Lower gastrointestinal bleeding refers to bleeding from the small and large intestines. Common causes include hemorrhoids, diverticulosis, angiodysplasia, inflammatory bowel disease, colon polyps and cancer. Diagnostic evaluation involves colonoscopy, CT/CT angiography, capsule endoscopy, nuclear scintigraphy and angiography. Colonoscopy allows for both diagnosis and treatment but other imaging modalities are useful when colonoscopy is non-diagnostic or not possible. Angiography can localize the bleeding site and provide therapeutic embolization in unstable patients. Surgical or endoscopic intervention may be needed depending on the cause of bleeding.

1. LOWER GI BLEED

2. • Gastrointestinal bleeding is typically categorized
as either upper or lower gastrointestinal
bleeding depending on the anatomic location of
the bleeding site.

7. • The celiac axis and the superiormesenteric artery (SMA) are the
first two branches of the abdominal aorta and provide a rich and
well-collateralizednetwork of branch vessels that supply blood to
the upper gastrointestinal tract.
• Extensive collateralizationbetween the celiac artery and the SMA
protects the upper gastrointestinal tract from ischemic insult and
permits surgical and embolizationprocedures to be carried out with
a relatively low risk of ischemic injury.

8. • Upper GI- Esophagus, stomach and duodenum
• Lower GI – Small and large bowels.

9. • Haematemesis : Vomiting of blood whether fresh and red or
digested and black.
• Melaena : Passage of loose,black tarry stools with a characteristic
foul smell.
• Coffee ground vomiting : Blood clot in the vomitus.
• Hematochezia : Passageof bright red blood per rectum (if the
haemorrhage is severe).

10. Blood on its own or streakingthe stool:
• Rectum : polyps or carcinoma,prolapsed
• Anus : Haemorrhoids, Fissure-in-ano,Anal carcinoma.
Stool mixed with blood:
• GIT above sigmoid colon.
• Sigmoid carcinoma or diverticulardisease.
Blood separatefromthe stool:
• Follows defaecation: Anal condition eg: Haemorrhoids.
• Blood is passed by itself : Rapidly bleeding carcinoma,inflammatory
bowel disease, diverticulitis, or passed down from high up in the gut.
Blood is on the surfaceof the stool: suggest a lesion such as polyp or
carcinomafurther proximallyeither in the rectum or descendingcolon
Blood on the toilet paper: Fissure-in-ano, Heamorrhoids.
Loose, black, tarry, foul smelling stool: from the proximal of DJ flexure

11. Causes
Small intestine Colon
IBD
Polyps
Meckel’s diverticulum
Bleeding diathesis
Angiodysplasia
Carcinoma
Polyps
Diverticular diseases
Angiodysplasia
Rectum Anus
Rectal carcinoma
Polyps
Prolapse
Hemorrhoids
Fissure-in-ano
Anal carcinoma
Warts

12. • ANATOMIC : Hemorrhoids,diverticula
• VASCULAR: Angiodysplasia,ischaemia,radiationinduced,
aortocolonicfistula
• INFLAMMATORY : Infectious and non-infectious
• NEOPLASTIC: Colorectal carcinoma and polyps

13. • Risk factors include :
• medications (e.g. NSAID, warfarin)
• recent colonoscopy with polypectomy (post polypectomy bleeding)
• prior abdominal/pelvic radiation (radiation proctitis/colitis)
• prior surgery
• history of alcoholism or chronic liver disease
• history of abdominal aortic aneurysm with or without surgical repair
(causing an aortoenteric fistula)

14. Imaging
• Colonoscopyis the first-line investigationfor both diagnosticand
therapeutic management.CT angiography(CTA), nuclear medicine
studies,and angiographycan all be used to assess LGIB but have
limited sensitivity when bleeding is intermittent or slow.

15. CT
• On non-contrast CT, hemorrhagemay be visualized as
circumferential thickeningof the bowel wall
• CTA provides a relatively non-invasiveand effective way of
localizing the source of bleeding,especially in patients with
continuous bleeding

16. • In some cases, while there is no evidence of active
extravasation, a sentinel clot (seen as an unchanging
hyperdensity) can be used to localize the site of recent
bleeding.
• Even in situations in which no acute bleeding is identified,
CTA can diagnose abnormalities that may be responsible
for the bleeding, such as ischemia, inflammatory bowel
disease, neoplasms and arteriovenous malformations
(AVMs) .
• CTA therefore provides an excellent road map guiding the
next step in triaging patients to either endoscopic, surgical
or angiographic management.

18. • Multiphase CTE
• MultiphaseCTE is most useful in evaluating hemodynamically
stable patients with intermittentand occult GI Bleeds, which
commonly have an underlyingsmall bowel source.
• The main difference between a multiphaseCTE and routine CTA
is that in a CTE study,the small bowel lumen is distendedwith a
bolus (about 1.5–2.0 litres) of a neutral oral contrast agent. This
luminal distentionallows optimal visualizationof enhancement
of the small bowel mucosa and wall following intravenous
contrast administration,thereby increasing the sensitivityof
detection of bleeding and non -bleedingabnormalities

19. Advantages Disadvantages
Non-invasive
Good localisation rate
Provides anatomic details
No bowel preparation
Requires active bleeding
Not therapeutic
Radiation exposure
IV contrast.

20. NUCLEAR IMAGING
• Erythrocytes are labeled with technetium-99m, then serial
scintigraphy is performed (a.k.a. 99mTc-labeled RBC
scintigraphy or tagged red blood cell scan) to detect focal
collections of radiolabelled material.
• It can be performed relatively quickly and may help
localize the general area of active bleeding to guide
subsequent endoscopy, angiography or surgery .
• A false-positive result can be produced by a rapid transit of
luminal blood so that labeled blood is detected in
the colon even though it originated from a more proximal
site in the gastrointestinal tract .

21. • Extravasated radiolabeled RBCs within the lumen of
the bowel are identified as an area of activity that
increases in intensity with time, and/or as a focus of
activity that moves in a pattern corresponding to the
lumen of the large or small bowel.
• Small bowel bleeding usually can be distinguished
from large bowel bleeding by its rapid serpiginous
movement

22. Delayed bleeding from a midjejunal site.
Findings at initial imaging performed 0-
60 minutes after injection were
normal. Anterior 5-minute static image
obtained 22 hours after injection
demonstrates activity throughout the
large bowel and in a few small bowel
loops in the pelvis (arrow).

23. Capsule endoscopy
• Also known as video capsule endoscopy (VCE) or wireless
capsule endoscopy,is a non-invasivemeans of investigating
the small bowel, principallyfor identifyingthe underlying cause
of occult gastrointestinal tract bleeding,such as due
to arteriovenous malformations,small bowel tumors, and
ulcers.
• It is also used for the detection of the earliest manifestations
of Crohn disease, such as mucosal ulceration,which are poorly
detected by other imaging modalities such as small bowel MRI or
ultrasound.

25. ANGIOGRAPHY
• Angiographyis an invasive examination that can be used for
accurate localizationas well as treatment of both upper and
lower gastrointestinal bleeding.
• Preffered in acutely unstablepatient,after a negative or failed
endoscopicevaluation,or as a first-lineexamination for lower
gastrointestinalhemorrhage.
• In patients with lower gastrointestinalbleeding who are
haemodynamically-stableand do not have ongoing fresh rectal
bleeding,an RBC-labeled Tc99m scan is recommended as a first
line of investigation.

26. • Angiographycan provide the opportunityfor therapeutic
interventionat the time of diagnosis .
• However, the bleeding rate must be ≥0.5 mL/min to detect
extravasation into the gut, which is significantlyhigher than in
nuclear medicine.
• Additionally,certain patient factors (e.g. contrast allergy,
acute/chronickidney disease) are potential contraindicationsto
angiography
• Extravasation of contrast material into the bowel lumen is
pathognomonicfor active gastrointestinal hemorrhage.
• Indirect signs includedetection of pseudoaneurysm,
arteriovenous fistula, hyperemia,neovascularity,and
extravasation of contrast material into a confined space

27. Active GI hemorrhage in a 67-year-old
woman with melena (a) Selective
angiogram of the gastroduodenal artery
shows contrast material extravasation
into the duodenal lumen(b, c)
Gastroduodenal artery (b) and celiac
trunk (c) angiograms, obtained after coil
embolization show stoppage of the GI
bleeding.

28. Active GI hemorrhage in an 82-year-old
man with hematochezia.
(a) Colonoscopic image of the right colon
shows a large quantity of blood, which
obscures the colonoscopic findings. (b)
Selective angiogram of the ileocolic
artery shows contrast material
extravasation into the colonic lumen . (c)
Ileocolic artery angiogram obtained after
coil embolization (arrow) shows
stoppage of the GI bleeding

29. A 70-year-old male presenting with bleeding per rectum and drop in
hematocrit. Colonoscopy was negative; underwent tagged RBC scan that
demonstrated site of active bleeding in the hepatic flexure of the colon
(A, arrow) which was subsequently embolized via conventional
angiography (B, C: arrowheads).

30. Finding Diagnosis
Extravasation Active bleed site
Filling of spaces outside the bowel
lumen
Aneurysm or pseudoaneurysm
Early arterial filling, accumulation in
vascular tufts, slow draining vessels
Angiodysplasia
Neovascularity Neoplasm
Hyperaemia Colitis

31. Advantages Disadvantages
Does not require bowel preparation
Can be done in emergency situation
Therapeutic uses
Low sensitivity rate
Requires active bleeding
Complication rate

32. Diverticula
• Outpouching of bowel wall
• Diverticulosis,Diverticulitis
• The site of protrusionis that of the
entry points of the bowel vascular
supply throughthe mesentery.
• In some cases, the incoming vessel
runs over the diverticulumdome. This
close relationshipis responsiblefor the
complicationof hemorrhage that results from diverticula.

36. Hemorrhoids
• Swollen veins in the lower
rectum
• Internal hemorrhoids often
result in painless,bright red
rectal bleedingwhen defecating
External hemorrhoids often result in pain and swelling in the area of
the anus
If bleeding occurs it is usually darker.
A skin tag may remain after the healing of an external hemorrhoid.

37. Perianal fistula
• presence of a fistulous tract across/between/adjacent to the anal
sphincters and is usually an inflammatorycondition
• Intersphincteric
• Transsphincteric
• Suprasphincteric
• Extrasphincteric

38. Angiodysplasia
• One of the most common causes of occult GI
bleed
• refers to dilated, thin-walled blood vessels
(capillaries, venules, veins) found in the
mucosa and submucosa of the
gastrointestinal tract

39. CT :
• appear as focal areas (<5 mm) of contrast enhancementin the
bowel wall (most prominent in the enteric phase )
• early filling of an antimesentericvein
Angiography:
• ectatic vessels but no discretelesion
• early venous enhancementindicatingarteriovenous shunting

41. Polyps
• adenomatous
• familial adenomatous polyposis syndrome (FAPS)
• Gardner syndrome
• attenuated FAP
• MYH syndrome
• hamartomatous
• juvenile polyposis syndrome
• Bannayan–Riley–Ruvalcaba syndrome
• Cowden syndrome
• Peutz-Jeghers syndrome
• Cronkhite-Canada syndrome
• mixed
• hereditary mixed polyposis syndrome

43. Aorto-Enteric fistula
• Aortoenteric fistulas are pathologiccommunicationsbetween
the aorta (or aortoiliac tree) and the gastrointestinaltract and
represent an uncommon cause of catastrophicgastrointestinal
hemorrhage

44. CT
Primary fistula Secondary fistula
Direct signs include:
• ectopic gas adjacent to or within the
aorta
• presence of vascular contrast within
the gastrointestinal tract
Indirect signs include:
• bowel/esophageal wall thickening
overlying an aneurysm
• disruption of the aortic fat cover
• retroperitoneal/mediastinal
hematoma or hematoma within the
bowel wall or lumen
• increased perigraft soft tissue
• pseudoaneurysm formation
• disruption of aneurysmal wrap
• increased soft tissue between the graft
and aneurysmal wrap

47. Colorectal carcinoma
• most common cancer of the gastrointestinal tract and
the second most frequently diagnosed malignancy in
adults
• Colorectal cancers can be found anywhere from the
cecum to the rectum, in the following distribution :
• rectosigmoid: 55%
• cecum and ascending colon: ~20%
• ileocecal valve: 2%
• transverse colon: ~10%
• descending colon: ~5%

48. IMAGING :
• Barium enema
• Appearances will reflect
macroscopicappearance,with
lesions seen as filling defects.
• These need to be differentiated
from residual fecal matter.
• Typicallythey appear as exophytic
or sessile masses or maybe
circumferential (apple core sign).
• Fistulas to bladder,vagina, or
bowel may also be demonstrated.

49. • CT :
• Used for staging
• soft tissue density that narrow the bowel lumen
• Ulceration in larger mass is also seen.
• Occasionally low-density masses with low-density lymph
nodes are seen in mucinous adenocarcinoma, due to the
majority of the tumor composed of extracellular mucin.
Psammomatous calcifications in mucinous adeno.ca can
also be present.
• Complications may also be evident, e.g.
fistulae, obstruction, intussusception, perforation

54. • Dukes (Astler-Coller modification)
• stage A: confined to mucosa
• stage B: through muscularis propria
• stage C: local lymph node involvement
• stage D: distant metastases

55. • MRI :
• MRI is having an increasing role to play in the staging of rectal
cancer

57. Thanq