Constipation, Iron Deficiency Anemia and Positive Fecal Occult Blood. Is it Colon Cancer? Not So Fast.

Author: V. Dimov, M.D.
Reviewer: S. Randhawa, M.D.

A 73-year-old Caucasian male (CM) with a negative past medical history (PMH) who never was followed by a doctor is admitted to the hospital with a chief complaint (CC) of constipation for 3 months. He also complains of profound weakness and exertional chest pain (CP), and shortness of breath (SOB) for that last 3-4 weeks.

He used to have daily bowel movements but starting 3 months ago he started to complain of severe constipation, passing large amount of hard stool. He had black bowel movements during the last week. He gained 15 pounds during the last year.


Advil (ibuprofen) PRN.

Physical examination

Stable vital signs (VSS).
Chest: CTA (B).
CVS: Clear S1S2.
Abdomen: Soft, NT, NS, +BS. The examination of the perirectal area exam showed a large lobulated pedunculated mass, measuring around 11 cm (the patient has had this tumor-like structure for a long time). The rectal examination showed guaiac positive stools.
Extremities: no c/c/e.

What is the most likely diagnosis?

Colon cancer until proven otherwise?
Peptic ulcer disease (PUD)?
Only the weight gain history does not fit the picture.

What laboratory work (labs) would you order?

CBC showed anemia with hemoglobin (Hgb) 5.7 mg/dL. He was transfused 2 inits (U) of packed red blood cells (PRBC) with an increase of Hgb to 9 mg/dL. MCV was 77 fL and the iron (Fe) profile showed a severe iron deficiency anemia. He was ruled out for acute coronary syndrome (ACS) on admission.

Anemia labwork (left); iron profile (right) (click to enlarge).

What would you do next?

A GI consult was called for upper and lower endoscopy. The patient had both procedures during the same session and they did not reveal a bleeding source but were interesting to have a look at and are posted below.

Esophagogastroduodenoscopy (EGD)

Esophagogastroduodenoscopy (EGD) (click to enlarge) shows superficial gastric erosions (upper right) from Advil (ibuprofen) use. The erosions were not the cause for the bleeding. The large hiatal hernia was not the likely cause of his symptoms. He also has lesions of Barrett's esophagus seen like "tongues" of darker-pink mucosa spreading upwards (lower left).


There was evidence of poor preparation ("prep") due to his severe constipation. You can see the appendix opening under the flushing fluid (six 50-ml syringes with normal saline), the gastronterologist was trying to clean out the stool and described the procedure as "a bit like scuba diving (upper left). There is a glimpse at the ileum mucosa which looks "velvety" as compared to the smooth shiny surface of the colon. It looks like we are "peeking through a key hole" (upper right). The ileocecal valve is looking like a cup (lower left).

Upper and lower endoscopies were negative. What is the source for bleeding?

Arteriovenous malformation (AVM)?
Small bowel tumor?

The most likely source of bleeding in this patient is a small bowel AVM. It does not look like an acute bleeding judging from the time needed to get such a low MCV in iron deficiency anemia.

What happened?

The patient was given iron sucrose 300 mg IV x 3 every other day (QOD) and subsequent oral iron replacement. The treatment team continued to watch closely his Hgb. If there was a further Hgb decrease, the patient would have needed a capsule enteroscopy to search for an AVM.

What happened to the perirectal tumor?

This is most likely a hypertrophied skin tag although we have never seen one so big. The patient was going to have a surgical excision with a pathology review of the lesion as an outpatient.

Final diagnosis

Iron deficiency anemia most likely due to an arteriovenous malformation (AVM).

What did we learn form this case?

Do not jump to conclusions. Even if it seems like everything is leading you to one diagnosis, this does not mean that your presumption will be right. Remember the saying "It may walk like a horse and talk like a horse but it may still be a cow."

Most AVM's (78%) occur in the cecum or right colon, the jejunum being the next most common site. Patients with AVM's tend to be elderly with a strong history of cardiovascular disease. A potential association between aortic stenosis, intestinal bleeding, and AVM's is suggested.

The cause of bleeding in many patients with recurrence remains undiagnosed despite repeat angiography.


Iron Deficiency Anemia. AFP, March 1, 2007.
Iron Deficiency Anemia. Marcel E Conrad, MD, BS. eMedicine Specialties, 2006.
Anatomic Features of AVM. GI Care.
Arteriovenous malformations of the bowel: an analysis of 22 cases and a review of the literature. Meyer CT, Troncale FJ, Galloway S, Sheahan DG. Medicine (Baltimore). 1981 Jan;60(1):36-48.
Arteriovenous malformation in chronic gastrointestinal bleeding. C M Cavett, J H Selby, J L Hamilton, and J W Williamson. Ann Surg. 1977 January; 185(1): 116–121.
Angiodysplasia of the Colon. eMedicine Specialties, Gastroenterology, Colon, 2006.

Published: 03/01/2004
Updated: 12/15/2008


  1. We just saw a similar one of these growing out of a nipple. We are referring to Surgery. What did your path results show?

  2. Hi! thanks for posting this really interesting one! Please let us know the cause of constipation here!

  3. The most likely cause (diagnosis of exclusion) was AVM.

  4. is AVM the same as angiodysplasia?

  5. Yes, it is. AVM = angiodysplasia.

    See here:

    "Galdabini first used the name angiodysplasia in 1974; however, confusion about the exact nature of these lesions resulted in a multitude of terms that included arteriovenous malformation, hemangioma, telangiectasia, and vascular ectasia. These terms have varying pathophysiologies, with a common presentation of GI bleeding."

  6. Yes but what caused the constipation???