An inguinal hernia (IH) is an abnormal protrusion of intraabdominal contents through the inguinal canal. IH is one of two different types of groin hernias (in addition to the less common femoral hernia), and can be further subdivided based on anatomic location: an indirect inguinal hernia protrudes lateral to the inferior epigastric vessels through the deep inguinal ring, whereas a direct inguinal hernia protrudes medial to the inferior epigastric vessels through a defect in the posterior wall of the inguinal canal. An uncomplicated inguinal hernia typically manifests as a mass in the groin with or without pain (inguinodynia). Incarceration, obstruction, and strangulation of hernial contents are collectively referred to as complicated inguinal hernia. IH is a clinical diagnosis. Imaging, preferably with ultrasound, is indicated if the clinical diagnosis is uncertain. Surgery is the only definitive management of IH and can be performed as an open surgery or laparoscopically. A strangulated inguinal hernia is a surgical emergency. In patients with an incarcerated hernia with/without bowel obstruction, manual reduction of the hernia may be considered as a temporizing measure before surgery. Conservative management may be considered in a select group of patients with small, uncomplicated inguinal hernia.
- Direct inguinal hernia: protrusion of abdominal and/or pelvic contents directly through the posterior wall of the inguinal canal
- Indirect inguinal hernia: protrusion of abdominal and/or pelvic contents into the inguinal canal through the deep inguinal ring
- Uncomplicated inguinal hernia: an inguinal hernia that is completely reducible and not associated with signs of bowel obstruction or strangulation
- Complicated inguinal hernia: an inguinal hernia that is either irreducible (incarcerated) or associated with mechanical bowel obstruction and/or strangulation
- Occult inguinal hernia: an inguinal hernia that is not identifiable on physical examination
- Sex: ♂ > ♀
Epidemiological data refers to the US, unless otherwise specified.
- Extends between the deep (internal) and superficial (external) ring
- Roof (superior): internal oblique and transversus abdominis muscles
- Floor (inferior): inguinal ligament (shelving edge of external oblique) and lacunar ligament (medially)
- Posterior wall: transversalis fascia laterally; conjoint tendon medially
- Anterior wall: external oblique aponeurosis and internal oblique muscle laterally
Hesselbach triangle borders
- Medially: rectus abdominis muscle
- Laterally: inferior epigastric vessels
- Inferiorly: inguinal ligament
Direct inguinal hernia
- Acquired condition
- Caused by weakening of the transversalis fascia
- Medial to the inferior epigastric blood vessels (within Hesselbach triangle); and lateral to the rectus abdominis
- Hernial sac protrudes directly through the posterior wall of the inguinal canal (without involvement of the spermatic cord or round ligament of the uterus)
- Only herniates through the superficial (external) ring
- Only surrounded by the external spermatic fascia
Indirect inguinal hernia
- Most commonly results from incomplete obliteration of processus vaginalis during fetal development (but can also be acquired).
- May not become apparent until adulthood despite being present since birth.
- Lateral to the inferior epigastric blood vessels (outside Hesselbach triangle)
- Runs from the deep inguinal ring through the inguinal canal to the superficial (external) inguinal ring (in men, along with the spermatic cord)
- Surrounded by the external spermatic fascia, cremasteric muscle fibers, and internal spermatic fascia
- Indirect inguinal hernia may be associated with a communicating hydrocele.
Uncomplicated inguinal hernia 
- Typically manifests as an ill-defined mass in the inguinal region with the following features:
- Inguinodynia with no palpable groin mass is typically the only manifestation of an occult inguinal hernia. 
- Ask the patient to perform a Valsalva maneuver and observe for an in the inguinal region.
- Palpate the inguinal canal
- Hernia is completely reducible
Complicated inguinal hernia 
- Incarcerated hernia
- Strangulated hernia
Manual reduction of inguinal hernia should not be attempted if there are any signs of strangulation!
- First-line; (in all suspected inguinal hernia) : ultrasound of the groin 
- Inconclusive ultrasound findings: CT or MRI of the abdomen and pelvis
- Complicated inguinal hernia: Consider CT of the abdomen and pelvis with IV contrast. 
- Suspected occult inguinal hernia or recurrent inguinal hernia: Consider any of the following modalities. 
- Visualization of the hernial sac with its contents (e.g. bowel, omentum)
- Uncomplicated inguinal hernia
Strangulated inguinal hernia 
- Absence of blood flow to the hernial contents
- Absence of peristalsis of bowel loops within the hernial sac
Incarcerated hernia with bowel obstruction 
- Free fluid and thickening of bowel wall within the hernial sac
- Dilated bowel loops within the abdomen (see “Mechanical bowel obstruction” for details)
Emergency surgery should not be delayed for imaging in unstable patients with signs of strangulation or bowel obstruction. 
Laboratory studies 
The following tests should be obtained in patients with strangulated inguinal hernia or incarcerated inguinal hernia with bowel obstruction for supportive diagnostic evidence and to assess for complications. 
Groin or scrotal mass 
- Femoral hernia
- Inguinal or femoral lymphadenitis and lymphadenopathy
- Femoral artery aneurysm or pseudoaneurysm
- Psoas abscess
- Round ligament varicosities
- Large cutaneous or subcutaneous masses in the inguinal region
A groin bulge with an expansile cough impulse above the inguinal ligament is diagnostic of an inguinal hernia. A femoral hernia typically manifests as a groin bulge below the inguinal ligament and lateral to the pubic tubercle. 
- Acute appendicitis
- Diverticulosis or acute diverticulitis
- Pathology of the hip joint
- Inflammatory bowel disease
- Lumbar disc herniation
- Testicular disorders
- Urinary tract infection
- Osteitis pubis
- Musculoskeletal pain
- Sports hernia
The differential diagnoses listed here are not exhaustive.
- Complicated inguinal hernias
- Uncomplicated inguinal hernia: elective surgery; consider watchful waiting in select patients
Complicated inguinal hernia 
- Strangulated inguinal hernia or incarcerated hernia with bowel obstruction: Immediate surgery consult for emergency surgery (see “Surgical procedures” below)
- Incarcerated hernia with bowel obstruction but no signs of strangulation: Consider as a temporizing procedure before surgery. 
- Administer supportive care as needed
Manual reduction of inguinal hernia 
- Indication: : Consider as a temporizing measure before surgery in patients with incarcerated hernia with/without bowel obstruction.
- Contraindication: strangulated inguinal hernia
Successful hernia reduction: Observe the patient for 12–24 hours.
- Symptoms improve: Schedule an elective hernia repair as early as possible.
- Symptoms worsen: Immediate surgical consult to evaluate for reduction en masse. 
- Unsuccessful hernia reduction: urgent surgery (see “Surgical procedures” below)
Manual reduction of hernial contents is contraindicated if there are signs of a strangulated hernia, as necrotic bowel or omentum can be pushed into the abdominal cavity, potentially leading to serious complications including peritonitis. 
Elective surgery 
Conservative management (watchful waiting) 
- Indications 
- Symptoms significant enough to limit daily activities 
- Complicated inguinal hernia
- Female patients
- General recommendations 
Once the hernial contents are reduced (i.e., returned to the abdominal cavity), the goal of hernia surgery is to reinforce the posterior wall of the inguinal canal with a synthetic mesh or through primary tissue approximation. Emergency surgery is associated with an increased risk of complications; elective surgery is preferred when it is an option.
Hernioplasty (mesh repair)
- Definition: repair of a hernial defect using a synthetic mesh
- Indication: gold standard for inguinal hernia repair 
- Preferred in patients with complicated inguinal hernia or contraindications for laparoscopic repair 
- Procedures include Lichtenstein repair, in which a synthetic mesh is placed between the transversalis fascia and the external oblique aponeurosis to reinforce the posterior wall of the inguinal canal. 
- Laparoscopic surgery: preferred in patients with bilateral or recurrent inguinal hernia 
Herniorrhaphy (non-mesh repair)
- Definition: open surgical repair of a hernial defect using autologous tissue
- Indication: Consider in patients at high risk of surgical site infection. 
- Options: Shouldice repair
- Important consideration: Herniorrhaphy is associated with a greater risk of recurrence than hernioplasty. 
- Urgent general surgery consult
- Consider imaging for inguinal hernia if clinical diagnosis is unclear
- Perioperative supportive care
- Transfer to OR or admit to surgical service for definitive management
Preoperative complications 
- Incarcerated hernia: progression to mechanical bowel obstruction or strangulation of hernia sac contents
- Strangulated hernia
- Early postoperative complications
- Delayed postoperative complications
We list the most important complications. The selection is not exhaustive.
Special patient groups
- Etiology and risk factors
- Premature infants with uncomplicated inguinal hernia: Surgery should be performed after discharge from the neonatal intensive care unit (NICU).
- If hernia can be reduced manually: Wait 24–48 hours before performing surgery to allow enough time for edema to decrease.
- If hernia cannot be reduced manually: immediate surgery
- Asymptomatic inguinal hernia: within 14 days of diagnosis