Inguinal hernia

Overview

•Protrusion of abdominal contents through the anterior abdominal wall into the inguinal canal - produces a visible/palpable groin bulge

•In children: virtually all are indirect - caused by a patent processus vaginalis

•Affects ~1-3% of children; male:female 7:1; right-sided predominance (right testis descends later)

•Premature infants at highest risk - processus vaginalis almost invariably patent at birth

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Direct hernias are rare in children - if present, suspect a connective tissue disorder (Ehlers-Danlos, Marfan's syndrome).

Presentation

•Intermittent groin swelling - appears with crying, coughing, or straining; disappears at rest

•Lies superior and medial to the pubic tubercle (cf. femoral hernia - inferior and lateral)

•Cough impulse - palpable expansion on coughing; absent if incarcerated

•Reducible - can be gently pushed back; failure to reduce = incarceration

•Incarcerated hernia - irreducible, tender, tense mass; nausea, vomiting, abdominal distension

•Strangulated hernia - as above plus ischaemia signs: exquisite tenderness, skin erythema, systemic sepsis (fever, tachycardia, hypotension)

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In infants, irritability and inconsolable crying may be the only signs of incarceration or strangulation. Always examine the groins in any infant with unexplained distress or vomiting.

Investigations

•Reducible inguinal hernia = clinical diagnosis - no investigations required

•Ultrasound groin - if diagnosis uncertain, especially in females (ovary may be in sac), or to assess vascularity

•FBC, CRP, U&E, lactate - if strangulation suspected (leucocytosis, metabolic acidosis, organ dysfunction)

Differential diagnosis

Key differentials for groin/scrotal swelling in children
ConditionKey distinguishing features
Femoral herniaInferior and lateral to pubic tubercle; more common in women; higher strangulation risk
HydroceleTransilluminates; non-tender; no cough impulse; does not extend above inguinal ligament
Undescended testisTestis absent from scrotum; groin mass = undescended testis; can co-exist with hernia
LymphadenopathyFirm, discrete, not reducible; no cough impulse; associated infection/malignancy
Testicular torsionScrotal pain and swelling; tender testis within scrotum; surgical emergency

Condition	Key distinguishing features
Femoral hernia	Inferior and lateral to pubic tubercle; more common in women; higher strangulation risk
Hydrocele	Transilluminates; non-tender; no cough impulse; does not extend above inguinal ligament
Undescended testis	Testis absent from scrotum; groin mass = undescended testis; can co-exist with hernia
Lymphadenopathy	Firm, discrete, not reducible; no cough impulse; associated infection/malignancy
Testicular torsion	Scrotal pain and swelling; tender testis within scrotum; surgical emergency

Management

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Watchful waiting is NOT appropriate in children. Incarceration rate is 12-16%, with 50% of cases occurring in infants under 6 months. All children require urgent referral to paediatric surgery.

Step 1 · Reducible hernia
1Urgent referral to paediatric surgery for elective repair
2Advise parents: return immediately if swelling becomes hard, red, and irreducible
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Incarcerated (irreducible, no strangulation signs)
Attempt gentle reduction (taxis); if successful, semi-urgent repair within days; if unsuccessful, emergency surgery
Strangulated (ischaemia/sepsis signs)
Emergency surgical exploration - no attempt at reduction; resect necrotic bowel if required; IV antibiotics, resuscitation
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Step 3 · Premature infants
1High incarceration risk - multidisciplinary decision (neonatologist + paediatric surgeon) on timing
2Many units repair prior to NICU discharge; some delay 1-2 months to reduce anaesthetic risk

Complications

•Incarceration - irreducible contents; bowel obstruction and ischaemia may follow

•Strangulation - vascular compromise → ischaemia, necrosis, perforation, peritonitis

•Testicular ischaemia and atrophy - compression of testicular vessels, especially in infants with delayed presentation

•Recurrence - ~1-3% after open repair