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Difficulty: MediumPediatric Gastrointestinal Disorders

A 22-year-old boy is brought to the emergency department by his parents after they noticed a large amount of maroon-colored stool in his diaper this morning. He has had one additional bloody bowel movement since arrival. The parents report that the child has been completely asymptomatic otherwise; he has had no fever, vomiting, diarrhea, or apparent abdominal pain, and his appetite has been normal. He has no significant past medical history and has met all developmental milestones. Vital signs are temperature 37.1∘37.1^\circ C (98.8∘98.8^\circ F), blood pressure 95/6095/60 mm Hg, pulse 115115/min, and respiratory rate 2222/min. Physical examination reveals an alert and playful child. The abdomen is soft, non-distended, and non-tender to palpation, with no palpable masses. Laboratory studies show a hemoglobin level of 10.410.4 g/dL and a platelet count of 250,000250,000/mm 3^3. Which of the following is the most appropriate next step in the diagnostic evaluation of this patient?

  1. A
    Abdominal ultrasonography
  2. B
    Colonoscopy
  3. Technetium-99m pertechnetate scanAnswer
  4. D
    Contrast enema
  5. E
    Immediate exploratory laparotomy

Answer

Technetium-99m pertechnetate scan
The patient is a toddler presenting with painless lower gastrointestinal bleeding (hematochezia), which is the classic presentation of a Meckel diverticulum. Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract and frequently contains ectopic gastric mucosa. This ectopic tissue secretes hydrochloric acid, which can ulcerate the adjacent normal ileal mucosa, leading to painless bleeding. Because the patient is hemodynamically stable, the most appropriate initial diagnostic test is a technetium-99m pertechnetate scan (Meckel scan), which specifically identifies and localizes the ectopic gastric mucosa.

Step-by-Step Solution

1
Analyze the patient's demographic profile and presenting symptoms.
The patient is a toddler presenting with large-volume, painless lower gastrointestinal bleeding (maroon stool) and a completely normal physical examination.
Identifying the pattern of isolated, painless bleeding in this specific age group significantly narrows the differential diagnosis.
2
Rule out alternative causes of pediatric gastrointestinal bleeding based on clinical stability.
The absence of severe, colicky pain and lethargy rules out intussusception. Normal vital signs indicate the patient is hemodynamically stable, eliminating the need for immediate surgical exploration.
Ruling out emergent or obstructive pathologies dictates whether the next step should be interventional or diagnostic.
3
Determine the most likely underlying condition and select the appropriate initial test.
The clinical picture is classic for a Meckel diverticulum, which often contains ectopic gastric mucosa that causes bleeding. The diagnostic test of choice is a Meckel scan.
A technetium-99m pertechnetate scan specifically localizes the ectopic gastric tissue responsible for the ulceration and bleeding.

Key Concept

Painless lower gastrointestinal bleeding in a toddler is highly suspicious for a Meckel diverticulum, which is best diagnosed using a technetium-99m pertechnetate scan to detect ectopic gastric mucosa.
Estimated Time:1m 0s
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Topics

Pediatric Gastrointestinal Disorders

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