Lower gastrointestinal bleeding—Computed Tomographic Angiography, Colonoscopy or both?
Clerc et al. World Journal of Emergency Surgery
Lower gastrointestinal bleeding-Computed Tomographic Angiography, Colonoscopy or both?
Daniel Clerc 0 1
Fabian Grass 0 1
Markus Schäfer 0 1
Alban Denys 1 2
Nicolas Demartines 0 1
Martin Hübner 0 1
0 Department of Visceral Surgery, University Hospital of Lausanne (CHUV) , Lausanne , Switzerland
1 This study was presented at the Annual Swiss Surgical Meeting 2015 , May 20-22, Bern , Switzerland
2 Department of Interventional Radiology, University Hospital of Lausanne (CHUV) , Lausanne , Switzerland
Background: Lower endoscopy (LE) is the standard diagnostic modality for lower gastrointestinal bleeding (LGIB). Conversely, computed tomographic angiography (CTA) offers an immediate non-invasive diagnosis visualizing the entire gastrointestinal tract. The aim of this study was to compare these 2 modalities with regards to diagnostic value and bleeding control. Methods: Tertiary center retrospective analysis of consecutive patients admitted for LGIB between 2006 and 2012. Comparison of patients with LE vs. CTA as first exam, respectively, with emphasis on diagnostic accuracy and bleeding control. Results: Final analysis included 183 patients; 122 (66.7%) had LE first, while 32 (17.5%) had CTA; 29 (15.8%) had neither of both exams. Median time to CTA was shorter compared to LE (3 (IQR = 8.2) vs. 22 (IQR = 36.9) hours, P < 0.001). Active bleeding was identified in 31% with CTA vs. 15% with LE (P = 0.031); a non-actively bleeding source was found by CTA and LE in 22 vs. 31%, respectively (P = 0.305). Bleeding control required endoscopy in 19%, surgery in 14% and embolization in 1.6%, while 66% were treated conservatively. Post-interventional bleeding was mostly controlled by endoscopic therapy (57%). 80% of patients with active bleeding on CTA required surgery. Conclusions: Post-interventional LGIB was effectively addressed by LE. For other causes of LGIB, CTA was efficient, and more available than colonoscopy. Treatment was conservative for most patients. In case of active bleeding, CTA could localize the bleeding source and predict the need for surgery.
Gastrointestinal hemorrhage; Colonoscopy; Computed tomographic angiography; Endoscopy
Lower gastrointestinal bleeding (LGIB) is a common
clinical problem, representing 20 to 30% of patients presenting
with gastrointestinal bleeding [1, 2]. LGIB incidence is
increasing over time, as it is associated with older age and
pre-existing comorbidities . Very distal bleeding, e.g. due
to hemorrhoids and low rectal cancer, is rather easy to
diagnose, but bleeding from the colon and small bowel remains
a diagnostic challenge. According to recent guidelines,
hemodynamic stabilization and resuscitation must be
performed prior to search any bleeding source. While
nasogastric lavage and/or esophagogastroduodenoscopy
can be considered to rule out upper gastrointestinal
bleeding for patients presenting severe hematochezia, lower
endoscopy (LE) is the preferred diagnostic approach for LGIB
[1, 4]. Nevertheless, computed tomographic angiography
(CTA) for evaluation of GI bleeding is increasingly used
and may challenges lower endoscopy as most appropriate
tool. This non-invasive diagnostic modality is readily
available in most hospitals and can be rapidly performed
without any bowel preparation. Reported sensitivity and
specificity rates are 86 and 95%, respectively and bleeding
as low as 0.4ml/min can be detected [5, 6].
So far, there is only limited evidence on the routine use
of CTA in the initial management of LGIB. Its accuracy
compared to LE remains unclear; and subsequently, its
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use as a first-line diagnostic modality is not considered in
current management algorithms [1, 4].
This current study aimed to compare the accuracy of
CTA and colonoscopy in the diagnosis of LGIB and their
influence on bleeding control.
Retrospective cohort study conducted at a tertiary care
academic center. The study was approved by the local
ethics committee (protocol 389/12) performed according
the STROBE recommendations, and registered under
www.researchregistry.com (# 726).
Patients and data collection
All consecutive patients admitted for LGIB to the
department of visceral surgery between January 2006 and
December 2012 were potentially eligible. The following
patients were excluded from analysis: (I) proctological
bleeding, (II) LGIB not being the primary cause of
admission, and (III) patients with LGIB admitted for
elective surgery. Patients underwent primary evaluation
at the emergency department by emergency physicians
and by a gastrointestinal consultant surgeon before
admission to the visceral surgery department. The initial
diagnostic modality (LE or CTA) was defined by the
physician in charge of the patient.
LE was defined as a flexible lower endoscopy performed
by a gastroenterologist. Procedures were performed by an
attending, junior staff or resident gastroenterologist
according to the policy of a Swiss university hospital. Resident
procedures were supervised by a board-certified
gastroenterologist. Gastroenterology consultant is available 24/7
in our institution, with in-hospital presence during daytime,
and available within 30 min during the nightshift. Type of
bowel preparation, if any, was upon the choice of the
gastroenterologist performing the procedure. A standard
flexible colonoscope was used for all procedures. Conscious
sedation or general anesthesia was used depending upon
patient’s general condition. Whenever possible, examination
was performed up to the ileo-caecal valve. Exam findings
were classified as positive with actively bleeding lesion,
positive with non-actively bleeding lesion or inconclusive.
LE was defined inconclusive when no lesion was detected
regardless of the quality of preparation and the amount of
blood clots present in the endoscopic view.
For actively bleeding lesions or non-actively bleeding
lesions with high risk of re-bleeding, endoscopic therapy
was directly applied with clips, adrenaline infusion or
thermal probe depending on the gastroenterologist’s
CTA was defined as a contrast-enhanced abdominal
and pelvic CT scan performed in a triphasic acquisition.
First, a native acquisition was followed by
contrastenhanced arterial phase after a bolus injection of 100ml
contrast media (300mg iodine/ml, 4ml/s) with automatic
triggering (collimation 16 × 0.625mm; pitch 1.75; table
speed 35mm/s). The venous acquisition was performed
70–80 s later. Exam findings were classified as positive
with active bleeding when CTA showed intraluminal
contrast material extravasation. CTA were defined
positive without active bleeding when the cause of bleeding
was spotted without contrast material extravasation.
CTA were defined inconclusive when no cause of
bleeding was found.
The time spent from the admission to the emergency
room to the execution of the diagnostic exams was
recorded. First hemodynamic parameters (heart rate (HR),
blood pressure) and hemoglobin (Hb) values recorded
upon admission were retrieved. The shock index (SI),
defined as the ratio of heart rate to systolic blood pressure,
and the mean arterial pressure (MAP), were calculated.
The cause of bleeding was classified in six categories:
small bowel, diverticular, colorectal neoplasia, colorectal
lesion, post-interventional, and unknown location. Small
bowel bleeding was defined as the source of bleeding
arising from the ligament of Treitz to the ileo-caecal valve.
Diverticular bleeding was defined as the source of bleeding
being related to a colonic diverticular disease. A colorectal
neoplasia was defined as benign or malignant lesion being
the cause of bleeding. Non-neoplastic, non-diverticular
colorectal lesions being the source of bleeding (colitis,
colonic ulcers or angiodysplasias) were grouped in the
colorectal lesion category. Post-interventional bleeding was
defined as a bleeding occurring following endoscopic or
surgical procedure. Bleeding of unknown location was
defined when the cause of bleeding was not found during
hospital stay. The control of bleeding was recorded
according to the last therapeutic intervention performed
(surgery, angio-embolization, endoscopic intervention
Patient’s characteristics, information on the performed
diagnostic procedures and clinical outcomes were
defined a priori. All eligible patients were collected by ICD
codes. Data was retrieved by retrospective chart review
and entered in a coded computerized database. Patients
were stratified according to the first diagnostic exam
performed at hospital admission, i.e. LE, CTA or none of
Descriptive statistics for categorical variables were
reported as frequency (%), while continuous variables were
reported as median (interquartile range). Chi-square and
Student’s t-test were used for comparison of categorical
and continuous variables, respectively. All statistical tests
were two-sided and a level of 0.05 was used to indicate
statistical significance. Data analysis was performed with
the Statistical Software for the Social Sciences SPSS
Advanced Statistics 22 (IBM Software Group, 200 W.
Madison St., Chicago, IL; 60606 USA).
Table 1 Patient characteristics
0.66 ± 0.22 0.72 ± 0.27 0.63 ± 0.18 0.082
Patients and clinical outcome
Within the study period, 301 patients were hospitalized
in the visceral surgery department with diagnostic of
GIB. 118 patients were excluded according to the a
priori defined rules. Final analysis included 183 patients,
with 109 male and 74 female patients with a median age
of 75 years (Fig. 1). One hundred and twenty-two
patients (66.7%) had LE as first diagnostic intervention, 32
(17.5%) had CTA. The remaining 29 patients (15.8%)
had neither of the two exams during their hospital stay.
Patient characteristics are presented in Table 1. Median
length of hospital stay (LOS) was 5 (IQR = 7) days. In
the CTA group, LOS was longer compared to the LE
group with 9 (IQR = 12.7) versus 5 (IQR = 6.6) days,
respectively (P = 0.026). In-hospital mortality rate was 2.7%
and concerned 5 patients. 3 patients died of postoperative
complications (septic shock, intravascular disseminated
coagulopathy, cardiac failure), one patient of multi-organ
failure following hemorrhagic shock and one patient
presented sudden cardiac arrest. Four out of these 5 deceased
patients were examined with CTA first. Twenty-eight
patients (15.3%) were referred after initial evaluation in a
regional center. The CTA group had the higher
proportion of referred patients (34.4%) compared with the LE
group (9.8%). Patients’ hemodynamics are detailed in
Comparison of baseline characteristics of patients who had CTA and patients
who had LE. Significant P-values (<0.05) are indicated in bold characters. SI is
defined as HR/Systolic blood pressure
CTA Computed tomographic angiography, LE Lower endoscopy, Hb
Hemoglobin level, MAP Mean arterial pressure, HR Heart rate, SI Shock index
MAP (mmHg), Mean ± SD 93 ± 18
Hb (g/L), Mean ± SD
Fig. 1 Study flow chart. Lower gastrointestinal bleeding (LGIB), Computed tomographic angiography (CTA), Lower endoscopy (LE)
with 0.72 ± 0.27 versus 0.63 ± 0.18 in those of LE group
(P = 0.082). No significant difference was observed in
the comparison of HR at admission in both groups
Radiological and endoscopic findings
In the first 3 years of the study period, LE was the
predominating diagnostic tool, while CTA gained of
importance in the second part of the study period only (Fig. 2).
Following hospital admission, CTA was performed
significantly earlier than colonoscopy, after a median of 3
(IQR = 8.2) versus 22 (IQR = 36.9) hours (P < 0.001).
Active bleeding was found significantly more frequently
with CTA compared to LE (31.3 vs. 14.8%, P = 0.031). A
non-active bleeding source was identified in 21.8 vs. 31.1%
by CTA and LE, respectively (P = 0.305). The rate of
inconclusive exams was similar in both groups (46,9 vs.
54.1%, P = 0.396).
Patients presenting post-interventional bleeding were
mostly evaluated by LE first, and rarely by CTA first
(73.9 vs. 8.7%, respectively). Patients with small bowel
bleeding underwent predominantly CTA first (55%)
compared to LE first (20%), this difference was
statistically significant (P <0.001).
The control of bleeding was achieved by conservative
measures in 120 (65.6%) patients, by endoscopic
intervention in 34 (18.6%), by surgery in 26 (14.2%) and by
embolization in 3 patients (1.6%), respectively. There
were no differences in the rate of conservatively
managed patients in the CTA group compared to the LE
group (56.3 vs. 61.5%, P = 0.591). A summary of the final
bleeding control according to the first exam used is
shown in Fig. 3. Active bleeding on CTA was found in
10 patients and surgery was needed for the final control
of the bleeding in 80% of cases, whereas the remaining
20% of patients were treated conservatively. After
positive CTA for these 10 patients, 4 underwent surgery
directly, 3 LE and 3 angiography. All 3 LE were
inconclusive because of impaired vision due to blood clots,
and only 1 out of 3 angiographies was positive allowing
embolization in one single patient who eventually
needed surgery for re-bleeding. In all these cases except
for one, the bleeding localization was confirmed by the
pathology report. Patients presenting post-interventional
bleeding were primarily controlled by LE in 57%.
Patients with small bowel bleeding needed more often
surgery (35%) compared with other pathologies (Fig. 4).
Of the 29 patients with no exam during hospital stay, 27
patients had conservative treatment and 2 underwent
immediate invasive treatment due to hemodynamic
instability. Embolization was performed for 1 patient and
1 patient underwent surgery directly. The remaining 27
patients were not further examined because of clinically
minor bleeding, with spontaneous resolution.
The results of this study suggest that CTA may be a
good choice in most patients with LGIB despite the fact
that LE was the most used modality in our series and
remains best choice for post-interventional bleeding. CTA
was quickly available, reliable to indentify the bleeding
source and helpful to guide further management.
In the group of patients assessed by CTA first, a
significantly greater rate of active bleeding was observed
compared to patients examined with LE first (31.3 vs.
14.8%, respectively, P = 0.031). While the shorter waiting
Fig. 2 Proportion of first diagnostic intervention per year. Computed tomographic angiography (CTA), Lower endoscopy (LE)
Fig. 3 Flow chart of the bleeding control according to the first exam used. Values are presented as number of patients. Computed tomographic
angiography (CTA), Lower endoscopy (LE)
time in the CTA group very likely increased the chance
to identify actively bleeding lesions, the delay taken to
perform LE increased the chance for spontaneous
bleeding cessation. Delay in performing LE is explained by
prior bowel preparation and limited gastroenterology
consultant availability out of office hours. Nonetheless,
about half of the exams were inconclusive in both
groups, without significant difference. In a study
including 115 patients with LGIB who underwent CTA, Chan
& al. found that 77% of patients with negative studies
did not need further intervention. In 68% of cases the
exam did not show features of active bleeding, which is
consistent with the present findings .
In the literature, the optimal time point of colonoscopy
for LGIB remains controversial. In a retrospective analysis,
Strate & al. revealed that shorter time to colonoscopy was
an independent predictor of shorter LOS, particularly if
colonoscopies were performed within 12–24 h . A further
trial confirmed that the source of bleeding was more
frequently found with urgent colonoscopy (within 8 h)
compared to elective colonoscopy (within 4 days) . On the
other hand, in a randomized trial comparing colonoscopies
performed within 12 h of presentation to those executed
within 36–60 h, the authors did not show differences in
clinical outcomes. However non-diagnostic colonoscopies
were more common in the elective group .
In this series, 65.6% of patients had spontaneous
cessation of bleeding regardless of the first diagnostic exam
chosen. This suggests that most patients presenting with
LGIB can be managed conservatively. In the literature,
self-limiting LGIB rates of up to 80% have been reported,
especially in case of diverticular bleeding [4, 11, 12].
Fig. 4 Bleeding control according to the final diagnostic
Surgery was required in 14% of patients in this serie
which is similar to the published range of 2.6 to 18%
[8, 9, 13, 14]. In-hospital mortality was 2.7% in the
present study. Previously published mortality rates
ranged from 2.4 to 8.8%, [3, 8, 13, 15].
The present results suggest that most patients with
post-interventional bleeding were effectively treated with
colonoscopy. In this sub-group of patients, examination
with CTA was not necessary, and patients should
directly undergo early colonoscopy to confirm diagnosis
and deliver treatment at the same time. In the literature,
several authors reported successful endoscopic
management of post-polypectomy bleeding for most patients
[16–18]. In the present series, 80% of patients with
active bleeding on CTA required surgery for bleeding
control. This is in line with Chan & al. reporting about
90% of patients with LGIB and positive CTA needing
intervention for bleeding control. However, surgery was
performed in 24% of cases whereas embolization was
successful in 64% of patients . In a study from Nagata
& al., early colonoscopy following CTA resulted in a
higher detection rate of colonic vascular lesions than
colonoscopy alone . These results contrast the present
findings were all 3 LE performed after positive CTA were
negative due to impaired visualization. Koh & al.
suggested that angiography should be performed as soon as
possible after positive CTA to allow embolization .
In their series, angiography was performed only after
CTA with signs of active bleeding and about half of
them were negative. In the present study, only 3
patients underwent angiography after positive CTA, 2 of
them were negative and one patient underwent
embolization first, followed by salvage surgery because
of early re-bleeding.
Based on these findings, our own institutional
algorithm for the management of LGIB was adapted (Fig. 5).
For post-interventional bleeding, urgent LE is advocated.
Patients presenting with minor bleeding can be observed
and prepared for elective colonoscopy within 24 h.
Patients presenting with more significant bleeding should
undergo CTA as first-line procedure. It is hypothesized
that this algorithm may help to decrease time to diagnosis
and guide successful treatment. In published practice
guidelines algorithms, radionuclide red blood cell scan
followed by mesenteric angiography is indicated for
patients unfit for colonoscopy or those with failed
endoscopic therapy, but use of CTA is not included [1, 4].
Other authors have integrated CTA in their management
algorithm. Copland & al. proposed, for clinically active
bleeding, CTA as first-line procedure after exclusion of
UGIB with nasogastric lavage. Colonoscopy is then
performed if CTA localized the bleeding . Another report
proposed an algorithm including CTA for all patients with
LGIB . Chan & al. proposed a management pathway
including CTA after negative endoscopic evaluation .
The fact that so much various algorithms are proposed
suggests that further research is needed.
This study has several limitations besides its
retrospective design and a limited number of patients. Within
the study period, there was a change in care providers
and hence in practice. Furthermore, the choice of the
first diagnostic exam was decided by the treating
physician. Significant lower MAP and trends to lower Hb
level and higher SI indicate a selection bias as the
severely affected patients were more likely to undergo
CTA first. Longer LOS in the CTA group also probably
reflects the greater severity of the bleeding. Patients’
comorbidites, medication, medical or surgical history also
probably led to a selection bias in the choice of the first
exam. The retrospective nature of the study precluded
us to ensure a valid comparison. We could not account
for the delay in performing LE during the night, as the
gastroenterology consultant’s availability was lower
outside office hours.
Fig. 5 Management of acute lower gastrointestinal bleeding, proposed algorithm. Minor bleeding is defined as patients presenting without signs of
hemodynamic comprise, need for transfusion or ongoing bleeding. Computed tomographic angiography (CTA)
In conclusion, our analysis describes current practice of
management for LGIB in a “real-world” setting in order
to propose a new treatment algorithm that needs to be
evaluated prospectively. The present study suggests that
CTA is an efficient and readily available tool to manage
patients with LGIB. CTA could be considered a suitable
first diagnostic option for acute LGIB except for
postinterventional bleeding which should entail immediate
LE. However, most patients with LGIB can be treated
Availability of data and material
The data supporting the findings of this study are available from University
Hospital of Lausanne (CHUV) but restrictions apply to the availability of these
data, which were used under permission for the current study, and so are not
publicly available. Data are however available from the authors upon
reasonable request and with permission of University Hospital of Lausanne
DC: design, analysis and interpretation, drafting/FG: analysis and interpretation,
critical revision/MS: design, interpretation, critical revision/AD: design,
interpretation, critical revision/ND: conception, interpretation, critical revision/
MH: conception and design, analysis and interpretation, drafting/All authors
approved the final version.
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