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During pregnancy,
non-invasive chlamydial screening is feasible in the community.
Detection of Chlamydia
trachomatis infection in early pregnancy using self-administered
vaginal swabs and first pass urines: a cross-sectional
community-based survey.
Oakeshott P, Hay P, Hay S, Steinke F,
Rink E, Thomas B, Oakeley P, Kerry S.
Brit J Gen Prac. 2002;52:830-832
Summary:
Question
What is the prevalence of chlamydial infection in newly pregnant women in
the community and how do self-administered vaginal swabs compare to
first-pass urines for detection of C. trachomatis by ligase chain
reaction assay in early pregnancy?
Design
This article describes a primary care-based study of C. trachomatis
infection in early pregnancy using new non-invasive tests, which can be
self-administered.
Participants
Consecutive pregnant women (n = 1214) presenting at less than 10 weeks
gestation to 32 general practice and five family planning clinics in south
London were tested. Women intending to have a termination were excluded.
The mean age was 31 years (range = 17 to 48 years), 12.5% and 3.5% were
less than 25 and 20 years old, respectively. The median gestation was 49
days (range = 12 to 69 days). Seventy-eight described their ethnic group
as white, 7% as black Caribbean, 4% as black African, 8% as Indian
subcontinent, and 5% as other.
Description of Tests and Diagnostic
Standard
Self-administered vaginal swabs and first-pass urines were collected from
each woman, stored at 4oC until transfer to a local hospital, then frozen
until they were tested for C. trachomatis by ligase chain reaction
(LCR, Abbott Diagnostics, Maidenhead). Positive results were confirmed by
direct immunofluorescence (Syva MicroTrak, California). Paired specimens
of adequate quality were available for 1161 (95%) women. Women were
considered positive if the LCR assay was positive on either the vaginal
swab or urine sample.
Main Outcome Measures
The prevalence of C. trachomatis infection as determined by LCR on
vaginal swab or urine samples were calculated by age, ethnicity, and
sampling method.
Main Results
The prevalence of chlamydial infection in newly pregnant women was 2.4%
(29/1214) overall, 8.6% in women less than 25 years old, and 14.3% in
teenaged women. Being less than 25 years of age (odds ratio 3.2, 95% CI =
1.3,7.9) and of black ethnicity (odds ratio 5.7, 95% CI = 2.4,13.7) were
independent predictors of infection. The results of chlamydia LCR tests on
vaginal swabs versus first-pass urines are shown in the table. When asked
which specimen they preferred to provide, 47% of 1057 women said urine, 5%
swab, and 48% both equally.
| Comparison of
chlamydia LCR results on vaginal swabs and urine samples from newly
pregnant women |
|
Vaginal swab |
First-pass urine |
|
Positive |
Negative |
Total |
|
Positive |
25 |
3 |
28 |
|
Negative |
1 |
1132 |
1133 |
|
Total |
26 |
1135 |
1161 |
|
Authors' Conclusions
Although swabs detected 10% more infections,
nearly half the women preferred providing urine specimens. The high
prevalence found in women less than 25 years old supports recommendations
for routine chlamydial screening in this age group.
Source of funding:
NHS London Regional Office Research and Development Responsive Funding
Programme, and the South London Faculty of the Royal College of General
Practitioners
For correspondence: Pippa
Oakeshott, Department of General Practice and Primary Care, St. George's
Hospital Medical School, Hunter Wing, Cranmer Terrace, London SW17 ORE.
E-mail address: oakeshot@sghms.ac.uk.
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