Hernias always contain a portion of peritoneal sac and may contain viscera, usually small bowel and omentum.
- When a hernia can no longer be reduced, it is irreducible or incarcerated.
- This can occur at any time, as can strangulation when visceral contents of hernia become twisted or entrapped by the narrow opening. This compromises the blood supply, causing swelling and eventually infarction.
- Strangulation leads to bowel obstruction.
Abdominal wall hernias are named according to the position of the fault in the abdominal wall. The common types include:
- Femoral hernias
- Inguinal hernias
- Incisional hernias
- Epigastric hernias
- Umbilical hernias
- The defect is seen approximately midline above the umbilicus in the linea alba.
- Prevalence is estimated at 0.5-10%, accounting for between 1.6-3.6% of all abdominal hernias.
- Most common in men between the ages of 20 and 50 years.
- Multiple hernias may be present.
- They are usually asymptomatic but can present with epigastric pain varying from mild to severe and penetrating. It may be accompanied by bloating, nausea and vomiting, often after meals.
- Small hernias may be tender.
- The hernia can be made to bulge by asking the patient to strain.
- Obese patients may need ultrasound or CT scanning to confirm diagnosis.
- They need to be differentiated from a diastasis recti, which is a widening of the linea alba without a defect in the fascia.
- Surgical repair is essential, as there is a high risk that they will incarcerate or strangulate.
- There is a 10-20% risk of recurrence after traditional repair by primary suture; however, this is reduced if polypropylene mesh is used[2, 3].
- Incisional hernia is a risk of any abdominal surgery and is estimated to occur in 12.8% of abdominal operations.
- They more commonly occur following open surgery but do also happen following laparoscopic surgery.
- They are caused essentially by failure of the wound to heal but are probably the result of multiple patient and technical factors.
- Attention to closure technique and suture material can reduce incidence. For example, monofilament sutures may reduce the risk of incisional hernia. However, a Cochrane review of wound closure methods found that further studies were required.
- They require urgent repair with reinforcing mesh used in large hernias. This is required particularly where the patient is obese.
- Recurrence occurs in up to 50% of large hernias and is more common in patients who are very overweight.
- Umbilical hernias comprise 10-30% of all hernias.
- They can be broadly categorised into the following groups:
- Congenital hernia (also called omphalocele) - can be further subdivided into fetal (occurring after eight weeks in utero) and embryonic (occurring before eight weeks in utero and may be associated with herniation of other abdominal cavity organs).
- Infantile hernia - associated with prematurity; it usually spontaneously resolves.
- Adult umbilical hernia - 90% of these are acquired - eg, in women they are associated with multiple pregnancies and difficult labour; however, they are also found in cases of abdominal swelling - eg, ascites and obesity. They result in both high levels of mortality and morbidity.
- Hernia gradually enlarges and may be multi-loculated.
- Sac normally contains omentum ± bowel.
- May present with pain on coughing or straining, or an ache or a dragging sensation if large.
- If <1 cm diameter, nearly always closes without treatment by age 5 years.
- If >1.5 cm or in a child aged >4 years, usually requires repair.
- Hernia is repaired surgically with preservation of the umbilicus, after removing causative factors such as ascites.
Rare hernias in adults
- Spigelian: this is a hernia through the linea semilunaris muscle. Initially this causes localised pain exacerbated by straining and coughing, but the pain may become less localised and more an ache with time. Bulge can often be seen in the lower abdomen with the patient erect and straining. This can be reduced by pressure with a 'gurgling' noise and then the hernia orifice can often be felt. However, the defect may not be palpable or a bulge may be found distant from the site. This needs prompt repair.
- Littre's: the hernia sac contains a Meckel's diverticulum. 50% are inguinal, 20% femoral, and 20% umbilical. The remaining 10% are in miscellaneous locations - eg, ventral incisional hernia.
- Lumbar or dorsal: these nearly always occur in the superior and inferior lumbar triangles. They present with a lump in the side with a heavy, pulling sensation.
- Obturator canal: these occur mainly in elderly women and carry a mortality of up to 40%. They present with symptoms of small bowel obstruction. Usually they are only palpable on pelvic or rectal examination.
- Perineal: these usually occur after perineal surgery and present with asymptomatic swelling.
- Sciatic: these are very rare, with herniation through the greater sciatic foramen with incarceration or strangulation of the bowel.
- Sportsman's: a debilitating condition which presents as chronic groin pain. A tear occurs at the external oblique, which may result in an occult hernia.
- Traumatic: these follow blunt trauma and present with pain, bruising and bulge.
Further reading and references
Ponten JE, Somers KY, Nienhuijs SW; Pathogenesis of the epigastric hernia. Hernia. 2012 Dec16(6):627-33. doi: 10.1007/s10029-012-0964-8. Epub 2012 Jul 24.
Muschaweck U; Umbilical and epigastric hernia repair. Surg Clin North Am. 2003 Oct83(5):1207-21.
Stabilini C, Stella M, Frascio M, et al; Mesh versus direct suture for the repair of umbilical and epigastric hernias. Ten-year experience. Ann Ital Chir. 2009 May-Jun80(3):183-7.
Bosanquet DC, Ansell J, Abdelrahman T, et al; Systematic Review and Meta-Regression of Factors Affecting Midline Incisional Hernia Rates: Analysis of 14,618 Patients. PLoS One. 2015 Sep 2110(9):e0138745. doi: 10.1371/journal.pone.0138745. eCollection 2015.
Le Huu Nho R, Mege D, Ouaissi M, et al; Incidence and prevention of ventral incisional hernia. J Visc Surg. 2012 Oct149(5 Suppl):e3-14. doi: 10.1016/j.jviscsurg.2012.05.004. Epub 2012 Nov 9.
Patel SV, Paskar DD, Nelson RL, et al; Closure methods for laparotomy incisions for preventing incisional hernias and other wound complications. Cochrane Database Syst Rev. 2017 Nov 311:CD005661. doi: 10.1002/14651858.CD005661.pub2.
Anthony T, Bergen PC, Kim LT, et al; Factors affecting recurrence following incisional herniorrhaphy. World J Surg. 2000 Jan24(1):95-100
Mederos R, Lamas JR, Alvarado J, et al; Laparoscopic diagnosis and repair of Spigelian hernia: A case report and literature review. Int J Surg Case Rep. 201731:184-187. doi: 10.1016/j.ijscr.2017.01.043. Epub 2017 Jan 20.
Horkoff MJ, Smyth NG, Hunter JM; A large incarcerated Meckel's diverticulum in an inguinal hernia. Int J Surg Case Rep. 20145(12):899-901. doi: 10.1016/j.ijscr.2014.09.036. Epub 2014 Oct 17.
Paajanen H, Brinck T, Hermunen H, et al; Laparoscopic surgery for chronic groin pain in athletes is more effective than nonoperative treatment: a randomized clinical trial with magnetic resonance imaging of 60 patients with sportsman's hernia (athletic pubalgia). Surgery. 2011 Jul150(1):99-107. doi: 10.1016/j.surg.2011.02.016. Epub 2011 May 5.