ROUTINE ANTENATAL SYPHILIS SCREENING IN SOUTH WEST NIGERIA- A QUESTIONABLE PRACTICE

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Adesina Olubukola and Oladokun Adesina

Department of Obstetrics and Gynaecology, College of Medicine, University of Ibadan, Nigeria.

Abstract

Background: Untreated maternal syphilis is strongly associated with adverse birth outcomes, especially in women with high titre syphilis. The WHO recommends routine serological screening in pregnancy. Some workers have advised a reappraisal of this practice, having demonstrated low sero-prevalence in their antenatal population. In view of this, the aim of this study was to determine the seroprevalence of syphilis in the antenatal population presenting at a major hospital in south-west Nigeria.

Methods: This was a cross sectional study of healthy pregnant Nigerian women attending Adeoyo Maternity Hospital in the capital of Oyo State. The case record of every pregnant woman presenting for their first antenatal clinic visit over a 4 month period (September 1st to December 31st 2006) was reviewed.

Results: During the study period, two thousand six hundred and seventy-eight women sought antenatal care. Three hundred and sixty-nine women (369; 13.4%) had incomplete records and were excluded from analysis. The records of the 2,318(86.6%) women with adequate records were subsequently reviewed. The mean age of the women was 27.4 years (± 5.34) and the mean gestational age 26.4 weeks (±6.36). The modal parity was 0. Only three patients were found to be reactive for syphilis giving a prevalence of 0.13%.

Conclusion: The sero- prevalence value in this study is quite low and may justify the call to discontinue routine antenatal syphilis screening. However, a more rigorous screening program using diagnostic tests with higher sensitivity maybe necessary before jettisoning this traditional aspect of antenatal care.

Keywords: Pregnancy; syphilis; prevalence; serology; screening

Introduction

Syphilis, caused by infection with Treponema pallidum, is a muco-cutaneous sexually transmitted infection (STI) with high infectivity in the early stages. It may also be passed transplacentally from the ninth week of gestation onwards¹. The basic pathology in all stages is vasculitis². Untreated maternal syphilis is strongly associated with adverse birth outcomes, especially in women with high titre syphilis (HTS) observed in earlier stages of the infection. These adverse birth outcomes include an increased incidence of stillbirths, low birth weight and premature live births compared with uninfected women³. An increased incidence of spontaneous abortions after 20 weeks of gestation has also been reported⁴. Congenital syphilis infection results in fetal or perinatal death in 40% of affected pregnancies, as well as disease complications in surviving newborns, including central nervous system abnormalities; deafness; multiple skin, bone, and joint deformities; and haematological disorders⁵.

The World Health Organization (WHO) recommends serological screening in pregnancy and treatment with injectable penicillin, including the partner, as a routine part of antenatal care⁶. Ideally, this screening should be done during the first trimester or at the first antenatal visit of the woman and again early in the third trimester, even in low- prevalence populations. There is observational evidence that suggests that the universal screening of pregnant women decreases the proportion of infants with clinical manifestations of syphilis infection and those with positive serologies⁵. Indeed, the benefits of screening all pregnant women for syphilis infection substantially outweigh potential harms^5,7. Some workers have however advised a reappraisal of the practice of universal antenatal screening for syphilis having demonstrated low sero-prevalence in their antenatal population. They questioned the cost-effectiveness of this practice given its low yield⁸.

Objectives
In view of these observations, the aim of this study was to determine the sero-prevalence of syphilis in a group of pregnant Nigerian women presenting at a secondary health care institution in south-west Nigeria.

MATERIALS AND METHODS
This is a cross sectional study of apparently healthy pregnant Nigerian women attending Adeoyo Maternity Hospital, a secondary health centre in Ibadan, the capital of Oyo State in the South-West of Nigeria. The case record of every pregnant woman presenting for their first antenatal clinic visit over a 4-month period (September 1st to December 31st 2006) was reviewed. Data was collected by the means of a prepared proforma. These data included selected demographic and obstetrics information. Information on the result for screening for syphilis was also extracted. Women with incomplete data were excluded from the study. Ethical approval was obtained from the University College Hospital/ University of Ibadan institutional ethical review committee.

Laboratory diagnosis of Syphilis
Venous blood (5ml) was collected from the antecubital vein of each woman into sterile tubes. The blood was allowed to retract and then centrifuged, and the serum was obtained and stored at –20oC until tested. All serum samples, test antigens and control samples were brought to room temperature (26oC) and tested by the Venereal Disease Research Laboratory test using a VDRL test kit (Cal-Tech Diagnostics Inc., Chino, California, USA).

Statistical Analyses
Data were summarized as means ± standard deviation, percentages and mode and analysed by independent T-test. Data entry and analysis was done using SPSS statistical package, version 15.0. P values less than 0.05 were considered significant.

RESULTS
From September 1st to December 31st 2006, 2678 two thousand six hundred and seventy- eight (2,678) women sought antenatal care, at Adeoyo Maternity Hospital, Yemetu, Ibadan. Three hundred and sixtynine women (369; 13.4%) had incomplete records and were excluded from further analysis. The records of the 2,318 women with adequate records were subsequently reviewed for the sero-prevalence of syphilis. The mean age of the women was 27.4 years (± 5.34) and they presented at a mean gestational age of 26.4 weeks (±6.36). Most of the patients were in the age group 20 to 34 years. The modal parity was 0. Slightly over half of the patients were in their second trimester of pregnancy. Only three patients were found to be reactive for syphilis giving a prevalence of 0.13%. There was no record of confirmatory tests in the patients’ records.