Hernia indd

Superior triangle lumbar hernias
Incisional hernia
Incisional hernias occur as a result of an iatrogenic defect in the ab-
dominal wall secondary to surgery. They usually occur within the 
first few months after surgery, however 5-10% can remain clinically 
silent for up to 5 years 
(6)
. They can manifest anywhere in the ab-
dominal wall and are more common with vertical than with hori-
zontal incisions 
(4)
. Incidence is increased in obesity. CT and MRI 
are better than US at differentiation between a true hernia and ab-
dominal rectus divarification where the linea alba is thinned but 
intact. CT can differentiate hernia from haematoma early after sur-
gery.
Spigelian hernia
This is a hernia through the lateral ventral wall at the point where 
the semilunar and semicircular lines intersect at the arcuate line of 
the abdominal rectus muscles. Intra-abdominal contents protrude 
between the aponeurosis of the internal and external oblique and 
that of the transverse abdominis (also known as the Spigelian apo-
neurosis). 
Spigelian hernias are predominantly found inpatients in their 50s. 
There is an equal male to female predominance. Typically, short 
segments of bowel or omentum herniate through the defect and be-
come incarcerated or strangulated. They traverse the full thickness 
of the abdominal wall muscles in contrast to interparietal hernias in 
which the hernia sac is confined between the muscular layers. While 
omental infarction is a common association, true bowel infarction is 
far less common.
Spigelian hernias classically present as a lump or intermittent swell-
ing above and medial to inguinal canal. Clinical examination can be 
difficult, particularly in obese patients. US can be helpful, but CT is 
generally considered more sensitive 
(5,10)
.
Pelvic hernias 
Pelvic hernias occur more commonly in elderly women secondary 
to acquired weakness or defect within the pelvic floor. These include 
hernias through the obturator foramen, the sciatic foramen and 
(most frequently) through the perineum.
Perineal hernia
While common amongst canines, perineal hernias are rare in hu-
mans and most commonly occur in elderly women. They are sec-
ondary to a weak pelvic floor, after abdominoperineal excision of 
the rectum and other major surgeries. Symptoms are usually mild 
and need for treatment is rare.
Sciatic hernia
Sciatic hernias are rare hernias involving protrusion of the small 
intestine or ureter through the greater or lesser sciatic foramina ad-
jacent to the anus. Greater sciatic foraminal hernias are thought to 
be secondary to congenital or acquired atrophy of the piriformis 
muscle. These rare hernias are more common in female and can be 
a cause of undiagnosed chronic pain. The majority of reported cases 
have been identified at laparotomy or laparoscopy. These hernias 
contained either fallopian tube or ovary in the majority of cases. In 
rare cases, there is herniation of the ureter. Incarceration is common 
(14)
.