ToxCard: Radiopaque toxins on radiography

Authors: Brian Shreve, MD (Emergency Medicine Resident, Carolinas Medical Center, Charlotte, NC), Ann-Jeannette Geib, MD (Emergency Medicine Attending, Medical Toxicologist, Carolinas Medical Center, Charlotte, NC) // Reviewed by: Cynthia Santos, MD (@Cynthia Santos, MD); Alex Koyfman, MD (@EMHighAK); and Brit Long, MD (@long_brit)

Case:

A 17-year-old male arrives via EMS confused and is having multiple episodes of nausea and vomiting. The history is limited but at the scene EMS found multiple pill bottles on the floor. He has an abdominal X-ray which is shown below:

Importance/Benefits of Imaging Studies in Poisoned Patients:

  • Laboratory screening with blood and urine can have long turnaround times and may not be available.
  • Toxicologic screening only affects management in 15% of cases (1).
  • Limited number of xenobiotics that are radiopaque thus limiting the number of agents that could have been ingested to a few entities (2).
  • Abdominal radiography can be used to quantify the amount involved which can be used to reassess efficacy of interventions through repeat imaging after gastrointestinal decontamination (2).

To aid in the memory of common radiopaque toxins a mnemonic has been developed.

C: Chloral hydrate/cocaine packets

O: Opiate packets

I: Iron and heavy metals

N: Neuroleptic agents

S: Sustained release products/enteric coated preparations

Limitations:

  • Radiographic appearance cannot identify the specific toxin that was ingested.
  • Many toxins are moderately radiopaque, and coupled with rapid dissolution these toxins may be impossible to detect.
  • Therefore, the utility of the presence or lack thereof of a radiopaque agent is dependent on the clinical scenario, and if misinterpreted may lead to a delay in diagnosis.
  • While the above mnemonic is useful in identifying the common radiopaque toxins, there are many other medications that are radiopaque not accounted for in the mnemonic.
  • O’Brien and colleagues examined 459 different medications and found that 29 of 459 drugs were equal to or more radiopaque than ferrous sulfate and 136 drugs were radiopaque. It is unclear whether they could be consistently identified on imaging in a clinical context (3).

A brief review of agents from the COINS mnemonic:

Chloral hydrate and other halogenated hydrocarbons:

  • Chloral hydrate is the agent in the mnemonic, but there are other halogenated hydrocarbons that are radiopaque such as carbon tetrachloride and chloroform.
  • Chloral hydrate, carbon tetrachloride, and chloroform have varying degrees of radiopacity which is proportionate to the number of chlorine atoms (7).
  • These substances will not dissolve in water and thus present with a triple layer seen in the stomach (air, radiopaque hydrocarbon layer, and lower gastric fluid); however, these ingestions are usually small and thus this imaging finding is rarely present (2).

Body Packers/Body stuffers:

  • Abdominal radiography has a sensitivity of 85-90% (2).
  • This sensitivity reflects that of patients with multiple packets and does not hold true in other situations (9).
  • Stools should be monitored. Repeat abdominal radiographs lack the sensitivity and specificity to safely disposition patients who presented as a body packer, and abdominal CT is recommended (6).
  • Body stuffers are much harder to detect using abdominal radiography unless it was a glass or thick plastic container, and plastic “baggies” are less commonly seen (2).

Ferrous sulfate:

  • Clear x-ray cannot exclude an ingestion as liquid, chewable, or encapsulated preparations rapidly disperse and are less radiopaque (4).

Heavy Metals:

  • Heavy metals include arsenic, cesium, manganese, mercury, and thallium.
  • Typically, heavy metals will produce significant GI distress with a spectrum ranging from nausea to acute GI bleeding.
  • Arsenic will typically present with extremely severe GI symptoms unlike a typical gastroenteritis.
  • Cesium will have pronounced cardiac effects with dysrhythmias but will also have neurologic manifestations of facial and acral paresthesias.
  • Manganese will be insidious in onset and will mimic Parkinson’s.
  • Thallium will have mild GI symptoms and is defined by alopecia and ascending peripheral neuropathy with preservation of reflexes, differentiating this from GBS.

Lead:

  • Imaging is beneficial in the case of patients eating paint chips containing lead.

Neuroleptic Agents:

  • Typically the phenothiazines and TCAs that are theoretically visual on abdominal radiographs.
  • TCAs were unable to be appreciated in a cadaver model, and prochlorperazine and trifluoperazine were able to be visualized (8).

Sustained-release medications:

  • Not all medications that have sustained release formulations are more radiopaque than their immediate release combinations.
  • Medications that utilized a capsule formulation to obtain a sustained release of the medications were more likely to be radiopaque (5).
  • These findings are not generalizable across the same agent, as manufacturers will use different formulations.

Moth Repellants:

  • There are multiple different types of mothballs with varying degrees of toxicity thus identification of the type of mothball ingested can be critical to patient care.
  • Paradichlorobenzene is moderately opaque and naphthalene is fairly radiopaque as compared to the non-radiopaque camphor (2).
  • In this case the naphthalene is important as paradichlorobenzene is non-toxic.

 

Summary:

  • Most toxicologic diagnoses are made based on the history and physical examination, but abdominal radiography can assist in making these diagnoses.
  • Care must be taken to interpret results of abdominal radiography in the context of clinical presentation.
  • Not all radiopaque agents are accounted for in the mnemonic COINS.
  • A negative abdominal radiograph after whole bowel irrigation in body packers is insufficient in ruling out retained packets.

 

References:

  1. Olson KR and Vohra R. Emergency Evaluation and Treatment. In: Olson KR, Anderson IB, Benowitz NL, et al. Poisoning and Drug Overdose, 7e. McGraw-Hill, 2012.
  2. Schwartz DT. Principles of Diagnostic Imaging. In: Nelson LS, Howland M, Lewin NA, Smith SW, Goldfrank LR, Hoffman RS. eds. Goldfrank’s Toxicologic Emergencies, 11e New York, NY: McGraw-Hill; . http://accesspharmacy.mhmedical.com.libproxy.lib.unc.edu/content.aspx?bookid=2569&sectionid=210267722. Accessed March 11, 2020.
  3. O’Brien, R. P., McGeehan, P. A., Helmeczi, A. W., & Dula, D. J. (1986). Detectability of drug tablets and capsules by plain radiography. The American journal of emergency medicine, 4(4), 302-312.
  4. Everson, G. W., Oudjhane, K., Young, L. W., & Krenzelok, E. P. (1989). Effectiveness of abdominal radiographs in visualizing chewable iron supplements following overdose. The American journal of emergency medicine, 7(5), 459-463.
  5. Tillman, D. J., Ruggles, D. L., & Leikin, J. B. (1994). Radiopacity study of extended-release formulations using digitalized radiography. The American journal of emergency medicine, 12(3), 310-314.
  6. Rousset, P., Chaillot, P. F., Audureau, E., Rey-Salmon, C., Becour, B., Fitton, I., … & Revel, M. P. (2013). Detection of residual packets in cocaine body packers: low accuracy of abdominal radiography—a prospective study. European radiology, 23(8), 2146-2155
  7. Dally, S., Garnier, R., & Bismuth, C. (1987). Diagnosis of chlorinated hydrocarbon poisoning by x ray examination. British journal of industrial medicine, 44(6), 424.
  8. Savitt, D. L., Hawkins, H. H., & Roberts, J. R. (1987). The radiopacity of ingested medications. Annals of emergency medicine, 16(3), 331-339.
  9. Flach, P. M., Ross, S. G., Ampanozi, G., Ebert, L., Germerott, T., Hatch, G. M., … & Patak, M. A. (2012). “Drug mules” as a radiological challenge: sensitivity and specificity in identifying internal cocaine in body packers, body pushers and body stuffers by computed tomography, plain radiography and Lodox. European journal of radiology, 81(10), 2518-2526.

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