By far the most common hernias (up to 75% of all abdominal hernias) are the so-called inguinal hernias. Inguinal hernias are further divided into the more common indirect inguinal hernia , in which the inguinal canal is entered via a congenital weakness at its entrance (the internal inguinal ring), and the direct inguinal hernia type, where the hernia contents push through a weak spot in the back wall of the inguinal canal. Inguinal hernias are the most common type of hernia in both men and women. In some selected cases, they may require surgery.
Femoral hernias occur just below the inguinal ligament, when abdominal contents pass into the weak area at the posterior wall of the femoral canal. They can be hard to distinguish from the inguinal type (especially when ascending cephalad): however, they generally appear more rounded, and, in contrast to inguinal hernias, there is a strong female preponderance in femoral hernias. The incidence of strangulation in femoral hernias is high. Repair techniques are similar for femoral and inguinal hernia.
They involve protrusion of intrabdominal contents through a weakness at the site of passage of the umbilical cord through the abdominal wall. Umbilical hernias in adults are largely acquired, and are more frequent in obese or pregnant women. Abnormal decussation of fibers at the linea alba may contribute.
An incisional hernia occurs when the defect is the result of an incompletely healed surgical wound. When these occur in median laparotomy incisions in the linea alba, they are termed ventral hernias. These can be the most frustrating and difficult to treat, as the repair utilizes already attenuated tissue.
Higher in the abdomen, an (internal) “diaphragmatic hernia” results when part of the stomach or intestine protrudes into the chest cavity through a defect. A hiatus hernia is a particular variant of this type, in which the normal passageway through which the esophagus meets the stomach (esophageal hiatus) serves as a functional “defect”, allowing part of the stomach to (periodically) “herniate” into the chest. Hiatus hernias may be either “sliding”, in which the gastroesophageal junction itself slides through the defect into the chest, or non-sliding (also known as para-esophageal), in which case the junction remains fixed while another portion of the stomach moves up through the defect. Non-sliding or para-esophageal hernias can be dangerous as they may allow the stomach to rotate and obstruct. Repair is usually advised. A congenital diaphragmatic hernia is a distinct problem, occurring in up to 1 in 2000 births, and requiring pediatric surgery. Intestinal organs may herniate through several parts of the diaphragm, posterolateral (in Bochdalek’s triangle, resulting in Bochdalek’s hernia), or anteromedial-retrosternal (in the cleft of Larrey/Morgagni’s foramen, resulting in Morgagni-Larrey hernia, or Morgagni’s hernia).
Since many organs or parts of organs can herniate through many orifices, it is very difficult to give an exhaustive list of hernias, with all synonyms and eponyms. The above article deals mostly with “visceral hernias”, where the herniating tissue arises within the abdominal cavity. Other hernia types and unusual types of visceral hernias are listed below, in alphabetical order:
- Amyand’s hernia: containing the appendix vermiformis within the hernia sac
- Cooper’s hernia: a femoral hernia with two sacs, the first being in the femoral canal, and the second passing through a defect in the superficial fascia and appearing almost immediately beneath the skin.
- Brain herniation, sometimes referred to as brain hernia, is a potentially deadly side effect of very high intracranial pressure that occurs when a part of the brain is squeezed across structures within the skull.
- Epigastric hernia: a hernia through the linea alba above the umbilicus.
- Hiatus hernia: a hernia due to “short oesophagus” — insufficient elongation — stomach is displaced into the thorax
- Littre’s hernia: a hernia involving a Meckel’s diverticulum. It is named after the French anatomist Alexis Littré (1658–1726).
- Lumbar hernia: a hernia in the lumbar region (not to be confused with a lumbar disc hernia), contains the following entities:
- Petit’s hernia: a hernia through Petit’s triangle (inferior lumbar triangle). It is named after French surgeon Jean Louis Petit (1674–1750).
- Grynfeltt’s hernia: a hernia through Grynfeltt-Lesshaft triangle (superior lumbar triangle). It is named after physician Joseph Grynfeltt (1840–1913).
- Maydl’s hernia: two adjacent loops of small intestine are within a hernial sac with a tight neck. The intervening portion of bowel within the abdomen is deprived of its blood supply and eventually becomes necrotic.
- Morgagni hernia: a type of hernia where abdominal contents pass into the thorax through a weakness in the diaphragm
- Obturator hernia: hernia through obturator canal
- Pantaloon hernia (Saddle Bag hernia): a combined direct and indirect hernia, when the hernial sac protrudes on either side of the inferior epigastric vessels
- Patient with a colostomy complicated by a large parastomal hernia.
- Parastomal hernias, which is when tissue protrudes adjacent to a stoma tract.
- Paraumbilical hernia: a type of umbilical hernia occurring in adults
- Perineal hernia: a perineal hernia protrudes through the muscles and fascia of the perineal floor. It may be primary but usually is acquired following perineal prostatectomy, abdominoperineal resection of the rectum, or pelvic exenteration.
- Properitoneal hernia: rare hernia located directly above the peritoneum, for example, when part of an inguinal hernia projects from the deep inguinal ring to the preperitoneal space.
- Richter’s hernia: a hernia involving only one sidewall of the bowel, which can result in bowel strangulation leading to perforation through ischaemia without causing bowel obstruction or any of its warning signs. It is named after German surgeon August Gottlieb Richter (1742–1812).
- Sliding hernia: occurs when an organ drags along part of the peritoneum, or, in other words, the organ is part of the hernia sac. The colon and the urinary bladder are often involved. The term also frequently refers to sliding hernias of the stomach.
- Sciatic hernia: this hernia in the greater sciatic foramen most commonly presents as an uncomfortable mass in the gluteal area. Bowel obstruction may also occur. This type of hernia is only a rare cause of sciatic neuralgia.
- Spigelian hernia, also known as spontaneous lateral ventral hernia
- Sports hernia: a hernia characterized by chronic groin pain in athletes and a dilated superficial inguinal ring.
- Volpeau hernia: a hernia in the groin in front of the femoral blood vessels
Surgery is recommended for some types of hernias to prevent complications like obstruction of the bowel or strangulation of the tissue, although umbilical hernias and hiatus hernias may be watched, or are treated with medication. Most abdominal hernias can be surgically repaired, but surgery has complications. Time needed for recovery after treatment is reduced if hernias are operated on laparoscopically. However, open surgery can be done sometimes without general anesthesia. Uncomplicated hernias are principally repaired by pushing back, or “reducing”, the herniated tissue, and then mending the weakness in muscle tissue (an operation called herniorrhaphy). If complications have occurred, the surgeon will check the viability of the herniated organ and remove part of it if necessary. Muscle reinforcement techniques often involve synthetic materials (a mesh prosthesis). The mesh is placed either over the defect (anterior repair) or under the defect (posterior repair). At times staples are used to keep the mesh in place. These mesh repair methods are often called “tension free” repairs because, unlike some suture methods (e.g., Shouldice), muscle is not pulled together under tension. However, this widely used terminology is misleading, as there are many tension-free suture methods that do not use mesh (e.g., Desarda; Guarnieri, Lipton-Estrin, etc.).
Evidence suggests that tension-free methods (with or without mesh) often have lower percentage of recurrences and the fastest recovery period compared to tension suture methods. However, among other possible complications, prosthetic mesh usage seems to have a higher incidence of chronic pain and, sometimes, infection. The frequency of surgical correction ranges from 10 per 100,000 (U.K.) to 28 per 100,000 (U.S.).
Many people are managed through day surgery centers, and are able to return to work within a week or two, while intense activities are prohibited for a longer period. People who have their hernias repaired with mesh often recover in a number of days, though pain can last longer. Surgical complications include pain that lasts more than three months, surgical site infections, nerve and blood vessel injuries, injury to nearby organs, and hernia recurrence. Pain that lasts more than three months occurs in about 10% of people following hernia repair.