Anaesthesiology Intensive Therapy, 2009,XLI,3; 133-135

Accidental intravenous injection of formalin

*Anna Smędra-Kaźmirska1, Leszek Żydek1, Maciej Barzdo2, Waldemar Machała3, Jarosław Berent1

1Department of Forensic Medicine, Medical University of Łódź

2Department of Medico-legal and Insurance Judicature, Medical University of Łódź

3II Department of Anaesthesiology and Intensive Therapy, Medical University of Łódź

Background. Formaldehyde can be found in operating theatres where it is used for preservation of biopsied tissues. Several misuse accidents have been described previously. We present a case where formaldehyde was mistakenly injected intravenously.

Case report. A 33-year-old man, scheduled for excision of a knee meniscus under spinal anaesthesia, was to receive an intravenous antibiotic at the end of surgery. The attending anaesthesiologist received a vial of cephazolin, marked with the patient name from a scrub nurse and injected its contents intravenously. Immediately after injection, the patient complained about strong pain at the site of injection and started to cough. The vial was checked again and a piece of meniscus preserved with 4% formaldehyde was found inside. It was intended to be offered to the patient on departure. The possible amount of formaldehyde injected was 400 mg (a lethal dose has been described as 12 g).
The patient, despite the lack of cardiorespiratory failure, was intubated, ventilated and dialysed for six hours, and then extubated without further consequences. His biochemical markers remained in the normal range. Based on the case as described, the possible medico-legal consequences of poor organisation and preventive measures are discussed.

Formalin is a 35-40% saturated aqueous solution of formaldehyde containing 3-10% ethyl alcohol (methanol) acting as an internal stabilizer preventing polymerisation of the solution. Formalin is a toxic substance mainly affecting the gastrointestinal tract, airways or skin. Exposure to formalin vapours may lead to symptoms of irritated eyes and airways: reddened conjunctivae, watering, cough, dyspnoea and palpitations, bronchospasm, laryngeal and pulmonary oedema. Skin exposure to formalin is likely to cause I and II degree burns. Oral intake may induce alimentary mucosa burns with abdominal pain, nausea and vomiting. The fatal dose after oral 40% formalin is 30-60 mL; when inhaled – above 125 mg m3 [1].

The literature reported cases of accidental [2, 3] and suicidal oral intake of formalin [4, 5] as well as of attempted murders using oral formalin [6]. Accidental administrations of formalin during therapeutic procedures are rare. A case of unintended use of formalin instead of physiological saline for washing the operative field in an 18-year-old patient undergoing extraction of third molars was described. When the mistake was spotted, the area was immediately washed with 0.9% NaCl and intravenous steroids administered [7]. Polish literature reports a fatal case of acute intoxication with formalin accidentally administered in the rectal drip infusion [8]. Moreover, there were cases of formalin penetrating the circulatory system in haemodialized patients, which was caused by contamination of haemodializers with formalin used earlier for disinfection. Two patients died due to respiratory disturbances and acute intravascular haemolysis [9]. In still another of such cases, symptoms of anaphylactic shock and acute intravascular haemolysis developed and caused death [10]. The study findings indicate that in patients undergoing haemodialysis with formalin-disinfected haemodializers, the anti-formaldehyde antibodies are formed; if bigger amounts of formalin get to the circulation, the antibodies may lead to anaphylactic shock [11].

In the clinical practice, mistakes connected with the preparation of drugs to be given intravenously may happen [12, 13]; the authors, however, know only one case in which improper preparation of the drug resulted in accidental intravenous injection of formalin instead of another therapeutic agent [14]. In the case in question, the solution of formalin was accidentally administered to a 21-year-old woman with post-delivery abundant haemorrhage who was supposed to receive the intravenous infusion of glucose and dextran. Once put on a drip, the patient lost consciousness, developed cyanosis and seizures followed by circulatory and respiratory arrest. Resuscitation was initiated yet failed. In this case, the bottle earlier containing dextran was filled with the solution of formalin used for fixation of tissue material for microscopic examinations and placed in the room with infusion fluids. The patient received about 4 g of formaldehyde, i.e. about 10 mL of concentrated formalin.

The present case report describes accidental formalin administration during block anaesthesia for orthopaedic surgery.  


A 33-year-old man was admitted to the orthopaedic ward with pain sensations in the knee joint. He was diagnosed with posttraumatic damage to the medial meniscus and scheduled for menisectomy. The attending anaesthesiologist decided to administer epidural anaesthesia. Anaesthesia and surgery were uneventful. Following the local tradition of giving the removed tissue fragments as a keepsake to patients, the scrub nurse passed the removed meniscus to the surgical nurse who placed it in the vial filled with the formalin solution, which earlier contained cephazolin. The vial was labelled with the patient`s name and left on the anaesthetic trolley. Shortly after, the anaesthetist asked whether this was for the patient, meaning the antibiotic vial and the nurse said “Yes”, meaning the meniscus to be given to the patient after surgery. Due to this misunderstanding, the anaesthetist drew off the liquid from the vial and injected it intravenously to the patient.  During administration, the patient reported a strong pain of the upper limb at the site of infection and started choking. The anaesthetist asked the nurse about the vial’s content and realized that the patient received formalin.  

The patient was sent to the intensive therapy unit and intubated; mechanical lung ventilation and the 6-hour haemodialysis were  initiated. Intubation was performed despite the lack of symptoms of respiratory failure to prevent possible life-threatening effects of formalin intoxication, such as respiratory disturbances, bronchospasm and lung oedema. No clinical and biochemical symptoms of formalin-related toxic effects were observed. The laboratory tests showed: urea – 4.1 mmol L-1, bilirubin - 15.4 mmol L-1, ASPAT - 11.0 U L-1, ALAT - 7.0 U L-1, prophrombin index- 82%, INR – 1.09, fibrinogen - 5.9 mmol L-1, D-dimers - 50.0 µg L-1, pH - 7.4, PaCO2 - 35.0 mm Hg, PaO2 - 84.9 mm Hg, and SpO2 - 97.7%. At day 2, the patient was weaned from the ventilator and extubated; at day 4, he was sent to the orthopaedic ward and later discharged in good general condition.


In the case described, accidental injection of formalin was associated with malpractice at two stages. Firstly, an organizational mistake was made – the removed tissues to be given to the patient, which is unacceptable for sanitary-epidemiological reasons. According to the directive of the Minister of Health on 23 December 2003 concerning acceptable ways and conditions for utilization of medical and veterinary wastes, the body parts removed should be burnt.  Moreover, the tissues should not be placed in formalin and kept in the operating theatre. The directive of the Minister of Heath on 10 November 2006 on sanitary requirements which should be met by rooms and devices of health care institutions defines that the rule of separation of workers, patients, clean and used materials, dirty equipment, clothes and postoperative wastes should be followed in the operating suite. The placement of the vial with the removed meniscus on the anaesthetist trolley was improper. Secondly, the executive error occurred – the anaesthetist took the drug from the surgical nurse and injected it intravenously without checking the vial content. According to proper measures, the drug should be taken from the anaesthesiological nurse and the vial’s content checked before injection.

Cephazolin is a dry substance prepared for ready use in 5, 8 or 10 mL vials. Assuming that in the case described the biggest vial was used and filled with the 4% formalin, the patient might have received intravenously at most 10 mL of the solution, i.e. <400 mg of formaldehyde. The fatal oral dose of 40% formalin solution is 30-60 mL, i.e. 12-24 g of formaldehyde. The available literature lacks data concerning fatal doses of i.v. formalin; nevertheless, the dose injected intravenously to our patient was relatively low – about 30-60 times lower than the fatal oral dose.

Thanks to the small amount of formaldehyde administered, the patient was not exposed to direct life- or health-threatening danger, as stated in the article 160 of the Penal Code. The offence in question consists in the transfer of an individual from safe conditions to those directly dangerous for life and health or the transfer from dangerous conditions to more dangerous ones. The danger must be direct, which means that in the situation already created by the perpetrator, thus without his/her further action, the realization of this danger is highly likely in the nearest future. In the case presented, however, the risk of potential effects was too low for the action to bear all the hallmarks of an offence. Moreover, the real consequences of accidental formalin administration, limited only to painful irritation of the site of intravenous injection, did not bear all the hallmarks of other punishable offences defined in the Penal Code. Therefore, the prosecutor’s offices dismissed the case – the prosecutor’s proceedings are legally valid.

The case of accidental injection of formalin indicates that the medical procedures should be strictly adhered to and any local habits, e.g. of giving the patients their removed organs as a keepsake – abandoned. Furthermore, our case shows that the words spoken by Paracelsus six centuries ago „Omnia sunt venena, nihil est sine veneno. Sola dosis faciu venenum”  (All substances are poisonous, there is none that is not a poison. The dose makes the poison) are still relevant.



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14. Bardzik S: Smiertelne zatrucie formalina wprowadzona dozylnie. Arch Med Sad i1971; 21: 83-84.



*Anna Smędra-Kaźmirska
Zakład Medycyny Sądowej
Katedry Medycyny Sądowej UM w Łodzi
ul. Sędziowska 18a, 91-304 Łódź
tel./fax: 0- 42 654-42-93, tel. kom.:0- 508-257-657

Received: 03.04.2009
Accepted: 03.07.2009