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Inguinal Hernia and Hydrocele

Inguinal hernia is a common condition of infancy and childhood, and repair is the most frequently performed general surgical operation in childhood.

Embryology

The occurrence of a congenital inguinal hernia and undescended testis is related to descent of the testis into the scrotum. The testes start developing in the abdomen and eventually drop into the scrotum. As the testes drop into the scrotum a membrane surrounding all the abdominal contents gets pulled into the scrotum with the testes. This is called the processus vaginalis. At approximately 3 months’ gestation, the testis descends into the scrotum because of the influence of hormones. The testes usually reaches its final destination in the scrotum by the third trimester. In approximately 90% of children, the processus vaginalis seals shut and becomes a thin band of tissue without a lumen or opening. If all or any portion of the processus remains open it may cause either a congenital inguinal hernia, hydrocele or a communicating hydrocele. (Fig. 42-1). The frequency that the processus vaginalis remains open is related to the gestational age of the infant and whether the testis drop into the scrotum or not. In girls, hernias are less common than in boys though inguinal hernia and, more rarely, a hydrocele may occur.

Incidence

It is possible to develop several types of groin hernias in humans. Congenital inguinal hernias in children are by far most commonly indirect hernias where the processus vaginalis has stayed open. Hernias in children are rarely due to a weakness in the muscles or tissues in the groin as would be more often found in adults. Approximately 3% to 5% of term infants may be born with a clinically apparent inguinal hernia. Preterm infants have a considerably higher incidence (9% to 11%). In infants less than 28 weeks’ gestation, the incidence is 35%. Clinical presentation of inguinal hernia occurs on the right side in 60% of patients and the left in 25%; 15% are on both sides. Inguinal hernia is much more common in boys than girls; however, presentation on both sides may be more likely in girls.

In addition to prematurity, several other conditions are associated with an increased risk of inguinal hernia. An increased incidence of inguinal hernia also is observed in patients receiving continuous ambulatory peritoneal dialysis and infants with a ventriculoperitoneal shunt for hydrocephalus. In both of these situations, an increased amount of fluid in the abdominal cavity raises the intra-abdominal pressure, which opens and enlarges the processus vaginalis.

Physical Examination

The most common presentation of inguinal hernia in male infants is a bulge in the groin or the scrotal sac. The bulge is seen more easily during straining or crying but is sometimes difficult to identify. The bulge is caused by either intestine or fluid entering the hernia sac. In girls the ovary or fallopian tube may also enter the sac and cause the bulge. If infants are relaxed, the bulge may go away spontaneously and if not a doctor may be able to reduce the hernia. Reducing the hernia means that the intestine or fluid in the sac has been pushed back into the abdomen. Infants may be examined while lying on their backs or standing. When the examination is performed in boys, it should be noted whether the testis is within the scrotal sac to avoid mistaking a retractile testis (See section on undescended testes) for a hernia. In some instances, it may be difficult to show the presence of a hernia. It may be difficult to rely on the physical finding of another physician or parent as an indication for surgery. If the physical examination is unconvincing, it is safer to re-examine the patient another day or ask the parents to photograph the bulge. The surgeon should document the presence of a hernia before an operation is undertaken.

It is important to determine the difference between a hernia, hydrocele and communicating hydrocele as the indication for surgery may differ. Patients with a very small opening in the processsus vaginalis frequently present with a scrotal swelling that changes in size over the course of the day. This is likely to be a communicating hydrocele . This is similar to a hernia. The main difference is that the opening in the sac is only large enough for fluid to enter the sac and not intestine or ovary. Most surgeons will recommend repair of these the same as congenital inguinal hernia. A non-communicating hydrocele usually presents as a soft, nontender, fluid-filled sac in the scrotum. This form of hydrocele does not change in size over the course of the day. These may gradually go away on its own over the first 12 months of life. Hydroceles that persist beyond that time probably require an operation to repair. Occasionally, hydroceles in older children may follow trauma, inflammation, or tumors affecting the testis.

Incarcerated Hernia

The most common complication of inguinal hernia is incarceration. This means that something has become stuck in the hernia sac and cannot be pushed back into the abdomen. This is also termed an irreducible hernia. The swelling is commonly caused by intestine or possibly the ovary in girls, having gotten caught in the hernia sac. Approximately 12% of all children (<12 years old) with hernia will develop incarceration. This event is far more common in the first year of life, when the incidence of incarceration may be 30% in a term baby. Preterm babies are more likely to have this happen. This problem will become apparent as sudden onset of a tender swelling in the scrotum or groin. Failure to reduce the tissue stuck in the hernia sac can cut off the blood supply to the incarcerated tissue and lead to a condition called strangulation. Because of the risk of incarceration (especially in the first few months of life), elective hernia repair should be scheduled shortly after the diagnosis of a hernia is made. While waiting for an early elective repair, parents of infants or children with a documented inguinal hernia should call their physician immediately if the hernia becomes irreducible or any discoloration to the skin occurs. In instances of incarceration, the physician will try to reduce the hernia and then schedule surgery electively. Infants may be admitted to the hospital in order to get the hernia repaired more quickly. Complications of incarceration include testicle shrinkage due to injury to the blood supply, loss of the testicle, intestinal blockage and dead bowel. The complication rate after emergency surgical repair of an incarcerated hernia may be greater than 10%, compared with a postoperative complication rate of 1.5% after elective surgery. The complication rate is higher because of all of the swelling that occurs if a hernia incarcerates. Postoperative complications may also include wound infection, recurrent hernia, and injury to the vas deferens and spermatic vessels.

Inguinal Hernia in the Premature Infant

Premature infants are at risk for developing an inguinal hernia. During hospitalization, premature infants with an inguinal hernia can be kept under close observation in the neonatal intensive care unit. If the hernia becomes incarcerated reduction of the hernia can allow the infant time to recover from the underlying neonatal illnesses that are due to prematurity such as problems with the lungs. As a general rule because of the high incarceration in premature infants, the hernia should ideally be repaired just before the infant’s discharge from the neonatal intensive care unit. These infants require postoperative monitoring because anesthesia may cause post operative apnea (not breathing enough) or bradycardia (low heart rate). The risks of these problems resolve after ~24 hours. For premature infants who have the hernia diagnosed after discharge from the hospital, repair may be done on an outpatient basis when the child is approximately 50-60 weeks’ gestation equivalent depending on the hospital and anesthesiologist. The decision to admit the baby or do outpatient surgery depends on criteria set by the anesthesiologists at each individual hospital. Hernia repairs performed on infants prior to 50-60 weeks gestational age need admission to the hospital for post-operative monitoring for ~24 hours.

Treatment

In most instances, inguinal hernia repair in infants and children can be done as an outpatient surgery. Outpatient surgery for infants and children requires skilled pediatric anesthesiologists and nursing staff, appropriate-sized pediatric equipment, monitoring equipment, and the ability to admit to a pediatric inpatient facility if necessary. Outpatient surgery for inguinal hernia is safe, effective, and well tolerated.

In addition to inguinal hernia, other problems requiring operative treatment for inguinal swelling in infants include hydrocele that persists for 1 year or more, and communicating hydrocele. The anatomy of these two problems is similar to congenital inguinal hernia and the surgical repair is similar.

Although occasional surgeons use local anesthetic or spinal anesthesia for small or premature infants during hernia repair, a well-administered general anesthetic is usually preferred. This can be performed very safely by an anesthesiologist experienced in the care of infants and children.

The incision for hernia repair is made in a natural skin crease on the side where the hernia exists. Bleeding is usually not an issue during this operation. Tbe ilioinguinal and iliohypogastric nerve are identified to avoid injury and then the hernia sac is identified. The spermatic vessels and vas deferens are then dissected away from the hernia sac. Great care is taken to avoid injury to these tissues. The sac is then tied closed with sutures and the part that extended into the scrotum is either removed or widely opened so that it will not collect fluid in the future. Prosthetic mesh or plugs that are commonly used in adult hernia repairs are not needed in childhood hernia repairs except occasionally in older teenagers.

The wound is closed with absorbable suture and various types of dressings may be used. Usually the dressing is waterproof to protect the wound from urine and stool in the diaper. Post operative pain control is usually accomplished with local injection of anesthetic during the operation or placement of a caudal anesthetic by the anesthesiologist. This is somewhat similar to the type of block pregnant women may get during labor though in the case of hernia repair it is a one time injection of anesthetic. Usually the child will then be sent home with pain medicine in syrup or pill form.

There is considerable controversy as to whether children with a hernia on one side should have the opposite side explored during surgery. At least 5% of infants and children have a clinically identifiable hernia on both sides before operation. Children younger than age 2 years have a high incidence of an opposite side open processus vaginalis. Because only 12% to 15% of adolescents and adults have indirect inguinal hernias on both sides, most open processes close spontaneously and do not develop into a hernia. Several reports indicate an incidence of only 7% of a late occurrence of a hernia on the opposite side in patients who had one side repaired previously. This low incidence suggests that perhaps opposite side exploration is not indicated. It has become popular with some surgeons to pass a small telescope through the hernia sac at the time of repair to view the opposite side from inside the abdomen, but this technique only verifies the presence of an open processus and not an actual hernia. Some pediatric surgeons still routinely explore both groins in children younger than age 2 years, in older boys with a clinical hernia that presents on the left side, and in girls younger than age 10 years because hernias on both sides are more common. In experienced hands, complications, such as injury to the ilioinguinal nerve, vas deferens, and spermatic vessels, are uncommon after an elective hernia repair. Intraoperative bleeding is very unusual. Postoperative complications include wound infection, scrotal hematoma, postoperative hydrocele, and recurrent inguinal hernia. The wound infection rate is approximately 1% in most institutions but may be higher after incarceration. Recurrent inguinal hernia occurs in about 2% of uncomplicated cases. Causes of recurrence include infection, missed hernia sac, unrecognized tear in the base of the sac, failure to repair an excessively large internal ring, operative injury to the floor of the inguinal canal resulting in the development of a direct inguinal hernia, and previous surgery for an incarcerated hernia. Patients with cystic fibrosis, ascites, peritoneal dialysis, and connective tissue disorders such as Marfans syndrome have a much higher risk of recurrence. Because of scarring, surgery for recurrence in boys can be technically challenging.

Sometimes a child may appear to have a recurrence when in fact they have a different type of hernia called a femoral hernia. Femoral hernias are unusual in the pediatric age group and are noted more commonly in girls. These hernias may be mistaken for congenital inguinal hernias in infants because the space between where the two different hernias occur is quite small. Usually these hernias present with a bulge below the groin crease. Occasional patients may develop a postoperative hydrocele that usually resolves. Removing the hernia sac if possible or widely opening it as described above may prevent this problem. If the hydrocele persists, sucking the fluid out with a needle may be useful and solve the problem. Rarely a persistent symptomatic postoperative hydrocele requires formal repair and excision.

Although laparoscopic hernia repair has become a popular alternative in adults, there is a limited role for this minimally invasive technique in infants and young children. This technique is used however by a small number of pediatric surgeons. Conventional inguinal hernia repair during infancy and childhood can be performed through a small incision in 20 to 30 minutes or less and is associated with little morbidity, almost no mortality, and prompt return to normal activity. This means that laparoscopic repair of the hernia in infants and young children may offer no advantage.