional age was 54 weeks with a gestational age 35 weeks.

A secondary analysis of the GAS study found that the overall risk of postoperative apnea was independent of the anesthetic technique used, although spinal/regional anesthesia was associated with a lower risk of early apnea; The study authors recommended cardiorespiratory monitoring in preterm infants less than 60 weeks corrected gestational age.73 In light of these data, institutional policies should be developed that define the need and duration of observation after anesthesia in premature newborns.

Inguinal hernias are a common surgical pathology in pediatrics, however, issues related to the approach and optimal time to resolve them continue to be questioned.

In general the risk of incarceration determines the timing of surgical repair. In premature newborns, surgery is usually safely considered after discharge from the NICU since at that time the risk of the technique, the higher recurrence rate, comorbidities associated with prematurity, and issues inherent to anesthesia are minimized.

Pediatric surgery specialists, pediatric urologists, or general surgeons with a significant case volume should achieve optimal results. The laparoscopic approach is at least as effective as open surgery.

In relation to the repair of incidentally discovered contralateral PVP, issues related to the risks and benefits of each approach must be considered. Laparoscopy appears to be a feasible alternative in the treatment of recurrent hernias.

There is no conclusive evidence to suggest that exposure to a single anesthetic of relatively short duration has adverse effects on neurodevelopmental outcomes in otherwise healthy children.