Aneurysm
and infarction
Aneurysm
of the splenic artery
This is an uncommon condition; estimates of its
incidence at post-mortem examination vary between 0.04 and 1 per cent. Whereas
aneurysms of other arteries are more common in men, in the splenic artery they
are about twice as common in women. They are usually single and situated in the
main trunk of the splenic artery (Fig.
53.3), but
more than one are found in a quarter of cases.
The
aneurysm is symptomless unless it ruptures. Occasionally it is palpable in the
epigastrium or associated with a bruit over the left hypochondrium. It may be
discovered accidentally, on plain radiograph of the upper abdomen, as a
calcified ring situated to the left of the first lumbar vertebra. Rupture of the
aneurysm is unsuspected in about half of all cases; it bursts into the
peritoneal cavity and the symptoms resemble those of splenic rupture. Nearly
half of all cases of rupture occur in patients less than 45 years of age,
and a quarter of all cases are in pregnant women (usually in the third trimester
of pregnancy or actually in labour).
The
treatment of choice is splenectomy and removal of the length of artery bearing
the aneurysm. If the aneurysm has eroded into the pancreas or is close to the
origin of the splenic artery, then proximal and distal ligation of the sac is
usually followed by thrombosis in the aneurysm. In younger patients, particularly women, with an
asymptomatic splenic artery aneurysm, surgery is indicated after the diagnosis
has been confirmed by selective coeliac arteriography. The maternal mortality
rate for surgery at the time of rupture, in late pregnancy, is over 70 per cent.
In elderly patients, particularly men, where an asymptomatic calcified aneurysm
is detected on plain radiograph, there is less risk of rupture and surgery is
not indicated.
Infarction
of the spleen (Fig. 53.4)
This occurs in patients with massive spleens resulting from myeloproliferative syndrome, or with vascular occlusion produced by sickle cell disease or an embolus from an infected heart valve in bacterial endocarditis. The infarct may be asymptomatic or may cause left upper quadrant abdominal pain radiating to the left shoulder with splinting of the hemidiaphragm and guarding and, at times, a friction rub may he heard over the splenic area. Sedation and bed rest are sufficient except rarely when a septic infarct causes an abscess necessitating splenectomy.