Umbilical, epigastric, and rarer abdominal wall hernias - technical article.
There are three distinct types of hernia that occur around the umbilicus:
- congenital (omphalocele or exomphalos),
- infantile umbilical hernia, and
- adult paraumbilical hernia.
This condition occurs in 1 in 5000 births and is associated with other serious congenital abnormalities in 60 per cent of cases.
During intrauterine development the amniotic sac contains the embryologic midgut. At 10 weeks of gestation the gut normally returns to the abdominal cavity. When this doesn't occur, the umbilical canal fails to close and at birth a broad funnel-shaped defect is present at the umbilicus. Viscera covered only by peritoneum protrude through this abdominal wall defect.
The diagnosis is immediately evident at the time of birth, with an obvious protrusion of abdominal viscera through the umbilicus. Its location in the midline and the presence of peritoneum covering the herniated viscera distinguishes this congenital abdominal wall defect from gastroschisis, where the abdominal wall defect is off midline, and the herniated viscera are uncovered by either peritoneum or skin.
Urgent surgical repair should be performed before rupture of the sac occurs or infection supervenes.
This hernia is present in 10 per cent of Caucasian infants (male:female ratio is 2:1) and 90 per cent of children of African decent. In babies of low birth weight, the incidence is as high as 75 per cent. The occurrence is also increased in Down syndrome, Beckwith–Wiedemann syndrome, and in the presence of ascites.
At birth, following division of the umbilical cord, the stump heals by granulation and scarring to fuse with the umbilical ring of the abdominal wall. Failure of fusion at the abdominal wall allows a peritoneal sac to protrude, usually at the superior margin of the ring. The infantile hernia, as opposed to the congenital type, is always covered with skin, and reaches its maximal size 1 month after birth.
This hernia is usually symptomless and presents as an easily reducible lump which becomes more prominent during crying and coughing. Incarceration or strangulation of this hernia is extremely rare, and congenital umbilical hernias rarely enlarge over time. The hernia contents usually remain virtually unchanged in size until just before final closure.
This hernia will spontaneously disappear in 93 per cent of children by the age of 2 years. Consequently, operative treatment in the newborn baby is deferred to allow time for spontaneous closure. Tapes, binders, and trusses to reduce the hernia contents are not recommended as they may lead to skin infection or necrosis. Surgical repair is indicated for any symptoms associated with the umbilical hernia, or if the hernia persists beyond 2 years of age. Hernias greater than 2 cm in size are less likely to close spontaneously. The operation is performed under general anesthesia on an outpatient basis. A semicircular infraumbilical skin incision allows elevation of the umbilicus and exposure of the edges of the fascial defect. Herniated content is usually reduced without entering the peritoneum. The fascial defect is then closed transversely with absorbable or non-absorbable suture. The base of the umbilicus is sutured to the fascia to invert the umbilicus and restore its normal contour.
Adult paraumbilical hernia
Most adult umbilical hernias are acquired. About 10 per cent of adult umbilical hernias are congenital hernias carried into adulthood.
The superior rim of the umbilicus is the site of attachment of the round ligament and the remnants of the urachus and umbilical arteries, thus creating a weak area in the abdominal fascia. Additionally, the lowest tendonous insertion of the rectus abdominis muscle into the linea alba is at the level of the superior umbilical rim. Stretching of the abdominal wall due to multiple pregnancies, ascites, or obesity predisposes to the development of an umbilical hernia. The condition usually occurs after the age of 35 years and, due to its association with pregnancy, is five times more common in females.
This hernia tends to enlarge progressively over time and may be asymptomatic depending on size and body habitus. It may produce localized pain as the fascial defect enlarges or herniated content stretches overlying subcutaneous tissue and skin. Gastrointestinal symptoms commonly occur owing to traction between the hernia contents and the stomach or transverse colon. When the hernia sac contains bowel, colic due to intermittent intestinal obstruction is possible. Thinning, discoloration, and necrosis of the skin may occur in patients with larger hernias. The paraumbilical hernia usually has a small neck and incarceration and strangulation are common. Diagnosis can be particularly challenging in the obese patient, where an abdominal wall defect can be impossible to feel, and a large hernia sac and content can be hidden within an abdominal pannus. CT scanning or ultrasound may be the best diagnostic tests in obese patients in whom an umbilical hernia is suspected.
Once diagnosed, an umbilical hernia should be repaired. In select cases where operative risk is excessive or in bedridden patients, umbilical hernias with a large defect and a low likelihood of incarceration need not be repaired. However, eventually these large hernias lead to disability and pain, requiring repair at a time when loss of abdominal domain makes repair extremely problematic. The elderly and those with ascites are at especially high risk of significant complications from an untreated umbilical hernia. In the presence of ascites, rupture of an umbilical hernia or necrosis and infection of overlying skin has a mortality of up to 30 per cent. Therefore, in patients with ascites, elective repair should be offered before these complications develop. Medical control of ascites perioperatively is critical to minimize wound complications and recurrence. Tapes, binders, and trusses often lead to skin infection or necrosis and are not recommended. Preoperative weight loss in the obese is extremely important to increase the likelihood of a successful operative repair. Small hernias can be repaired under local anesthesia. Larger hernias require general anesthesia. Most umbilical hernias can be repaired on an outpatient basis. Elderly patients and those with ascites or medical comorbidities will require admission to hospital. A curvilinear infraumbilical incision provides the best access for encircling the hernia sac at its base and exposing the fascial edges of the defect. The raphe of the umbilicus often requires release and dissection off of the hernia sac. Entering the peritoneum is not necessary unless abdominal content is adherent to the sac or incarcerated and requiring investigation for viability. Small hernias ( Avoidance of heavy lifting is recommended for 4 to 6 weeks after operative repair of an umbilical hernia. Following a posterior buttressed repair, return to heavy lifting and usual activity may be allowed earlier. Patients with ascites require careful medical control of their ascites postoperatively. In those with ascites, paracentesis or placement of a peritoneovenous shunt at the time of herniorrhaphy may help minimize postoperative wound breakdown and recurrence.
All primary hernias occurring in the midline of the abdomen, with the exception of those of the umbilicus, are hernias of the linea alba. These hernias are far more common above the umbilicus and are termed epigastric hernias. An epigastric hernia is present in 5 per cent of individuals at autopsy, and 25 per cent of individuals have multiple hernias. This hernia may present at any age, but is most common between 20 and 50 years of age, and is three times more common in men than in women.
Epigastric hernias are protrusions of preperitoneal fat through a fascial defect in the decussating fibers of the supraumbilical portion of the linea alba. The defect usually occurs where the linea alba is pierced by a blood vessel. A peritoneal sac may accompany fat through the defect, containing omentum or rarely bowel. Diagnosis The majority of epigastric hernias are asymptomatic. Vague upper abdominal pain and nausea, associated with epigastric tenderness may be present. These symptoms tend to be more severe when the patient is supine, owing to traction on the hernia contents. A lump, which may be tender, is usually palpable in non-obese subjects. Gangrene of the contents of the hernia occasionally occurs, producing severe epigastric tenderness and localized muscular rigidity. These features may mimic those of an intra-abdominal catastrophe. The presence of a non-tender epigastric hernia should never be considered to be an adequate explanation for dyspepsia or epigastric pain except following extensive investigation of the upper gastrointestinal tract. Conversely, in obese patients with chronic upper abdominal symptoms, an epigastric hernia may remain undiagnosed for years because it is often not palpable. CT scanning or ultrasound evaluation may be necessary to diagnose an epigastric hernia in the obese patient.
Once diagnosed, these hernias should be repaired. As with umbilical hernias, select patients with large defects and a low risk of incarceration may not need repair. This circumstance is very unusual. Only in the non-operative candidate should any form of truss or external compression be utilized. An upper midline incision affords the best exposure. The hernia sac is dissected free from the surrounding subcutaneous tissues and at least 1 cm of the fascial edges of the defect exposed. Since up to 25 per cent of epigastric hernias are multiple, a thorough search for additional hernias should be carried out. If other midline defects are found, the linea alba is incised incorporating the multiple hernias into one defect. The hernia is then closed longitudinally with interrupted or running non-absorbable suture. Wound drains are unnecessary and, depending on the size of the repair, patients are instructed to avoid heavy lifting for 4 to 6 weeks postoperatively.
Spigelian hernias are uncommon. They are most common in women over 50 years of age.
The transversus abdominis muscle becomes aponeurotic at the semilunar line which stretches from the ninth rib to the pubic tubercle. The part of the aponeurosis between the semilunar line and the lateral edge of the rectus muscle is called the spigelian aponeurosis. This area of transition from muscle to aponeurosis is an area of potential abdominal wall defects. It is through such a defect that a spigelian hernia emerges, passing between the fibers of overlying internal oblique muscle and spreading out deep to the external oblique muscle. Most spigelian hernias appear below the umbilicus, level with the termination of the posterior rectus sheath (linea semicircularis), close to a point one-third of the way along a line between the umbilicus and the anterior superior iliac spine. The hernia usually lies lateral to the rectus sheath and extends out towards the iliac fossa; occasionally it lies within the sheath alongside the rectus muscle. Only rarely does it penetrate the external oblique muscle to lie subcutaneously. Preperitoneal fat most commonly herniates, but a hernia sac of peritoneum may contain small bowel, colon, or omentum. The fibrous bands of the spigelian fascia give these hernias a rigid neck making incarceration and strangulation common.
Because the hernia sac or content is usually deep to the external oblique muscle, these hernias are difficult to palpate and the diagnosis is often obscure, especially in the obese patient. Frequently, the only symptoms are obscure abdominal pain or small bowel obstruction. In a thin standing patient, a mass with a cough impulse may be palpable in the iliac fossa; this disappears on lying down. Twenty per cent of these hernias have strangulated at presentation resulting in a tender mass in the abdominal wall which may be difficult to differentiate from an abdominal wall hematoma, a muscular tear, or an intra-abdominal inflammatory mass. Ultrasound and CT may be useful in confirming the diagnosis, especially in the obese patient. Recently, laparoscopy has proved useful in both the diagnosis and repair of spigelian hernias.
Once diagnosed or suspected, these hernias should be operatively repaired. A transverse incision is made over the site of localized tenderness or palpable mass, and the external oblique fibers split to expose the hernia sac. Herniated content is reduced, the sac excised, and the defect closed by direct suture. If the diagnosis is in doubt, or the location of the hernia unclear, laparoscopy through an infraumbilical site will allow identification of the abdominal wall defect for subsequent laparoscopic or open repair. Alternatively, a midline laparotomy with reduction of the hernia and repair from the inside can be performed.
These hernias are rare, with fewer than 600 cases having been reported in the world literature. Most surgeons will never see an obturator hernia.
The hernia follows the obturator canal which courses between the superior pubic ramus and the obturator membrane and normally transmits only the obturator nerve and vessels. The sac of an obturator hernia exits the obturator canal and spreads out deep to the adductor muscles in the groin, where it is difficult to detect clinically. The sac usually contains small bowel, often as a Richter's type hernia. Less commonly, omentum, colon, fallopian tube, ovary, or bladder herniate. Strangulation is common because of the size and rigidity of the obturator canal.
The majority of these hernias occur in elderly women who have recently lost weight. The higher incidence in women is probably due to the wider pelvis and flatter angle of the obturator canal. Most patients present with acute groin pain, or abdominal symptoms ranging from small bowel obstruction to mild and obscure discomfort. Approximately one-third of patients report having had similar episodes in the past. Occasionally, straining due to constipation or other factors appears to precipitate herniation. The diagnosis is rarely made preoperatively; it is usually made during laparotomy for small bowel obstruction. Even if the correct diagnosis is entertained preoperatively, the pathognomonic signs (￼Table 1) are present in fewer than 50 per cent of cases.
Table 1 Pathognomonic signs of obturator hernia
- Howship–Romberg sign—pain radiating to medial thigh with hip extension, internal rotation, and adduction
- Hannington–Kilf sign—loss of adductor reflex elicited 5 cm above the knee (compression on obturator nerve)
- Bruising below the medial edge of the inguinal ligament due to strangulation and blood in the hernia sac
- A palpable tender mass on vaginal examination (not rectal examination)
Whether known preoperatively or found intraoperatively, an obturator hernia should always be repaired. If the diagnosis is made preoperatively, an extraperitoneal approach provides ideal exposure for hernia reduction and repair. However, since the diagnosis is rarely made preoperatively, most obturator hernias are repaired during urgent laparotomy for small bowel obstruction. Regardless of approach, after placing the patient in the Trendelenburg position, the hernia sac can be seen disappearing into the obturator canal. If the hernia has reduced spontaneously, a defect can be felt just below the ischiopubic tract at the obturator membrane. An incarcerated hernia should be reduced by gentle traction. If compromised bowel is present in the hernia, the bowel should be clamped before reduction to prevent spillage. Rarely, it may be necessary to enlarge the obturator canal by incising posteromedial to the neck of the hernia, thereby avoiding damage to the obturator nerve. After reduction, bowel is carefully inspected and non-viable bowel resected. Without infection or spillage of intestinal content, the defect is repaired with an overlay of non-absorbable mesh. Primary suture closure or overlay of urinary bladder may be necessary when spillage has occurred. The mortality in these patients remains high (13 to 20 per cent) primarily due to their advanced age and the small number of correct preoperative diagnoses.
Lumbar hernias are uncommon, with fewer than 300 cases having been reported in the literature. This hernia is most commonly the consequence of trauma (penetrating or operative). More rarely it is congenital or acquired.
In the area between the twelfth rib and the iliac crest a number of back and abdominal muscles come together and create an area of potential weakness. This area can be divided into the superior and inferior lumbar triangles. The inferior triangle (of Petit) is the usual site of congenital lumbar herniation, which accounts for 25 per cent of cases. The boundaries of this area are the iliac crest inferiorly, the latissimus dorsi muscle superomedially, and the posterior boundary of the external oblique muscle superolaterally. Acquired hernias are rare in this area, except when both internal and external tables of iliac crest have been removed for bone grafting. The quadratus lumborum, twelfth rib, and internal oblique muscle form the superior lumbar triangle. This is the usual site of acquired hernias secondary to trauma (surgery, penetrating injury), infection (such as wound infection following nephrectomy), or of those occurring spontaneously. These hernias most commonly contain small or large bowel and are at little risk of strangulation owing to their wide neck.
Lumbar hernias usually occur in middle-aged men. They present as a lumbar bulge that appears with standing and disappears on lying down. The only symptom is usually a dull ache. Large hernias may contain a significant segment of colon causing abdominal bloating or constipation. CT scan may be helpful in diagnosis, especially in the obese patient. Treatment Lumbar hernias should be repaired operatively if symptomatic, or if there are signs of strangulation or incarceration. The hernia can be repaired through a flank or posterior approach, with the patient in the lateral position, or through an anterior retroperitoneal approach. The sac is emptied and closed off. The muscle defect is best repaired using non-absorbable suture and mesh. If the hernia is small it may be possible to coapt adjacent muscles with non-absorbable sutures, but in most cases simple suture repair has a high failure rate. When mesh is used, it is ideally placed deep to the defect in a buttressed fashion ensuring adequate overlay and secure fixation to the edges of the defect. Alternatively, a flap of fascia lata and gluteus maximus can be mobilized and rotated up to close the defect. Giant lumbar hernias are unlikely to strangulate and have a high recurrence rate. These may be best treated non-operatively.
These are extremely rare hernias.
The hernia sac exits the pelvis through either the greater sciatic foramen, above or below the piriformis muscle, or, most commonly, through the lesser sciatic foramen. The sac then lies deep to the gluteus maximus, where it is well hidden unless it is large enough to protrude below the buttock crease.
Diagnosis is usually made at the time of laparotomy for small bowel obstruction caused by the hernia. The bowel is seen disappearing out through a posterior pelvic defect, behind the broad ligament in women.
As with obturator hernia, the patient is placed in the Trendelenburg position and the contents of the sac reduced. The neck of the sac is ligated, and the defect is covered by fascia mobilized from the piriformis muscle.
Perineal hernias are uncommon. They are typically the result of prior pelvic surgery.
They occur through defects in the muscular pelvic floor and usually follow pelvic exenteration or abdominoperineal resection of the rectum. The hernia contents are usually small bowel or bladder. There are rarely any associated symptoms. Treatment The usual approach is transabdominal. Once small bowel and bladder have been mobilized out of the pelvis, the defect is closed with non-absorbable mesh. If there is potential for infection, synthetic implants are best avoided and gracilis muscle can be transposed from the thigh to form a sling across the defect via a perineal approach.
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