B4. Hernias in general.

Page created on October 11, 2021. Last updated on January 14, 2022 at 10:05

Hernias in general


A hernia is a condition where intraabdominal contents (usually intestine or fat) prolapse through a hernia “gate”, causing it to bulge out of the area in question.


  • External hernias (visible externally)
    • Inguinal hernia – herniation through the inguinal canal
    • Incisional hernia – herniation through the abdominal wall
    • Umbilical hernia – herniation through the umbilicus
  • Internal hernias
    • Diaphragmatic hernia (a congenital condition, covered in paediatrics)
    • Hernia into the compartments of the peritoneum


The cause for any abdominal hernia is the same: increased intraabdominal pressure. This can be caused by:

  • Obesity
  • Heavy lifting
  • Heavy coughing (chronic lung disease)
  • Constipation

A family history of hernia is also a risk factor.

Clinical relevance

Most hernias are not dangerous, but cosmetically bothersome to the patient. However, in some cases dangerous complications may occur, most notably bowel incarceration or strangulation.

When examining a hernia, it’s important to note:

  • The size
  • Whether it’s reducible or not (may be pushed back into the abdomen)
  • The size of the hernia gate
  • The content of the hernia
  • The complaint of the patient

Irreducible hernias can lead to bowel incarceration, in which case it’s known as an incarcerated hernia. The incarcerated bowel will be obstructed, causing bowel obstruction. In some cases, incarcerated bowel may also be cut off from its blood supply, which is called strangulated hernia. This causes severe pain due to the ischaemia and necrosis.


Both incarcerated hernia and strangulated hernia are surgical emergencies. In case of incarcerated hernia without strangulation we try manual reduction first. If that doesn’t work, the patient needs emergency surgery. If reduction does work, the patient should receive surgery during the same hospital admission (but not urgently). If the patient has strangulated hernia, they need emergency surgery anyway; manual reduction is not tried.

Emergency surgery for incarcerated and strangulated hernia is usually performed open. If performed within 6 hours from the onset of symptoms, bowel loss may be prevented.

Other hernias are mostly cosmetic issues and may be treated with elective surgery if the patient wishes and there are no contraindications.

With hernia surgery, the hernia is first reduced and then the hernia gate is reinforced to prevent herniation from re-occurring. Reinforcement may be with a synthetic mesh or by using the patient’s own tissues as reinforcement.

If the risk for surgery is too high, conservative treatment should be used.

Inguinal hernia


Inguinal hernia refers to herniation of intraabdominal contents into the inguinal region. It is the most common type of hernia and is mostly a disorder of older men. There are two types, indirect and direct.


In indirect inguinal hernia, the contents herniate into the inguinal canal through the deep inguinal ring. The hernial sac lies within the spermatic cord.

In direct inguinal hernia, the contents herniate directly through the posterior wall of the inguinal canal. The hernial sac lies outside the spermatic cord.

During surgery, the two types of inguinal hernia can be differentiated by observing the hernia’s relation to the inferior epigastric vessels. Indirect hernia lies laterally to the vessel, while direct hernia lies medially.


Surgical treatment for inguinal hernia may be with tension (Bassini or Shouldice operation) or tension-free with mesh repair (Lichtenstein or laparoscopy).

In Lichtenstein repair, a synthetic mesh is placed between the transversalis fascia and the external oblique aponeurosis during open surgery to reinforce the posterior wall of the inguinal canal. With laparoscopy, transabdominal preperitoneal repair (TAPP) or total extraperitoneal repair (TEP) are options to place the fascia. With TAPP the mesh is placed preperitoneally. With TEP the mesh is placed is an extraperitoneal position, outside the peritoneum.

Recurrence is more common with tension repair, and so tension-free repair is preferred with mesh is usually preferred. If the risk of infection is high (nearby infection, bowel injury), the hernia is very small, or the patient is very young, mesh repair is not preferred.

Incisional hernia


An incisional hernia is a hernia which occurs at or close to a previous surgical incision which hasn’t completely healed, in which the surgical incision acts as the hernia “gate”. It’s the most common complication of laparotomy.


Incisional hernia is managed with tension-free mesh repair. This may be accomplished open or laparoscopically. Unfortunately, the recurrence rate of incisional hernia reconstruction is quite high, 20 – 50%.

2 thoughts on “B4. Hernias in general.”

  1. Hey 🙂
    One extra thing that may be useful is how to distinguish between indirect/direct inguinal hernia during the surgery. I was asked this on the exam and he said it was important. Apparently something to do with whether the hernia is medial or lateral to the path of the inferior epigastric artery. If its medial it’s direct, and lateral is indirect.

    1. Thank you. I’ve added it.

      Really annoying question, though. Yeah, it might be important for a surgeon to know this, but as a med student? Who gives a shit..

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