Groin Lumps

In this article, we cover the differential for the range of groin lumps including surgical, infective & malignant pathologies.

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Anatomy

The groin, also known as the inguinal region, extends from the anterior superior iliac spine (ASIS) anterolaterally, the thigh inferiorly and the pubic tubercle medially. It is an anatomical region vulnerable to surgical pathology due to a weakening of the abdominal wall occurring during embryology.

Groin anatomy
From Gray’s Anatomy for Students

The abdominal wall has eight layers:

  1. Skin
  2. Superficial subcutaneous fatty tissue (Camper’s fascia)
  3. Deep fibrous tissue (Scarpa’s fascia)
  4. External oblique muscle
  5. Internal oblique muscle
  6. Transversalis fascia
  7. Extraperitoneal fat
  8. Peritoneum

Important groin structures

  • Inguinal ligament – from ASIS to pubic tubercle
  • Inguinal canal – an tubular structure parallel to the inguinal ligament, contains spermatic cord in genotypal males, round ligament in genotypal females, gonadal nerves (genital branch of the genitofemoral nerve) and the ilioinguinal nerves
  • External iliac artery à femoral artery. Site for catheterisation i.e. cardiac
  • Psoas major – the psoas muscle extends from T12 to L5 and passes below the inguinal ligament before attaching to the lesser trochanter of the femur.
  • Lymph nodes receiving lymphatics from lower limb, gluteal region, genitalia, anterior abdominal wall below umbilicus.

Embryology

  • The inguinal canal was developed during the descent of the gonads from the lumbar region of the posterior abdominal wall
  • 12th week of gestation: a portion of the peritoneum protrudes through the abdominal wall, creating an outpouching called the processus vaginalis which guides the migration of the gonads through the abdominal wall
  • The protrusion of the processus vaginalis through the deepest layer, the transversalis fascia, is known as the deep inguinal ring, whereas the superficial inguinal ring corresponds to the superficial opening through the external oblique aponeurosis
  • The processus vaginalis usually degenerates during development, but a failure to do so renders the groin vulnerable to inguinal hernias and hydroceles

Differentials

Groin lumps can be broadly categorised as

  1. Surgical
    • Hernias
    • Femoral artery aneurysm
  2. Infective
    • Infective lymphadenopathy
    • Pseudoaneurysm
  3. Malignant
    • Malignant lymphadenopathy

The most common causes of groin lumps are hernias and lymphadenopathy.

Hernias
  • Protrusion of peritoneal tissue through the abdominal wall
  • Femoral hernia
    • Abdominal viscera enters the narrow femoral canal into the upper portion of the medial thigh.
    • Higher rate of strangulation and are therefore important to identify.
  • Inguinal hernia
    • Peritoneum enters the inguinal canal
    • More common than femoral
    • Indirect or direct
      • Indirect inguinal hernia: peritoneum passes through the deep inguinal ring laterally to the inferior epigastric artery
      • Direct inguinal hernia: peritoneum passes through the posterior wall of the inguinal canal medially to the inferior epigastric artery
  • Examination
    • Inguinal hernia: superior and medial to the pubic tubercle
    • Femoral hernias: inferolateral to the pubic tubercle
Femoral artery aneurysm
  • Risk of dissection and massive haemorrhage
  • More commonly a groin lump may represent a femoral artery pseudoaneurysm developed as a result of femoral catheterisation or due to illicit intravenous drug use
  • Examination
    • Pulsatile and may be bilateral 
Saphena varix
  • Dilatation/varicosity of the saphenous vein at the junction to the femoral vein
  • Clinical features
    • Soft and compressible
    • Positive cough impulse
    • Disappears when supine
  • Management
    • High saphenous ligation 
Infective lymphadenopathy
  • May be caused by skin ulcers and infections
  • Risk factors
    • EBV
    • HIV
    • TB
    • STIs
    • UTIs
Psoas abscess
  • The psoas muscle extends from T12 to L5 and passes below the inguinal ligament before attaching to the lesser trochanter of the femur
  • Risk factors
    • Diabetes
    • IVDU
    • CKD
    • Chron’s disease
    • Immunosuppression
  • Clinical features
    • Fever
    • Limp
    • Malaise
    • Weight loss
    • Swelling below the inguinal ligament
Malignant lymphadenopathy
  • Lymphoma: singular lymph node
  • Chronic lymphocytic leukaemia (CLL): widespread lymphadenopathy

Assessment of a patient with a groin lump

Offer the patient a chaperone for a full groin examination

  • History
    • Onset
    • Duration
    • Pain – an acutely painful lump indicates a strangulated hernia, infectious lymphadenopathy or rarely a psoas abscess
    • Fever
    • Weight loss
    • Night sweats
    • Note: A strangulated hernia will have a short duration to presentation, and symptoms such as fever, nausea and vomiting may indicate infective lymphadenopathy, whereas night sweats, fevers and weight loss may point towards malignancy or psoas abscess.
  • Examination
    • Examine the patient with a groin lump in a standing position
    • Assess size, shape, consistency (a varicocele will be fluid filled and soft, an incarcerated hernia or malignant lymph node will be hard, and an infected or reactive lymph node will be rubbery), and borders (a hernia will not have a palpable superior border)
  • Assess the cough impulse as the increased intra-abdominal pressure will accentuate a hernia unless incarcerated
  • Assess the anatomical relationship with the pubic tubercle and inguinal ligament to differentiate between a femoral and inguinal hernia
  • Attempt to reduce the hernia with the patient in a supine position. In irreducible hernia indicates incarceration
  • Examine the genitalia to assess for signs of infection or undescended testes. Assess for lymphadenopathy elsewhere.
  • If a psoas abscess is suspected the patient will experience pain on resisted flexion of the hip

Investigations

  • VBG – a raised lactate will point towards a strangulated hernia
  • FBC/CRP – may reveal infectious or malignant processes
  • Urinalysis and urine microscopy and culture – urinary leukocytes and/or nitrites may indicate a UTI or STIs
  • Surgical workup – if you suspect a surgical cause complete an FBC, U&Es, CRP, clotting and G&S. Always remember Beta-hCG in a woman of childbearing age.
  • Wound swabs – if genital lesions or leg ulcers are present
  • Serological HIV or TB testing
  • USS – rarely used to diagnose hernias, but may be useful in distinguishing strangulated hernias from lymphadenopathy

Escalation

  • Minimally symptomatic hernias patients may be managed with a watchful-wait approach and a non-urgent referral to surgeons. A symptomatic but reducible hernia should be referred to the general surgeons for elective surgery. All patients should be educated on the symptoms of incarceration and strangulation.
  • Suspected strangulation is a surgical emergency and requires urgent inpatient assessment
  • A pulsatile mass should warrant an urgent referral to vascular surgery

Written by Dr Freya Bakko (FY2)

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