Introduction
An Obturator hernia is a rare type in which the contents of the abdomen protrude out, causing a bowel obstruction. The abdominal contents protrude out through the obturator canal, hence the name. Hernia means when the intestinal contents push out through a weak spot in the body. Hernia can be femoral, inguinal, umbilical, or hiatal, depending on the protrusion point. Despite the progression of diagnostic imaging modalities, an obturator hernia is difficult to diagnose due to the delayed onset of signs and symptoms. Because of this delay in diagnosis, the prognosis of the hernia is poor, even after corrective surgery.
How Does Obturator Hernia Occur?
When the abdominal contents protrude through the obturator foramen in the pelvis, this condition is called an obturator hernia. Due to the presence of many structures, it is not easy to be palpated or detect.
What Are the Clinical Features of Obturator Hernia?
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Obturator hernia is an extremely rare condition. It accounts for 1 % of all hernias.
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It is usually observed in thin, older women. It is seen in women between the ages of 70 to 90 years. It is nine times more common in women when compared to men. This is due to the anatomical factor of women having a wider pelvis and more triangular obturator canal. This increases the risk of hernia in women.
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Intestinal obstruction is associated with obturator hernia in 90 % of the cases. An obturator hernia has been observed in 0.2 to 1.6 % of patients with mechanical obstruction of the small bowel.
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The cardinal features seen in the obturator hernia are intestinal obstruction, Howship Romberg's sign, and palpable mass on the inner aspect of the thigh.
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The signs and symptoms of the disorder are often delayed and non-specific, which hinders the early detection of the disease.
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Howship-Romberg's sign:
One of the striking features of this condition is the Howship-Romberg sign. This is the pain in the inner aspect of the thigh. It is believed that the close relationship between the obturator nerve and the hernia is the cause of this pain. This neuralgia (nerve pain) is relieved by flexion of the hip; it is worsened by medial rotation of the hip, adduction, and extension.
What Are the Risk Factors for Obturator Hernia?
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Although it is a rare condition, it is believed that certain risk factors can cause the relaxation of the pelvic floor, which can lead to a hernia. Such as advanced age, emaciation, increased intraabdominal pressure, and multiparity (having given birth multiple times).
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All these factors can lead to the progressive relaxation of the pelvic floor.
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Aging and malnutrition can cause the loss of preperitoneal fat and lymphatic tissue over the obturator canal. This results in a large space around the nerves and blood vessels, facilitating the formation of a hernia.
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The obturator hernia has the nickname "little old lady's hernia" as it primarily affects thin, malnourished elderly women.
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Several factors contribute to hernia formation, such as obstructive pulmonary disease, chronic constipation, kyphoscoliosis (curvature of the spine), ascites (accumulation of fluid in the peritoneal cavity leading to abdominal swelling), and multiparity. These conditions can increase intra-abdominal pressure and relax the peritoneum.
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Obturator hernia is more frequent on the right side because a sigmoid colon covers the obturator foramen on the left side, thereby preventing herniation.
What Are the Stages of Obturator Hernia?
The formation of the obturator hernia can be described in three stages.
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First Stage: Entrance of the preperitoneal fat into the pelvic orifice of the obturator canal. This forms a fat plug.
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Second Stage: Peritoneal sac is formed as the peritoneal dimple develops through the canal.
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Third Stage: The herniation of the viscera into this peritoneal sac causes the onset of symptoms.
How to Diagnose Obturator Hernia?
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Obturator hernia is often associated with high mortality and morbidity due to its difficulty in diagnosis. It is a rare condition with delayed onset of symptoms, which are non-specific. Therefore it poses a diagnostic challenge.
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Since the signs are non-specific, diagnosis is made during exploration for intestinal obstruction. Acute intestinal obstruction is the cardinal sign of an obturator hernia. The specific signs of obturator hernia are a pain in the inner aspect of the thigh called Howship Romberg's sign, palpable mass on the inner (medial) aspect of the thigh, and intestinal obstruction.
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Obturator hernia is rarely diagnosed if the symptoms are absent.
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The Howship-Romberg's sign is often confused with patients suffering from osteoarthritis. Therefore in many cases, patients may be referred to orthopedic surgeons, further delaying the diagnosis.
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The Hannington-Kiff sign can also be used, which is more specific than the Howship-Romberg sign. The Hannington-Kiff is an absent adductor reflex; the contraction of a muscle when stimulated shows the presence of an adductor reflex. But this sign is difficult to elicit. It is elicited by placing a finger on the adductors five centimeters above the knee and then percussing this finger with a tendon hammer.
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The pain due to strangulation of the intestine can mask the less severe symptoms.
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Obturator hernia can not be detected by physical examination or cannot be palpated because it is located between the adductor longus and pectineus muscles. A palpable mass near the vagina or rectum can indicate an obturator hernia. However, physical examination is non-specific. In many cases, an obturator hernia is diagnosed while operating for intestinal obstruction or peritonitis.
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Various imaging techniques, such as ultrasound, computed tomography (CT), and herniorrhaphy, can be used, of which CT scan has more accuracy and sensitivity. Plain X-rays can show dilatation of the small bowel.
How to Treat Obturator Hernia?
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Treatment for obturator hernia is surgical correction. This can be done through inguinal, transperitoneal, and retropubic approaches; the surgical approach can be made through any of the above methods.
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A low midline incision can be done in emergency conditions. This enables the surgeon to identify and resect the ischaemic bowel.
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As advances have been made in laparoscopic surgeries, the use of laparoscopy for operating obturator hernia has increased. Laparoscopy can reduce postoperative pain, lower complications, and shorten the hospital stay. However, it requires precision and has a longer learning curve. Therefore it is restricted to non-strangulated hernia.
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While surgery, bowel obstruction is identified, the hernia is reduced, and if ischaemic bowel is present, it is resected. A thorough inspection is required during surgery.
Conclusion:
Obturator hernia is a rare type of abdominal hernia due to the protrusion of abdominal contents through the obturator canal. It is seen in multiparous elderly women. It has a delayed onset of symptoms making it difficult to get diagnosed. This increases the morbidity of the condition. However, if diagnosed, it can be treated surgically. In most cases, the condition is diagnosed while exploring intestinal obstruction, as the signs and symptoms are usually non-specific.
