The prevalence of angiodysplasia in
healthy individuals (mean age 61 years) in whom screening colonoscopies were
performed (0.93%).7 Most patients with angiodysplasia do not
experience GI bleeding; whereas <10% actively bleed.
The increased propensity of patients with VWD
to have formation of angiodysplasias is well established.3 The
underlying mechanism of this clinical conditions appears associated with the
role of high-molecular-weight multimers of plasma VWF as an antiangiogenic
factor. Endothelial VWF has recently been identified as a negative modulator of
VEGF-dependent angiogenesis and angiogenesis has shown to be increased in VWF
deficiency.8-9
The diagnosis and treatment of recurring
GI bleeding in VWD is challenging and associated with significant morbidity: patients
frequently experience intractable bleeding episodes resulting in recurrent
hospital admissions and exposure to multiple therapies of limited efficacy.
Bleeding episodes can also develop and increase in severity with age.10
Due to diagnostic difficulty, in many patients the angiodysplastic lesions
cannot be identified and the patients are described as having occult GI
bleeding. The diagnosis is challenging due to accessibility, especially when
the lesions are in the small bowel, and the requirement that active bleeding be
present at the time of the examination for optimal identification.4
Whilst treatment of acute bleeding is
fairly standard, a major issue is the recurrent nature of the bleeding and its
prevention. Multiple physical and pharmacological therapies have been reported
but none proven to be fully effective in every case.11
About pharmacological treatment, von
Willebrand factor concentrate demonstrated to be effective for acute bleeding
in 94.9% and was also effective in preventing bleeding in 84.6% of patients
when given prophylactically.12 In a previous report from the VWN PN
on the effectiveness of prophylaxis in VWD, Abshire and colleagues13
reported a reduction of annualized bleed rate from 8.4 to 6; the dose required
for effective GI bleeding prevention remains unknown and although the VWD PN
was designed to identify this, the number of patients enrolled with GI bleeding
is so low that the answer is unlikely to come from this network. Other
pharmacological approaches proposed for the prevention of recurrent GI bleeding
from angiodysplasia include oestrogens, octreotide, thalidomide, atorvastatin
and tamoxifen but no definitive data have been published until now.
We reported a case of a misdiagnosis of
VWD in a patients with melena and acute reduction of hemoglobin levels. The
classical approach with basic routine coagulation evaluation and gastroscopy
and colonoscopy didn't add useful information; moreover, second-level imaging
tests aimed at finding the source of possible bleeding obviously yielded
negative results. The choice of an exploratory laparotomy (hesitated in an intestinal
resection) seemed to be the only applicable strategy.
Under a clinical point of view, it is always
necessary to consider the risk of a VWD before decide for a surgical approach
to a GI bleeding. Diagnostic problems can be minimized by: (i) using improved methodologies
(e.g., enzyme linked immunosorbant assay ELISA) (ii) extending the test
panel, (iii) repeat testing using a fresh sample for confirmation, (iv)
avoiding testing of stressed, ill or pregnant patients, and (v) using data from
a desmopressin (DDAVP) challenge test.14
In conclusion, in order to prevent or
reduce the risks erroneous surgical approach, we consider the future
perspective to be the routine screening a VWD in presence of GI bleeding and signs
of intestinal angiodysplasia.