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Introduction and Definitions

A hernia is – a protrusion of a viscous out of a containing cavity –  i.e. when a structure passes through an anatomical barrier and ends up somewhere it shouldn’t be.
Umbilical Hernia
Example showing a defect in abdominal wall to allow formation of a hernia – in this instance an umbilical hernia. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
They are typically associated with abdominal structures – usually where the contents of the abdominal cavity have herniated through a weakness in the abdominal wall. This can happen in several common locations – such as at the umbilicus (umbilical hernia), inguinal canal (inguinal hernia), femoral region (femoral hernia), or at sites of previous surgery (incisional hernia).
  • A hiatus hernia occurs through a different mechanism – where the stomach passes up into the chest cavity through the diaphragm.
Common hernia sites
Common hernia sites. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Most hernias accrue int he groin region (inguinal or femoral). Inguinal hernias are the most common type – approximately 10 times more common than femoral hernias. They are much more common in men than women due to the differing anatomy of the inguinal canal.
Hernias – especially groin hernias are caused by a chronic increase in abdominal cavity pressure. This can be due to obesity, chronic cough or COPD. Other risk factors include smoking, family history and low BMI.
  • Heavy lifting is not conclusively proven to be a risk factor. It is believed that an actual of heavy lifting can cause the hernia to present to the patient, but is not actually the cause and that the defects that result in a hernia are more chronic
Most of the time, a hernia is not dangerous. Typically, in smaller hernias the hernia itself only consists of fat or other non-critical structures. However, over time these defects can become larger and allow loops of bowel to pass through the defect. In some cases, large hernias may arise more quickly. Bowel that passes into a hernia can become stuck, and ischaemia – and this is a life-threatening emergency. We call this a strangulated hernia. 
  • There is roughly a 1% chance per year that any given hernia can become strangulated
  • As such, it is usually recommended that all hernias undergo surgical repair
    • In some older, sedentary patients, conservative management may be appropriate

A typical hernia repair is a relatively minor surgery that involve sewing together the defect in the abdominal wall, and the placement of some sort of mesh at the site of the defect to prevent recurrence in the event that repair defect splits open again.

  • Recurrence rates are about 10-15%

Recovery is typically 6 weeks of avoiding certain activities – such as lifting and squatting. This can mean a long time off work for those with a manual job – and unfortunately hernias are also more common in those with manual jobs!

There are also several terms you might come across that refer to the status of the hernia:
  • Reducible – the contents of the hernia can be pushed back to where its supposed to be
  • Irreducible – the contents of the hernia can’t be pushed back to where its supposed to be
  • Incarcerated – the contents of the hernia sac are stuck inside it (e.g. by adhesions)
  • Obstructed – the contents of the bowel is prevented from passing along the bowel as an obstruction has occurred as a result of the hernia
  • Strangulated – ischaemia of the tissue inside the hernia occurs. This patient will become toxic and requires urgent surgery. Note that with a strangulated hernia, it is possible to push the strangulation back inside where it has come from, and thus give the appearance of a successful reduction, but in actual fact, you have not de-strangulated the hernia.

The three signs of bowel obstruction:

  • Distension
  • Vomiting
  • Absolute constipation(no wind or faeces)

Checking for hernias

Abdominal hernias can be found in the following places (indicated on diagram). They are most common in the inguinal region.
Anatomy landmarks guide to location of a hernia. No expense spared in the production of this original image.


These are more common in men, and are more common than femoral hernias.
To understand inguinal hernias, we have to know a little bit about the inguinal canal. We find the inguinal canal, just above the medial half of the inguinal ligament. The inguinal ligament goes from the anterior superior iliac spine, to the pubic tubercle. The inguinal canal ahs the deep inguinal ring at its lateral side, and the external inguinal ring at its medial side. The inguinal canal is the canal between these two rings. In men, the rings and the canal are larger, hence the fact that inguinal hernias are more common in men. The contents of the canal are the genitofemoral nerve, and the spermatic cord (round ligament in women).

Inguinal Hernia
Inguinal hernia. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Indirect inguinal hernias – these come through the deep inguinal ring, and if large enough, out of the superficial inguinal ring. To reduce these, you have to go from medial to lateral. You will see this above and medial to the pubic tubercle – if it is large enough to have come out of the superficial ring. These account for 80% of inguinal hernias. They can strangulate – and usually at the deep inguinal ring as this is narrow.
If the hernia is really big it can descend into the scrotum and the labia majora.
Direct inguinal hernias – these come into the inguinal canal through a defect in the posterior wall of the canal. These are easier to reduce – they should just pop straight back in! these account for 20% of inguinal hernias. They are generally easy to reduce and do not strangulate.

As this fantastic diagram demonstrates, you can see the deep inguinal ring is located ½ way along the inguinal ligament, 1 ½ cm above this midpoint. The superficial ring is just about above the pubic tubercle.

Differentiating direct and indirect hernias – this is loved by examiners, but is actually of no clinical use as the repair for both is the same – you should reduce the hernia, then occlude the internal inguinal canal with 2 fingers. Ask the patient to cough. If it pops out, then is direct, if it stays in then its indirect!
Don’t forget the acronyms for remembering what stuff is around here! – NAVEL – (or NAVY)
  • N – Nerve
  • A – artery
  • V – vein
  • E – empty space
  • L – lymphatics


These tend to occur more in females. They tend to be irreducible and strangulate.  These go down the femoral canal (not the inguinal canal). They are usually found below and lateral to the inguinal ligament – this is the opposite of inguinal hernias! However, remember they can present above the inguinal ligament as well – but when they do, they will point along the femoral canal, and down the leg, as opposed to towards the groin (like inguinal ones do).  Repair is recommended for these hernias.

Paraumbilical hernias

These are found just above or just below the umbilicus. Omentum or bowel can herniated through them. Surgery involves repair of the rectus sheath. Risk factors involve obesity and ascites.
Umbilical Hernia
Umbilical Hernia. This file is taken from wikimedia commons and is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.


Umbilical hernias are most commonly seen in children and typically resolve by the age of 2-5 without intervention.

Epigastric hernias

These pass through the linea alba above the umbilicus.

Inscisional hernias

These appear along lines of previous incision due to surgery. They occur in up to 11-20% of cases of surgery. Below you can see a diagram of incisional scars.
Eponymous names of incisional hernias.

Spigelian Hernias

These occur at the lateral edge of the rectus sheath, below and lateral to the umbilicus.


Note that other hernias can occur all over the abdomen – the ones described are just the main types.
Irreducable hernia – often you may be asked to reduce a hernia. They can often be present for a long time, but still suddenly become painful. It is important to try and reduce it yourself, because you can prevent strangulation (which can be a surgical emergency due to necrosis). You should perceiver when trying to reduce – especially with obstruction – remember it can prevent surgery!
Reducing a hernia – requires lots of practice! The patients themselves are often experts. Generally they tend to use the flat of the hand, and push with the hand of the opposite side.


  • Hernias are often diagnosed on examination and further imaging is not required
  • If there is doubt about the diagnosis, or, occasionally for surgical planning – then an USS may be performed – this is becoming more common as USS becomes cheaper and more widely available

Repairing an inguinal hernia

This is usually done as a laparoscopic (keyhole) or open technique with a mesh technique. The patient should be advised to lose weight and stop smoking before the operation. In these procedures, a synthetic mesh is used to re-enforce the posterior inguinal canal wall. The same technique is used regardless of if it is a direct or an indirect hernia. The recurrence rate is less than 2%.
It is a very common operation – >100 000 per year in the UK. Often now it is performed as a day case (sometimes even under local anaesthetic if the open technique is used).
Patients can return to work, including manual labour and driving after 2 weeks if they feel comfortable. Older practice used to advice 4 weeks rest.
  • Laparoscopic surgical techniques generally result in shorter recovery times. The rate of complications between laparoscopic and open are similar
  • Laparoscopic technique is becoming more popular
  • In emergency surgery for strangulated hernia, open technique is still generally preferred

Reducing a hernia

Can be an OSCE skill!
  • Get a chaperone
  • Wash hands
  • Introduce to patient – explain what you are going to do, get consent etc.
  • Get hands + gloves
  • Ask the patient if they are having any pain anywhere
  • Ask them to stand up and expose themselves
  • Cough – whether you can see a bulge or not, ask them t cough. You might then see one even if you couldn’t see it to begin with.
  • Feel – if you can see a bulge, put your hand on it, and get them to cough. You should feel it bulge when they cough.
  • Still not felt anything? – then you should you feel around a bit! Remember where the deep inguinal ring is – ½ way along the inguinal ligament – just above it. Just below the inguinal ligament in this place is the femoral pulse. Identify the pubic tubercle to help you identify what type of hernia (direct, indirect, femoral). You might also want to check the scrotum for inguinal scrotal hernia.
  • Try reducing the hernia – along with the info you have got from the site of the hernia, this should help you tell what type it is.
  • Wash your hands and report your findings!
Other bits of info:
  • Lymph nodes of greater than 1cm in this region are pathological and should not be ignored


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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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