Inguinal hernia in children

INTRODUCTION — 

The epidemiology, clinical presentation, and management of inguinal hernia in children are reviewed here.

The evaluation of inguinal swelling and the causes and evaluation of scrotal pain and swelling in children and adolescents are discussed separately. (See "Evaluation of inguinal swelling in children" and "Causes of painless scrotal swelling in children and adolescents" and "Causes of scrotal pain in children and adolescents" and "Evaluation of nontraumatic scrotal pain or swelling in children and adolescents".)

DEFINITIONS — 

Important definitions related to the diagnosis and management of an inguinal hernia include:

●Hernia — A hernia is the protrusion of a portion of an organ or tissue through an abnormal opening in the wall that normally contains it. Common locations of inguinal hernias in children occur in regions with embryologic and anatomic predisposition. (See 'Testes' below and 'Anatomy' below.)

●Incarceration — Incarceration describes a hernia that is trapped in the hernia sac and cannot be reduced by normal manipulation. An incarcerated hernia may or may not be strangulated.

●Strangulation — Strangulation refers to vascular compromise of the contents of an incarcerated hernia caused by progressive edema from venous and lymphatic obstruction. It can occur within two hours of incarceration [1]. Prolonged strangulation may rarely lead to necrosis and, in the case of bowel, perforation.

●Hydrocele — A hydrocele is a fluid-filled collection that is often mistaken for an inguinal hernia; it can occur anywhere along the path of descent of the testis or ovary. (See 'Testes' below and 'Ovaries' below.)

EMBRYOLOGY

Testes — The testes appear on the ventromedial aspect of the urogenital ridge on the posterior abdominal wall during the fifth to sixth week of gestation [1]. The embryonic testis forms adjacent to the adrenal gland explaining the presence of the occasional adrenal rest of the spermatic cord [2]. By the 10^th week, the testes have descended into the coelomic cavity. The gubernaculum, a mesenchymal structure that extends from the caudal pole of the testis, extends from the inguinal region toward the scrotum, guiding the later descent of the testis and the genitofemoral nerve [3].

The processus vaginalis forms during the third month of gestation from an outward protrusion of the peritoneum that lines the ventral abdominal wall and forms a diverticulum at the internal ring (figure 1) [4]. Between the seventh and ninth months of gestation, the testes follow the path of the gubernaculum and descend through the internal canal and into the scrotum, pushing the processus vaginalis ahead and protruding into its cavity. Once this process is complete, the processus vaginalis obliterates spontaneously, usually by age two years [5].

The right testicle is thought to descend later than the left, and the right processus vaginalis similarly obliterates later than the left, contributing to the observation that right sided hernias are twice as common as left-sided hernias [6].

Ovaries — The descent of the ovaries is similar to that of the testes except that the ovaries do not leave the abdominal cavity. The gubernaculum forms the round ligament in females, which travels through the inguinal ring to the labia majora. Similarly, the canal of Nuck in females corresponds to the processus vaginalis in males and is a pocket of peritoneum that extends from the peritoneal cavity into the labia majora. It normally closes spontaneously at about seven month's gestation [7].

The persistence of smooth muscle may hinder the closure of the processus vaginalis. Myofibroblasts, thought to represent dedifferentiation of smooth muscle and failed apoptosis, were found by electron microscopy in all inguinal hernia sac specimens of 20 children (10 males and 10 females) [8].

ANATOMY — 

A good understanding of inguinal anatomy aids the clinical recognition and diagnosis of inguinal hernias in children:

●Inguinal canal – The inguinal canal is an oblique channel through the abdominal wall through which the spermatic cord passes from the abdomen into the scrotum in males; the round ligament passes from the abdomen into the labia majora in females. It is formed by the aponeurosis of the external oblique muscle (anteriorly) and the transversus abdominus muscle and the transversalis fascia (posteriorly) (figure 2A-B).

The external inguinal ring is formed by the external oblique muscle just superior and lateral to the pubic tubercle. The internal inguinal ring is located in the transversalis fascia and is composed of the transversus abdominus and internal oblique muscles (figure 2B).

Hesselbach's triangle, which is medial to the internal inguinal ring, is bounded by the inferior epigastric vessels, the inguinal ligament, and the rectus sheath. It is a relatively weak area of the abdominal wall through which direct inguinal hernias occur.

In infants, the inguinal canal is short and crosses the abdominal wall perpendicularly rather than obliquely so that the external ring is situated almost directly over the internal ring [1,9]. This anatomic alignment places infants at particular risk for development of inguinal hernia, especially premature infants in whom intraabdominal pressure may be increased by mechanical ventilation [10]. In addition, this perpendicular orientation is important to consider when attempting reduction of an inguinal hernia in an infant.

●Processus vaginalis – Various types of inguinal hernias and hydroceles may occur depending on where and to what degree the processus vaginalis becomes obliterated. This is illustrated in the following examples:

•Indirect inguinal hernia – A widely patent processus vaginalis that permits herniation of the bowel or other peritoneal contents through the internal inguinal ring results in an indirect inguinal hernia (figure 3 and figure 4A-B). The peritoneum lining a hernia is called a hernia sac. In the case of an indirect inguinal hernia, this is anatomically equivalent to the patent processus vaginalis.

The hernia sac generally contains peritoneal fluid (as in a communicating hydrocele) or bowel. Sliding hernias occur when the hernia sac is partially formed by the wall of a viscus (ie, cecum or bladder). In females, the ovary is commonly involved. Hernias also containing fallopian tube and uterus have been reported [11-13].

•Communicating hydrocele – A narrowly patent processus vaginalis that only permits passage of peritoneal fluid results in a communicating hydrocele (figure 5).

•Hydrocele of the spermatic cord – Obliteration of the processus vaginalis proximally and distally with a patent midportion along the spermatic cord can result in a hydrocele of the cord if peritoneal fluid is trapped in the "pocket" of the processus vaginalis.

●Types of hernias – The types of hernias in the inguinal region include:

•Indirect – Indirect inguinal hernias, pass lateral to the deep epigastric vessels through the inguinal canal (figure 3 and figure 4A-B). An inguinal hernia in a child can be safely assumed to be indirect in nature until proven otherwise.

•Direct – Direct inguinal hernias are medial to the inferior epigastric vessels and do not go through the inguinal canal (figure 6). These are generally acquired, rather than congenital, so they are rare in children without a prior history of hernia repair [14].

•Femoral – Femoral hernias, below the inguinal ligament and medial to the femoral artery (figure 7), are also rare in children [15,16].

EPIDEMIOLOGY

Incidence — Primary inguinal hernia occurs in 1 to 5 percent of all newborns and 9 to 11 percent of those born prematurely [4,17]. Among low- and very low-birth-weight infants, the frequency of inguinal hernia varies by birth weight with the highest frequency in extremely premature infants [18-20].

The incidence in males is approximately three to four times higher than in females, with the right side being affected more commonly in both groups [21-23]. In males, the incidence is highest during the first year of life and peaks during the first month [1,22,24]. The right-sided preponderance is related to the later descent of the right testicle and later obliteration of the processus vaginalis. The incidence of bilateral hernias is approximately 10 percent in full-term and nearly 50 percent in premature and low-birth-weight infants [25,26]. In addition to prematurity, risk factors for bilateral hernias include female sex, initial presentation with left-sided hernia, and history of an undescended testicle.

Incarceration — The incidence of incarceration ranges from 14 to 31 percent, usually occurring in infants younger than one year of age [4,27,28]. Among children with incarcerated inguinal hernias, as many as 85 percent occur before the first birthday.

Incarcerated inguinal hernia occurs more frequently the right-side hernias compared with the left side (17 versus 7 percent) and in females compared with males (17.2 versus 12 percent) [21,29]. In females, when incarceration occurs, an ovary, rather than an intestine, is typically involved.

Some authors describe an increased incidence of incarceration in preterm infants [21,29]. However, one review of inguinal hernia in 251 infants younger than six months, including 89 preterm infants, found that incarceration was less common in preterm than in term infants (13 versus 24 percent) [10]. More recently, an incarceration rate of 4 percent was reported in preterm infants with inguinal hernias who were awaiting delayed repair [30].

Associated conditions — Inguinal hernias are more common in children with [21]:

●Abdominal wall defects (eg, Eagle-Barrett [prune belly] syndrome) (see "Prune-belly syndrome")

●Conditions that increase intraabdominal pressure (eg, continuous ambulatory peritoneal dialysis, ventriculoperitoneal shunts [31], ascites, chronic respiratory disease)

●Connective tissue disease (eg, Ehlers-Danlos syndrome) (see "Ehlers-Danlos syndromes: Clinical manifestations and diagnosis")

●Abnormalities of the genitourinary system (eg, atypical genitalia, hypospadias, bladder exstrophy, cryptorchid testis) (see "Clinical manifestations and initial management of infants with bladder exstrophy" and "Undescended testes (cryptorchidism) in children: Clinical features and evaluation", section on 'Examination')

●Family history of inguinal hernia

Complete androgen insensitivity should be suspected in phenotypically normal female infants or children who have inguinal hernias or inguinal or labial masses. As many as 1 to 2 percent of females with inguinal hernias may have this disorder [32,33]. In a survey of androgen insensitivity diagnosis and management in the United Kingdom, inguinal hernia was the presenting complaint in 22 of 29 (76 percent) and was present in 28 of 29 (96 percent) phenotypically female children with complete androgen insensitivity [34]. (See "Diagnosis and treatment of disorders of the androgen receptor".)

CLINICAL FEATURES AND DIAGNOSIS — 

Children with an inguinal hernia may present with clinical features that include a history of an intermittent mass, an examination demonstrating a mass that is reducible, or an incarcerated mass. Many of these children can be diagnosed with an inguinal hernia on physical examination:

●No mass (intermittent bulge) – Most children with an inguinal hernia have a history of an intermittent bulge in the groin that may have been noted at times of increased intraabdominal pressure, such as straining or crying [1]. They are usually asymptomatic when this occurs.

An inguinal mass is frequently not present on examination. Maneuvers to increase intraabdominal pressure and demonstrate the hernia are often unsuccessful [35]. The "silk sign" is a palpable silky thickening of the cord that may sometimes be appreciated by placing a single finger parallel to the inguinal canal at the level of the pubic tubercle and rubbing it from side to side. However, this is not a reliable finding [1,21].

Having the parents document with a cellphone photograph or video the presence of a bulge in the groin and/or scrotum also helps make the diagnosis.

●Reducible mass – Often, parents or primary caregivers seek medical care because an inguinal mass has developed that has not spontaneously reduced (picture 1 and picture 2 and figure 3). Nonspecific symptoms such as irritability and decreased appetite may be reported. In males, the inguinal mass can extend into the scrotum. It should not be tender on examination.

●Incarcerated mass – Infants with an incarcerated inguinal hernia usually are irritable and crying. Vomiting and abdominal distention may develop depending on the duration of incarceration and whether intestinal obstruction has occurred [1]. In females, a herniated ovary or fallopian tube may be present in the hernia.

Physical examination of children with incarcerated inguinal hernias is usually diagnostic. A firm, discrete inguinal mass, which may extend to the scrotum or labia majora, can be palpated in the groin. The mass is usually tender and often surrounded by edema with erythema of the overlying skin [28]. In males, the testicle may appear dark blue because of venous congestion caused by pressure on the spermatic cord.

●Equivocal physical examination – An ultrasound (US) examination of the groin is often helpful when the etiology of an acute groin swelling cannot be determined on clinical examination. (See 'Imaging' below.)

LABORATORY EVALUATION — 

Routine laboratory work is not helpful in evaluating children with inguinal hernias. One study reported white blood cell counts of 4600 to 21,000 cells/µL (4.6 to 21.0 x 10(9)/L) in 69 children with incarcerated hernias and found no correlation between the white blood cell count and the degree of vascular compromise of the entrapped bowel described at surgery [28].

Karyotyping should be considered when a testicle is palpable in the inguinal canal or found at herniorrhaphy in phenotypic females because there is an association between androgen insensitivity and inguinal hernia. (See 'Associated conditions' above.)

IMAGING — 

In many children, an inguinal hernia is a clinical diagnosis made by history and physical examination. An ultrasound (US) examination is often helpful when the etiology of an acute groin swelling cannot be determined on clinical examination [36,37]. The diagnostic accuracy of ultrasound for acute groin conditions in infants is about 93 percent [38]. The sensitivity for detection of a patent processus vaginalis is approximately 90 percent [39]. (See "Evaluation of inguinal swelling in children".)

Plain abdominal radiographs are of limited use in the evaluation of a patient with an incarcerated hernia unless there are signs of bowel perforation and peritonitis.

DIFFERENTIAL DIAGNOSIS — 

The causes and diagnostic approach to inguinal swelling, including inguinal hernias, are discussed in detail separately (table 1). (See "Evaluation of inguinal swelling in children", section on 'Causes of inguinal swelling' and "Evaluation of inguinal swelling in children", section on 'Diagnostic approach'.)

In males, some scrotal conditions may cause swelling that extends up into the external inguinal ring and appears similar to inguinal hernias. These include the following (see "Causes of painless scrotal swelling in children and adolescents" and "Causes of scrotal pain in children and adolescents"):

●Hydrocele – An acute hydrocele generally involves only the scrotum; no mass is palpated in the area of the internal ring. This is in contrast to a communicating hydrocele, which is, in fact, a hernia containing peritoneal fluid (see 'Anatomy' above). Hydroceles transilluminate and usually are cystic, irreducible, and nontender. An acute hydrocele of the spermatic cord may occasionally be difficult to distinguish from an incarcerated inguinal hernia [1]. In rare cases, a large scrotal hydrocele in the neonatal period can gradually expand retrograde through the inguinal canal into the abdomen, creating an abdominoscrotal hydrocele as a source of abdominal mass [40]. (See "Causes of painless scrotal swelling in children and adolescents", section on 'Hydrocele'.)

●Varicocele – Varicoceles, typically seen in the adolescent age group, are dilated veins of the pampiniform plexus of the spermatic cord. They usually increase with the Valsalva maneuver to produce a large, soft scrotal mass ("bag of worms") that decompresses in the recumbent position. They occur almost exclusively on the left side with a small percentage of patients having bilateral varicoceles. The rare right-sided varicocele is associated with venous obstruction from large intraabdominal tumors such as a Wilms tumor or neuroblastoma. (See "Causes of painless scrotal swelling in children and adolescents", section on 'Varicocele'.)

●Testicular torsion – Testicular torsion causes severe pain and vomiting. The affected testicle is typically swollen, tender, and retracted toward the external ring. The cremasteric reflex is absent on the affected side. (See "Causes of scrotal pain in children and adolescents", section on 'Testicular torsion'.)

●Torsion of the appendix testis – Torsion of the appendix testis produces a tender nodule on the upper pole of the testicle that may appear as a blue dot once the torsed tissue has become necrotic. (See "Causes of scrotal pain in children and adolescents", section on 'Torsion of the appendix testis or appendix epididymis'.)

●Retractile testis – An inguinal mass may represent a retractile testis that has moved into the inguinal canal as a result of an exaggerated cremasteric reflex. It can be distinguished from an inguinal hernia by bringing the testis into the scrotum. A finger is then placed transversely across the top of the scrotum at the base of the penis. This will prevent a retractile testis from ascending into the inguinal canal when the cremasteric reflex is again elicited [1]. In addition, an empty hemiscrotal sac suggests an abnormal testicular location. (See "Evaluation of inguinal swelling in children", section on 'Testicular dislocation' and "Evaluation of inguinal swelling in children", section on 'Testes: Retractile, ectopic, or undescended'.)

●Testicular cancer – Testicular cancer usually presents as a painless mass discovered by the patient or clinician on physical examination, although rapidly growing germ cell tumors may cause acute scrotal pain secondary to hemorrhage and infarction. Other common signs are testicular enlargement or swelling. (See "Causes of painless scrotal swelling in children and adolescents", section on 'Testicular cancer'.)

INITIAL MANAGEMENT — 

The initial management of a child with an inguinal hernia is provided in the algorithm (algorithm 1).

Specialty referral or consultation — Inguinal hernias require operative repair. Surgical outcomes are optimal when the procedure is performed by pediatric urologists, pediatric surgeons, or general surgeons with significant pediatric experience [4]. Children with incarcerated inguinal hernias need emergency surgical evaluation and treatment. Otherwise, timing of referral or consultation depends upon the age of the patient and if the hernia is reducible. (See 'Timing of repair' below.)

Incarcerated inguinal hernia — An incarcerated inguinal hernia requires emergency reduction either manually or surgically. Once incarceration is recognized, children should have no oral intake.

Manual reduction — Manual reduction is successful in an estimated 70 to 100 percent of children with incarcerated hernias. [27,41-46]. When laparoscopic surgery is not available, successful reduction avoids emergency surgery, which is associated with a higher risk of operative complications [21].

However, if the child is ill-appearing with signs of peritonitis, intestinal obstruction, or toxicity possibly related to gangrenous bowel, then the clinician should not perform manual inguinal hernia reduction and obtain emergency surgical consultation.

●Preparation – Prior to reduction, the clinician should place the patient in reverse Trendelenburg position. Reduction is facilitated by analgesia (eg, intranasal or intravenous fentanyl) [46]. For the initial reduction attempt, the clinician may also provide mild sedation (eg, intranasal midazolam or inhaled nitrous oxide) to further reduce distress and degree of crying. (See "Procedural sedation in children: Approach" and "Procedural sedation in children: Selection of medications", section on 'Sedation for painful procedures'.)

●Techniques – Several bimanual reduction techniques are described. Evidence is lacking to indicate the superiority of any one technique. The choice of technique depends upon clinician experience and preference and includes:

•Option 1 – Pressure is applied along the proximal inguinal canal with one hand, while the other hand attempts to "milk" the gas or contents out of the incarcerated bowel with gentle pressure for up to five minutes (figure 8). After reducing the contents of the incarcerated bowel, pressure should be increased slightly over the distal aspect of the hernia to reduce the bowel.

•Option 2 – The examiner uses the thumb and index finger of one hand to form a funnel where the mass exits the inguinal ring and then exerts steady, circumferential pressure with the other hand on the inferomedial aspect of the mass. A "hiss" of air and a decrease in the size of the mass may accompany a successful reduction. Success is indicated by a reduction of the mass.

•Option 3 – The practitioner sweeps along the inguinal hernia into the scrotum and applies longitudinal tension while providing traction that opens the internal and external hernial rings (figure 9). The hernia is then walked through the opening.

If the clinician is unable to reduce the incarcerated hernia, they should obtain emergency consultation with a surgeon who has pediatric expertise. In females, if not already performed, the clinician should obtain a Doppler ultrasound to determine if the hernia sac contains an ovary and to assess for torsion. (See 'Inguinal mass in a female' below.)

Because these patients may require prolonged continuous pressure to achieve reduction and children may be more likely to cry or resist subsequent reduction attempts, we advise moderate sedation with agents that provide both sedation and analgesia. This may be performed by an experienced pediatric sedation provider or under general anesthesia in the operating room. (See "Procedural sedation in children: Selection of medications", section on 'Moderately or severely painful procedures'.)

Success rates for manual reduction are influenced by the duration of incarceration and the age of the child. In one report of 85 children younger than two years, those with failed manual reductions were younger (three versus five months) and had a longer duration of symptoms (34 versus 12 hours) compared with those who had successful manual reductions [47].

●Postreduction management – After successful manual reduction of an incarcerated hernia, surgical consultation is warranted to determine the optimal timing of repair. The patient should be observed to ensure that normal feeding resumes. The surgeon may recommend discharge with close follow-up and scheduled repair or admission for repair.

If the reduction was delayed or difficult, or if the child does not tolerate oral intake during emergency department (ED) observation, then bowel injury is more likely. In this situation, we advise admission for observation. Patients may be admitted to a surgical service or a medical service with surgical consultation available. Patients who have an uneventful recovery should have either surgical consultation prior to discharge or a prompt referral to a surgeon with pediatric expertise for timely repair. During observation, the development of feeding intolerance while advancing to a full diet or increasing pain, abdominal distension, or signs of peritonitis (eg, fever or rebound tenderness) requires urgent evaluation for bowel perforation and emergency surgery. (See 'Incarcerated hernia' below.)

Surgical reduction — In patients with an incarcerated hernia and an unsuccessful manual reduction, the hernia must be reduced and surgically repaired. (See 'Surgical management' below.)

No mass, reducible mass — A convincing history of intermittent groin swelling or a reducible inguinal mass in a male child is an indication for referral to a surgeon. Surgical evaluation should be obtained promptly (eg, within one to two weeks) but is not an emergency. While awaiting evaluation, caretakers should be informed of the signs and symptoms of incarceration and provided with indications for seeking medical attention. (See 'Timing of repair' below.)

Inguinal mass in a female — All female patients with an irreducible inguinal hernia should have an ultrasound (US) with Doppler flow to identify contents of the incarcerated hernia sac and, for patients with an incarcerated ovary, assess for torsion [11,48]. They should also have prompt surgical consultation. Because of the significant likelihood that reproductive organs are within the hernial sac, the clinician may attempt a gentle reduction. If reduction is not easily achieved, then further reduction attempts should be avoided.

Hernias in females are caused by the persistence of the canal of Nuck and contain the suspensory ligament of the ovary [11,13]. A significant number of these hernias also contain the ovary and/or fallopian tube [49,50]. Rarely, the uterus may also be present [51]. All females with inguinal hernias that contain incarcerated reproductive organs warrant emergency surgical consultation.

SURGICAL MANAGEMENT

Laparoscopic versus open repair — In children with inguinal hernias, both laparoscopic and open approaches are widely used with excellent results. For healthy patients with no contraindications to laparoscopy and when the surgeon has training, experience, and proficiency with this technique, we suggest laparoscopic rather than open repair. Advantages of laparoscopic repair include the ability to perform routine contralateral exploration and repair without additional incisions, less postoperative pain, fewer complications, faster recovery, and no inguinal scar [4,52-56]. However, open herniorrhaphy is a reasonable alternative and may be performed according to the surgeon's discretion. Laparoscopic repair is relatively contraindicated in children with prior abdominal surgery. Furthermore, some children with comorbidities, especially those with cardiac and/or pulmonary insufficiency may not be able to tolerate laparoscopy and will require open repair.

●Minimally invasive (laparoscopic) repair — Laparoscopic high ligation for pediatric inguinal hernia is an alternative to open herniorrhaphy and is commonly performed with favorable results. It encompasses a variety of techniques including laparoscopic intracorporeal purse-string suturing and laparoscopic-assisted percutaneous extracorporeal ligation. Of the two main approaches, surgeons commonly use the assisted percutaneous extracorporeal ligation technique because intracorporeal purse-string suturing requires additional trocars and incisions [4,57].

While many technical variations exist, the common elements of the laparoscopic percutaneous extracorporeal ligation technique include (picture 3):

•Transumbilical camera placement to inspect both inguinal canals

•Cauterization of the peritoneum at the internal inguinal ring

•Percutaneous passage of a suture to ligate the patent processus vaginalis while protecting the vas deferens and testicular vessels

Compared with open herniorrhaphy, minimally invasive techniques have similar recurrence rates when performed by experienced surgeons [58,59]. Advantages of laparoscopic repair include [4,52-56]:

•Lower rates of wound complications

•No inguinal scar

•Reduced early postoperative pain

•Routine contralateral exploration and repair without additional incisions, which is accompanied by a reduction in rates of contralateral metachronous hernia (see 'Contralateral exploration' below)

●Open herniorrhaphy – The traditional or open herniorrhaphy is an alternative to laparoscopic repair and involves [60]:

•A transverse incision over the inguinal canal

•Careful separation of the processus vaginalis from the vas deferens and testicular vessels

•Ligation and excision of the processus vaginalis; in females, before ligation of the processus vaginalis, usually along with the round ligament confirm that the hernia sac does not contain reproductive organs [61].

In children, in whom >90 percent of hernias are indirect, high ligation of the hernia sac is preferred; the addition of a mesh has potential long-term complications such as recurrence, postherniorrhaphy neuralgia, and unilateral injury to the reproductive system. In select cases of recurrent or direct hernia, especially in an older teenager with a large hernia sac, weak posterior wall, and internal inguinal ring diameter ≥3 cm, the use of mesh to reinforce the repair may be appropriate based on surgeon practice [62,63]. Otherwise, the use of prosthetic mesh for inguinal hernia repair (Lichtenstein technique), while standard in adult hernia care, is rarely required in pediatric patients. (See "Open surgical repair of inguinal and femoral hernia in adults", section on 'Surgical techniques'.)

Additional considerations during open herniorrhaphy include:

•When the inguinal ring has been enlarged by repetitive herniation, plication of the floor of the inguinal canal (the transversalis fascia) may also be necessary.

•In small infants who have large hernias that have gone untreated and have developed progressive enlargement of the inguinal ring and total breakdown of the transversalis fascia, complete reconstruction of the floor of the inguinal canal using the conjoint tendon is occasionally required [64].

•Males who have an associated undescended testis should have orchidopexy at the same time as open inguinal hernia repair [1,21,61]. For children less than six months of age with symptomatic hernia and undescended testis, reasonable options include laparoscopic repair of the inguinal hernia (as discussed below) with delayed orchidopexy as needed for no descent by one year of age or combined open repair and orchidopexy.

Contralateral exploration — The increased use of laparoscopic inguinal hernia repair has altered the risk/benefit profile of contralateral repair of a patent processus vaginalis because it permits bilateral exploration and repair without additional incisions. While data from open repair series suggest that many of the contralateral repairs are unnecessary because a minority of patent processus vaginalis may evolve into a clinical hernia [65], the reduction in morbidity from contralateral laparoscopic repair supports a lower threshold to perform the repair under a single anesthetic and per parent/primary caregiver preference during informed consent. Furthermore, contralateral exploration is warranted for children at particular risk for metachronous inguinal hernia, including those with increased intraabdominal pressure, connective tissue disease, chronic pulmonary disease, or other comorbid condition that makes the child at increased risk for anesthesia-related complications [21,61,66].

The need for contralateral inguinal exploration has been debated, especially when performing open inguinal hernia repair in otherwise healthy children [4]. The natural history of a patent processus vaginalis is closure within two months after birth in 40 percent of children and within two years in an additional 20 percent [26]. Of the remaining 40 percent of children, clinical hernias may develop in one-half. Thus, the finding of a patent processus vaginalis in the absence of a clinical hernia is not a clear indicator of a future hernia. Based on retrospective observational studies that have evaluated contralateral hernia repair with expectant management, approximately two-thirds of contralateral repairs may be unnecessary [67].

Transinguinal laparoscopic evaluation of the contralateral side during ipsilateral open repair has been suggested as an alternative to open surgical exploration and leads to successful visualization of the contralateral inguinal ring in up to 97 percent of patients [68,69]. This technique is an adjunct to open transinguinal repair and not a laparoscopic repair. It has a sensitivity of 99.4 percent and a specificity of 99.5 percent for detecting a patent processus vaginalis and can be performed with a mean operative time of six to eight minutes and a complication rate <1 percent [69-71]. However, estimates primarily from retrospective observational studies suggest that about two-thirds of these surgeries are unnecessary. Given the uncertainty of benefit, preoperative discussion and shared decision-making with parents/primary caregivers regarding whether to close a contralateral patent processus vaginalis is warranted during informed consent for an open transinguinal repair [4].

Timing of repair — The suggested timing for inguinal hernia repair in children varies by presentation, patient factors, and surgical technique (laparoscopic versus open repair).

Incarcerated hernia — Immediate laparoscopic surgical repair after successful manual reduction of incarceration eliminates the risk of repeated incarceration and is favored by some surgeons [72].

By contrast, if performed immediately, open repair is technically difficult and increases the risk for development of a direct hernia as a complication. In addition, tissue swelling after incarceration can cause distortion of the anatomic landmarks, rendering detection of a coincident direct hernia difficult. On the other hand, a delay in definitive open repair carries the risk of recurrent incarceration and the need for emergency surgery. The risk of recurrent incarceration is between 16 and 35 percent [41,43]. To reduce this risk, we suggest open repair of an incarcerated hernia within five days of manual reduction (within two days for infants born prematurely). Many pediatric surgeons hospitalize children after successful manual reduction of incarcerated inguinal hernia and repair the hernia within 24 to 48 hours. The short delay allows the involved tissues to return to their normal texture before surgery.

Asymptomatic hernia (outpatients) — For an asymptomatic child diagnosed with an inguinal hernia, the timing of repair is based on the size of the hernia and patient age. Smaller hernias in infants (<1 year old) are more prone to incarceration than larger hernias that are easily reducible in older patients. For large hernias at low risk of incarceration, the timing of repair is elective and can be performed to maximize convenience for the family. For hernias that are more prone to incarceration, we advise repair within 30 days of diagnosis.

The optimal timing for elective repair after the diagnosis of an asymptomatic hernia is debated. Some experts propose that the waiting time should be limited because a longer waiting time from outpatient diagnosis to surgery has been associated with an increased risk for incarceration in some patients, particularly young children and infants [4,30,73-75]. For example, in an observational study of 1065 children undergoing elective hernia repair, surgery within 14 days from the time of diagnosis was associated with a lower risk of incarceration compared with repair at 35 days, the median wait time in this study (5 versus 10 percent respectively) [73]. On adjusted analysis, a wait time for surgery >14 days also had an increased risk of incarceration (adjusted odds ratio [aOR] 1.9, 95% CI 1.1 to 3.3).

However, more recent and larger observational studies have not found an association between waiting time and incarceration when repair occurs several weeks after diagnosis [76,77]. In a multicenter, retrospective cohort study of 1404 patients undergoing inguinal hernia repair (604 with cancellation of elective surgery due to the COVID-19 pandemic), interval incarceration rates were not associated with longer time to surgery (2.5 percent pre-pandemic versus 3.1 percent post-pandemic, aOR 1.5, 95% CI 0.9 to 2.2) [77]. The median time from outpatient inguinal hernia diagnosis to surgery was slightly longer pre- versus post-pandemic (29 days versus 31 days).

Preterm infants (inpatients) — For any premature infant with a reducible inguinal hernia, surgical consultation is recommended at the time of diagnosis to establish a relationship with the patient's family, delineate criteria that would warrant early repair (ie, symptomatic hernia, difficult reduction), and provide the opportunity for patient- and family-centered decision-making about the timing of repair.

The optimal timing of repair for reducible hernias in preterm infants depends upon a variety of factors and should take into account a neonate's risk of serious adverse effects associated with anesthetic exposure and risk of hernia-related complications, primarily incarceration [30,74].

For pre-term infants with reducible inguinal hernias, late repair (after NICU discharge and when the patient is older than 55 weeks postmenstrual age) rather than early repair (before NICU discharge) reduces the risk of serious adverse events related to anesthesia, especially in infants with bronchopulmonary dysplasia and those born at <28 weeks gestation [30,74]. However, the surgeon should consider several factors when deciding when to operate including the likelihood of incarceration based upon physical examination, family preferences expressed during shared decision-making, and the family’s ability to monitor for hernia incarceration after discharge and to seek timely medical care.

Regardless of timing of repair, preterm infants who are at risk for apnea and bradycardia should be monitored closely in the postoperative period. For any infant with a history of prematurity, if younger than 55 weeks postmenstrual age, an overnight observation is indicated.

Support for late hernia repair in preterm infants comes from a multicenter, randomized trial of 308 preterm infants with inguinal hernia [30]. In this study, 28 percent of patients assigned to early repair (prior to neonatal intensive care unit [NICU] discharge) had one or more serious adverse events compared with 18 percent of the late repair group (after NICU discharge and older than 55 weeks postmenstrual age). The majority of serious events were related to anesthesia (apnea, bradycardia, or prolonged intubation); the benefit of late repair was most pronounced in infants with bronchopulmonary dysplasia and those younger than 28 weeks gestation [30]. In addition, clinical resolution of the hernia was noted in 4 percent of infants in the early repair group, and 11 percent in the late repair group, also supporting late repair. An important consideration of this study is the low incarceration rate: 4 percent in the late repair group versus 1.3 percent in the early repair group. These findings contrast with a systematic review and meta-analysis of retrospective cohort studies in which incarceration rates for early versus late hernia repair in preterm infants were 9 and 18 percent, respectively [74].

Postoperative care — Most children who undergo repair of inguinal hernia have an uncomplicated postoperative course. Scrotal edema can occur as a postoperative complication; it usually resolves spontaneously over approximately three weeks. Postoperative hematomas and hydroceles, on the other hand, can take up to three months to resolve and should be followed to resolution by the operating surgeon. Postoperative infection is uncommon (<1 percent of patients) [61].

COMPLICATIONS — 

Important complications of inguinal hernias in children include:

●Bowel infarction – Bowel infarction is the most serious complication of an inguinal hernia. Infarction may occur within two hours of incarceration. However, despite the fact that incarceration is not uncommon (particularly in young infants), the need for intestinal resection is rare [27,29].

Incarceration of an inguinal hernia can compromise the blood supply to the testis, resulting in ischemic necrosis and atrophy. Incidences of testicular atrophy from 2 to 9 percent have been reported after emergent operative reduction of incarceration [27,78]. Males with inguinal hernias also can have injury to the vas deferens, with the development of sperm-agglutinating antibodies [79,80].

●Ovarian torsion (females) – In females with incarcerated inguinal hernia, torsion rather than direct compression compromises the blood supply to the ovary. Strangulation is reported to occur in between 2 and 33 percent of females with inguinal hernias with an irreducible ovary. Because torsion can occur in an irreducible ovary while awaiting elective inguinal hernia repair, some surgeons recommend immediate reduction and repair [81].

●Recurrence – After surgical repair of an inguinal hernia, the risk of recurrence ranges from 1 percent after elective hernia repairs up to 24 percent in patients with risk factors such as elevated intraabdominal pressure (ventriculoperitoneal shunt, cystic fibrosis, ascites), malnutrition, prematurity, arrested testicular descent, connective tissue disorders, or a history of incarceration [4,82-84].

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Inguinal hernia in children".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Groin hernias (The Basics)" and "Patient education: Groin (inguinal) hernias in children (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Etiology – A congenital inguinal hernia develops when the processus vaginalis fails to obliterate during late gestation, allowing persistent communication between the abdominal cavity and the inguinal canal. Abdominal contents can then herniate into the inguinal canal. The vast majority of inguinal hernias in children are indirect (figure 3). (See 'Embryology' above and 'Anatomy' above.)

●Clinical features and diagnosis – The diagnosis of an inguinal hernia is frequently made based on history and physical examination. Asymptomatic inguinal hernias in children often manifest in the first year of life as an intermittent or easily reducible inguinal mass (picture 1 and picture 2). The history may include an intermittent bulge in the groin that occurs when the patient is straining during defecation or crying in a patient with no inguinal mass on examination. When present on examination, the inguinal hernia is nontender and easily reduced. (See 'Clinical features and diagnosis' above.)

Infants with an incarcerated inguinal hernia are usually irritable and crying. They have a firm, discrete inguinal mass that may extend to the scrotum or labia majora on groin palpation. The mass is usually tender and often surrounded by edema with erythema of the overlying skin.

When examination findings are equivocal, an ultrasound (US) examination may be helpful to confirm the diagnosis of an inguinal hernia or diagnose another etiology for the acute groin swelling (table 1). Photographic documentation by the parents when the hernia/bulging is intermittently present may also be helpful. (See 'Differential diagnosis' above and "Evaluation of nontraumatic scrotal pain or swelling in children and adolescents".)

●Management – The approach to a child with an inguinal hernia is provided in the algorithm (algorithm 1):

•Incarcerated hernia – Children with an incarcerated hernia should have no oral intake in case they need emergency surgery. Patients with signs of peritonitis or intestinal obstruction (eg, abdominal pain with bilious vomiting, distension, rebound tenderness, or rigid abdomen) should not undergo manual reduction; they require emergency evaluation and surgical consultation. (See 'Incarcerated inguinal hernia' above.)

All female patients with an irreducible inguinal hernia should have a US with Doppler flow because of a high likelihood of an incarcerated ovary with possible torsion. Male patients without signs of peritonitis and female patients without an entrapped ovary should receive analgesia (eg, intranasal or intravenous fentanyl) and undergo emergency manual reduction (figure 8 and figure 9). (See 'Manual reduction' above and 'Inguinal mass in a female' above.)

Children with successful manual reduction of an incarcerated hernia may undergo laparoscopic repair. In settings where laparoscopic repair is not feasible, they should be observed for bowel injury suggested by feeding intolerance or signs of peritonitis. Surgery is typically performed within five days of the reduction (within two days for infants born prematurely).

Patients whose hernia cannot be manually reduced require emergency surgery for reduction and repair (laparoscopic or open approach).

•Intermittent or easily reduced hernia – A child with an intermittent or easily reduced hernia requires referral to a surgeon for evaluation and elective repair. The timing of repair depends upon the age of the child and the size of the hernia. Hernias that are more prone to incarceration (eg, smaller hernias in infants) are typically repaired within 14 to 30 days of diagnosis. For large hernias at low risk of incarceration, the timing of repair is elective. (See 'Asymptomatic hernia (outpatients)' above.)

For pre-term infants with reducible inguinal hernias in the inpatient setting, late repair (after neonatal intensive care unit [NICU] discharge and when the patient is older than 55 weeks postmenstrual age) rather than early repair (before NICU discharge) reduces the risk of serious adverse events related to anesthesia, especially in infants with bronchopulmonary dysplasia and those born at <28 weeks gestation but increases the risk of incarceration. Shared decision-making with the family is advised. (See 'Preterm infants (inpatients)' above.)

•Choice of procedure – For healthy infants and children with no contraindications to laparoscopy and when the surgeon has training, experience, and proficiency, we suggest laparoscopic rather than open repair (Grade 2B). Advantages of laparoscopic repair include:

-The ability to perform routine contralateral exploration and repair without additional incisions in accordance with parent or caregiver preference

-Less postoperative pain

-Fewer complications

-Faster recovery

-No inguinal scar

However, open herniorrhaphy is a reasonable alternative and may be performed according to the surgeon's discretion. Laparoscopic repair is relatively contraindicated in children with prior abdominal surgery. Furthermore, some children with comorbidities, especially those with cardiac and/or pulmonary insufficiency, may not be able to tolerate laparoscopy and will require open repair. (See 'Laparoscopic versus open repair' above and 'Contralateral exploration' above.)

ACKNOWLEDGMENT — 

The UpToDate editorial staff acknowledges Erin Endom, MD, who contributed to earlier versions of this topic review.