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By Steve Dassel, MD
February 2009: Children with Hernia
I talked to John Meehan, MD, FACS, attending surgeon at Seattle Children's Hospital and associate professor of surgery at the University of Washington, about hernias. Dr. Meehan is co-director of robotic surgery at Seattle Children's. He received his MD from the University of Iowa and is an avid Hawkeye. That was followed by residencies at the University of Alabama, Birmingham, fellowships in pediatric trauma and critical care at Children's Mercy in Kansas City and a pediatric surgery fellowship at USC. He returned to his alma mater, joined the faculty at the University of Iowa, was very involved with robotic surgery and has been at Seattle Children's for a year.
Q: Let's begin with a bit about the embryology of inguinal hernias, John.
A: In inguinal hernias, the testis migrates from the area of the kidneys and arrives in the scrotum by way of the inguinal canal at about 6-7 months. As it descends, it pulls a sac of peritoneum (processus vaginalis) with it. That canal should then close, but if it doesn't, it leaves an open avenue (a hernia) which may allow a loop of bowel to slide in.
Q: Just to tidy things up, how is that associated with a hydrocele?
A: Sometimes the sac of peritoneum closes, but peritoneal fluid was able to accumulate before that closure happened, forming the hydrocele. Alternatively, there may be a tiny opening that almost acts like a one-way valve and allows fluid to trickle down around the testes.
Q: What is the timing of hernia formation?
A: All of this should be completed by 7 months gestation. So, there is an increased incidence of hernias in premature babies, and because the left testis descends before the right testis, there is also an increased incidence of right over left inguinal hernias.
Q: And in the female?
A: Substitute the labia for the scrotum and the ovary for the testis, and you have the same situation. There is much lower incidence, however, because there is no natural migration of the ovary into the labia.
Q: So what are the relative incidences of each?
A: The incidence of hernias in the general population is about 1%, but in the premature population, the incidence is 16%-25%. The ratio of male to female is 10 to 1, and the ratio of right to left is 6 to 4.
Q: Tell us about the differential diagnosis of a scrotal mass.
A: If the onset of the mass is abrupt, painful and tender, think of testicular torsion. The twisting of the cord pulls this testicle up a bit, so in addition, the mass rides high in the scrotum. If onset is not as abrupt and cannot be reduced, think of either an incarcerated hernia or a hydrocele. The incarcerated hernia is tender and the child is often irritable and perhaps vomiting. The hydrocele should be asymptomatic and one can often palpate the cord above the hydrocele.
Q: I always have trouble figuring out the results of my attempted transillumination.
A: Transillumination in children is unreliable for distinguishing between hydrocele and incarcerated hernia. I wouldn't even bother to do it, as it may give a false sense of security. It is a reasonable quick test in adults but has a reputation of being somewhat unreliable there, too. In children, the bowel will easily transilluminate just like fluid. The examiner will not be able to distinguish between hydroceles and incarcerated bowel in these children, so the test is useless.
Q: What about tumor?
A: Testicular tumors usually present in the older child, and you can often feel the lump on the testis. Additionally, the lump is actually on the testicle, instead of a fullness in the scrotum. Finally, there may be other key elements in the history, such as growth of the lump over time or other symptoms, that have already distinguished this entity as a tumor.
Q: Are there risk factors for inguinal hernias?
A: Prematurity is certainly the biggest risk, and there is a somewhat loose association with family history, but the majority tend to be random. There is a higher incidence of herniation with twins.
Q: What are the complications of inguinal hernia?
A: Incarceration leading to strangulation, leading to necrosis is the most concerning complication. Less well understood is an association with future infertility. In 4% of couples with infertility problems, there was a history of bilateral inguinal hernia repair. We do not know if this incidence is due to having hernias or if it is due to having surgery.
Q: We will come back to the infertility issue later, but back to the progression of strangulation and necrosis. Tell me about the urgency for the primary care doctor in getting his patient to a surgeon.
A: The reducible hernia should be operated on. Unlike umbilical hernias, which may close spontaneously in the first couple years of life, inguinal hernias do not go away, and the potential for incarceration increases with age. Trusses are a Band-Aid and don't fix the problem. Although it is usually an elective procedure, patients should be scheduled for surgery in a few weeks or so. The longer you wait, the more chance for an incarceration to occur, and then it becomes an emergency. Repairs on incarcerated hernias have tremendously higher complication rates.
Q: And when incarceration is suspected?
A: First we need to reduce the bowel. If we cannot reduce, surgery is emergent and needs to be done immediately. If we are able to get the bowel reduced, then we gain a bit of benefit by letting the swelling go down, so we wait a short time, usually 24 to 48 hours. But we don't wait too long because it can incarcerate again.
Q: John, how do you differentiate strangulation from incarceration?
A: The term strangulation has been used rather loosely but should be a term that we should reserve to describe bowel that has been incarcerated so long or so severely that it has lost its blood supply. That bowel is now dead. The examiner can't determine this from the exam alone, but these patients may present more ill than a typical incarcerated bowel. The strangulated, or dead bowel determination, is really discovered at the time of exploration. That's why bowel that cannot be reduced needs immediate exploration.
Q: What is current thought about exploring the other side?
A: That is a controversial topic that continues to be debated. Some surgeons believe the other side should be explored in children less than 2 years old; others say less than 6 months old. This is based on the 5% to 8% incidence of bilateral hernias in children with a known hernia on one side when they are this young. But that incidence may be not as great as we thought and if we explore both sides on everybody, we are doing surgery on one side that may be unnecessary in maybe 92% to 95% of these patients, perhaps even more.
Q: And your approach?
A: I prefer waiting to see if a hernia ever develops on the other side. In addition with the low incidence of true bilateral hernias, I'm concerned about the infertility association with bilateral inguinal hernia repair. We don't know if this association is related to the presence of having a hernia on both sides or having undergone repair or exploration on both sides. But we don't want to contribute to this statistic by exploring a side that may not really have a hernia. So I operate on just the side containing the known hernia. If the other side eventually demonstrates a hernia, then fine...we'll deal with it when it shows up, but we no longer routinely explore the opposite side. We realize that as many as 5% to 8% of our patients will return someday with a hernia on the other side. But we accept this fact and prefer this risk over the risk of infertility. Our entire practice of 10 pediatric surgeons has recently adopted this approach as well.
Q: Can you contrast inguinal hernias with umbilical hernias?
A: Umbilical hernias do close spontaneously, and they generally do not incarcerate. So, universally, we wait and watch.
Q: For how long?
A: This is another area of controversy, but it's a minor debate. Everyone agrees that these hernias may spontaneously close, but the chance of closing drops significantly with age. Most close by 2 years of age if they will close. A very small percentage may close after that, but the chance has really dropped off. But then risk of incarceration increases with age, though usually the risk is not significant until well over age 5. Using these physiological facts, some surgeons wait for five years, others wait for two, but both timelines are acceptable. The main point to remember is that the chance for spontaneous closure has decreased tremendously by 2 years of age.
Q: Why repair at all? Just cosmetic reasons?
A: No, there truly is some risk of incarceration eventually, and that risk does increase with age. So if they haven't closed by 2 years or so, then they likely won't close thereafter, and the incarceration risk starts climbing.
Q: How do you handle the family's observation that they know somebody who taped a quarter on their child's umbilical hernia and cured it?
A: That is a common misguided old family treatment. The hernia closed spontaneously, yet the family often thinks the quarter did the closure. However, the very smart human physiology did the spontaneous closure, and the human body deserves the credit, not the George Washington quarter.
Q: Thanks, John.
Incidentally, John's title of co-director of robotic surgery piqued my interest. Learn more about robot-assisted surgery as well as other pediatric surgery services provided at Seattle Children's on the surgery section of our website. The General Surgery division at Children's has added four pediatric surgeons in the last year and has appointments available as early as the same day.
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