In many families, the phrase "my tummy hurts" is heard with some regularity. These complaints are usually not long lasting or associated with significant abdominal pathology, and, fortunately, most of the worries fade as the child's attention span wanders. Occasionally, a child presents with vague abdominal complaints that suggest the presence of an abdominal wall hernia, but supporting findings on physical examination are not readily apparent. There are also a significant number of asymptomatic children with findings on abdominal examination that suggest a hernia. These uncertainties often prompt a referral to a pediatric surgeon.
Although not seen as often as otitis media, viral illnesses, and rashes, abdominal wall hernias are common and are routinely diagnosed by hospital-based and office-based pediatricians. Although the diagnosis may be obvious, the appropriate timing of surgical consultation is not always as clear, largely due to the ongoing controversies involving the diagnosis and surgical management of these conditions. Improvements in neonatal and anesthetic care and technologic advances have only increased the choices available for evaluating and treating these children. Although usually based on surgical principles, operative decisions are occasionally based on historical practices that have little scientific support. Future practice will likely be based on the results of collaborative studies involving multiple surgical centers.
Although the first documentation of inguinal hernias as a medical entity appeared as early as the second century, it was nearly 300 years before a surgical repair was reported.1,2 The concept of high ligation and excision of the sac without altering the layers of the inguinal canal was introduced at the end of the 19th century.3 This concept has become the basis for the standard repair of pediatric inguinal hernias. Today, inguinal hernia repair is one of the most common procedures performed in pediatric surgical practices.4
The ovenvhelming majority of inguinal hernias in children are indirect hernias (ie, their formation is dependent on the presence of a patent processus vaginalis). The gonads develop near the kidneys, and begin a downward retroperitoneal descent at 3 months of gestation. By the seventh month, they reach the internal inguinal ring and, during the course of 4 to 5 days, arrive at the external ring. During the next 4 weeks, the testes migrate deep into the scrotum. It is not until the last few weeks of gestation that the processus vaginalis normally closes, becoming the tunica vaginalis. Failure of the processus vaginalis to close accounts for most inguinal hernias in infants and children.
An indirect inguinal hernia exists when abdominal or pelvic viscera, or fluid, enter the patent processus and travel through the internal ring into the inguinal canal. In boys, bowel is most frequently found in hernia sacs. In girls, it is common to have ovaries or fallopian tubes within the sac, and rarely even a portion of the bladder. Hydroceles are fluid-filled collections anywhere along the path of testicular descent or within the canal of Nuck. The latter is the female equivalent of the inguinal canal, through which the round ligament is located. Hydroceles may be confined to the scrotum, present only within the cord, or vary in size, as with communicating hydroceles. Some surgeons regard a communicating hydrocele as an indirect hernia whose orifice is large enough to allow only the passage of fluid.4
The incidence of inguinal hernias ranges from 0.8% to 4.4% in children.5 Hernias are most common in infants, especially premature infants.6-7 Boys are 3 to 10 times more likely to have a hernia than are girls, but this difference is less evident among premature infants. Nearly two-thirds of hernias present on the right, one-third present on the left, and the remaining present as bilateral defects.8
The abnormality most frequently confused with an inguinal hernia is a hydrocele. Unlike most hernias, hydroceles usually produce minimal symptoms and cannot be reduced. Hydroceles are more common in infancy and are more often bilateral. Most congenital hydroceles resolve by the second year of life, but those that develop after infancy are more likely to require surgical repair. Although sometimes used to differentiate between hydroceles and hernias, transillumination is frequently unreliable, especially when the bowel is filled with fluid. Other conditions confused with hernias are testicular torsion, inguinal adenopathy, undescended testes, retractile testes, and, rarely, testicular neoplasms.
Several conditions are associated with the development of an inguinal hernia. These include congenital urogenital disorders, such as cryptorchidism, bladder exstrophy, and cloacal exstrophy. Conditions in which mtra-abdominal pressure is increased, from either additional peritoneal fluid or congenital anomalies, are also more commonly associated with inguinal hernias. These include abdominal wall defects, severe ascites, the presence of ventriculoperitoneal shunts and peritoneal dialysis catheters, meconium peritonitis, connective tissue diseases, and some pulmonary problems such as cystic fibrosis.
Presentation and Initial Management
Most hernias present as symptomatic or asymptomatic bulges in the lower abdomen, scrotum, or labia, and are commonly seen with straining and crying. The patient is usually sent to the surgeon after the parent or the pediatrician identifies a suspicious mass. Despite a compelling history by the parents and a mass detected by the pediatrician, the presence of the hernia often cannot be confirmed by the surgeon, despite multiple maneuvers to increase intra-abdominal pressure. Having the patient stand and lean back, cough, growl, cry, blow bubbles, or do sit-ups is useful for increasing intra-abdominal pressure and thereby enhancing the ability to identify a hernia. Although many surgeons will accept the diagnosis based on an accurate history alone, additional visits are occasionally required before deciding to operate.
Inguinal hernias present in several predictable ways. Caregivers may note that they spontaneously reduce and then reappear without any signs of discomfort to the child. Other children will present with an asymptomatic inguinal or scrotal mass that has never decreased and may have gradually enlarged. Regardless of whether me hernia produces symptoms, every attempt should be made to reduce it when it is first recognized. This involves gently squeezing the most dependent portion of the hernia in the direction of the canal with one hand, while providing gentle pressure on the external ring with the thumb and the forefinger of the other hand. Fortunately, most hernias can be reduced in this manner. Occasionally, the administration of a minimal amount of a sedative or a narcotic may be useful to assist in the reduction, especially for older children. This should usually be done only after the surgeon has attempted reduction, because necrotic bowel has been reduced after the administration of sedation.
Reduction should be considered in the presence of an early bowel obstruction, but should be avoided when peritonitis exists or if the hernia was not recognized for a long time. If the hernia is not reduced after a careful attempt by the surgeon, it is incarcerated and requires emergent repair.
Most inguinal hernias can be repaired as elective outpatient procedures. Premature children and those with other major comorbid conditions are frequently admitted overnight to observe for potential anesthetic complications, including apnea, bradycardia, and desaturation episodes. These problems are uncommon and closely related to the postgestational age of the child. The greatest risk of complications occurs in the most severely premature infants. Because apnea may occur after repair, many centers require that former premature infants be admitted overnight for monitoring. The accepted cutoff for doing this varies from center to center and is usually between 45 and 60 weeks of postconceptual age.9 Some centers have no set requirements and base their decisions on the postoperative condition of the infant.
When a severely premature, very low-birthweight infant is identified with an inguinal hernia while in the neonatal intensive care unit, the timing of repair depends on his or her postgestational age, weight, oxygen requirement, and comorbid conditions and the accessibility of a surgical facility. Some believe that the repair should be performed prior to discharge to reduce the risk of incarceration and delayed repair. Others believe that as long as the infant is closely monitored and lives an acceptable distance from a pediatric surgical facility, the surgery may be delayed until he or she has matured. Criteria usually include a pattern of increased growth, diminished oxygen requirements, and decreasing episodes of apnea or bradycardia. With the cautious delay of the repair it is hoped mat there will be a reduction in problems associated with surgery in a premature infant, including impaired healing, injury to the spermatic cord during repair, recurrence, and, most commonly, postoperative respiratory failure. There is no definitive evidence that either approach yields better results.
I regularly observe the premature infant with an inguinal hernia in the neonatal intensive care unit or closely monitor him or her at home, as long as the hernia is easily reducible and the infant is not experiencing any problems related to it. I will usually repair the hernia when the infant has reached a postconceptual age of 60 weeks. The hernia is promptly repaired if there is an episode of incarceration, difficulty in reduction, or any problem attributed to it. I do not routinely explore the contralateral side, unless the infant has a history suggesting increased intra-abdominal pressure or is predisposed to such problems (eg, cystic fibrosis or peritoneal dialysis). If there is a risk in sending the infant home because of social circumstances, or the distance from the home to the hospital is enough to make transport dangerously lengthy, I will commonly fix the hernia prior to discharging the infant from the neonatal unit.
In most centers, hernia repairs are performed while patients are under general anesthesia. For infants and younger children, endotracheal anesthesia is usually required. In older children, general mask or laryngeal mask anesthesia is frequently used. For premature infants and children with severe respiratory disease, regional anesthesia has been found to reduce the risks associated with endotracheal intubation.10 This technique is often technically challenging and tirne-limited, making it less attractive when repairing bilateral hernias or incarcerated hernias. Regional anesthesia, either caudal blocks performed by the anesthetists or ilioinguinal, hypogastric, and field blocks placed by surgeons, is routinely used for postoperative pain control.
Because most pediatric hernias do not involve disruption of the inguinal floor (as is the case for adult hernias), the principle of repair is high ligation of the sac at the internal ring. Most incisions can be placed in a transverse skin crease above and lateral to the pubic tubercle, although this is dependent on the postgestational age and size of the child. The cord structures are identified beneath the external oblique fascia or through the external ring, and the sac carefully dissected from the cord structures. After it is confirmed that the sac contains no viscera, the sac is divided and the proximal sac dissected to the level of the internal ring. The sac is twisted and suture ligated, and the excess sac excised. If the internal ring is markedly dilated, sutures may be placed to narrow the ring. Inspection, dissection, and resection of the distal sac are not required and may produce some morbidity, including injury to the vessels, testis, or vas deferens. The testis is returned to the hemiscrotum, absorbable sutures are placed, and a dressing is applied.
Figure 1. Normal inguinal canal.
Figure 2. Patent processus vaginalis.
In girls, the principles of repair are the same as those for boys. High ligation of the sac is performed after all viscera are removed from the sac. In girls, it is common to have an ovary or a fallopian tube (or occasionally the bladder) within the lumen of the sac or, as in a sliding hernia, actually within the wall of the sac itself. When this occurs, the distal sac is ligated, the remaining sac and pelvic structure are invaginated into the peritoneal cavity, and then the internal ring is closed on top of it or a purse string suture is applied to close off the sac.
The decision to explore the contralateral side remains controversial. This debate has only intensified as pediatric surgeons have performed diagnostic and therapeutic laparoscopic explorations more frequently. Some recommend contralateral exploration because of the high incidence of a persistent patent processus vaginalis and the associated risk of a subsequent inguinal hernia and potential incarceration. The risk of injury to the blood supply and the vas deferens during contralateral exploration exists, but is low. Although the overall likelihood of having a contralateral patent processus is relatively high, the actual risk of having a contralateral hernia is only 10% to 15%.4 This implies that routine exploration of the contralateral groin incurs an 85% to 90% chance that this operation (and its risk for associated complications) is unnecessary.
Laparoscopic evaluation of the contralateral side has become a safe and effective technique to identify a patent processus.11 The laparoscope is placed through the ipsilateral hernia sac or a separate abdominal incision, and the contralateral groin is visualized (Fig. 1). Identification of a patent processus is easily accomplished, but its clinical relevance remains debatable (Fig. 2). The role of laparoscopy in the management of pediatric inguinal hernias has not yet been established due to the limited association of a patent processus vaginalis with the eventual development of a clinical hernia.12
Although the risks of contralateral exploration are low, it is difficult to advocate routine exploration. Children at a higher risk for bilateral hernias or die development of a metachronous contralateral hernia would probably benefit from contralateral groin exploration However, most children with inguinal hernias do not fall into a high-risk category and thus probably undergo an unnecessary operation with some risks if contralateral exploration is performed. The surgeon must understand the risks and benefits of each approach and decide which is appropriate for each patient. These issues should be explained to the parents when deciding on an operative plan. It is hoped that carefully controlled multicenter trials will provide the data needed to clarify the roles of contralateral exploration and laparoscopy.
The contents of incarcerated hernias cannot easily be reduced into the peritoneal cavity. Although many incarcerated hernias remain asymptomatic, a significant number will lead to intestinal strangulation and testicular ischemia. The overwhelming majority of complications in children undergoing inguinal hernia repair occur in those with incarcerated hernias. More than 60% of incarcerated hernias occur before 2 years of age, with the greatest risk before 6 months of age.13 Interestingly, the risk of incarceration is often less in premature infants, probably because of the larger internal ring and close surveillance by medical personnel while in the neonatal unit. If the hernia was difficult to reduce, repair may be delayed for 24 hours to allow edema to decrease. Repairing an incarcerated hernia can be technically difficult and involves a greater risk of recurrence and spermatic cord injury, especially in premature infants. For incarcerated hernias that fail reduction, even after the administration of sedation, emergent repair is performed after appropriate resuscitation. This includes the placement of a nasogastric tube and the administration of intravenous antibiotics. A routine inguinal approach is usually adequate, although the sac should be opened and trie contents inspected. If necessary, a laparotomy should be performed to identify any ischemic bowel and, if present, the bowel should be resected. In some cases, resection can be accomplished through an inguinal approach by enlarging the inguinal ring.
Major complications are uncommon following routine inguinal hernia repairs. If scrotal swelling occurs, it usually resolves spontaneously and rarely requires aspiration, even in the presence of a scrotal hematoma. Recurrences are rare, although the true incidence is difficult to determine because of inadequate long-term follow-up and underreporting. Estimates of recurrence rates range from less than 1% for routine repairs to as high as 20% for incarcerated hernia repairs.14,15 Most recurrent hernias are indirect defects and probably result from a tear in the sac proximal to the repair or incomplete identification and ligation of the sac.
Injury to the vas deferens is uncommon and may not be identified until an infertility evaluation as an adult. Manipulation of the vas deferens with surgical instruments has led to permanent injuries in animals.16 Additional reports have linked infertility to previous vas deferens injuries during hernia repairs, whereas others have noted an association between infertility and hernia repairs with no reported vas deferens injuries.16
Testicular atrophy is also rarely reported, although a recent study suggests that it probably occurs more frequently than previously thought.17 Not surprisingly, testicular atrophy has also been implicated as a cause of subsequent infertility. This is seen more commonly after repair of incarcerated hernias. Earlier practices involved excising the ischemic testis to prevent the potential development of antisperm antibodies and injury to the contralateral testis. Because this has never been proven in humans, orchiectomy should be considered only when the testis is nonviable.
Similar to inguinal hernias, umbilical hernias are one of the most common problems seen by pediatric surgeons. Unlike inguinal hernias, however, almost all umbilical defects will close spontaneously and not require operative closure. The timing of repair depends on the age and race of the child, the size of the fascial defect, and the shape of redundant skin.
Closure of the umbilical ring normally begins at the end of the first trimester of gestation and follows the return of the intestines into the abdominal cavity. The obliterated umbilical vessels occupy the defect in the umbilical ring and help to obliterate the space, which likely occurs as the rectus muscles and fascia migrate medially. There is still no clear explanation why the umbilical ring closes incompletely and eventually becomes an umbilical hernia in some children.
Figure 3. Giant umbilical hernia. (A) Front view. (B) Side view.
Umbilical hernias are one of the more common pediatric conditions. Although the exact incidence is not really known, it has been estimated that 1 of every 6 children has an umbilical hernia. African American children are nearly 10 times more likely to have an umbilical hernia by 1 year of age than are white children.18 No factors have been identified to explain such differences. Hernias are also seen more frequently in children with Down's syndrome, children with hypothyroidism, and premature children.
Natural History and Presentation
The three most important factors in predicting spontaneous hernia closure are the age and race of the patient, the size of the fascial ring, and the amount of protruding skin. Most umbilical hernias close spontaneously by 3 to 5 years of age, especially among white children.
Several studies have demonstrated that the likelihood of spontaneous closure markedly decreases if the fascial defect is greater than 1.5 cm in diameter. This becomes more evident by the time the child reaches 4 years of age.19 For children who have a large, proboscis-like skin defect, the chances of spontaneous closure are also low (Fig. 3).
Although most hernias are asymptomatic, some parents report that their children complain of frequent periumbilical discomfort. Incarceration is extremely rare and has been estimated to occur in 1 of every 1,500 hernias.20 It occurs more frequently in hernias smaller than 1.5 cm in diameter. On examination, children with incarceration typically present with umbilical pain, periumbilical erythema, and tenderness. Similar to inguinal hernias, if reduction is unsuccessful even after sedation, emergent operative reduction and repair are indicated. Unlike inguinal hernias, most incarcerated umbilical hernias contain omentum and not intestine. Incarceration and strangulation, which is exceptionally rare, are the only absolute indications for operative repair.
Umbilical hernias are usually repaired through a curved infraurnbilical incision in one of the umbilical skin folds. The sac is completely dissected from the umbilical skin and inverted into the peritoneal cavity and the defect is repaired. Alternatively, a portion of the sac is excised back to strong fascia and the fascia is then repaired. In this approach, a small section of residual sac is used to approximate the umbilical skin to the fascia and reduce the risk of a postoperative seroma or hematoma. Buried absorbable sutures are used to close the skin, and a compressive dressing is placed to help reduce the risk of a postoperative seroma. Dressings are removed after 4 to 7 days, and an otherwise healthy child may resume full activity by 2 weeks after surgery. For children with excessive proboscis-like skin defects, an umbilicoplasty may be required. Several techniques have been described, including flap dosures and purse string repairs. In these instances, it is important to stress to the parents that aesthetically appealing repairs may be difficult to achieve and that the ultimate appearance of the umbilicus may not be apparent for several months.
Postoperative complications are exceptionally rare and usually occur in children with comorbid conditions or in premature infants. These include recurrence, formation of a seroma or a hematoma, trapped or perforated bowel, and bowel obstructions.
Despite the relative frequency of inguinal and umbilical hernias in the pediatric population, an accurate diagnosis is occasionally difficult to make. Although technologic advances continue to enhance our abilities to identify these defects, the applicability of these techniques in the diagnosis and treatment of pediatric hernias remains to be proven. It is hoped that timely referral to a pediatric surgeon will hasten the diagnosis and avoid delays in treatment and their possible consequences.
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