Most Missed Question in Internal Medicine Exam Prep This week
A 52-year-old postmenopausal woman presents to you for the management of recently discovered iron deficiency anemia. She has a glycated hemoglobin level of 8.7 g/dL and a ferritin level below 5 ng/mL. She has a history of ovarian cancer with debulking surgery 3 years prior and partial small bowel obstruction 2 years ago.
She denies any changes in her bowels, changes in weight, or any new symptoms. Further workup reveals guaiac plus brown stools, and subsequent esophagogastroduodenoscopy (EGD) and colonoscopy do not reveal a source of bleeding. Small bowel biopsies do not demonstrate villous atrophy.
In addition to starting iron replacement, what is the next step in the management of this patient's condition?
Answers:
- computed tomography (CT) enterography
- capsule endoscopy
- position emission tomography (PET)
- diagnostic laparoscopy
- start estrogen/progesterone therapy
The correct answer is (1), CT enterography.
The recurring theme in missed exam questions in Internal Medicine is usually about overlooking signs and symptoms. Kind of the nature of the specialty field. (The same way we see a lot of misses in Emergency Medicine where they focus on a presenting trauma and miss internal injuries or conditions). If there's a lesson to be learned in Internal Medicine, it's to rigorous diagnosis.
Why This Question Is Often Missed
– Clinicians may default to capsule endoscopy after negative EGD/colonoscopy, overlooking the risk of obstruction in a patient with prior small-bowel surgery or partial obstruction.
– The absence of overt bleeding and negative small-bowel biopsies can lead to underestimating the likelihood of a small-bowel lesion requiring cross-sectional imaging first.
What the Distractors Indicate
| Option | What It Tests / Implies | Why It’s Wrong Here |
|---|---|---|
| computed tomography (CT) enterography | Recognition of non-endoscopic imaging for small-bowel evaluation | Correct—safe in partial obstruction and excellent for detecting masses or strictures. |
| capsule endoscopy | Knowledge of endoscopic visualization of the small intestine | Risky in partial obstruction; contraindicated without prior imaging to exclude strictures. |
| positron emission tomography (PET) | Understanding of metabolic imaging for malignancy recurrence | Low sensitivity for small bleeding sources; not first-line for obscure GI bleeding. |
| diagnostic laparoscopy | Surgical exploration to directly visualize and biopsy small bowel | Invasive; reserved for when noninvasive imaging is unrevealing or if an acute surgical pathology. |
| start estrogen/progesterone therapy | Recognition of HRT for menopausal symptoms and possible anemia improvement | Irrelevant to iron deficiency anemia workup; won’t address bleeding source. |
High-Yield Pearl
Iron deficiency anemia with negative EGD/colonoscopy and partial small-bowel obstruction mandates cross-sectional imaging (CT enterography) before capsule endoscopy.
Core Learning Objectives
- Identify appropriate next-step modalities for obscure GI bleeding in patients with suspected small-bowel obstruction.
- Understand contraindications to capsule endoscopy and when to favor imaging over endoscopy.
The “Test Trick” at Play
The question leverages the common trap of jumping to capsule endoscopy after negative bidirectional endoscopies; it tests whether you recognize that a history of small-bowel surgery and partial obstruction shifts the next diagnostic step toward imaging first.
Additional Practice Questions and Remediation
Question 1
A 60-year-old man with chronic melena and iron deficiency anemia underwent negative EGD and colonoscopy. He reports intermittent crampy abdominal pain and bloating. Which is the best next step?
A. CT enterography
B. Capsule endoscopy
C. Technetium-99m RBC scan
D. Push enteroscopy
Answer and Remediation
Remediation
- If you chose A: Correct response! CT enterography evaluates small-bowel lesions safely in the setting of intermittent obstruction.
- If you chose B: Review: Capsule endoscopy is contraindicated if there is suspicion of obstruction.
- If you chose C: Review: RBC scan detects active bleeding but is insensitive for low-grade bleeding and doesn’t localize strictures.
- If you chose D: Review: Push enteroscopy only reaches proximal jejunum and misses mid/distal lesions.
Question 2
A 48-year-old woman with celiac disease presents with fatigue and new iron deficiency anemia. EGD, colonoscopy, and duodenal biopsies are normal. She has mild post-prandial discomfort but no frank obstruction. Next diagnostic step?
A. CT enterography
B. Video capsule endoscopy
C. MR enterography
D. Diagnostic laparoscopy
Answer and Remediation
Remediation
- If you chose B: Correct response! In absence of obstruction, capsule endoscopy is first-line for small-bowel mucosal disease.
- If you chose A: Review: CT enterography is useful but capsule endoscopy is more sensitive for mucosal lesions without obstruction.
- If you chose C: Review: MR enterography is alternate but less available and lower resolution than capsule for mucosal detail.
- If you chose D: Review: Invasive; reserved after noninvasive modalities fail.
Question 3
A 70-year-old man with a history of Crohn’s disease presents with iron deficiency anemia and melena. Prior small-bowel resection raises concern for strictures. EGD and colonoscopy are unrevealing. Next step?
A. Video capsule endoscopy
B. CT enterography
C. Double-balloon enteroscopy
D. Technetium-99m pertechnetate scan
Answer and Remediation
Remediation
- If you chose B: Correct response! CT enterography is preferred to assess for strictures prior to endoscopic evaluation.
- If you chose A: Review: Capsule endoscopy risks retention in strictures.
- If you chose C: Review: Double-balloon enteroscopy is invasive and used after imaging localizes a lesion.
- If you chose D: Review: Meckel scan only detects ectopic gastric mucosa, unlikely here.
Mini Case Discussion Prompt
Discuss how the presence of small-bowel motility disorders versus structural lesions influences your choice between CT enterography, MR enterography, and capsule endoscopy.
