Groin swelling

A groin swelling is a lump at or near the junction of the lower abdomen and the thigh. Most are hernias.

Anatomy. The inguinal canal runs from the deep ring (lateral to the inferior epigastric vessels, midway between the anterior superior iliac spine and the pubic symphysis) to the superficial ring (superolateral to the pubic tubercle). The femoral canal lies medial to the femoral vein, inferolateral to the pubic tubercle. The saphenofemoral junction, inguinal nodes (horizontal and vertical groups) and the spermatic cord (or round ligament in women) are also in this region.

Hernia types.

• Indirect inguinal: through the deep ring, lateral to the inferior epigastric vessels, and may descend into the scrotum.
• Direct inguinal: through the posterior wall of the canal medial to those vessels, and rarely strangulates.
• Femoral: through the femoral canal, with a narrow rigid neck and the highest risk of strangulation. More common in women than men, although inguinal hernias are still the commonest hernia in women.
• Others: Richter hernia (part of the bowel wall trapped), sliding hernia, pantaloon hernia (both direct and indirect), obturator hernia, Spigelian hernia, sports hernia (pain without a palpable lump), and incisional hernia.
• Complications: reducible (returns with pressure or when lying), irreducible or incarcerated (cannot be reduced), obstructed (bowel lumen obstructed), and strangulated (blood supply compromised).

Epidemiology. The lifetime risk of an inguinal hernia is about 27% in men and 3% in women. Hernias occur in infants through a patent processus vaginalis, and are commoner in preterm infants and boys.

Sections in this article. Reducible, painful and irreducible groin swelling are separate sections in assessment and management.

Key distinctions. An inguinal swelling lies superomedial to the pubic tubercle and a femoral swelling lies inferolateral to it, though large femoral hernias ride upward over the inguinal ligament. A swelling with a cough impulse that reduces on lying is a hernia until proved otherwise. A pulsatile and expansile swelling is a femoral artery aneurysm. A swelling that disappears on lying with a thrill on coughing is a saphena varix.

A scrotal swelling whose upper limit cannot be felt is an inguinoscrotal hernia, whereas a swelling whose upper limit can be felt is a hydrocele or other scrotal lesion.

History.

• Duration, mode of onset (sudden after lifting or coughing), size changes, reducibility, pain, and relation to posture and activity.
• Reducible swelling: cough impulse, disappears lying down, increases on standing or straining.
• Painful or irreducible swelling: sudden onset of pain, tense swelling, vomiting, abdominal distension, constipation and obstipation (strangulation or obstruction), skin redness.
• Contributing factors: chronic cough, constipation, straining at micturition (prostatic obstruction), heavy lifting, obesity, previous hernia repair or appendicectomy, ascites, peritoneal dialysis, connective tissue disorder, smoking, pregnancy.
• Other causes: fever, leg or genital infection and lymph node drainage, genital ulcers or discharge, weight loss, night sweats, HIV risk, intravenous drug use or recent femoral catheterisation (pseudoaneurysm), sports injury.

Examination (standing and lying).

• Inspection for site, size, skin changes, scars and visible pulsation, with the patient coughing. Observe the scrotum.
• Palpation: temperature, tenderness, consistency, reducibility, relation to the pubic tubercle, expansile pulsation, thrill. Examine the opposite groin, and the testes and cord.
• Lymph nodes: size, consistency, tenderness, mobility, and the drainage areas (lower limb, foot, perineum, anus, genitalia, lower abdominal wall), then the popliteal and other node groups, liver and spleen.
• Abdomen: distension, tenderness, bowel sounds, scars, masses. Rectal and pelvic examination when appropriate.

Reducible groin swelling. Painless or mildly aching swelling that is reducible, with a cough impulse and no obstruction, belongs to this section. A direct hernia reduces straight back, and an indirect hernia reduces up and out.

Painful groin swelling. Pain in a hernia may be caused by incarceration, obstruction or strangulation, or may be mechanical discomfort. In a lymph node, pain suggests infection. Pain with fever and redness in a groin lump suggests an abscess or infected node.

Irreducible groin swelling. A swelling that cannot be reduced and is tender or tense, with vomiting or obstructed bowel signs, is an emergency. Irreducible and non-tender hernias without obstruction are chronic incarcerated hernias, often containing omentum.

Red flags.

• Tense, tender, irreducible lump with overlying erythema, vomiting, distension or absolute constipation.
• Femoral hernia (any), fever or tachycardia, peritonism, signs of shock.
• Expanding pulsatile mass, limb ischaemia, or leg swelling.
• Infant with irreducible swelling, inconsolable crying, vomiting or discolouration.
• Hard, fixed or matted nodes with weight loss, night sweats or fever.
• Testicular mass or absent testis in the scrotum.

Special groups. Infants and children (patent processus vaginalis, higher risk of incarceration under 1 year), pregnancy (round ligament varicosities, hernias), women (femoral hernia, hydrocele of the canal of Nuck, endometriosis), older adults (strangulation and delay), patients on peritoneal dialysis, and patients with cirrhosis and ascites (umbilical and inguinal hernias with leak risk).

Hernias. Indirect inguinal hernia, direct inguinal hernia, femoral hernia, pantaloon hernia, sliding hernia, Richter hernia, obturator hernia, Spigelian hernia, incisional hernia, Amyand hernia (appendix in the sac), Littre hernia (Meckel diverticulum), recurrent hernia.

Spermatic cord and testis. Hydrocele of the cord, encysted hydrocele, varicocele, undescended or ectopic testis, torsion of an undescended testis, epididymal cyst, spermatic cord lipoma, spermatic cord sarcoma (liposarcoma, rhabdomyosarcoma), testicular tumour.

Female specific. Hydrocele of the canal of Nuck, round ligament varicosities, endometriosis in the inguinal canal, ectopic ovary in the hernia sac.

Lymph nodes.

• Reactive lymphadenopathy from skin and soft tissue infection of the leg, foot, perineum, anus or genitalia.
• Sexually transmitted causes: lymphogranuloma venereum, chancroid, primary syphilis, genital herpes.
• Other infections: tuberculosis, HIV infection, filariasis, plague, cat scratch disease.
• Malignancy: lymphoma, leukaemia, metastasis from penile, vulval, anal, cervical or skin cancer (squamous cell carcinoma, melanoma), and sarcoidosis.

Vascular. Femoral artery aneurysm, femoral artery pseudoaneurysm (after catheterisation or in intravenous drug users), saphena varix, femoral vein varicosity, lymphocele after vascular surgery.

Soft tissue and bone. Lipoma, sebaceous or epidermoid cyst, abscess, hidradenitis suppurativa, haematoma, soft tissue sarcoma, psoas abscess (pyogenic or tuberculous), iliopsoas bursitis, adductor tendinopathy, osteomyelitis of the pubis, pubic bone tumour.

Mimics. Sportsman's groin (athletic pubalgia) with pain but no lump, hip joint disease, and referred pain from the spine or testis.

Typical reducible inguinal hernia in a man. Clinical diagnosis. Imaging is unnecessary before repair.

Uncertain, small, recurrent or occult swelling, and any groin lump in a woman.

• Dynamic ultrasound with Valsalva manoeuvre, in lying and standing positions. It is operator dependent but sensitivity is high with a dynamic technique. It also finds femoral hernias, hydroceles, nodes, aneurysms and varices.
• Doppler ultrasound for pulsatile masses and saphena varix.
• CT abdomen and pelvis with intravenous contrast for suspected obstruction or strangulation (bowel wall thickening, reduced enhancement, mesenteric oedema, free fluid), unexplained lumps and suspected abscess, sarcoma or lymphadenopathy. MRI for occult hernias in athletes, sarcoma and endometriosis.

Strangulation or obstruction work up. Blood gas with lactate (a normal lactate does not exclude ischaemia), full blood count, CRP, urea, creatinine, electrolytes, group and crossmatch, and abdominal radiograph. Do not delay surgery for imaging when signs are clear.

Lymph node work up. Full blood count with film, CRP, HIV test, syphilis serology, nucleic acid amplification tests for chlamydia (including lymphogranuloma venereum serovars), gonorrhoea and herpes, culture of any ulcer or pus, tuberculosis tests (interferon gamma release assay, sputum, node aspirate), chest radiograph, and ultrasound of the node. Excision biopsy is preferred when lymphoma is suspected, and core or fine needle aspiration for other causes. Examine the drainage area and arrange staging imaging for malignancy.

Testis and cord. Scrotal ultrasound for suspected undescended testis, hydrocele, varicocele or tumour.

Limitations. Clinical examination misses small femoral and occult hernias, especially in women and obese patients. Ultrasound is poor for deep or very small defects. Lactate and white cell counts can be normal in early strangulation.

Reducible groin swelling.

• Repair is the definitive treatment. Elective mesh repair (open Lichtenstein or laparoscopic transabdominal or totally extraperitoneal) is usual, as a day case under local, regional or general anaesthesia. Mesh is not used in the presence of contaminated tissue or strangulation with bowel resection, where tissue repair may be chosen.
• In men with minimal or no symptoms, watchful waiting is a reasonable choice, since the risk of acute incarceration is low but not zero. Review for increasing pain, size or irreducibility. Femoral hernias and all groin hernias in women are repaired promptly because the risk of strangulation is higher and many are femoral.
• Reduce modifiable risks before elective surgery: stop smoking at least 4 weeks before, treat chronic cough, constipation and urinary obstruction, and encourage weight loss.
• A truss gives symptomatic relief only and is used when surgery is not possible.
• Prophylactic antibiotics are not routine for low risk elective mesh repair, and evidence is limited. When used: cefazolin 2 g IV as a single dose at induction (3 g if weight over 120 kg); monitor for allergy; in severe penicillin allergy use clindamycin 600 mg IV once, or vancomycin 15 mg/kg IV (maximum 2 g) over 60 to 120 minutes.
• Thromboprophylaxis for high risk patients with enoxaparin 40 mg subcutaneously once daily (20 mg daily if CrCl 15 to 30 mL/min).

Painful groin swelling.

• Establish whether pain is from the hernia contents, a node or another source. Examine for tenderness, redness and obstruction.
• Analgesia: paracetamol 1 g orally or IV every 6 hours (maximum 4 g daily; 3 g daily if weight under 50 kg, malnutrition, alcohol excess or liver disease). Avoid NSAIDs when obstruction or strangulation is possible.
• Infected node or abscess: incision and drainage of pus, swab culture, and flucloxacillin 500 mg orally every 6 hours (maximum 4 g daily) for 5 to 7 days for cellulitis; monitor liver tests (cholestatic jaundice) and reduce the dose in severe kidney impairment; clindamycin 300 to 450 mg orally every 6 hours (maximum 1.8 g daily) in penicillin allergy; monitor for Clostridioides difficile infection.

Irreducible groin swelling.

• Nil by mouth, IV access, balanced crystalloid (500 mL boluses to restore perfusion), nasogastric tube if vomiting or distended, and urinary catheter in the unwell.
• Analgesia: paracetamol 1 g orally or IV every 6 hours (maximum 4 g daily; 3 g daily if weight under 50 kg, malnutrition, alcohol excess or liver disease) and morphine 0.05 to 0.1 mg/kg IV in 2 mg boluses every 5 minutes (maximum 10 mg before reassessment; monitor respiration and sedation; reduce in older adults and kidney impairment).
• Ondansetron 4 mg IV every 8 hours (maximum 16 mg daily).
• Gentle manual reduction (taxis) with the patient supine, hips flexed and the foot of the bed raised, for up to 10 to 15 minutes under adequate analgesia, is attempted only in the absence of strangulation signs (skin change, toxicity, peritonism, long duration over 12 to 24 hours) and is not attempted in femoral hernias in many practices. A successful reduction still needs surgical review within 24 hours, because reduction en masse or return of non-viable bowel can occur.
• Emergency surgery for failed reduction, strangulation or obstruction: repair of the defect, assessment of bowel viability, resection of non-viable bowel, and mesh decisions by the surgeon.
• When strangulation or sepsis is suspected give ceftriaxone 2 g IV once daily (maximum 4 g daily) plus metronidazole 500 mg IV every 8 hours (maximum 1.5 g daily); monitor creatinine, liver tests and diarrhoea.

Infants and children.

• Inguinal hernia: repair soon after diagnosis (within about 2 weeks in term infants, and before discharge from neonatal care in preterm infants), because the risk of incarceration is highest in the first year.
• Incarcerated hernia: analgesia (paracetamol 15 mg/kg every 6 hours; maximum 60 mg/kg daily), sedation by an experienced operator, and gentle reduction. Admit and repair within 24 to 48 hours after reduction, once swelling has settled. Operate at once for failed reduction, bowel obstruction or discolouration.
• Girls: the hernia may contain an ovary, so avoid prolonged attempts at reduction.

Other causes.

• Femoral artery pseudoaneurysm or aneurysm: vascular surgery, ultrasound directed compression or thrombin injection for pseudoaneurysm, and open or endovascular repair for aneurysm.
• Saphena varix: reassurance, and surgery for symptoms.
• Lymphogranuloma venereum: doxycycline 100 mg orally every 12 hours for 21 days (maximum 200 mg daily; avoid in pregnancy and children under 8 years; take upright with water); alternative azithromycin 1 g orally once weekly for 3 weeks; aspirate fluctuant buboes through normal skin and do not incise.
• Primary syphilis: benzathine benzylpenicillin 2.4 million units IM as a single dose; monitor for Jarisch-Herxheimer reaction; no kidney adjustment.
• Chancroid: azithromycin 1 g orally as a single dose, or ceftriaxone 250 mg IM as a single dose.
• Tuberculous lymphadenitis: after tissue diagnosis, isoniazid 5 mg/kg (maximum 300 mg), rifampicin 10 mg/kg (maximum 600 mg), pyrazinamide 25 mg/kg (maximum 2000 mg) and ethambutol 15 mg/kg (maximum 1600 mg), all orally once daily for 2 months, then isoniazid and rifampicin for 4 months, with pyridoxine 10 to 25 mg daily; monitor liver tests, visual acuity and uric acid; adjust for liver and kidney impairment.
• Lymphoma, sarcoma and metastatic disease: urgent oncology referral.
• Psoas abscess: image directed or surgical drainage plus antibiotics directed by culture.

Special groups. Pregnancy: round ligament varicosities need only reassurance. Complicated hernias are repaired in any trimester. Elective repair is postponed until after delivery. Cirrhosis with ascites: treat ascites before elective repair, and repair complicated hernias urgently.

Monitoring. Serial examination of the groin and abdomen every 4 to 6 hours while in hospital, lactate and electrolytes after resuscitation, and wound review at 1 to 2 weeks after repair.

Referral and escalation. General surgery for all hernias. Paediatric surgery for infants and children. Vascular surgery for aneurysm and pseudoaneurysm. Urology for cord and testicular lesions. Genitourinary medicine for sexually transmitted infections. Haematology or oncology for lymphadenopathy. Infectious diseases for tuberculosis.

Admission criteria. Any painful irreducible lump, obstruction, strangulation, suspected abscess with systemic illness, expanding pulsatile mass, or an infant with an irreducible hernia.

Discharge and safety netting. Patients with reducible hernias awaiting surgery can go home with advice to avoid heavy lifting and straining. They are told to return at once for a hernia that cannot be pushed back, severe pain, vomiting, redness, a hard lump or inability to pass stool or wind. After repair, patients return for fever, wound discharge, increasing swelling, severe pain or urinary retention.