Spigelian hernia is a very rare hernia of the abdominal wall. It occurs along the lateral edge of the rectus muscle and aponeurosis of the transverse abdominus muscle. Because of its small size, it has a high risk of incarceration.
The symptoms of a spigelian hernia are not specific and may include the following
- Vague lower abdominal pain
- Bulge in the lower abdomen, which may decrease when supine
- Tenderness to touch
- Recurrent pain when stretching or bending
- Nausea, vomiting
- Abdominal distension (indication bowel obstruction)
Spigelian hernias are often difficult to see when very small. Only in a thin person a spigelian hernia can be palpated. Often during the physical exam, it is mistaken for a muscle spasm or localized soft tissue trauma.
Entire Body System
There is no blood work that is specific for diagnosis of a spigelian hernia. However since all spigelian hernias do require surgery, routine workup should include:
- Complete blood count
- Coagulation profile
- Urine analysis
- Chest X-ray
- Abdominal X-ray is done if there is suspicion of bowel obstruction
Ultrasound is now widely used as the first imaging test of choice. The test can scan the abdominal wall and reveal the discontinuity in the Spigelian fascia caused by the hernia orifice at the point of tenderness. However, because the test is very operator dependent, small hernias may be missed. CT scan or MRI is the definitive test to make a diagnosis of a spigelian hernia.
All spigelian hernias need to be repaired. In asymptomatic patients the surgery can be done on an elective basis. In symptomatic patients, the surgery should be done as soon as the diagnosis is made. If there is bowel incarceration or strangulation immediate surgery is required   .
The surgery may be done under general or regional anesthesia. The types of surgical procedures for spigelian hernia include the open approach and laparoscopy. The open technique requires general anesthesia. The laparoscopic procedure results in faster recovery, less need for analgesia and faster discharge from hospital.
The surgical treatment is the same as for any hernia. The hernia sac is identified and excised, the bowel contents are reduced and a mesh is used to repair the defect. Whatever procedure is done most surgeons now use a mesh to prevent tension along the suture lines and prevention of recurrence.
Most patients are discharged home the same day or after an overnight stay in the hospital. The recovery is slow for the first week. Ambulation is encouraged but sports and heavy lifting should be avoided for 6 weeks.
The prognosis for most patients with a spigelian hernia is excellent. Elderly patients with multiple comorbidities may not do well, especially if there is bowel incarceration or strangulation. All spigelian hernias need surgical treatment. If the diagnosis is missed or surgery is delayed, there is a high risk of incarceration. The surgery to repair a spigelian hernia has few complications and most people do not have recurrences.
Spigelian hernia has the same causes as other hernias and that include the following:
- Chronic coughing
- Sporting activities that involve excessive turning or twisting motions  
- Straining during defecation or urination
- Lifting heavy objects
- Injury to the abdomen
- Multiple pregnancies
- Spigelian hernias have also been described in patients who have had abdominal peritoneal dialysis catheter.
Disorders that are often mistaken for a spigelian hernia include:
Less than 50% of spigelian hernias are diagnosed on a physical exam. In many cases, surgeons have frequently discovered spigelian hernia only during surgery.
There are no large data banks on spigelian hernia. It appears that these hernias are not very common and only isolated reports exist. Spigelian hernias can occur in both genders and in all races. Overall spigelian hernias are very are and only account for about 1 out of every 1,000 abdominal wall hernias. Spigelian hernias tend to occur most commonly in individuals between the fourth and seventh decade of life, are related to stretching actions of the abdomen and can be caused by multiple pregnancies, obesity, prior abdominal surgery or scars.
The spigelian hernia frequently occurs at the level of the semicircular line (also known as the arcuate line of Douglas). Just underneath this line of Douglas, the spigelian aponeurosis is a single layer and resistant to herniation. However, at the level of the semicircular line, the fascias of transverse abdominus and the fascia of the oblique muscles divide to form two separate layers. It is at this point that the aponeurosis is the weakest and prone to hernia. Sometimes perforating vessels may also cause weakening of the Spigelian fascia, which allows fat to enter the defect.
Some defects occur below the level of the arcuate line of Douglas and pass through the internal oblique muscles and conjoined tendon of transverse abdominus. These low spigelian hernias are often mistaken for inguinal hernia. Sometimes an umbilical, incision or epigastric hernia may be associated with a spigelian hernia.
In most cases, the hernia sac only contains the greater omentum; however cases have been described which report presence of other organs such as small bowel, stomach, colon, gallbladder, appendix, ovaries, testes and even meckel diverticulum trapped in the hernia  .
Spigelian hernias like all other hernias occur because of increased abdominal pressure or trauma. Thus, the individual should refrain from lifting heavy weights, discontinue sports that require intense abdominal exertion, have benign prostate hypertrophy treated and eat a high fiber diet to prevent constipation. Any action that increases intraabdominal pressure can cause a hernia, so it is essential to prevent unnecessary increases in abdominal pressure.
Spigelian hernia was first described in the mid 1600s. By the late 1700s, the anatomical defect in a spigelian hernia had been shown in autopsy studies. Over the years, it was observed that spigelian hernias, even though small, had a high probability of entrapping bowel. Spigelian hernias may be congenital or acquired. The primary defect occurs in the spigelian fascia, which is the anatomical area along the lateral edge of the rectus muscle and aponeurosis of the transversus abdominus muscle. It is at this point where there is transition of the transversus abdominus muscle to its aponeurotic tendon.
Spigelian hernias generally tend to be very small (< 2-3 cm) and hence bowel obstruction is likely, compared to large umbilical hernias. While most patients only present with abdominal pain, at least 1/5th of patients present with bowel obstruction   .
A spigelian hernia is a hernia that occurs just about the pubis. The hernia usually occurs because of weakness in the supporting tissues and presents with vague abdominal pain and sometimes a small mass. The hernia often feels and hurts like a bruise. A spigelian hernia is not common and it is often not easy to diagnose just by looking. Doctors usually order an ultrasound or CT scan to make the diagnosis. The treatment of all spigelian hernias, whether symptomatic or not, is surgery. The surgery today is done via a scope and most patients can be discharged home the same day. Recovery is fast. There is a very small chance of recurrence if the patient continues to lift heavy weights.
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