A white line hernia is an extra-abdominal hernia that occurs in the midline of the abdominal wall (i.e., the white line). White line hernias are common in the upper abdomen (between the umbilicus and the glabellar process), so they are also known as epigastric hernias. (1) The white line of the abdomen extends from the saber process to the pubic symphysis, and the white line is thin and wide above the umbilicus, while narrow and thick below the umbilicus, and even the rectus abdominis muscle on both sides of the umbilicus is fused, making it difficult to distinguish the white line. (2) The influence of the dense fibrous ring of the umbilicus, the white line tear is difficult to break through the umbilicus.
The white line of the abdomen is formed by the fusion of the anterior and posterior sheaths of the rectus abdominis muscles on both sides, and the sheath fibers on both sides of the fusion are interlaced to form a mesh, and the larger mesh becomes a weak point on the white line, which can easily lead to hernia, and about 20% of patients have multiple fascial defects, i.e. multiple white line hernias. The incidence of white line hernia is about 0.5% to 3.0% in the population, more common in men than in women, with a male to female incidence of about 3:1, and more common in the age group of 20-50 years.
Etiology
White line hernia is rare in infants and children and is a congenital condition. The occurrence of congenital white-line hernia may be related to incomplete fusion of the white lines of the abdominal wall, and the site of hernia is the same as the common site of onset of white-line hernia in adults.
In adults, white line hernia is an acquired disorder associated with excessive stretching of the anterior abdominal wall tendon membrane. When the abdomen expands, the white line must be elongated and widened at the same time, resulting in fiber tearing or stretching to increase the fiber gap, thus forming a white line hernia. Long-term physical labor, trauma, pregnancy, obesity, and large amounts of ascites can all be causes of white line hernia. When the diaphragm and epigastrium contract at the same time in an uncoordinated and powerful manner, such as when coughing or holding one’s breath, the force generated by pulling the diaphragm upward and pulling the tendon-like cross laterally is greatest at the midpoint between the glabella and umbilicus, so this is the most common site for white line hernia.
Pathogenesis
A white line hernia is first protruded from the interstitial space by extraperitoneal fat. Therefore, in the early stage, the contents of a white line hernia are fatty tissue and there is no hernia sac. As the disease progresses, the protruding extraperitoneal fat may pull the peritoneum outward to form a hernia sac, creating conditions for the viscera (mainly the greater omentum) to protrude, and the greater omentum can easily adhere to the hernia sac and become a difficult hernia. As the disease progresses, the hernia sac gradually increases in size and herniated contents increase, and some organs such as small intestine and stomach may also enter the sac, resulting in gastrointestinal symptoms and even intussusception.
Clinical manifestations
According to the process of white line hernia, it can be divided into two types: without hernia sac and with hernia sac. The majority of white line hernias (up to 75% ) can be asymptomatic and only a subcutaneous mass is found at the midline of the abdomen (white line) during abdominal examination. The mass will protrude significantly outward toward the abdominal wall when the intra-abdominal pressure increases, and the diagnosis can be confirmed by the presence of a small hole (hernia hole) palpable in the white line area after retraction. During the examination, the patient is asked to perform a small supine movement and the mass can be seen protruding from the white line. Holding the mass with the thumb and index finger and pulling it outward often induces pain, which is a characteristic sign of white line hernia. About 25% of patients have a midline epigastric mass along with various upper gastrointestinal symptoms, including dull, burning, or spasmodic pain in the epigastrium, sometimes radiating to the lower abdomen, back, or chest; occasionally accompanied by bloating, dyspepsia, nausea, and vomiting. It is often worse on standing after a full meal. The typical pain is epigastric pain on exertion, which is due to reflex pyloric spasm caused by pulling of the abdominal wall or viscera by the contents of the white line hernia. Because of the low incidence of the disease and the small size of the herniated mass, it is often missed or misdiagnosed as a gastrointestinal disease (e.g. biliary tract disease, ulcer disease, chronic pancreatitis, etc.) and also often misdiagnosed as an abdominal mass (e.g. lipoma, sebaceous adenoma, subcutaneous fibroma, etc.), with a misdiagnosis rate of 30% to 54%.
Diagnosis
The diagnosis can generally be confirmed based on typical symptoms and signs. Patients with obesity, signs that are not obvious or difficult to reopen hernias should also undergo abdominal imaging examinations: ultrasound, CT, and other examinations. Ultrasonography is not only inexpensive, convenient and reproducible, but also the first choice for the diagnosis of white line hernia. Three-dimensional CT and MRI examinations can not only accurately measure the size of the hernia defect, but also visualize the hernia image and detect missed hidden hernias or multiple hernias.
Treatment
Preschool white line hernia: the treatment principle is basically the same as that of umbilical hernia, and surgery is usually not considered within 5 years of age.
Adult white line hernia: The treatment of small white line hernia is also basically the same as that of umbilical hernia, and the treatment of large white line hernia is the same as that of incisional hernia of the abdominal wall. However, surgical repair of both large and small hernias is the only means of permanently curing a white line hernia.
Conservative treatment: A hernia belt or a hernia brace is used as a pocket and temporary relief of symptoms, but there is no possibility of cure.
Surgical treatment: Although white line hernia rarely occurs as intussusception or strangulation, 10% of patients still have difficulty in recurrence, causing discomfort and even risk of intussusception or strangulation, so patients with symptomatic white line hernia larger than 0.5 cm in diameter, larger white line hernia or white line hernia with difficulty in recurrence, intussusception or strangulation should be treated surgically.
The following procedures are commonly used for white line hernia
1.Open tension-free repair: The anterior and posterior sheaths of the rectus abdominis muscle around the defect are fully freed, and synthetic material is inserted so that the edges are larger than the surrounding defect by at least 2 cm, and then fully expanded and fixed. The advantages of this repair method include simplicity, shortened operative time, shorter hospital stay, reduced postoperative complications, and a recurrence rate of less than 1%. It is particularly suitable for older patients with large defects and multiple chronic diseases. Disadvantages: It is necessary to free a wide range of tissues around the hernia ring, and postoperative incisional complications such as painful incision, fluid accumulation, and even secondary infection are likely to occur.
2.Laparoscopic tension-free repair: laparoscopic technique is applied to establish a pneumoperitoneum and then place laparoscopic instruments far from the defective area, separate and then place artificial materials for repair. Advantages of this repair method: the incision is chosen far from the weak area of the white line, which interferes less with the normal cross tendon structure of the white line and can effectively reduce various incision-related complications; the patch is fixed in the natural state and the patch matches the abdominal wall completely, realizing a true tension-free repair; hidden white line hernias can be detected, avoiding the possibility of secondary surgery; fast postoperative recovery and small wound. Disadvantages: professional lumpectomy equipment is required, surgery under general anesthesia, and more costly surgery.
3.Traditional open simple repair: For white line hernia with small defect, simple interrupted transverse suture is feasible; for larger defect, transverse overlapping repair is feasible. This method is more traumatic, with serious damage to local blood flow and greater tension, which can easily lead to repair failure and a postoperative recurrence rate of about 11%-20%.