A hernia is a protrusion of part of or a whole organ from one space bounded by a weakened or defective wall, into another space or cavity outside its confines.
The abdomen is the commonest place hernias occur. There are different types of hernia, which include:
• Inguinal hernia
This is the most common hernia in children, especially boys, occurring in about one in every 50 children. The ratio for boys and girls is 4:1.
There is a higher incidence among premature infants (7-30%), as well as higher risk of hernia irreducibility and other complications.
If an inguinal hernia presents early in life, about half tend to become problematic within the first six months of life, and more than two-thirds in the first year.
Surgical correction is therefore advised as early as possible for this group.
Overall, the risk of complications is 12 -17%, being slightly more in girls.
About 60% of inguinal hernias occur on the right, 30% on the left, and 10% on both sides. However, with routine exploration of the opposite side, the incidence of bilaterality is found to be more than 60%, especially among children less than five years old.
Other risk factors that predispose to inguinal hernia include a parent, close relative or sibling who had a hernia as an infant; undescended testes; ambiguous genitalia; and congenital dislocation of the hip.
An inguinal hernia usually presents with swelling at the groin-scrotal region. Typically, the lump is painless and appears on standing, playing and straining (as in crying, coughing, defaecating and other physical activities). When relaxed or lying down, it disappears.
Hernias can also come about after a short, but severe bout of coughing. Usually, these are recurring swellings and most parents are not concerned by them unless they become very large because they are usually painless.
Then, suddenly and without warning, the swelling can become fixed and painful. The child may have associated vomiting and abdominal distension.
This is a sign that the hernia has become complicated. It happens more commonly in infants less than six months of age, and hence, the more urgent need for early surgery in this age group.
Often, parents are advised by general practitioners to wait till the child is two or three years old before surgery – this is wrong.
The worst complication is when the contents of the hernia get “strangled”, i.e. the blood supply to the hernia content is cut off.
If there is delay in operation, the affected part may die and perforate (leak or burst), and the patient may suffer peritonitis, septicaemia, and even, death.
There are certain conditions that may mimic an inguinal hernia. An experienced surgeon can usually differentiate these from a hernia simply on clinical grounds upon seeing the child. However, ultrasound scans are becoming more commonly employed nowadays, usually to please anxious parents.
Operative correction is the mainstay of treatment. The operation is a herniotomy, where the hernia sac is tied and divided at its neck. Large defects sometimes need repair of the inguinal canal and internal ring (herniorrhaphy).
Post-operative complications are not a major problem as these are rare, and the recurrence rate is very low. Leaving the hernia alone carries a higher risk to the child.
• Umbilical hernia
There are other types of hernias that are common in children and babies. The most common of these is the umbilical hernia.
It occurs in about 10% of babies, of which about 80% subside spontaneously without any complication by one year of age.
This umbilical swelling, which appears on and off, can look alarmingly large when the baby is screaming, and can be a source of anxiety for parents. It is more common among Africans, Down’s syndrome children and preterm babies.
The underlying muscle defect is about 0.5-2cm while the swelling itself is typically about 2.5cm, but varies from 2-5cm in diameter. In a normal baby, the abdominal defect constricts to about 1cm or less, and only the cord stands out from the abdominal wall.
When the umbilical cord dries up and falls off around 7-10 days post-delivery, the opening at the muscle layer underneath the umbilicus initially closes off spontaneously with muscular contraction, and the linea alba – the midline fascia that lies between the two rectus muscles – fuses in about two weeks.
If there is any delay of this fusion, a defect remains and can predispose to the development of a hernia.
With time, the muscular defect closes spontaneously in most cases, though many grandmothers would advise taping a 50 sen coin over it till this happens.
If the hernia remains beyond three or four years, or if the defect is large, or pain or strangulation (rare) has occurred, then surgical repair is necessary.
The operation employs the open technique under general anaesthesia. A small semi-circular incision is made below or above the umbilicus. The contents (which may be gut or fat) is pushed back into the abdominal cavity and the sac is sutured and excised.
It is a day surgery and the child is allowed home in two to four hours.
During intrauterine life, in the first five to eight weeks of gestation, there is a stage in the development of the foetus when the intestines spill out of the umbilicus into a sac.
This is the period when the liver and other organs are growing rapidly into the tiny space available, and the intestines, too, are elongating. This is called a physiological umbilical hernia. It is a temporary feature and not a defect as such.
Subsequently, at weeks 11-12, they return into the developing abdominal cavity, and eventually, only the umbilical cord remains.
If the return is not completed by the beginning of the second trimester, there is a risk that the baby may be born with a congenital defect called an omphalocoele (exomphalos), which occurs once in every 4,000 to 5,000 live births.
This is a hernia containing intestines, parts of the liver and other internal organs. It is usually detectable on antenatal ultrasound.
The sac is not covered by skin, but by a translucent bag made of peritoneum and the Wharton’s jelly of the umbilical cord.
Surgery and intensive care are necessary to ensure survival of these babies.
The mortality of this condition depends on several factors, such as the hernia’s size, as well as other genetic, congenital and environmental influences.
• Epigastric hernia
Another hernia, also in the midline of the abdomen, lying between the xiphisternum and the umbilicus, is the epigastric hernia.
It is often brought on by physical effort, e.g. straining at the potty and excessive crying or coughing, arises from a defect in the linea alba.
The epigastric hernia is usually small, about 0.5-1.5cm in size. Usually, it contains pre-peritoneal fat, which tends to get incarcerated in it and causes pain.
Epigastric hernias seldom resolve on their own. The definitive treatment is surgery, either open or key-hole.
• Femoral hernia
A femoral hernia is a rare hernia in children, occurring once in every50 groin hernias. It appears just below the inguinal ligament. Only 15-30% are diagnosed pre-operatively. Due to its rarity, it is often missed by general practitioners.
Complications like strangulation and irreducibility in this form of hernia are about 10 times higher than in inguinal hernia.
About a third of femoral hernias are admitted as emergencies.
Recurrence rate also tends to be higher, at about 10%, because of the likelihood of the sac being missed in the first operation.
For these reasons, attempts must be made to differentiate this hernia from inguinal hernia prior to surgery.
Dr Ahmad Zulkiflee Laidin is a consultant paediatric surgeon. This article is courtesy of the Malaysian Association of Paediatric Surgery. For further information, e-mail firstname.lastname@example.org. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice.