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Chapter 4: Disorders of the abdominal wall 155

toneum dragged down into the testes during the
embryonic descent of the testes from the posterior
Skin abdominal wall. It is usually obliterated leaving the
tunica vaginalis as a covering of the testes.
Direct inguinal hernias occur as a result of weakness in

the floor of the inguinal canal (through Hesselbach’s
Intestine triangle which is formed inferiorly by the inguinal lig-
ament, the inferior epigastric vessels laterally and the
Hernia internal oblique muscle superiorly).
Femoral hernias are due to a weakness of the femoral

sheath,thetopofwhichisthefemoralringboundedby
the inguinal ligament anteriorly, the femoral vein lat-
Muscle
erally, the lacunar ligament medially and the superior
ramusof the pubis posteriorly. Femoral hernias are
particularly prone to incarceration or strangulation,
Figure 4.3 Abdominal wall hernia.
as the angle of the canal makes the hernia difficult to
reduce. Females have femoral hernias more often than
males, but inguinal hernias are still the most common
Aetiology/pathophysiology
hernia in females (by 4 to 1).
Congenital hernias exploit natural openings and weak-
Incisional hernias occur at weakened areas caused by
nesses. They may not become obvious until later in
surgical incisions and muscle splitting. They occur in
life and may be predisposed to by coughing straining,
lifting, trauma or weak musculature. Examples of her- approximately 5% of postoperative patients, risk fac-
nias include inguinal (direct and indirect), femoral, tors include infection, poor wound healing, coughing
paraumbilical, umbilical and ventral hernias (see and surgical techniques.
Fig. 4.4).
Of groin hernias, 60% are indirect inguinal, 25% are
direct inguinal and 15% are femoral. Clinical features
Indirect inguinal hernias are a result of failure of oblit-
Hernias may be completely asymptomatic, or present
eration of the processus vaginalis, a tube of peri- with a painless swelling, sudden pain at the moment of
herniation and thereafter a dragging discomfort made
worse by coughing, lifting, straining and defecation
(which increase intra-abdominal pressure). Persistent or
severe pain may be a sign of one of the complications of
hernias, i.e. incarceration or strangulation. In most cases
the hernia is not visible when the patient is lying supine.
They are best examined standing and when the patient
is coughing or straining. A bulge may be visible and a
cough impulse is normally palpable. It can be difficult to
distinguish the groin hernias.
Umbilical Indirect hernias once reduced can be controlled by
pressure applied to the internal ring. This distin-
Inguinal guishes indirect from direct hernias, which cannot be
controlled, and where on reduction the edges of the
Incisional
defect may be palpable.
Femoral An inguinal hernia passes above and medial to the
pubic tubercle whereas a femoral hernia passes below
Figure 4.4 Sites of abdominal wall hernias. and lateral.