Inguinal hernia
An inguinal hernia or groin hernia is a hernia of abdominal cavity contents through the inguinal canal. Symptoms, which may include pain or discomfort, especially with or following coughing, exercise, or bowel movements, are absent in about a third of patients. Symptoms often get worse throughout the day and improve when lying down. A bulging area may occur that becomes larger when bearing down. Inguinal hernias occur more often on the right than the left side. The main concern is strangulation, where the blood supply to part of the intestine is blocked. This usually produces severe pain and tenderness in the area.
Risk factors for the development of a hernia include: smoking, chronic obstructive pulmonary disease, obesity, pregnancy, peritoneal dialysis, collagen vascular disease, and previous open appendectomy, among others. Predisposition to hernias is genetic and they occur more often in certain families. Deleterious mutations causing predisposition to hernias seem to have dominant inheritance. It is unclear if inguinal hernias are associated with heavy lifting. Hernias can often be diagnosed based on signs and symptoms. Occasionally, medical imaging is used to confirm the diagnosis or rule out other possible causes.
Groin hernias that do not cause symptoms in males do not need repair. Repair, however, is generally recommended in females due to the higher rate of femoral hernias, which have more complications. If strangulation occurs, immediate surgery is required. Repair may be done by open surgery or by laparoscopic surgery. Open surgery has the benefit of possibly being done under local anesthesia rather than general anesthesia. Laparoscopic surgery generally has less pain following the procedure.
In 2015, inguinal, femoral, and abdominal hernias affected about 18.5 million people. About 27% of males and 3% of females develop a groin hernia at some time in their life. Groin hernias occur most often before the age of one and after the age of fifty. Globally, inguinal, femoral, and abdominal hernias resulted in 60,000 deaths in 2015 and 55,000 in 1990.
Signs and symptoms
Hernias usually present as bulges in the groin area that can become more prominent when coughing, straining, or standing up. The bulge commonly disappears on lying down. Mild discomfort can develop over time. The inability to "reduce", or place the bulge back into the abdomen, usually means the hernia is 'incarcerated' which requires 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. Significant pain at the hernia site is suggestive of a more severe course, such as incarceration and subsequent ischemia and strangulation. 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.
Pathophysiology
In males, indirect hernias follow the same route as the descending testes, which migrate from the abdomen into the scrotum during the development of the urinary and reproductive organs. The larger size of their inguinal canal, which transmits the testicle and accommodates the structures of the spermatic cord, might be one reason why men are 25 times more likely to have an inguinal hernia than women. Although several mechanisms, such as the strength of the posterior wall of the inguinal canal and shutter mechanisms compensating for raised intra-abdominal pressure, prevent hernia formation in normal individuals, the exact importance of each factor remains under debate. The physiological school of thought thinks that the risk of hernia is due to a physiological difference between patients who develop a hernia and those who do not, namely the presence of aponeurotic extensions from the transversus abdominis aponeurotic arch.Inguinal hernias mostly contain the omentum or a part of the small intestines, however, some unusual contents may be an appendicitis, diverticulitis, colon cancer, urinary bladder, ovaries, and rarely malignant lesions.
Diagnosis
There are two types of inguinal hernia, direct and indirect, which are defined by their relationship to the inferior epigastric vessels. [|Direct inguinal hernias] occur medial to the inferior epigastric vessels when abdominal contents herniate through a weak spot in the fascia of the posterior wall of the inguinal canal, which is formed by the transversalis fascia. [|Indirect inguinal hernias] occur when abdominal contents protrude through the deep inguinal ring, lateral to the inferior epigastric vessels; this may be caused by failure of embryonic closure of the processus vaginalis.In the case of the female, the opening of the superficial inguinal ring is smaller than that of the male. As a result, the possibility for hernias through the inguinal canal in males is much greater because they have a larger opening and therefore a much weaker wall through which the intestines may protrude.
| Type | Description | Relationship to inferior epigastric vessels | Covered by internal spermatic fascia? | Usual onset |
| Direct inguinal hernia | Enters through a weak point in the fascia of the abdominal wall | Medial | No | Adult |
| Indirect inguinal hernia | Protrudes through the inguinal ring and is ultimately the result of the processus vaginalis failing to close after the testicle's passage during the embryonic stage | Lateral | Yes | Congenital / Adult |
Inguinal hernias, in turn, belong to groin hernias, which also includes femoral hernias. A femoral hernia is 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.
In Amyand's hernia, the content of the hernial sac is the appendix.
In Littre's hernia, the content of the hernial sac contains a Meckel's diverticulum.
Clinical classification of hernia is also important, according to which the hernia is classified into
- Reducible hernia: can be pushed back into the abdomen by putting manual pressure on it.
- Irreducible/Incarcerated hernia: cannot be pushed back into the abdomen by applying manual pressure.
- Obstructed hernia: is one in which the lumen of the herniated part of the intestine is obstructed.
- Strangulated hernia: is one in which the blood supply of the hernia contents is cut off, thus leading to ischemia. The lumen of the intestine may be patent or not.
Direct inguinal hernia
A direct inguinal hernia protrudes through a weakened area in the transversalis fascia near the medial inguinal fossa within an anatomic region known as the inguinal or Hesselbach's triangle, an area defined by the edge of the rectus abdominis muscle, the inguinal ligament and the inferior epigastric artery. These hernias are capable of exiting via the superficial inguinal ring and are unable to extend into the scrotum.
When a patient develops a simultaneous direct and indirect hernia on the same side, it is called a pantaloon hernia or saddlebag hernia because it resembles a pair of pants with the epigastric vessels in the crotch, and the defects can be repaired separately or together. Another term for pantaloon hernia is Romberg's hernia.
Since the abdominal walls weaken with age, direct hernias tend to occur in the middle-aged and elderly. This is in contrast to indirect hernias, which can occur at any age, including the young, since their etiology includes a congenital component where the inguinal canal is left more patent. Additional risk factors include chronic constipation, being overweight or obese, chronic cough, family history and prior episodes of direct inguinal hernias.
Indirect inguinal hernia
An indirect inguinal hernia results from the failure of embryonic closure of the deep inguinal ring. In the male, it can occur after the testicle has passed through the deep inguinal ring. It is the most common cause of groin hernia. A double indirect inguinal hernia has two sacs.In the male fetus, the peritoneum gives a coat to the testicle as it passes through this ring, forming a temporary connection called the processus vaginalis. In normal development, the processus is obliterated once the testicle is completely descended. The permanent coat of peritoneum that remains around the testicle is called the tunica vaginalis. The testicle remains connected to its blood vessels and the vas deferens, which make up the spermatic cord and descend through the inguinal canal to the scrotum.
The deep inguinal ring, which is the beginning of the inguinal canal, remains as an opening in the fascia transversalis, which forms the fascial inner wall of the spermatic cord. When the opening is larger than necessary for passage of the spermatic cord, the stage is set for an indirect inguinal hernia. The protrusion of the peritoneum through the internal inguinal ring can be considered an incomplete obliteration of the processus.
In an indirect inguinal hernia, the protrusion passes through the deep inguinal ring and is located lateral to the inferior epigastric artery. Hence, the conjoint tendon is not weakened.
There are three main types
- Bubonocele: In this case, the hernia is limited to the inguinal canal.
- Funicular: here, the processus vaginalis is closed at its lower end just above the epididymis. The content of the hernial sac can be felt separately from the testis, which lies below the hernia.
- Complete : here, the processus vaginalis is patent throughout. The hernial sac is continuous with the tunica vaginalis of the testis. The hernia descends to the bottom of the scrotum, and it is difficult to differentiate the testis from the hernia.