REVIEVV ARTICLE

Occupational
infection risks in

interventional
radiology

Abstract
South African
radiologists
performing
interventional and
angiographic
procedures are at
risk of occupational
exposure to
hepatitis Band C
and the human
immunodeficiency
virus (HIV). Simple
precautions reduce
this risk
substantlallv, It is
important that
radiologists and
personnel working
in the
interventional suite
are aware of the
risk of infection,
how to reduce the
risk and how to
prevent
seroconversion
after need Ie stick
injuries.

PCorr
MBChB, FFRad

17 SA JOURNAL OF RADIOLOGY· November 1998

Occupational exposure to viral
material during invasive procedures
is a major concern to health profes-
sionals in many countries. I South Af-
rica has a particularly high prevalence
of HIVand hepatitis Band C infec-
tion in the population.P Radiologists,
radiographers and nurses who per-
form and assist with angiography or
interventional procedures are at risk
through needle stick injuries or cor-
neal splashes from blood.'> It is im-
portant that radiologists be aware of
the risk, how to reduce the risk and
what to do after needle stick injuries."

Risk of HIV
infection

South Africa currently has an epi-
demic of HIV infection from hetero-
sexual spread. The latent period from
sera conversion to the development of
the acquired immunodeficiency syn-
drome (AIDS) is approximately ten
years. Many of our patients requiring
interventional or invasive procedures
will be incidentally seropositive. The
HIV positivity rate varies from less
than 5% in the Western Cape to 23%
in routine antenatal clinic screening
in KwaZulu Natal.' Patients with
clinical AIDS are more likely than
other patients to have invasive pro-
cedures such as biopsies, drainage of
intra-abdominal collections or ab-
scesses and angiography for arterial
occlusions and an urysms.

It is very important for the radi-
ologist, radiographer and nurse to be
aware of the occupational risk from
HIV. Data about the risk of
seroconversion are derived mostly
from studies in the United States re-
ported by the Center for Disease Con-
trol and Prevention (CDC). Occupa-
tional infection has been definitely

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Occupational infection risks in
interventiona I rad iology

from page 17

documented in 52 health profession-
als and probably in III other work-
ers.' The majority of the documented
cases (90%) involved blood exposure.
Eighty-seven percent of all these cases
followed needle stick injuries. The
CDC reviewed 25 studies of HIV
seroconversion from 1983 to 1994
recently.'" The documented risk for
percutaneous exposure is 0.3% (21
infections in 6498 documented expo-
sures) .7

A retrospective review comparing
incidents involving seroconversion
versus those workers who did not
seroconvert, found that those work-
ers who seroconverted had the follow-
ing increased risks: a deep percutane-
ous injury, visible blood on the instru-
ment or needle, the instrument was
used for arterial or venous access, and
the patient was terminally ill.?
Seroconversion is more likely with a
large volume of blood and a high vi-
ral load," The risk for mucous mem-
brane exposure was estimated to be
0.] % and for intact skin exposure less
than 0.] %.8

Risk of hepatitis
B infection

Hepatitis B is the most common
occupational infection world-wide.'
In South Africa the prevalence of
hepatitis envelope antigen (HBeAg)
is particularly high, in the region of
10%.3 Hepatitis B is extremely infec-
tious because of much higher circu-
lating blood viral antigen levels ( 1013

viral particles per ml) than with HIV.
The virus survives in dried blood for
up to a week, unlike HIV, which dies
within minutes. The risk of
seroconversion is 12% in non-immu-
nised workers after percutaneous in-
oculation of the hepatitis surface an-
tigen (HBsAg) . The risk increases to

30% after exposure to the envelope
antigen of the virus (HBeAg).9 How-
ever the risk of seroconversion is mini-
mal in the fully immunised worker."

It is essential that all health work-
ers have full immunisation for hepa-
titis B. The recombinant DNA vaccine
is proven to be extremely safe and
effective. It is critically important that
a protective antibody level greater
than 10 mIU/ml be documented in
all workers to ensure effective immu-
nisation. Immunisation failure is due
to a variety of reasons, usually includ-
ing incorrect administration of the
vaccine or failure to receive the 6
month and 5 year boosters. Health
workers should not be allowed to
work in the interventional room with-
out immunisation.

Infection with hepatitis B may re-
sult in chronic hepatitis in 10-25% of
patients. The risk of resultant cirrho-
sis and hepatoma is about 10%. The
CDC estimates that in the United
States 8 700 health professionals are
infected every year with hepatitis B.
This results in up to 190 deaths from
hepatitis per year."

Risk of hepatitis
C infection

Hepatitis C is the most common
cause of non-A and non-B hepatitis
infections from blood transfusions.
The prevalence of hepatitis C is in the
region of 1.2% in donated blood in
South Africa.' In the USA the preva-
lence is 0.6%. The risk of developing
chronic liver disease is much higher
than with hepatitis B, with 85% of
patients with acute infections remain-
ing chronically infected. Twenty per-
cent of these patients develop chronic
liver disease and cirrhosis. The esti-
mated risk of infection following a
percutaneous injury is between 6 and

18 SA JOURNAL OF RADIOLOGY- November 1998

10%, making it more infectious than
HIV but far less infectious than hepa-
titis B. No vaccine has been developed
yet and there is no obvious benefit in
giving hyperimmune globulin for post
exposure prophylaxis.

Precautions
Most precautions involve common

sense. Remember to treat every pa-
tient as infectious until proven other-
wise. Normal precautions include:

1. Do not recap needles - this is the
single most important precaution you
can take. Most needle sticks occur
during recapping of the needle. Great
care must be used when reinserting
the stylet of the Potts needle into the
cannula. Never hand a sharp needle
or instrument to an assistant. Always
place sharps on the tray first.

2. Do not use glass syringes for con-
trast injections because of the risk of
shattering. Polycarbonate syringes are
much stronger than conventional
plastic syringes.

3. Ensure adequate lighting over the
working area during the procedure.
There has been shown to be a risk in
many interventional rooms where
lighting is poor.

4. Always wear latex gloves, prefer-
ably double-gloving. Occult perfora-
tions occur in 10% of gloves during
interventional procedures, increasing
to 23% in those procedures lasting
more than two hours. Double gloving
reduces this risk substantially, particu-
larly during long procedures.

5. Always wear a sterile gown, mask
and transparent face shield when per-
forming procedures, particularly an-
giography. It is extremely important
to remember to use facemasks with

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Occupational infection risks in
interventional radiology

from page 18

the attached plastic shield to cover the
eyes to prevent corneal splashes.
6. The modified arteriography Pott's
needle with a vacuum side arm pre-
vents blood splashes during arterial
puncture. It is now available in South
Africa and costs RIS more than the
conventional needle.
7. A closed angiographic flush system
avoids blood splashes when flushing
syringes. One can aspirate heparinised
saline and contrast and dispose of
bloody fluid into a closed drainage
container. Try to avoid using open
bowls on the tray, as there is a sub-
stantial risk of splashes. The closed
flush system is available commercially.
However one could probably make
one's own from drip tubing, a three
way tap, a vacolitre of normal saline
and a urine bag for blood disposal.
8. Remember to cover the image in-
tensifier with sterile plastic to prevent
blood splashes.

EXp'osure to
blood

If you are splashed with blood,
wash the exposed skin with soap and
water, and flush mucous membranes
and eyes with water. If a sharp injury
occurs, you must notify the infection
control officer in your hospital. Take
blood from the patient with his or her
written consent to check the HIV sta-
tus. Your blood will be required for
baseline HIV testing. If the patient is
HIV positive, postexposure prophy-
laxis should be started as soon as pos-
sible, preferably within 1 to 2 hours.
Early prophylaxis is critical in pre-
venting seroconversion. The window
of opportunity to prevent viral spread
is a few hours. Zidovudine (AZT)
200 mg tds and Lamivudine (Epivir)
150 mg bd for four weeks is currently
recommended by the CDC in the

USA (CDC website address for cur-
rent information is http://
www.cdc.gov j.lt It is important that
early counselling of the risks of
seroconversion commences as soon as
possible. Testing for HIV should be
repeated at 6 weeks, 3 months and 6
months. This prophylaxis is highly ef-
fective, reducing the risk of
seroconversion by 79%. If the patient
is positive for hepatitis B, and you are
not fully immunised, immune globu-
lin must be administered within 24
hours and the hepatitis B booster
given. There is no evidence that
hyperimmune globulin prevents hepa-
titis C infection.

Conclusions
It is critically important that all

health care workers, especially radiolo-
gists performing interventional proce-
dures, be aware of the risk of infec-
tion in their daily practice. Precautions
involve common sense and care when
handling sharps. You must be aware
of your local hospital policy on post
exposure prophylaxis, whom to con-
tact and try to educate your working
colleagues on safe working conditions
in the interventional room.

Acknowledgements
I would like to thank Professor

Susan Wall, Interventional Radiology,
University of California, San Francisco,
USA for permission to use her data in
preparation for this article.

References

1. Gerberding JL. Management of
occupational exposures to blood borne
viruses. NEIM 1995; 332: 444-51.

2. Williams B, Campbell C. Understanding
the epidemic of HIV in South Africa:
analysis of the antenatal clinic screening
data. S Afr Med I 1998; 88(3): 249-51.

19 SA JOURNAL OF RADIOLOGY- November 1998

3. Kew Me. Progress towards the
compr hensive control of hepatitis Bin
Africa: a view from South Africa. Gut
1996; 38(supp 2: S31-36).

4. McWilliams RG, Blanshard KS. The risk
of blood splash contamination during
angiography. Clinical Radiology 1994;
49: 59-60.

5. Hansen ME, Miller GL, Redman HC,
McIntire DD. Needle stick injuries and
blood contacts during invasive
radiologic procedures: frequ ncy and
risk factors. AIR 1993; 160: 1119-22.

6. Wall SD, Howe JM, Sawhney R. Human
immunodeficiency virus infection and
hepatitis: biosafety in radiology.
Radiology J997; 205(3): 619-28.

7. Centers for Disease Control and
Prevention. Case control study of HIV
seroconversion in health care workers
after percutaneous exposure to HIV-
infected blood- France, UK, USA
January 1988-August 1994. MMWR
1995; 44: 929-933.

8. Centers for Disease Control and
Prevention- HIV/AIDS surveillance
report: US HIVand AIDS cases
reported through December 1996-97;
8(2): 20-21.

9. Zuckerman AI. Occupational exposure
to hepatitis B virus and human
immunodeficiency virus. A comparative
risk analysis. Am I lniect COlltro11995;
23: 28.

10. Center for Disease Control and
Prev ntion. Recommendations for
prevention of transmission of
immunodeficiency virus and hepatitis
B virus to patients during exposure
prone invasive procedures. MMWR
1991;40:1-9.

11. Center for Disease Control and
Prevention. Public health servi e
guidelines for the management of
health care worker exposure to HIV
and recommendations for post
exposure prophylaxis. MMWR 1998;
47:1-10.

http://www.cdc.gov