Overview
A hernia is defined as the protrusion of an organ or its fascia through the wall of the cavity it normally belongs in. This occurs due to weakness in the muscle or tissue wall. Hernias commonly affect the abdomen and groin.
Definitions
Reducible – when the herniated tissue can be pushed back into its place through the defect and stays there. If this does not occur, then the hernia is irreducible or incarcerated.
Incarcerated – when a hernia is irreducible, meaning it does not stay in place when attempting to push it back through the defect.
- Incarcerated hernias are typically painless, but can have dull pain in some people. They are at an increased risk of strangulation.
Strangulated – a surgical emergency when the contents of an incarcerated hernia become twisted or entrapped by a narrow opening, resulting in compromised blood flow, which can lead to ischaemia and infarction.
- Strangulated hernias are painful, tender, and the hernia may turn red, purple or dark in colour. If bowel contents are present in the hernia, this can lead to bowel obstruction.
Abdominal Hernias
Inguinal hernia
Inguinal hernias are the most common type of abdominal hernia, making up 75% of cases. Around 90% of people affected are men. They are found above and medial to the pubic tubercle. Strangulation is relatively rare. See Inguinal Hernia for more.
Femoral hernia
Femoral hernias make up around 5% of abdominal hernias and are more common in women than in men, especially older women (around >65 years old) and multiparous women. They are found below and lateral to the pubic tubercle and are at high risk of strangulation. See Femoral Hernia for more.
Umbilical hernia
Umbilical hernias are found at the site of the umbilicus. They can be divided into:
- Congenital hernias (omphalocele)
- Infantile hernia – usually spontaneously resolves by 3 years of age
- Adult umbilical hernia – associated with causes that increase intra-abdominal pressure such as obesity, multiparity, and ascites
Obturator hernia
Obturator hernias are rare hernias of the pelvic floor that protrude through the obturator foramen. They are more common in older women (>60 years old), especially if they are thin, and multiparous women.
Obturator hernias often present with small bowel obstruction and may only be palpable on a pelvic or rectal exam.
Epigastric hernia
Epigastric hernias are located in the upper, central (epigastric) part of the abdomen and are more common in men aged 20-50 years. Other risk factors include excess coughing and excess physical exertion.
They are often seen in the midline above the umbilicus but below the xiphisternum and may appear or disappear with activities that change abdominal pressure (e.g. bowel movements). Patients are often asymptomatic but may have bloating, nausea, and vomiting.
Incisional hernia
Incisional hernias occur due to the failure of a surgical wound to heal completely and may affect up to 12% of abdominal operations. They are more common after open surgery but also can occur after laparoscopy. A key risk factor is obesity.
They require urgent repair with reinforcing mesh.
Spigelian hernia
Also known as a lateral ventral hernia, a Spigelian hernia is a hernia through the linea semilunaris muscle. They are rare and most commonly seen in women and people >60 years old.
This can present with pain that is worse with training and coughing. Straining may cause a bulge in the lower abdomen.
Richter’s hernia
Richter’s hernia is a rare hernia when the antimesenteric (opposite the mesenteric attachment) wall of the bowel herniates through a defect in the abdominal fascia. It is more common in older patients (>60 years old) but can occur at any age.
This can present with bowel strangulation and ischaemia, without the features of bowel obstruction present.
Diaphragmatic Hernia
Hiatus hernia
A hiatus hernia describes the herniation of the stomach through the diaphragm into the chest cavity. This may result in features of gastro-oesophageal reflux (dyspepsia), dysphagia, and chest pain. Its main risk factors are obesity and causes of increased intra-abdominal pressure (e.g. pregnancy, ascites etc.).
See Hiatus Hernia for more.
Congenital diaphragmatic hernia
Congenital diaphragmatic hernia (CDH) is a life-threatening congenital malformation that occurs due to the failure of the diaphragm to fuse properly. This leads to the herniation of the abdomen’s contents into the chest, impairing lung formation which can lead to pulmonary hypertension and pulmonary hypoplasia, resulting in severe respiratory distress.See Congenital Diaphragmatic Hernia for more.
