A 2 week old male infant, born at 38 weeks gestational age, presents for his first visit to a pediatric clinic. According to his parents, he has been doing well since birth. Their only concern is the persistence of a bulge in his right scrotum. On review of birth records, a moderate-sized scrotal mass had been appreciated on newborn examination with no other abnormalities noted. According to his parents, the bulge has not changed in size since birth and there has been no noticeable discomfort.

On exam, a moderate sized right scrotal mass is palpated. It is firm, smooth, non-fluctuant and non-tender. It brilliantly transilluminates. There is no reduction with compression of the mass. Both testes are descended. No inguinal or abdominal masses are appreciated on palpation. A diagnosis of non-communicating hydrocele is made. His parents are reassured and counseled on the possibility of a communicating hydrocele/complete inguinal hernia and to proceed to an emergency room if signs or symptoms of incarceration and strangulation occur. On subsequent well child visits, the right scrotal mass is noted to minimally decrease in size. His parents continue to report no fluctuation in size during activity, crying or defecation. At his 12 month well child visit, the right scrotal mass is noted to be unchanged since his last visit 3 months prior. He is referred to a pediatric general surgeon for evaluation. Elective surgical correction is performed.

Inguinal-scrotal swelling is a common finding in the pediatric population. Of the possible causes, the most common diagnoses are hernias and hydroceles. Approximately 1-2% of male newborns have a hydrocele. Most are non-communicating hydroceles (1). The estimated incidence of inguinal hernias in children is 5-50/1,000 live births. It is seen more frequently in males than females with a ratio of about 5:1 with a definite familial tendency. About 50% of cases present before 12 months of age with most occurring in the first 6 months of life. Approximately 99% of all inguinal hernias in children are indirect inguinal hernias. Direct hernias are rare. Most inguinal hernias are unilateral with about 60% occurring on the right side and 30% on the left side. Ten percent are bilateral (i.e., clinically apparent at initial presentation). Of note, inguinal hernias are more common in premature infants with an incidence of 5-30%. Most cases are bilateral, occurring in about 62% of affected premature infants (2-5).

Normally, in the male fetus, the testes descend to the vicinity of the internal ring of the inguinal canal by approximately 28 weeks gestational age. Then, by about 29 weeks gestation, the testes descend into the scrotum. With testicular descent, the lining of the peritoneal cavity extends into the inguinal canal and scrotum. This peritoneal canal is referred to as the processus vaginalis. Each testis descends through the inguinal canal external to the processus vaginalis. In the female fetus, a similar mechanism with descent of the ovaries into the pelvis occurs. The processus vaginalis in females extends through the inguinal canal into the labia majoris and is referred to as the canal of Nuck (2). In males, a hydrocele is formed when there is patency of the processus vaginalis between the scrotum and the peritoneal cavity resulting in an accumulation of fluid between the layers of the tunica vaginalis surrounding the testis. In the weeks prior to birth or shortly after, the processus vaginalis closes spontaneously in the area of the internal ring, obliterating the entrance to the inguinal canal. The scrotal fluid collection that remains within the tunica vaginalis is referred to as a scrotal hydrocele, or a non-communicating hydrocele. If the processus vaginalis fuses proximally and distally but remains open in between, the isolated fluid collection is referred to as a hydrocele of the cord. This type of hydrocele, although not in communication with the peritoneal cavity or the scrotum, is often associated with a hernia and/or a scrotal hydrocele (6). In some older boys, a scrotal hydrocele may result from inflammation within the scrotum caused by various conditions including testicular torsion, torsion of the appendages, epididymitis, and testicular cancer (1,4). When the processus vaginalis fuses distally but remains patent proximally, abdominal contents can enter the inguinal canal resulting in an inguinal hernia. However, if the processus vaginalis fails to fuse completely, there will be communication between the scrotum and the peritoneal cavity through the patent processus vaginalis resulting in an inguinal-scrotal hydrocele, or communicating hydrocele. Of note, there is a rare but important type of communicating hydrocele called an abdominal-scrotal hydrocele. With this type of hydrocele, the communication is between the scrotum and a cystic loculation of fluid within the lower abdomen. This may result in recurrent communicating hydroceles or unusually large hydroceles. If a communicating hydrocele is large enough, abdominal contents may extend through the patent processus vaginalis to the scrotum resulting in an inguinal-scrotal hernia (complete inguinal hernia). A similar mechanism may result in hernias in girls. The hernia sac in males and females may contain intestine or omentum, with the ileum being the most common intestinal component. However, other possible intestinal components include colon, appendix, and Meckel's diverticulum (hernia of Littre). In males with undescended testes, a testis may be contained within a hernia sac. In females, a hernia sac may contain an ovary, fallopian tube, or both (6). Of note, it is possible for a testis to be found in the hernia sac of a female infant if testicular feminization (complete androgen insensitivity) is present. More than half of patients with testicular feminization have an inguinal hernia (4).

In differentiating a hydrocele from a hernia, history and physical examination can be diagnostic. The most important information elicited from parents is a history of fluctuation in the volume of the mass that would be consistent with a hernia or communicating hydrocele. Parents may report an increase in size that is particularly noticeable at times of increased intra-abdominal pressure (activity, crying or straining). At rest, the bulge will be noted to spontaneously decrease in size. Parents may also report previous reduction of the mass by either themselves or another physician. A history of fussiness, obvious discomfort, poor feeding, vomiting, and abdominal distention would suggest incarceration. The physical examination starts with the child supine. The child should be positioned with legs extended and arms raised over the head. This usually results in crying, thereby causing an increase in intra-abdominal pressure. The mass is palpated and evaluated for tenderness, tenseness, and associated skin discoloration that, if present, would suggest incarceration and possible strangulation. This would be an indication for immediate referral to a pediatric surgeon. If the mass is non-tender, smooth, firm and located in the scrotum, a hydrocele is likely to be present. Of note, a hydrocele may also be found in the spermatic cord. A scrotal hydrocele should be moved away from the inguinal canal and palpation of normal cord structures superiorly should be performed to exclude the presence of a hernia. The testes may not be palpable. If a patient presents with a large hydrocele or a history of recurrent communicating hydroceles with or without a palpable ipsilateral lower abdominal mass, an abdominal-scrotal hydrocele should be suspected. If compression of the fluid-filled mass completely reduces the size of the hydrocele, a communicating hydrocele or hernia is the likely diagnosis. An inguinal hernia is non-tender, soft, reducible and can be located in the inguinal canal or may extend into the scrotum (inguinal-scrotal hernia). Of note, retractile testes, a common finding in infants and young children, can resemble an inguinal hernia. To avoid misdiagnosis, palpation of the testes should be done prior to palpation of an inguinal mass. The physical examination continues with the child erect. This raises the intra-abdominal pressure. Any fluctuation in the size of the mass should be noted. If the child can cooperate, cough and Valsalva maneuvers (e.g., attempts to blow into an obstructed straw or a balloon) should be encouraged. An increase in size of the mass would be consistent with a hernia or communicating hydrocele.

Transillumination of the mass can be attempted. A hydrocele will brilliantly transilluminate. However, in children, inguinal-scrotal hernias and incarcerated bowel may also brilliantly transilluminate. Thus, transillumination in the pediatric setting may be unreliable. The internal ring of the uninvolved side should be examined before proceeding to the internal ring of the affected side. If an inguinal hernia is present, abdominal contents may be palpated extending through the internal ring (2,3,6).

If there is a history suspicious for a hernia but no mass can be demonstrated on examination, it may be helpful to empty the bladder which, when full, can block the internal inguinal ring and mask an inguinal hernia. Otherwise, a classic history of intermittent inguinal, scrotal or labial swelling that spontaneously reduces may be all that is necessary for diagnosis. However, another physical examination finding that can be present with inguinal hernias is a thickened spermatic cord with an associated "silk" sign. The spermatic cord is palpated over the pubic tubercle and a "silky sensation" is appreciated when the two layers of peritoneum are rubbed together. This finding, along with a history of a hernia, is highly suggestive of an inguinal hernia (2).

A scrotal hydrocele that is sufficiently large and tense may cause ischemic injury to the testis. A communicating hydrocele may enlarge and lead to development of an inguinal-scrotal hernia (6). Nine to twenty percent of inguinal hernias in children become incarcerated with more than half of those cases occurring in children less than 12 months of age. The incidence of incarceration increases in premature infants and in term female infants (2,5). When incarcerated, complete manual reduction of the hernia may not be possible. Strangulation of the hernia can occur and ischemic injury to intestine and testis/ovary may result (3,6). Intestinal obstruction, intestinal gangrene, and gonadal infarction occur more commonly in the first 6 months of life (4). Thus, because the risk of incarceration is high, particularly in infants, with a risk of strangulation, prompt surgical intervention is recommended as soon as the diagnosis is made.

The differential diagnosis of inguinal-scrotal swelling in children (6,7) can be classified based on acuteness of presentation, tenderness, location (intratesticular versus extratesticular), and transillumination. All hydroceles are non-acute, non-tender and they transilluminate. They are extratesticular, but scrotal hydroceles may be difficult to distinguish from an enlarged testicle on palpation. Communicating hydroceles are compressible (that is, they decrease in size with pressure), while non-communicating hydroceles will not change in size.

Inguinals hernias are usually non-acute and non-tender. They usually do not transilluminate. Incarcerated inguinal hernias are usually acute and tender. Vomiting may be present. Non-communicating hydroceles are frequently mistaken for incarcerated hernias, because they do not change in size with compression (seemingly non-reducible). However, scrotal hydroceles are spherical or oval in shape, while an incarcerated inguinal hernia is usually tubular in shape (often shaped like a small banana with a slightly tapered point at the end). Additionally, hydroceles are usually softer in consistency, while incarcerated hernias are the consistency of a refrigerated hot dog and sometimes harder than this. A hydrocele of the cord can be very difficult to distinguish from an incarcerated hernia, but this should be suspected if the onset is non-acute, it is non-tender, and the child's behavior appears to be normal.

Other diagnoses in the differential include lymph nodes, undescended or retracted testis (smaller in size), varicocele (soft spaghetti or bag of worms consistency), and spermatocele. Other considerations include epididymal cyst, testicular cancer, peritesticular rhabdomyosarcoma, benign soft tissue tumors, meconium sequestration, testicular torsion (tender), torsion of appendages, epididymitis, trauma, idiopathic scrotal edema, and Henoch-Schonlein purpura.

If there is uncertainty in the diagnosis, an ultrasound examination may aid in differentiating a hydrocele from a hernia, may confirm the presence of an abdominal-scrotal hydrocele, or may rule out other causes of inguinal-scrotal swelling. In a female, ultrasound examination can be used as part of the evaluation for testicular feminization (4). It can also be used to examine both ovaries when an incarcerated ovary is suspected (6). Abdominal x-rays are unnecessary for diagnosis of an incarcerated hernia, although they may be helpful in confirming an intestinal obstruction. If an incarcerated or strangulated hernia is associated with bowel obstruction or shock, laboratory studies and vascular access are indicated (5).

Treatment is usually not required for uncomplicated, simple hydroceles (non-communicating) because they tend to decrease in size with complete resolution in the first 2 years of life. Significant hydroceles persisting beyond 12-24 months are likely to be communicating and are generally surgically corrected at that time (1). However, early surgical repair is recommended for large, tense hydroceles because they rarely disappear spontaneously, they can cause ischemic injury to the testis, and they may be difficult to distinguish from hernias. Communicating hydroceles also require early surgical repair due to the fact that they may progress to symptomatic inguinal-scrotal hernias (6). All inguinal hernias will eventually require surgery. In fact, inguinal hernia repair is the most common surgical procedure in children (4). However, the urgency of surgical correction varies. In an outpatient setting, if a child presents with an inguinal hernia but is otherwise well (no obstruction or shock), manual reduction should be attempted. About 95% of inguinal hernias can be reduced by applying gentle but steady upward pressure on the hernia sac. If the hernia is easily reducible, referral to a pediatric surgeon should be done for elective surgical repair. While awaiting repair, parents should be counseled to seek immediate evaluation and treatment in an emergency department if signs and symptoms of incarceration and strangulation occur. Inguinal hernias that cannot be easily reduced are incarcerated and require immediate referral to an emergency department. In an emergency department, manual reduction can be attempted with sedation. Once the child is sedated, firm steady upward pressure can be applied to the hernia sac using one hand while the other hand gently guides the neck of the hernia sac into the distal ring of the inguinal canal. A Trendelenburg position may be helpful. If reduction is successful, a pediatric surgeon should be consulted for outpatient follow-up. However, children with difficult to reduce hernias or a history of incarceration in the past are at high risk for future incarceration and strangulation and should be managed more urgently. Some cases require inpatient observation. If reduction is unsuccessful, then a pediatric surgeon must be consulted immediately. If, however, a child presents with an incarcerated inguinal hernia and symptoms of intestinal obstruction or shock, a pediatric surgeon must be consulted emergently while resuscitation begins with intravenous fluids and nasogastric tube decompression of the stomach (5).

In young females, an ovary may incarcerate in the hernia sac. This has a spherical shape and the child is often asymptomatic with the exception of the inguinal mass. While incarcerated bowel is at risk for ischemia and must be surgically corrected immediately, the vascular supply to the incarcerated ovary is usually not compromised, thus, this is often less emergent.

Elective surgical repair can be safely done as an outpatient. Hospitalization may be necessary for children at high risk for post-operative/post-anesthesia complications (e.g., premature infants <60 weeks of post-conception age and infants with chronic medical conditions including heart disease, respiratory disease and seizure disorder) (2). Surgical correction is done through an inguinal incision. The spermatic cord is identified and, if present, a hydrocele is excised. If a hernia is present, reduction is performed. In the case of an incarcerated hernia, careful inspection of the incarcerated bowel is done to assess viability. After inspection and reduction, a high ligation of the processus vaginalis is performed (1,4). Of note, females undergoing surgical correction of a hernia should be evaluated for the possibility of testicular feminization. A rectal examination should be done to palpate the uterus. If a uterus is not palpable beneath the symphysis pubis in the midline, a pelvic ultrasound examination should be done to evaluate for normal female anatomy. If the results are inconclusive, the hernia sac must be explored during surgery and the presence of a fallopian tube verified. If present, testicular feminization can be ruled out. Conversely, the presence of testes confirms the diagnosis. If neither fallopian tube nor testis is found, an endoscopic examination of the vagina after surgery should be performed to evaluate for a cervix. If a cervix is present, testicular feminization can be ruled out. However, if it is absent, chromosomal analysis will need to be done (2,6).

There is controversy surrounding the topic of contralateral surgical exploration at the time of herniorrhaphy. Studies have shown that development of a contralateral inguinal hernia after unilateral herniorrhaphy occurs with an incidence of 12-30% (>10% since the contralateral hernia often develops later). Bilaterality is more frequent in females, children less than 12 months of age, and children with left-sided inguinal hernias. For this reason, it is recommended that bilateral surgical exploration be done in males less than 12 months of age, females less than 24 months of age, and children at high risk for development of inguinal hernias. Bilateral surgical exploration should also be strongly considered in children less than 24 months of age with left-sided inguinal hernias. Of note, contralateral exploration can be avoided with laparoscopic herniorrhaphy. This technique allows for visualization of the contralateral side during repair of the affected side. However, the surgeon must be experienced in laparoscopic technique. In general, the decision to undergo bilateral surgical exploration should be based on surgical expertise and a child's pre-operative medical condition (2).

Premature infants will often develop a symptomatic hernia while remaining hospitalized for prematurity. These infants should have surgical correction of the hernia prior to discharge from the hospital. Other significant risk factors for development of an inguinal hernia include presence of a ventriculoperitoneal shunt or peritoneal dialysis catheter. These devices cause increased intra-abdominal pressure resulting in a high incidence of inguinal hernias in affected infants. They are also associated with greater risk for surgical complications. It is recommended that prophylactic antibiotic therapy with ampicillin and gentamicin be given perioperatively to children with ventriculoperitoneal shunts. This is also the recommendation for children with congenital heart disease. Other conditions associated with an increased incidence of inguinal hernias include congenital dislocation of the hip, ascites, congenital abdominal wall defects, meconium peritonitis, connective tissue disorders (Ehlers-Danlos syndrome), mucopolysaccharidosis (Hunter-Hurler syndrome), ambiguous genitalia, hypospadias/epispadias, cryptorchid testes, and cystic fibrosis. Cystic fibrosis is also associated with agenesis of the vas deferens. Thus, if bilateral absence of the vas deferens is noted incidentally during herniorrhaphy in a child without a prior diagnosis of cystic fibrosis, an evaluation for cystic fibrosis should be done including a sweat chloride test and/or DNA testing. However, agenesis of the vas deferens can also be an isolated finding. If a child has cryptorchid testes and an inguinal hernia, elective orchiopexy should be done along with herniorrhaphy to reduce the risk for ischemia and infarction or the testis (2,4).

Most hydroceles resolve by 12-24 months of age following reabsorption of the hydrocele fluid. However, if the hydrocele persists beyond this time frame, if it is large and tense, or if the hydrocele is communicating, it is unlikely to resolve spontaneously and can be difficult to distinguish from a hernia. In these cases, as with hernias, surgery can be curative. However, there can be complications of surgery including damage to intestine, testis and vas deferens or to ovary and fallopian tube. Rarely, the bladder may be damaged with resultant urinary ascites. A surgeon should be able to recognize and appropriately manage such injuries (6). Post-operative complications including wound infection and hernia recurrence are uncommon. In fact, the hernia recurrence rate is less than 1% (2). More commonly, a recurrent swelling is due to reaccumulation within the tunica vaginalis and/or enlargement of retained tunica vaginalis tissue due to edema. These will often resolve spontaneously without the need for reoperation (6). However, there is an increased risk for hernia recurrence after repair of incarcerated or strangulated hernias as compared to elective surgical repair (4). Children with connective tissue disorders, chronic respiratory disease, and chronic illnesses associated with increased intra-abdominal pressure are also at higher risk for hernia recurrence (2).

Questions

1. True/False: Bilateral inguinal hernias are common in premature infants.

2. Which of the following statements is false?
. . . . . a. Each testis descends through the inguinal canal into the scrotum within the processus vaginalis.
. . . . . b. A hydrocele can result from incomplete fusion of the processus vaginalis.
. . . . . c. A scrotal hydrocele, or simple hydrocele, is a type of non-communicating hydrocele.
. . . . . d. A communicating hydrocele can develop into an inguinal-scrotal hernia. Some use the terms interchangeably.
. . . . . e. A hernia sac can contain intestine, omentum, testis/ovary or fallopian tube.

3. What is the classic clinical presentation of an inguinal hernia?

4. True/False: The risk of incarceration and strangulation of an inguinal hernia is highest in the first 12 months of life.

5. Which of the following is not part of the differential diagnosis of an inguinal-scrotal swelling in children?
. . . . . a. Varicocele
. . . . . b. Undescended or retracted testis
. . . . . c. Volvulus
. . . . . d. Testicular torsion
. . . . . e. Testicular cancer

6. True/False: All inguinal hernias will eventually require surgery.

7. Which of the following is not a risk factor for development of an inguinal hernia?
. . . . . a. Presence of a ventriculoperitoneal shunt
. . . . . b. Congenital heart disease
. . . . . c. Prematurity
. . . . . d. Cystic fibrosis
. . . . . e. Family history of inguinal hernias

8. True/False: After herniorrhaphy, hernia recurrence is rare.

References

1. Elder JS. Chapter 553 - Disorders and Anomalies of the Scrotal Contents. In: Behrman RE, Kliegman R, Jenson HB (eds). Nelson Textbook of Pediatrics, 16th edition. 2000, Philadelphia: W.B. Saunders Company, pp. 1650-1653.

2. Schochat SJ. Chapter 346 - Inguinal Hernias. In: Behrman RE, Kliegman R, Jenson HB (eds). Nelson's Textbook of Pediatrics, 16th edition. 2000, Philadelphia: W.B. Saunders Company, pp 1185-1188.

3. Fuloria M. The Newborn Examination: Part II. Am Fam Phys 2001;64(11):1853-1860.

4. Engum SA, Grosfeld JL. Chapter 67 - Pediatric Surgery. In: Townsend CM, Beauchamp DR (eds). Sabiston Textbook of Surgery, 16th edition. 2001, Philadelphia: W.B. Saunders Company, pp. 1499-1501.

5. D'Agostino J. Common Abdominal Emergencies in Children. Emerg Med Clin North Am 2002;20(1):139-153.

6. Sheldon CA. The Pediatric Genitourinary Examination. Pediatr Clin North Am 2001;48(6):1339-1380.

7. Kaplan GW. Scrotal Swelling in Children. Pediatr Rev 2000;21(9):311-314.

Answers to questions

1. True

2. a

3. Intermittent inguinal, scrotal or labial swelling that spontaneously resolves.

4. True

5. c

6. True

7. b

8. True