It’s 3am on the back end of one of those horrible casino shifts in the Paediatric Emergency Medicine Department. Triage says there’s a mum in the cubicle with a 4 month old. He’s snotty and screaming his head off, Mum says, “He’s swollen down there Dr. He won’t stop crying and I can’t get him to feed.” Sure enough, the nappy contains a few unpleasant surprises, not the least of which is an obviously swollen groin. As you reach for the torch thinking of transillumination, you wish you’d paid more attention to that chapter on Paediatric Surgery1. “Hernia or hydrocele? 50:50 or phone a friend?” But at 3am the surgical registrar is not going to be impressed if it’s just a hydrocele. Hmm.
Emergency paediatrics includes paediatric surgery. This makes up very little of the undergraduate or postgraduate curriculum of the physician caring for such patients whether that is Emergency Physicians, Paediatricians or General (Adult) Surgeons. Understanding a few simple points of anatomy and examination will convert this challenge into a simple problem. This is the first in a series of posts offering some insights into Paediatric Surgery 101.
A simple understanding of embryology of the region is the best place to start. The testis is made within the abdominal cavity and descends under the influence of various hormones effectively through a tunnel of peritoneum known as the processus vaginalis. The processus shrinks to fit around the testis, vas and vessels by around the 30th week of gestation. Failure of this closure in various manners leads to three problems:
- Unclosed leads to an inguinal hernia
- Closed around the cord but not the testis leads to a hydrocele
- Closed completely but with the testis high results in an undescended testis
Clearly, an infant who is born prematurely has a higher risk of all of these problems but, intriguingly, the problems are inconsistent in both laterality and time. They are never present at birth. They develop in the second month postnatally but are a congenital abnormality. Paediatric inguinal hernias are, almost without exception, a failure of closure of the processus vaginalis and thus an indirect hernia. Hernias in an adult are due to a different pathological process, a weakness of the muscles within this area, and may be direct or indirect depending on other factors. The different pathological process is the reason behind a different surgical repair.
The initial challenge for the Emergency Physician is usually of an infant presenting with a swelling in the groin and or scrotum. History, as in all branches of medicine, is important. When did the swelling arise? Has there been previous swelling? Where exactly is the swelling, if intermittent? What associated symptoms are there? Is the child vomiting? Is the child distressed? Were any notes made at the postnatal examination relating to genitals? What do the parents think the problem is?
The basis of examination requires an understanding of the inguinal canal. The examining physician must be able to pinpoint 4 structures: inguinal ligament, superficial (A) and deep (B) inguinal rings and the testis. There is real value in establishing these points on the contralateral side for subsequent comparison.
The inguinal ligament runs from the anterior superior iliac spine to both the pubic tubercule and pubic symphysis. This latter attachment to tubercule and symphysis often confuses non surgeons; it is this gap in the external oblique that is the external inguinal ring and through this gap passes the neck of an inguinal hernia. Superior to the mid-point of the inguinal ligament is the deep ring of the inguinal canal. The femoral artery is inferior and deep to this point. The inguinal canal runs from the deep ring to the superficial ring and palpably contains the testicular vessels and vas deferens. The swelling of an inguinal hernia will extend from the deep ring down into the scrotum.
The testis is palpable within the scrotum in 98% of boys. Very few boys have bilaterally undescended testes so in over 99% of the time a testis should be palpable. If the testis isimpalpable this is usually an issue of technique. Often overlooked is the value of inspection; look before you attempt to examine the testis. The cremasteric reflex may so brisk and effective as to reduce a testis from the scrotum into the inguinal canal. This is the commonest cause of a physician failing to identify a child’s normally descended testes.
Examination is a simple, step wise process. With the non dominant hand sweep medially from the deep ring and fix and maintain the examining fingers over the external ring in a two finger pinch grip over the cord. Scoop the whole of the scrotum in the examining hand, fingers posterior to the scrotum attempting to pass superiorly to meet the thumb anteriorly and rolling the tissue in between. Particularly in the chubby infant this can be a challenge but the look of disquiet as his testis pings between examining fingers is often the best guide to the location of a hidden testis. Palpate the cord structures passing medially to the tubercule.
Once the normal anatomy has been established, examine the affected side. One needs to establish the answer to three questions.
- Where exactly is the swelling relative to the inguinal ligament?
- Where is the testis relative to the swelling?
- Can one get above the swelling?
1. Where exactly is the swelling relative to the inguinal ligament?
Draw an imaginary line between fingers placed on the pubic tubercule and the anterior superior iliac spine. An inguinal hernia will pass from the deep ring above the line of the ligament, medial to the pubic tubercule and into the scrotum. Enlarged inguino-femoral lymph nodes are inferior to the mid-point of the ligament. A hydrocele does not occupy the inguinal canal and the cord, when examined is the same thickness on both sides.
2. Where is the testis relative to the swelling?
In a hernia, the testis is separate to the swelling, usually inferior and slightly posterior. In a hydrocele, the testis is within the swelling. An undescended testis, present in less that 1% of hernias should be identified.
3. Can one get above the swelling?
This phrase is beloved of physicians but virtually none understands what its true meaning. The obvious, yet misunderstood point, is that an inguinal hernia is a herniation of bowel from the abdominal cavity. Thus it passes from the deep ring inferiorly into the scrotum and the superior aspect of the swelling will be at the deep ring. Many are confused by a tense hydrocele filling the whole of the scrotum that the examining hand cannot “get above” at the external ring. Comparison of the cord on both sides will give clarity to this point. A cord, containing herniated bowel, will be markedly thicker than one superior to a hydrocele containing little more than a sliver of fluid. Thus the swelling of a hernia extends from the scrotum to the deep ring. More correctly, the swelling extends down from the abdominal cavity at the deep ring. One cannot “get above” this swelling as it continues from scrotum up and through the deep ring as opposed to a hydrocele that “ends” at the external ring.
These three facts will allow the physician to differentiate between a hernia or a hydrocele. At no point is transillumination of the swelling of any value save the amusement of small boys. Trust me, they love it! It is important to recognise that a bright light will transilluminate the hernia or hydrocele of a small child. The actual description of the test reports “brilliant” transillumination as being definitive but the subtleties of this brilliance are lost on the majority. Do not use transillumination to differentiate between a hernia and hydrocele.
It is incumbent on every examining clinician to understand the principles of reducing a hernia and perform this as part of their examination. In every setting a hernia must be reducible. Every second a hernia remains unreduced it swells due to venous obstruction. This increases the risk of the bowel ischaemia, the risk of testicular atrophy, the risk and extent of the surgery and causes the postoperative outcome for the child to deteriorate. It is never acceptable to wait for the surgeon to reduce a hernia.
The technique for reduction of a hernia is simple and is a mirror of the technique for examining the testis. The main concern of non experts undertaking the procedure is that harm will come from their actions; the opposite is true. More harm comes of waiting and not reducing a hernia than attempting to reduce a hernia. The non dominant hand should sweep medially from the deep ring and fix and maintain the examining fingers over the external ring in a two finger pinch grip over the cord, pressing firmly onto the cord. The dominant hand should scoop the whole of the scrotum in the examining hand, fingers posterior to the scrotum. Rather than the “adult” approach of squeezing the hernia en masse in the direction of the canal, the paediatric physician should bring the thumb and fingers together squeezing firmly in an attempt almost to pop the cystic structure contained in the grip. Maintain this pressure, feeling with the fingers posteriorly if there is a knuckle of bowel palpable at the external ring. The usual weakness of technique is releasing the pressure of the non dominant hand. This stops the exerted pressure of the dominant hand being directed solely at the external ring. The hernia will pop with a rapid gush and the infant will often stop with their distress immediately. Confirm reduction by comparison of the two inguinal canals.
Various authorities suggest adjuncts to this technique: morphia and other analgesias delivered by various routes2,3, gallows traction or long journeys by ambulance. All of these have their merits, the reality is that the sooner direct pressure is applied, the sooner the hernia is reduced. Do not delay attempted reduction whilst adjuncts, including those of alternate disciplines or seniority are sought.
It should be noted that female infants can also develop inguinal herniae. Rather than the testis, it is the round ligament of uterus that “descends” through the canal which then remains patent. Importantly the commonest organ to herniate into this processus in a female infant is the ovary, Reduction of this is of equivalent urgency as in a male. Two points are important to clarify. When an ovary herniates it does so in the same trajectory as a testis- through the external ring. A small, olive sized lump palpable in the groin of a female infant overlying the inguinal canal must be reduced but in the direction of herniation back towards the superficial ring, ie medially, not laterally in the mistaken belief that the ovary is just “within” but not exited the inguinal canal. Additionally a female infant may present with a significant cyst swelling at the external ring, the so called “Hydrocele of the Canal of Nuck.” Virtually without exception this is a patent processus obstructed by a herniated ovary. Reduction by the same technique as for a male infant in a medial direction will decompress the hydrocele and allow the ovary to reduce.
If reduction at any time fails to reduce the herniated structure, contact should be made urgently with specialist Paediatric Surgical services. Attempts at reduction of the hernia should not cease whilst the specialist opinion is awaited. If reduction is successful the specialist must still be contacted, but with less urgency and perhaps (please) at a more reasonable hour of the day. They will advise on local practice regard definitive surgical intervention.
In terms of adjuvant therapy there is significant variation amongst surgeons and it is worthwhile determining local practice. Some surgeons prescribe prophylactic antibiotics, some insist on intravenous fluids, some value sedatives or analgesics, some admit overnight following difficult reductions, some feed immediately, some see in out patients and some simply don’t believe that it was a difficult reduction. For this variation I can only apologise.
Swellings in the groin of infants are a management challenge which can be overcome through better experience, supervision and specific knowledge4. Identify the anatomy, assess the swelling and reduce every hernia. Babies with hydroceles can go home and sleep off the snottiness. Babies with hernias need them reducing. Knowing you’ve done a great job for your patient, you phone a friend…
Ross Fisher (aka @ffolliet)
Consultant Paediatric Surgeon
Sheffield Children’s Hospital