CORRESPONDENCE
Hazards of blood collection To the editor: I have several comments about the article "Evacuated blood-collection tubes - the backflow hazard" by Katz and colleagues (Can Med Assoc J 113: 208, 1975) on the study of unsterile vacutainer tubes. In the article the use of multiple-sample vacutainer needles was not mentioned. These are used by many hospitals in preference to ordinary vacutainer needles. Multiple-sample needles decrease the risk of infections such as hepatitis for the technician and patient caused by backflow of blood through the needle while the tubes are being changed. The authors did suggest avoiding thc application of pressure on the end of the tube during filling, but this maneuver is necessary at times when one is using multiple-sample needles because the rubber sleeve may eject the tube, particularly with the first sample. If the tourniquet is left on until the tube is full and a backflow of blood may occur, is it not also possible to have a backflow of air when the arm is positioned so that a bubble of air is at the cork site? In hospitals vacutainer tubes are often carried from floor to floor. The authors did not discuss the risk of infection from unsterile, possibly contaminated cork stoppers. This may also create a potential risk through backflow when the needle punctures the cork. The bureau of medical devices of Health and Welfare Canada has taken an important stand by proposing the use of sterile tubes. However, the only completely sterile products available are needles and syringes. Contributions to the Correspondence section are welcomed and if considered suitable will be published as space permits. They should be typewritten double spaced and, except for case reports, should not exceed 1½ pages in length.
The present change to sterile tubes doesn't completely eliminate the risk of infection, especially via contaminated cork stoppers. One wonders whether the increased cost of sterile tubes justifies an unsatisfactory end. BARBARA HILL, RN Head nurse, intravenous team Toronto East General and Orthopaedic Hospital Toronto, Ont.
To the editors: Ms. Hill has raised two interesting points regarding infection of the patient during venipuncture. First, it is true that if the blood-collection tube is 'maintained with the stopper uppermost a small volume of air may be drawn into the vein if the conditions for backflow are satisfied. However, although the air in a nonsterile tube may in principle contain microorganisms, the risk of infection by this mechanism is small. Also, since the volume would typically be less than 0.05 ml there would be practically no danger of air embolism. Second, bacteria on the outer surface of the tube stopper can be introduced into the tube by the blood-collection needle. The answer is to swab the stopper before puncturing it, as is standard clinical practice when using sterile containers. DAVID L. JOHNSON, PH D Bureau of medical devices Health protection branch Health and Welfare Canada Ottawa, Ont.
Cervical cancer screening programs: the SOGC's view To the editor: The Society of Obstetricians and Gynaecologists of Canada (SOGC) has deferred making comment on the report of the task force on cervical cancer screening programs the Walton report (Can Med Assoc I 114: 1003, 1976) -- to give its members, who have a primary role in the
detection of cancer of the female generative organs, time to discuss and evaluate the report. In June 1976, members of the council of the SOGC urged the Board of Directors of the Canadian Medical Association not to publish this report in the Journal until an opportunity had been given the SOGC to study its content in depth. It is understandable that obstetricians and gynecologists, who have demonstrated responsibility in health care by their review of maternal and perinatal morbidity and mortality for upwards of 50 years, are sensitive to the increasing number of government task forces reviewing standards of medical care and norms of practice within their discipline - in areas such as cancer screening, periodic physical examination, hysterectomy and cesarean section - a function that is rightfully the role of the profession. The SOGC acknowledges the scientific content of the report. The thoroughness with which this study was made refutes the need for yet another study. And the members of its council are satisfied from discussion with members of the task force that its recommendations were made without interference or suggestions of modification by members of Health and Welfare Canada. The report has been a stimulus to interested disciplines both within and without Canada to review the epidemiology, natural history, and early diagnosis and management of cancer of the cervix. It reinforces the conviction that there is a need for cytologic screening programs by means of which squamous carcinoma of the cervix can be controlled, and that such programs are effective in reducing the mortality of carcinoma of the cervix. It outlines the minutiae of a cytologic screening program, including quality control and
CMA JOURNAL/MAY 7, 1977/VOL. 116 971
Hazards of blood collection To the editor: I have several comments about the article "Evacuated blood-collection tubes - the backflow hazard" by Katz and colleagues (Can Med Assoc J 113: 208, 1975) on the study of unsterile vacutainer tubes. In the article the use of multiple-sample vacutainer needles was not mentioned. These are used by many hospitals in preference to ordinary vacutainer needles. Multiple-sample needles decrease the risk of infections such as hepatitis for the technician and patient caused by backflow of blood through the needle while the tubes are being changed. The authors did suggest avoiding thc application of pressure on the end of the tube during filling, but this maneuver is necessary at times when one is using multiple-sample needles because the rubber sleeve may eject the tube, particularly with the first sample. If the tourniquet is left on until the tube is full and a backflow of blood may occur, is it not also possible to have a backflow of air when the arm is positioned so that a bubble of air is at the cork site? In hospitals vacutainer tubes are often carried from floor to floor. The authors did not discuss the risk of infection from unsterile, possibly contaminated cork stoppers. This may also create a potential risk through backflow when the needle punctures the cork. The bureau of medical devices of Health and Welfare Canada has taken an important stand by proposing the use of sterile tubes. However, the only completely sterile products available are needles and syringes. Contributions to the Correspondence section are welcomed and if considered suitable will be published as space permits. They should be typewritten double spaced and, except for case reports, should not exceed 1½ pages in length.
The present change to sterile tubes doesn't completely eliminate the risk of infection, especially via contaminated cork stoppers. One wonders whether the increased cost of sterile tubes justifies an unsatisfactory end. BARBARA HILL, RN Head nurse, intravenous team Toronto East General and Orthopaedic Hospital Toronto, Ont.
To the editors: Ms. Hill has raised two interesting points regarding infection of the patient during venipuncture. First, it is true that if the blood-collection tube is 'maintained with the stopper uppermost a small volume of air may be drawn into the vein if the conditions for backflow are satisfied. However, although the air in a nonsterile tube may in principle contain microorganisms, the risk of infection by this mechanism is small. Also, since the volume would typically be less than 0.05 ml there would be practically no danger of air embolism. Second, bacteria on the outer surface of the tube stopper can be introduced into the tube by the blood-collection needle. The answer is to swab the stopper before puncturing it, as is standard clinical practice when using sterile containers. DAVID L. JOHNSON, PH D Bureau of medical devices Health protection branch Health and Welfare Canada Ottawa, Ont.
Cervical cancer screening programs: the SOGC's view To the editor: The Society of Obstetricians and Gynaecologists of Canada (SOGC) has deferred making comment on the report of the task force on cervical cancer screening programs the Walton report (Can Med Assoc I 114: 1003, 1976) -- to give its members, who have a primary role in the
detection of cancer of the female generative organs, time to discuss and evaluate the report. In June 1976, members of the council of the SOGC urged the Board of Directors of the Canadian Medical Association not to publish this report in the Journal until an opportunity had been given the SOGC to study its content in depth. It is understandable that obstetricians and gynecologists, who have demonstrated responsibility in health care by their review of maternal and perinatal morbidity and mortality for upwards of 50 years, are sensitive to the increasing number of government task forces reviewing standards of medical care and norms of practice within their discipline - in areas such as cancer screening, periodic physical examination, hysterectomy and cesarean section - a function that is rightfully the role of the profession. The SOGC acknowledges the scientific content of the report. The thoroughness with which this study was made refutes the need for yet another study. And the members of its council are satisfied from discussion with members of the task force that its recommendations were made without interference or suggestions of modification by members of Health and Welfare Canada. The report has been a stimulus to interested disciplines both within and without Canada to review the epidemiology, natural history, and early diagnosis and management of cancer of the cervix. It reinforces the conviction that there is a need for cytologic screening programs by means of which squamous carcinoma of the cervix can be controlled, and that such programs are effective in reducing the mortality of carcinoma of the cervix. It outlines the minutiae of a cytologic screening program, including quality control and
CMA JOURNAL/MAY 7, 1977/VOL. 116 971
