Child with punctate opacities in the colon

April 1, 2019

An 11-year-old male presents to the emergency department (ED) with complaint of 2 days of focal, crampy, periumbilical abdominal pain associated with anorexia, fever, and 1 episode of emesis. What's the diagnosis? 

The case

An 11-year-old male presents to the emergency department (ED) with complaint of 2 days of focal, crampy, periumbilical abdominal pain associated with anorexia, fever, and 1 episode of emesis. The patient denies diarrhea, cough, and testicular pain. He does report decreased oral intake along with decreased urination accompanied by mild suprapubic pain and no bowel movement for 3 days. The remaining review of systems is negative. Parents of the patient deny attempts of using laxatives or any other medications to alleviate the symptoms.

Evaluation and testing

On physical exam, the patient was afebrile. The abdomen was soft and nondistended but had diffuse lower abdominal tenderness, rebound tenderness, and a positive Rovsing sign. Digital rectal examination was deferred.

Labs showed white blood cells at a level of 11.6 K/mcL; absolute neutrophil count, 7.37 K/mcL; C-reactive protein, 2.97 mg/dL; hemoglobin, 12.8 g/dL; hematocrit, 36.5%; platelets, 244 K/mcL; creatinine, 0.6 mg/dL; and sodium, 132 mmol/L. All other electrolytes were normal. Urinalysis was normal. On abdominal ultrasound, no fluid collection or abscess was identified, and the appendix was not visualized. An x-ray of the chest looking for pneumonia showed no acute findings.

The patient was admitted for observation because of concern for early/possible retrocecal appendicitis. The following day, abdominal single-view x-ray was performed to evaluate constipation (Figure) and revealed punctate opacities equally distributed throughout the colon suggestive of ingested material, a moderate amount of stool in the rectosigmoid colon, and a nonobstructive bowel gas pattern.

Differential diagnosis

The abdominal radiograph observed in this patient was novel to the Radiology Department and concerning for possible ingestion of lead, antacids, bismuth medication, or heavy metal. Differential diagnosis ranged from ingestion of a radiopaque substance to chronic inflammation (Table).

It is important to consider ingestion of heavy metals, such as lead, when punctate opacities in the bowels are observed. Lead ingestion can occur from a number of household objects including paint, fishing sinkers, jewelry, curtain weights, and traditional medicines. Depending on the source ingested, abdominal radiographs may appear punctate and similar to this case or vastly different in distribution.1,2 Absorption of lead is increased relative to retention time in the stomach and intestine, so early detection of this heavy metal ingestion is imperative for best outcomes.3

In addition to lead, mercury is an accessible agent that can be readily ingested by a child. However, these radiopacities may appear more amorphous because of the liquid state of this metal at body temperature.4 Fortunately, ingestion of elemental mercury is benign and absorption by the gastrointestinal tract is unlikely in healthy patients. There is an exception in patients with diverticulosis and other disease states in which ingested mercury remains in the gut for longer periods of time, leading to possible systemic absorption secondary to bacterial metabolism to organic mercury. Conversely, ingestion of organic mercury compounds may be readily absorbed.5

Also common in the pediatric population is ingestion of potentially toxic amounts of iron supplements. Ferrous sulfate tablets are notoriously found as round radiopacities on plain film x-ray, often mistaken for pathologies such as gallstones.6,7 Chewable, iron-containing multivitamins are radiopaque in vitro, but clinical radiographic visualization of this material has been found to be unreliable.8 An additional potential etiology of these radiographic findings, albeit rare in the pediatric population, is colonic diverticulosis with calcifications. The literature identifies a few cases of pediatric colonic diverticular disease secondary to total colonic Hirschsprung disease, connective tissue disease, cystic fibrosis, chronic renal failure, and other genetic syndromes.9-11

Discussion

Through further history elicited from the parents, it was revealed that the patient was given bismuth subsalicylate chewable tablets, colloquially known as Pepto-Bismol (Procter & Gamble; Cincinnati, Ohio) for the 2 days leading up to admission. This history was not disclosed until the parents were specifically questioned about the use of Pepto-Bismol.

The heavy metal bismuth appears sufficiently radiopaque on plain film and can be visualized in the gastrointestinal tract after Pepto-Bismol ingestion.12 The discoloration effects of Pepto-Bismol on stool and the tongue are well known and described on the medication’s drug facts. However, the possibility of bismuth appearing incidentally on abdominal radiograph is not well known. As many patients do not recognize that disclosing over-the-counter medications is important, it is imperative that specific questioning is utilized when there is suspicion for ingestion or poisoning.

The literature describes 1 case of a 45-year-old male presenting with disorientation, tinnitus, and tachypnea after consumption of 16 ounces of Pepto-Bismol daily to self-medicate unrelenting abdominal pain.13 This patient exceeded the daily dosage by more than 4 times the recommended amount at 4160 mg of salicylate and 8383 mg of bismuth daily, which began to accumulate in chronic stores. The patient was found to have similar abdominal radiograph findings as the patient in this case, acute salicylate toxicity, and profound acidosis, and was treated with forced alkalinized diuresis and hemodialysis. One should note that overuse of bismuth subsalicylate can present as chronic or acute salicylate toxicity.14-16

The clinicians managing the patient in this current case had low suspicion of acute salicylate toxicity based on the dosages disclosed by the parents and absence of tinnitus, tachypnea, and disorientation. However, if clinical evidence of toxicity had been present, a serum salicylate and urine bismuth level would have been obtained.

Patient follow-up

The diagnosis of constipation was made with incidental radiographic evidence of bismuth ingestion. The patient was given polyethylene glycol 3350 daily for 7 days and was discharged home, as no specific treatment is required for bismuth ingestion. He had resolution of his constipation and no follow-up radiography was indicated.

Conclusion

The ability to differentiate radiographic findings in the pediatric population as incidental versus disease-related will aid clinicians by preventing further unnecessary evaluation and testing. Radiologists and pediatricians should recognize that Pepto-Bismol ingestion is a possible etiology of punctate radiopacities found in the colon that can lead to acute or toxic salicylate toxicity. Additionally, ingestion of other foreign bodies must always be considered.

References:

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12. Hunter TB, Taljanovic MS. Foreign bodies. Radiographics. 2003;23(3):731-757.

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14. Sainsbury SJ. Fatal salicylate toxicity from bismuth subsalicylate. West J Med. 1991;155(6):637-639.

15. Vernace MA, Bellucci AG, Wilkes BM. Chronic salicylate toxicity due to consumption of over-the-counter bismuth subsalicylate. Am J Med. 1994;97(3):308-309.

 

16. Parker V, Goldberg D, King MA. Case 1: Mysteriously rising salicylate levels in a 15-year-old girl. Pediatr Rev. 2017;38(6):280-281.

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