I. Definition
An inguinal hernia is an extra-abdominal hernia that occurs in the inguinal region, where a hernial sac structure protruding toward the body surface is present and intra-abdominal organs or tissues can enter the sac through a congenital or acquired abdominal wall defect. A typical inguinal hernia has a hernia ring, hernia sac, hernia contents and hernia cover. According to the anatomical concept of “musculo-pubic foramen”, inguinal hernia includes hiatal hernia, straight hernia, femoral hernia and the rare anterior and lateral femoral vascular hernia.
Etiology and pathophysiology of inguinal hernia
1.Etiology
(1) Unclosed sphincter This is a congenital factor for the occurrence of inguinal hernia.
(2) Intra-abdominal pressure changes Intra-abdominal pressure and instantaneous intra-abdominal pressure changes are the driving force for the occurrence of extra-abdominal hernias.
(3) Weakness of the abdominal wall Various causes of weakness of the abdominal wall due to changes in tissue collagen metabolism and composition, such as changes in tissue collagen composition and atrophy of abdominal wall muscles in the elderly, are associated with the development of inguinal hernia.
(4) Other genetic factors, smoking, obesity, and low incision in the lower abdomen may be related to the occurrence of hernia.
2.Pathophysiology
When organs or tissues in the abdominal cavity enter the hernia sac, the presence of the hernia ring can compress the hernia contents and form an incarcerated hernia. If it is intestinal, it can cause mechanical obstruction of the intestine and produce a series of clinical manifestations and pathophysiological changes. With the prolongation of the compression time, edema, exudation and blood flow disorders of the intestine may occur, which may lead to necrosis and perforation of the hernia contents, serious peritonitis and even endanger the patient’s life if not treated in time.
Classification and typing of inguinal hernia
The purpose of classification and typing of hernia is to accurately describe the condition, select the appropriate treatment and compare and evaluate the effect of various treatment methods.
1.Classification
(1) Classification according to the anatomical site of hernia
Inguinal hernia can be divided into hiatal hernia, straight hernia, femoral hernia, compound hernia, etc. (this is the most common clinical classification).
(1) Hiatal hernia: a hernia that enters the inguinal canal from the internal ring.
(2) Direct hernia: hernias that protrude from the triangle of direct hernia.
(3) Femoral hernia: a hernia that enters the femoral canal through the femoral ring.
(4) Composite hernia: hernia with two or more of the above types.
(5) Perifemoral hernia: A hernia that enters the anterior or lateral aspect of the femoral vessels, which is rare in clinical practice.
(2) Classification according to the condition of hernia contents into the hernia sac
They can be classified as
(1) easily recurring hernia: the hernia often appears during standing activities and can be retracted into the abdominal cavity after lying down at rest or being pushed by hand.
(2) Refractory hernia: the hernia cannot be completely retracted, but there is no organic pathological change in the hernia contents. Sliding hernia is a type of refractory hernia and refers to the abdominal viscera (e.g., cecum, sigmoid colon, bladder, etc.) forming part of the hernia sac.
(3) Incarcerated hernia: the hernia contents are compressed at the hernia ring and cannot be returned, but blood flow disorders have not yet occurred.
(4) Strangulated hernia: a continuation of the course of an incarcerated hernia, the hernia contents become obstructed in blood flow and if not treated in time, serious complications may occur, even life-threatening due to intestinal perforation and peritonitis.
3) Special type of hernia
Because the contents entering the hernia sac are relatively special, they have certain influence on the development and treatment of the disease, including
(1) Richter’s hernia. (1) Richter’s hernia, in which the contents are only part of the intestinal wall and the clinical manifestations may be without complete intestinal obstruction, despite the presence of impaction or strangulation.
(2) Littre’s hernia. The contents of an incarcerated hernia are diverticula of the small intestine (usually Meckel’s diverticula). These hernias are also prone to strangulation.
(3) Maydl hernia. Two or more intestinal collaterals enter the hernia sac and the intervening collaterals remain in the abdominal cavity in the shape of a “W.” The collaterals in the hernia sac may have normal blood flow, but the intra-abdominal collaterals may be necrotic and require a complete examination.
(4) Amyand’s hernia. The content of the hernia is the appendix, and the repair is affected by the appendix with infection and abscess.
2.Typing
So far, there are more than 10 types of inguinal hernia typologies at home and abroad, which mainly describe the condition of abdominal wall defects and have anthropogenic factors, and the ones still in use are CHARTS, Nyhus, Bendavid, Stoppa, EHS and the Hernia and Abdominal Wall Surgery Group of the Chinese Medical Association (2003). However, none of them is widely accepted and used, and none of them is supported by sufficient evidence-based medical evidence. At present, the Hernia and Abdominal Wall Surgery Group of the Chinese Medical Association has not reached a complete consensus on the staging of inguinal hernia. Therefore, there is no particular recommendation on which typing method to use.
IV. Diagnosis and differential diagnosis
1. Diagnosis
The diagnosis of a typical inguinal hernia can be determined on the basis of history, symptoms (the presence of a reversible mass in the inguinal region, i.e., it appears on standing and can be retracted or disappears after lying down) and physical examination. When the diagnosis is unclear or difficult, imaging examinations such as B-ultrasound, MRI or CT can be used to assist in the diagnosis. The inguinal hernia can be clearly diagnosed by the reconstruction technique of the hernia sac in imaging.
2.Differential diagnosis
(1) Diseases to be differentiated in the presence of inguinal masses include enlarged lymph nodes, aneurysms, varicose veins (saphenous veins), soft tissue tumors, abscesses, ectopic testes, endometriosis, etc.
(2) Diseases to be identified when there is local pain and discomfort in the inguinal region include adductor tendinitis, pubic osteochondritis, hip osteoarthritis, iliopsoas bursitis, radiation lumbago, endometriosis, etc.
V. Treatment
In adults, inguinal hernia once formed has no possibility of self-healing. Non-surgical methods such as local injection lack both theoretical basis and clinical evidence to support, and surgery is still the only means and method of cure.
1. Treatment principles
(1) Asymptomatic inguinal hernia can be followed up and observed. However, if the hernia is a femoral hernia (with a higher chance of entrapment and strangulation) or if the hernia sac is recently found to be enlarged, surgery should be performed promptly. For those who cannot tolerate surgery due to old age and frailty, conservative treatment with a hernia support can be chosen.
(2) Symptomatic inguinal hernia should be operated at an elective stage.
(3) Incarcerated and strangulated hernia should be operated urgently.
（Evidence-based studies have shown that tension-free hernia repair can reduce postoperative pain, shorten recovery time, and decrease the recurrence rate of hernia. The aseptic principle should be strictly enforced for patch implantation. The use of patches in emergency surgery for incarcerated hernias is still controversial, and the use of patches that cannot be absorbed by the body is not recommended for repair of contaminated surgical wounds.
(5) Surgical treatment of recurrent hernia Avoidance of anatomical ambiguity and increased surgical difficulty caused by previous surgical trauma are priority factors in the surgical treatment of recurrent hernia. If the previous surgery was a conventional open surgery, a posterior approach or laparoscopic surgery is used to repair the recurrent hernia after reoperation. In addition, the experience of the operator is another factor to be considered in the choice of recurrent hernia treatment.
2.Surgical method
According to the principle of surgery and the level of repair, inguinal hernia surgical methods can be divided into the following categories.
(1) Classical suture repair to strengthen the posterior inguinal wall, such as Bassini, Shouldice, etc.
(2) Tension-free hernia repair to strengthen the posterior inguinal wall, such as simple flat patch repair (Lichtenstein, Trabucco, etc.) and mesh plug plus flat patch repair (Rutkow, Millikan, etc.).
(3) Tension-free hernia repair of the anterior peritoneal space, such as Kugel, Gilbert, Stoppa, etc.
4) Laparoscopic inguinal hernia repair.
(1) Transperitoneal extraperitoneal pathway repair (TEP).
(2) Transabdominal preperitoneal repair (TAPP).
(3) Intraperitoneal patch repair (IPOM)
3.Perioperative management
(1) General treatment.
(1) In addition to the routine preoperative examination, it is necessary to understand and check cardiac, pulmonary and renal functions and blood glucose levels in elderly patients before surgery.
(2) Elderly patients with chronic medical diseases should be evaluated for risk before surgery, especially for those with respiratory and circulatory diseases, which should be treated and managed before surgery.
(3) Those with factors causing increased intra-abdominal pressure, such as severe ascites, prostatic hypertrophy, constipation, and chronic cough, should be given aggressive medical management before surgery to obtain symptomatic relief and improvement.
(4) If the hernia defect is huge and the medical condition is unstable, it is advisable to postpone the surgical treatment.
(2) Use of antibiotics
The prophylactic use of antibiotics for routine inguinal hernia surgery is controversial. Evidence suggests that prophylactic antibiotics in high-risk groups may reduce the rate of infection. Risk factors for the presence of infection include advanced age, diabetes, obesity, chronic respiratory infections, multiple recurrent hernias, post-chemotherapy or radiation therapy and other causes that can lead to immunocompromise.
The timing of prophylactic antibiotic application should be started intravenously 30~45min before skin incision.
4.Complications
(1) Early complications include surgical site hematoma and seroma, scrotal hematoma, scrotal effusion, bladder injury, vas deferens injury, urinary retention, early wound pain, incisional infection, etc.
(2) Late complications Including chronic pain, spermatic cord and testicular complications (ischemic orchitis, testicular atrophy, etc.), late deep patch infection, etc.
(3) Recurrence There is still a possibility of recurrence with the various surgical methods currently available for inguinal hernia treatment, with an overall surgical recurrence rate of about 1%-3%. The causes of hernia recurrence can be attributed to both patient’s own factors and surgical operation: improper surgical operation (e.g. patch displacement); patient’s collagen metabolism disorder, chronic metabolic diseases and increased abdominal pressure are all factors contributing to postoperative recurrence.