nature reviews | gastroenterology & hepatology
volume 6 | novemBer 2009 | 637
Department of Internal
Medicine III, Klinikum
Germany (J. Barnert,
H. Messmann, Klinikum
Diagnosis and management of lower
Jürgen Barnert and Helmut Messmann
abstract | Lower gastrointestinal bleeding (LGIB) can present as an acute and life‑threatening event or
as chronic bleeding, which might manifest as iron‑deficiency anemia, fecal occult blood or intermittent
scant hematochezia. Bleeding from the small bowel has been shown to be a distinct entity, and LGIB is
defined as bleeding from a colonic source. Acute bleeding from the colon is usually less dramatic than
upper gastrointestinal hemorrhage and is self‑limiting in most cases. Several factors might contribute to
increased mortality, a severe course of bleeding and recurrent bleeding, including advanced age, comorbidity,
intestinal ischemia, bleeding as a result of a separate process, and hemodynamic instability. Diverticula,
angiodysplasias, neoplasms, colitis, ischemia, anorectal disorders and postpolypectomy bleeding are the
most common causes of LGIB. Volume resuscitation should take place concurrently upon initial patient
assessment. Colonoscopy is the diagnostic and therapeutic procedure of choice, for acute and chronic
bleeding. Angiography is used if colonoscopy fails or cannot be performed. The use of radioisotope scans is
reserved for cases of unexplained intermittent bleeding, when other methods have failed to detect the source.
Embolization or modern endoscopy techniques, such as injection therapy, thermocoagulation and mechanical
devices, effectively promote hemostasis. Surgery is the final approach for severe bleeding.
Barnert, J. & Messmann, H. Nat. Rev. Gastroenterol. Hepatol. 6, 637–646 (2009); doi:10.1038/nrgastro.2009.167
Hemorrhage from the lower gastrointestinal tract accounts
for about 20% of all cases of acute gastro intestinal bleed-
ing.1 lower gastrointestinal bleeding (lGiB) has tradi-
tionally been defined as an abnormal loss of blood beyond
the ligament of treitz. However, results from capsule
and double-balloon endoscopy have revolutionized the
manage ment algorithm of small bowel bleeding, and it
has been shown that bleeding from the small bowel repre-
sents a distinct entity.2 it therefore seems reason able to
divide gastrointestinal bleeding into three cate gories:
upper, middle, and lower bleeding. in this article, we
define lGiB as the acute or chronic loss of blood from a
source in the colon or anorectum. acute lGiB is defined
as being of recent duration (arbitrarily designated as less
than 3 days) and might result in instability of vital signs,
anemia and/or the need for blood transfusion. Chronic
lGiB is the passage of blood from the rectum over a
period of several days or longer and usually implies that
blood loss is intermittent or slow. a patient with chronic
bleeding can show occult fecal blood, iron- deficiency
anemia, occasional episodes of melena, hemato chezia or
maroon stools, or small quanti ties of visible blood per
rectum.3 alternatively, however, lGiB can be subdivided
into two categories: clinically overt gastro intestinal bleed-
ing (melena, hematochezia) or occult bleeding, identified
by an unexplained iron deficiency and/or positive fecal
occult blood testing result.
the incidence of lGiB in the us ranges from 20.5
to 27 cases per 100,000 adults.4 in the netherlands,
an overall incidence of 8.9/100,000 per year has been
The authors, the Journal Editor N. Wood and the CME questions
author D. Lie declare no competing interests.
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Upon completion of this activity, participants should be able to:
1 Describe clinical features of lower gastrointestinal bleeding
2 Distinguish among different causes of acute LGIB and
3 Describe the diagnostic approach for angiodysplasia in
patients with LGIB.
4 Identify the most common causes of anemia associated
with chronic LGIB.
5 Describe effective treatment strategies for different types of
© 2009 Macmillan Publishers Limited. All rights reserved
638 | NOVEMBER 2009 | VOluME 6
reported.5 Differences in incidence might be explained
by the different populations, use of medicine, endo-
scopic and pharma ceutical management, and different
selection criteria. the age range of patients with lGiB
is 63–77 years;4 the incidence increases with age, with a
>200-fold increase between 20 and 80 years. lGiB occurs
more often in men than in women.6
Compared with acute upper gastrointestinal bleed-
ing, patients with acute lGiB are significantly less likely
to experience shock (19% versus 35%, respectively),
require fewer blood transfusions (36% versus 64%) and
have a significantly higher hemoglobin level (84% versus
61%).7,8 Colonic bleeding necessitates fewer blood trans-
fusions compared with bleeding from the small intestine.8
acute bleeding in the lower gastrointestinal tract stops
spontaneously in the majority (80–85%) of patients. the
overall mortality rate ranges from 2% to 4%.4
in this review, we aim to provide a critical overview
of the existing published data concerning the evaluation
and management of lGiB.
Initial evaluation and resuscitation
on presentation with lGiB, a number of factors relat-
ing to the patient’s history should be considered: intake
of aspirin or nsaiDs, occurrence of vascular disease,
past bleeding episodes, radiation therapy for prostatic
or pelvic cancer, occurrence within the previous 2 weeks
of colonoscopy or polypectomy, Hiv infection, liver cir-
rhosis, iBD, coagulopathy (including anticoagulation
therapy), and indication of colorectal cancer (family
history, weight loss, changes in bowel habits). the dura-
tion of bleeding, frequency of bleeding episodes and
stool color are of further importance. Hematochezia is
indicated by bright red or maroon blood per rectum and
must be differentiated from melena, the passage of tarry
stool, the presence of which is suggestive of an upper
gastrointestinal bleeding source (although bleeding from
the cecum and right-sided colon occasionally present in
this manner). up to 11% of patients with hematochezia
have massive upper gastrointestinal bleeding.9 Passage
of bright red blood resulting from upper gastro intestinal
bleeding is associated with hemodynamic instability
(shock or orthostatic hypotension). the presence of
blood in nasogastric tube aspirates is highly predictive
The severity of acute lower gastrointestinal bleeding (LGIB) is variable, but
overall mortality is low
In most cases, bleeding will stop spontaneously
Mortality is higher in older adults, and in those with intestinal ischemia and
Colonoscopy is the diagnostic and therapeutic mainstay in the management of
acute and chronic LGIB
Visceral angiography is the preferred diagnostic and therapeutic method in
patients with hemodynamic instability
The existing scoring systems are time consuming and offer little help in clinical
of bleeding proximal to the ligament of treitz, but
this source cannot be excluded if blood is absent from
Careful digital rectal examination should be per-
formed to exclude anorectal pathology and to confirm
the patient’s description of stool color. Physical examina-
tion also helps to assess the severity of bleeding and to
stratify patients according to the severity of hemorrhage.
Blood loss of <200 ml has no effect on heart rate or blood
pressure; however, loss of >800 ml causes a drop in
blood pressure of 10 mmHg and an increase of 10 heart-
beats/min. extensive blood loss (>1500 ml) might induce
shock. other signs of hemodynamic compromise include
postural changes, fatigue, pallor, palpitations, chest pain,
dyspnea and tachypnea. the initial laboratory evaluation
should contain a complete blood count, a coagulation
profile, serum chemistry and a sample for blood type
Patients with clinical evidence of ongoing or aggressive
bleeding, those with a transfusion requirement of greater
than two units of packed red blood cells, and those with a
significant morbidity should be monitored in an intensive
care unit (iCu) setting. Conversely, a young, nonanemic
patient with scant bleeding, who is otherwise healthy, can
be managed as an outpatient. Coagulopathy (defined as
an international normalized ratio of prothrombin time
>1.5) or thrombocytopenia (<50,000 platelets/μl) should
be treated using fresh frozen plasma or platelets, respec-
tively. in patients receiving warfarin, anti coagulation
should be reversed with vitamin K, although the onset
of action is delayed compared with the use of fresh frozen
plasma or prothrombin complex. the ideal plasma
substitute for volume replacement remains a matter of
debate. in general, crystalloids (for example, lactated
ringer’s solution) are recommended for volume sub-
stitution in the us,10 whereas colloids, such as low and
medium mol ecular weight hydroxyethylstarch prepara-
tions with low molar substitution, are considered to
be more appropriate for treating intravascular volume
deficits in europe.11 if there is ongoing hemorrhage or
severe anemia, red blood cells should be used. the ideal
hemoglobin concen tration/hematocrit depends on the
patient’s age, rate of bleeding, and any comorbidi ties. a
young and otherwise healthy person will tolerate a hemo-
globin concen tration of less than 7–8 g/dl (hematocrit
<20–25%), whereas older patients develop symptoms
at this level. maintaining the hemoglobin concentra-
tion around 10 g/dl (hemato crit 30%) in high-risk
patients (for instance, an elderly patient with coronary
heart disease) would be reasonable. However, it must be
emphasized that all these recommenda tions have been
given on an empirical basis.
the sources of acute lGiB and their frequency as
reported in the literature are listed in table 1. Colonic
diverticula (Figure 1) seem to be the most frequent
source of hematochezia, followed by angiodysplasias,
© 2009 Macmillan Publishers Limited. All rights reserved
646 | NOVEMBER 2009 | VOluME 6
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Désirée Lie, University of California, Irvine, CA, is the
author of and is solely responsible for the content of
the learning objectives, questions and answers of the
MedscapeCME‑accredited continuing medical
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