A hernia involves the abnormal exit of tissue or an organ through a weak spot or defect in the surrounding muscle or fascia, allowing an internal structure, such as intestine or fatty tissue, to push through. While most hernias develop in the groin or central abdomen, they can occur in the side. Hernias that develop in the lateral abdominal wall are generally referred to as flank hernias, and they are considerably less common than inguinal or umbilical hernias. This area spans the space between the lower ribs and the hip bone, representing the posterolateral abdominal wall.
Understanding Hernias of the Flank and Side
The term “side hernia” primarily encompasses two rare types of abdominal wall defects: Lumbar hernias and Spigelian hernias. Lumbar hernias occur in the posterolateral abdominal wall, developing through weakened areas within the muscle and fascia layers of the flank.
Lumbar hernias are sub-classified based on their anatomical location, often protruding through the superior or inferior lumbar triangles. The superior lumbar triangle (Grynfeltt-Lesshaft’s triangle) is located beneath the twelfth rib. The inferior lumbar triangle (Petit’s triangle) is found lower in the flank area above the hip bone.
The Spigelian hernia is the second type, occurring more anteriorly along the side of the abdomen. This defect appears in the Spigelian fascia, a fibrous layer situated between the rectus abdominis muscle and the more lateral abdominal muscles. Because the protruding sac travels through layers of muscle, a Spigelian hernia can be difficult to detect during a physical examination.
Specific Causes of Side Hernia Development
The formation of a side hernia results from underlying structural weakness combined with forces that increase pressure within the abdomen. A significant cause is the development of an incisional hernia following prior surgery in the flank or back region. Procedures like kidney surgery require incisions through the lateral abdominal wall, and if the tissue does not heal with original strength, a weakness remains.
Traumatic injury to the side is another primary trigger, as blunt force can tear or compromise the integrity of the abdominal wall musculature. Falls, severe impact injuries, or motor vehicle accidents can create an immediate defect. In some cases, the weakness is congenital, meaning the structural defect was present from birth.
Factors that repeatedly raise internal abdominal pressure act as secondary contributors, pushing contents through the weak spot. Chronic coughing, straining, or consistently lifting heavy objects can exacerbate the defect over time. These activities accelerate the process in someone with an anatomical predisposition or a prior surgical scar.
Identifying the Symptoms of a Side Hernia
The most common sign is a visible or palpable bulge on the side or back, situated between the rib cage and the hip bone. This lump becomes more prominent when the patient is standing, coughing, or straining, actions that increase abdominal pressure. Conversely, the bulge may disappear when the person lies down and the internal pressure decreases.
Pain is generally described as a dull ache, heaviness, or a persistent dragging sensation localized to the flank area. This discomfort often worsens with physical activity. Spigelian hernias can present with pain without a visible bulge because the protrusion is contained beneath dense muscle layers.
A sudden, sharp increase in pain signals a medical emergency, known as incarceration or strangulation. Incarceration occurs when the protruding tissue becomes trapped. Strangulation is more serious, indicating the blood supply to the trapped tissue has been cut off, leading to severe pain, nausea, vomiting, or fever.
Diagnosis and Treatment Options
Diagnosis typically begins with a physical examination, where a physician tries to feel the defect and observe the bulge while the patient strains. Due to the deep anatomical location of many flank and Spigelian hernias, imaging is often required. An ultrasound scan is a common first step, using sound waves to visualize the defect and the protruding tissue.
If the diagnosis is unclear or the hernia is complex, a Computed Tomography (CT) scan provides a detailed view of the abdominal wall layers. This technique is useful for mapping the defect’s size and location, which is necessary for planning surgical repair. Side hernias do not resolve on their own, and surgery is the standard treatment to prevent complications like strangulation.
Surgical repair focuses on returning the protruding tissue to the abdominal cavity and closing the defect. Surgeons may use an open approach (a single incision) or a minimally invasive laparoscopic technique. Mesh reinforcement is routinely used to strengthen the weakened area and reduce the risk of recurrence.