Incidence of potential conjunctival contamination in tonsillectomy

A prospective study of 100 consecutive tonsillectomies was performed to assess the incidence of potential blood contamination of the surgeons' conjunctivae. Operating masks with plastic visors were used during these operations and examined by microscopy to detect blood contamination. 46% of visors were contaminated by blood. There was no significant difference with respect to how the operation was performed, or with the addition of adenoidectomy, but there was a significant difference between the rate of contamination between some surgeons. No surgeon performing more than three operations, however, escaped contamination. We recommend that eye protection be worn routinely in tonsillectomy.

In Scotland in 1990, tonsillectomy was the most commonly performed operation in children.¹ It is regarded as a 'safe' procedure for the operator as it is free from the risk of needle stick injuries which contribute the greatest hazard of blood exposure to the surgeon. Both Hepatitis B (Hep B) and the Human Immunodeficiency Virus (HIV) are transmissible by the inoculation of the conjunctiva by contaminated blood.^2,3 Literature suggests that some otolaryngological operations have a high risk of conjunctival contamination with patients' blood but that tonsillectomy is not amongst these.4 In a literature review, we found no study had specifically looked at the risk to the surgeon of conjunctival contamination during tonsillectomy. With the blood loss that can occur during tonsillectomy and the instrumentation with suction and electrocautery we felt that the potential for conjunctival contamination may have been higher than generally accepted.

A consecutive series of patients scheduled for tonsillectomy (with or without adenoidectomy) was entered into the study. All surgeons carrying out a tonsillectomy took part in the study. A 'Fluidsheild' mask (Tecnol, Inc, Figure 1) was worn throughout the procedure and a standard, blunt dissection tonsillectomy was performed. The lower tonsillar pole was snared or ligated, depending on the surgeon's preference. Bipolar diathermy was used to secure haemostasis in all cases. After the procedure the surgeon noted whether he had been aware of blood contamination of the visor, without examining it. Details of the operation were recorded. Masks were then analysed by viewing their surface for blood spots with a binocular microscope under six times magnification. The visor was placed against a white background and blood contamination was identified as a visible blood spot which could be removed from the visor by scraping its surface. Data was analysed, with the aid of a statistician, using a 'Minitab' statistical package where the effects of patient age, operation, lower tonsillar pole technique and surgeon were investigated by logistic regression. Blood loss at operation was not recorded.

One hundred procedures were carried out (72 tonsillectomies, 28 adenotonsillectomies). 55 patients were adults, 45 patients were children. In 77 cases, the lower tonsillar pole was ligated and the snare was used in 23 cases. Eight surgeons carried the procedures.

In 46 cases, blood contamination was found and was on the outer surface of the visor in all but two cases. Contamination ranged from one blood spot to 50 blood spots (Figure 2). The surgeon was aware of blood spotting on the visor in six cases (13% of cases where contamination occurred). Table 1 shows the numbers and percentages of visors contaminated with respect to age of patient and technique of dealing with the lower tonsillar pole. Logistic regression on the variables: age of patient, lower pole technique and adenoidectomy showed no significant influence on blood contamination of the mask. The effect the surgeon had on blood contamination of the mask was analysed. There was a significant difference between some surgeons, but no surgeon, who had performed more than three operations, escaped some degree of blood contamination.

Table 1: Numbers and percentages of contaminated masks with respect to patient's age and procedure (n=100)

	Age		Snared
	Child	Adult	Yes	No
Number of contaminated masks	16	30	10	36
Percentage of contaminated masks	36	55	43	45

The transmission of blood-borne disease (particularly viral) from the patient to the operating surgeon is of great concern. The risk is regarded to be highest with needle stick injuries, and surgical glove perforation by suture needles occurs in 37.5% of general surgical operations.⁵ The hazards of blood splashes at operation have also been reported suggesting that both Hep B and the HIV virus can be transmitted by conjunctival contamination.^2,3 The risk of blood contamination of the conjunctiva has been shown to be high in vascular surgery,⁶ obstetrics⁷ and even in interventional radiology.⁸

In otolaryngology, the risk of blood contamination of the eye, is high in tracheostomy, operations preceded by local anaesthetic injections and operations using the drill.⁴ This study grouped tonsillectomy with operations such as laryngoscopy, myringoplasty and grommet insertion, and it could be argued that these operations are less likely to cause conjunctival contamination than tonsillectomy. In this group, contamination occurred in 14% of cases although no figures were given for tonsillectomy only.

Few surgeons would consider the necessity for eye protection in tonsillectomy. It is, after all, a procedure that does not require sutures or scalpels. We have shown however, a much higher figure of contamination by eye protection than was previously realised, regardless of how the procedure is performed, in adults or children The individual surgeon has a significant impact on the amount of contamination of eye protection. None of the operators in this study, however, that carried out more than three procedures escaped contamination. Furthermore, in only 13% of cases where contamination occurred was this noticed by the surgeon, when this was being looked for specifically. This suggests that the threat of blood contamination is passing largely unnoticed by surgeons performing tonsillectomies. Although this study did not examine the relationship between blood loss at operation and contamination of eye protection (which may or may not correlate) the high incidence of contamination supports the routine implementation of eye protection in all cases of tonsillectomy.

We would like to thank Dr Bill Adams, Department of Medical Statistics, University of Edinburgh, for his help and advice regarding this study.

Correspondence: Gerard Kelly, Department of Otolaryngology, Head and Neck Surgery, The Royal Infirmary of Edinburgh, Lauriston Place, Edinburgh EH3 9 YW, U.K.

The incidence of potential conjunctival contamination in tonsillectomy