Definition and classification of hernias

Anatomy of a hernia protrusion

Every true abdominal hernia has a strict anatomical structure and consists of three mandatory components:

1. Hernia ring — a weak spot in the abdominal wall (a natural canal or a newly formed opening) through which the hernia extends beyond its normal location.
2. Hernia sac — a protrusion of the parietal layer of the peritoneum. In surgical anatomy, the sac is usually divided into three parts:
3. Neck — the narrowest part, located directly within the hernia ring.
4. Body — the middle, expanded part.
5. Fundus — the most remote (distal) part of the sac.
6. Hernia contents — internal organs that have protruded into the hernia sac. Most commonly, the greater omentum and small intestine loops are found in the hernia.

Classification of hernias by localization and course

Depending on their relation to anatomical cavities, all hernias are divided into two major groups:

• External hernias (herniae abdominales externae). The contents protrude beyond the abdominal cavity. This is the most common variant of the pathology. External hernias include inguinal (direct and indirect), femoral, umbilical, white line of the abdomen (epigastric), Spigelian (semilunar) line, lumbar, obturator, and incisional hernias.
• Internal hernias (herniae abdominales internae). In this case, organs herniate into peritoneal pockets or orifices located within the abdominal cavity. These include hernia of the duodenojejunal recess (hernia recessus duodenojejunalis), hernia of the omental bursa (hernia bursae omentalis), retrocecal hernia (hernia retrocaecalis), and diaphragmatic hernias. They are extremely difficult to diagnose preoperatively, and therefore most commonly discovered intraoperatively during the treatment of acute intestinal obstruction.

By clinical signs, the following are distinguished:

• Reducible (herniae reponibilis) — the contents are freely and easily reducible back into place.
• Irreducible (herniae irreponibilis) — the contents cannot be reduced due to formed adhesions with the hernia sac. At the same time, there are no signs of intestinal obstruction.
• Incarcerated (herniae incarceratae) — a dangerous complication with acute compression of organs in the hernia ring.

By etiology, hernias can be congenital, acquired, incisional, recurrent, and traumatic.

Pathogenesis of incarceration and its special forms

Incarceration develops due to compression of the contents in the narrow hernia ring. This leads to circulatory disorders: venous stasis and edema occur, making reduction impossible. Phenomena of acute intestinal obstruction develop. Hemorrhagic effusion ("hernia water") accumulates in the closed cavity of the hernia sac and becomes infected. The final stage of the process is pronounced intoxication and necrosis of the incarcerated organs.

In surgery, several specific variants of incarceration are distinguished:

• Parietal (Richter's) incarceration. Not the entire intestinal loop is trapped in the hernia ring, but only a part of the intestinal wall (usually its antimesenteric border). The danger is that the intestinal lumen may remain partially patent, smoothing out the symptoms of obstruction. Often occurs with narrow rings (umbilical, femoral, epigastric hernias).
• Retrograde (W-shaped) incarceration. Two loops of the intestine enter the hernia sac, while the loop connecting them remains in the abdominal cavity. It is this "internal" loop that undergoes the greatest ischemia and becomes necrotic due to compression of the common mesentery, while the loops in the sac itself remain viable.
• Sliding hernia. A unique form in which one of the walls of the hernia sac is formed by a hollow organ located mesoperitoneally (not completely covered by visceral peritoneum). Most commonly this is the cecum or urinary bladder. When such an organ fills, the hernia can spontaneously "slip" back into the abdominal cavity.

Principles of surgical treatment

Surgery for a hernia pursues two main goals: elimination of the hernia protrusion itself and reliable plastic reinforcement of the weak spot of the abdominal wall (the hernia ring).

There are various types of hernioplasty, the choice of which depends on the anatomical localization and size of the defect:

• Aponeurotic.
• Musculo-aponeurotic.
• Musculo-fascial.

Basic stages of surgery:

1. Layer-by-layer dissection of tissues over the hernia protrusion.
2. Careful dissection of the hernia ring.
3. Isolation of the hernia sac from surrounding soft tissues.
4. Opening of the sac and inspection of its contents (assessment of organ viability).
5. Reduction of organs, ligation, and transection of the hernia sac at its very neck.
6. Plastic closure of the hernia ring according to the chosen technique.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Mechanisms of development and pathophysiology of strangulated intestinal obstruction.
• Anatomical features of narrow hernia rings: the umbilical ring, femoral canal, and linea alba.
• Specifics of surgical approaches and content inspection when intestinal necrosis is suspected.
• Topography of intraperitoneal recesses (duodenojejunal, lesser sac, retrocecal space).
• Comparative characteristics of musculo-aponeurotic and musculo-fascial hernioplasty of the hernia ring.

Other topics in the section «Surgery for Abdominal Wall Hernias»

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