Section: Abdominal wall and retroperitoneum Sub-section: Hernias Curriculum: Curriculum, page 2

Definition

Failure of obliteration of processus vaginalis resulting in abnormal protrusion of abdominal contents through the resultant defect
Therefore indirect (99% of paediatric hernias are indirect)

Incidence

1 in 50 live male births
M:F 6:1
Male hernias:
- Greatest incidence is in first year of life
- Esp. First 3 months
Female hernias can appear at any age
NB: Risk of metachronous hernia ≈ 7.2%

Hx of intermittent swelling over external inguinal ring
Painless / occasional discomfort
Esp. during straining (e.g. crying or straining, seen during nappy changes)
No transillumination
Impulse on straining (unless incarcerated → no impulse)
Spermatic cord thicker vs contralateral side
Side
- 60% are on the RHS
- 25% on LHS
- 15% bilateral
Strangulation is seen more often in infants <6months old
- ≈ 30% of infants with a hernia initially present with strangulation
In incarceration:
- Abdo pain, distension, constipation & N+V are usually late signs, appearing ≥ 12hrs after onset of the lump

Hernial sac usually contains loops of small bowel and sometimes omentum
In girls the canal of Nück undergoes the same obliteration (but earlier) as the processus vaginalis in boys
- Lower incidence of hernias than boy
- But higher incidence of bilateral hernia
Fallopian tube/ovary can enter a hernial sac → May be difficult to reduce

For incarcerated hernia:
- Attempt reduction
- Testicular ischemia more an issue than bowel ischemia
- Hernia compresses testicular blood supply
- Tips of fingers on fundus & other fingers on external ring → Pressure for 2 minutes (± with sedation)
After reduction, ensure that you can still feel the testicle
Then surgery on same inpatient episode / on next available list, usually after 24hr, to give time for oedema of the sac and its investing tissue to subside
If reduction unsuccessful ⇒ Immediate operation necessary
NB: Friable sac; surgery best performed by a paediatric surgeon

Make sure testis is down, if not perform orchidopexy at same time.
High ligation of the hernia sac at level of deep ring
Herniotomy (excise the hernia sac only)
- Not herniorrhaphy (excise the hernia sac and repair the posterior wall) – unless has a neuromuscular disorder
Herniotomy through the inguinal canal
Incision 2cm in skin crease, midway between two rings
Down to EOA. Divide 1cm above IL
- Don’t open superficial ring
Dissect out cord; enter cremasteric fibres just below ilioinguinal nerve, grasp ISF and mobilise cord, split ISF, sweep away cord structures, identify sac, free up to deep ring (until IEV’s seen)
Twist the neck of the sac, ligate flush with deep ring

Mortality from inguinal hernia in infants and children ≈ 0.25% (1994)
Testicular vessels can be severely compressed by a tense, strangulated hernia
- Some degree of atrophy of the testis develops in ≈ 15% of baby boys after an episode of irreducibility and strangulation
Recurrence of hernia: 0.1-12%
Development of metachronous contralateral hernia ≈ 7%
50% ↑ chance of development of contralateral hernia if the original hernia was on the LHS (due to later embryological descent of R testicle)
- 90% develop within 5 yrs of first repair
Other potential complications
- Displacement of testicle 1.2%
- Injury to Vas 1.4%
- Stich granuloma 0.6%