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Inguinal hernia
Classification & external resources

Diagram of an indirect, scrotal inguinal hernia ( median view from the left).
ICD-10	K40.
ICD-9	550
DiseasesDB	6806
MedlinePlus	000960
eMedicine	med/2703  emerg/251 ped/2559
MeSH	C06.405.293.249.437

Inguinal hernias are protrusions of abdominal cavity contents through an area of the abdominal wall commonly referred to as the groin, and known in anatomic language as the inguinal area or the myopectineal orifice. They are very common and their repair is one of the most frequently performed surgical operations. There are two types of inguinal hernia, direct and indirect.

Femoral hernias occur within the same "myopectineal orifice," but are usually classed as separate from the "inguinal" hernias.

Contents 1 Origin 2 Clinical presentation 3 Diagnosis 4 Surgical treatment 5 Subtypes of inguinal hernias 6 Theories of hernia formation 7 Additional images

Inguinal hernias usually arise as a consequence of the descent of the testes from the abdomen into the scrotum during early fetal life. They are more commonly seen in men due to larger size of their inguinal canal, which transmitted the testicle and accommodates the structures of the spermatic cord. Men are 25 times more likely to have a groin hernia than women, but since this is such a common problem in the general population (it is estimated that 5% of the population will develop an abdominal wall hernia), inguinal hernia is not extremely uncommon in women. Direct hernias however are very uncommon in women.

Hernias present as bulges in the groin area that can become more prominent when coughing, straining, or standing up. They are often painful, and the bulge commonly disappears on lying down. The inability to "reduce" the bulge back into the abdomen usually means the hernia is "incarcerated," often necessitating emergency surgery.

As the hernia progresses, contents of the abdominal cavity, such as the intestines, can descend into the hernia and run the risk of being pinched within the hernia, causing an intestinal obstruction. If the blood supply of the portion of the intestine caught in the hernia is compromised, the hernia is deemed "strangulated," and gut ischemia and gangrene can result, with potentially fatal consequences. The timing of complications is not predictable; some hernias remain static for years, others progress rapidly from the time of onset. Recent data questions the routine elective repair of all inguinal hernias. Some studies indicate that inguinal hernias can be left alone with no greater risk than prompt elective treatment. Nevertheless, the bias remains toward surgical repair. Provided there are no serious co-existing medical problems, patients are advised to get the hernia repaired surgically at the earliest convenience after a diagnosis is made. Emergency surgery for complications such as incarceration and strangulation carry much higher risk than planned, "elective" procedures.

The diagnosis of inguinal hernia rests on the history given by the patient and the physician's examination of the groin. Further tests are rarely needed to confirm the diagnosis. However, in unclear cases an ultrasound scan or a CT scan might be of help, especially to rule out a hydrocele.

See main article at herniorrhaphy.

Surgical correction of inguinal hernias, called a herniorrhaphy or hernioplasty, is now often performed as an ambulatory, or "day surgery," procedure.

Type	Description	Relationship to inferior epigastric vessels	Covered by internal spermatic fascia?	Usual onset
indirect inguinal hernia	protrudes through the inguinal ring and is ultimately the result of the failure of embryonic closure of the internal inguinal ring after the testicle passes through it	Lateral	Yes	Congenital
direct inguinal hernia	enters through a weak point in the fascia of the abdominal wall	Medial	No	Adult

A third type of groin hernia (though technically not an inguinal hernia), the "femoral hernia," exits not via the inguinal canal, but via the femoral canal, which normally allows passage of the common femoral artery and vein from the pelvis to the leg.

It was previously thought that hernias arose as the result of abnormal stress on the abdominal wall; this theory persists in the belief that hernias are caused by coughing too much or lifting heavy objects.

Most researchers still point to a patent processus vaginalis or a failure of the abdominal wall "shutter" (an involuntary movement of the abdominal muscles that closes off the inguinal canal during increased intra-abdominal pressure) as the root cause of indirect hernias. In either case, abdominal contents may herniate through the open inguinal canal.

Current research indicates that patients with direct inguinal hernias are heavily predisposed to herniate elsewhere, and that both direct and indirect hernias tend to run in families. As a result of these and other findings, a few researchers now believe that all direct hernias and many indirect hernias are a symptom of a congenital deficiency of collagen, the major structural fiber in connective tissue. Lack of collagen, according to this theory, results in weakened, attenuated connective tissue that cannot withstand the stresses of normal activity, and hence a hernia forms at the area of greatest weakness - which, in most individuals, lies within the myopectineal orifice. However, as the collagen problem extends to tissues throughout the body under this theory, these patients may also suffer from an increased risk of ventral or incisional hernia.

Different types of inguinal hernias.