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There are many physiological changes in pregnancy including the urinary tract system due to hormonal change [1,2]. The ureter is more elongated and decreased in function as well as urinary bladder has less capacity as it is affected by uterine and fetal part compression [3]. These are the causes of urinary tract infection in pregnancy [4].

Some infected pregnant women had no clinical symptom that was asymptomatic bacteriuria, which was diagnosed by clean voided urine specimen, contained organism greater than 105 CFU/mL [1,5,6]. If asymptomatic bacteriuria is not treated, infected cases will develop symptomatic cystitis or acute pyelonephritis with serious complication such as sepsis syndrome and acute respiratory distress syndrome and referred to adverse pregnancy outcomes [7,8]. In addition, urinary tract infection is associated with increased risk for preterm delivery, low birth weight, anemia and pregnancy-associated hypertension [1,6,8,9].

At present, American Academy of Pediatrics and American College of Obstetricians and Gynecologists (2018) has recommended screening asymptomatic bacteriuria for all pregnant women at first prenatal visit by urine culture that is gold standard [1,10-14]. A positive culture should be treated by antibiotic single dose or three-day course [1,8]. The most common organism in pregnancy is Escherichia coli that is similar to general population [1,6,8]. Asymptomatic bacteriuria is known as a cause of preterm labor and delivery. The prevalence of preterm birth in our institute was almost 12 percent and we have never screened asymptomatic bacteriuria in pregnancy. Thus, we need to screen the urine for all pregnant women to improve the quality of antenatal care and prevent premature labor. Mid-stream urine voided was collected after cleansing external genitalia with water but there was a high contamination rate of 52 percent. Therefore, resampling should be undertaken with an unnecessary loss of expenses and resources. Furthermore, the treatments in infected pregnant women were delayed. We presumed that cleansing with water alone might not be enough. Thus, the aim of this study was to compare the urine culture contamination rate between cleansing external genitalia with water and antiseptic solution and to determine the prevalence of asymptomatic bacteriuria among pregnant women.

A randomized control trial study was carried out in 300 pregnant women who presented for first antenatal care during October 2017 to April 2018 at Department of Obstetrics and Gynecology, Faculty of Medicine, Navamindradhiraj University. This study was approved by Vajira Institutional Review Board (Registered Number 042/60). Eligibility criteria were pregnant women who came for their first antenatal booking and maternal age was more than or equal 18 years old. Exclusion criteria were women who had medical disorder or any condition which may have affected outcomes such as renal disease, diabetes, vaginal bleeding, abnormal vaginal discharge, previous symptomatic urinary tract infection and/or treatment during the week before visiting. Written informed consent was obtained from all participants.

Pregnant women were randomized into two groups (study and control group) by block randomization technique. The control subjects received a cleansing kit-containing water while study subjects got antiseptic (4% chlorhexidine gluconate). The cleansing kit had same material for example cotton ball and tissue paper but the difference was the 30 mL solution bottle. Antenatal care unit staff explained the selfcleaning process to all participants. The first was to pour the solution (water or antiseptic) into cotton ball and then separated labia majora and minora by their fingers. After that they wiped the urethral meatus with the soaked cotton ball from the anterior to the posterior, which was followed by washing with water and using tissue paper to dry. The second step: Mid-stream urine voided specimen was collected in a sterile container and sent to the laboratory for culture within 40 min. A positive culture was defined as greater than 10⁵ CFU/mL whereas contamination was found more than one organism or less than 105 CFU/mL. No growth of organism was reported as negative culture. Pregnant women who had positive urine culture will be treated with antibiotic and repeated urine culture after treatment.

Bernard formula was used to calculate sample size. From our pilot study of total 60 cases (30 cases per group), the contamination rate of control group was 18 cases while the study group was 13 cases. The sample size was calculated using 90% of power and 5% level of statistical significance for determining the difference between groups. We added 10% to number calculated in both groups. This resulted in total of 150 study subjects and 150 controls needed. Data collection included maternal demographic and antenatal characteristics. BMI was calculated from self-reported pre-pregnancy weight (kg) divided by square of height (m2). Low graduation was below or equal grade 6.

Statistical analysis was performed using SPSS software package version 22.0 (SPSS Inc., Chicago, IL, USA). Continuous variables were compared using Mann-Whitney U test while categorical variables and contamination rate were compared by Chi-square test. p-value <0.05 was considered statistically significant.

A total 300 pregnant women who met the inclusion criteria were enrolled. They were randomized into control and study group, there were one hundred and fifty subjects per group. Maternal demographic and antenatal characteristics of pregnant women in study and control groups were presented in table. Both groups had similar characteristics of maternal age, BMI, income, graduation, parity, gestational age and hemoglobin level. Most of participants in both groups had over weight, income less than or equal 20,000 bath/month and graduation more than grade 6. The majority of gestational age at first visiting and screening asymptomatic bacteriuria was 2nd to 3rd trimester (Table 1).

Table 1: Demographic and antenatal characteristics of the study population.

The urine culture contamination rate in study group was 36% (54 in 150 cases) while control group was found 58% (87 in 150 cases). There was less contamination rate in study group than control group, which was statistical significant (p- value <0.001) as showed in table. The prevalence of asymptomatic bacteriuria in pregnancy was 9% and infection rate was similar in both groups (control group=20.6%, study group=14.6%, P value 0.320). In addition, the negative culture was not difference in both groups (control group=79.4%, study group=85.4%). The total 27 cases for positive culture, the most common organism was Gardnerella vaginalis which was found 25.9% (7 in 27 cases) and Streptococcus mitis was 14.8% (4 in 27 cases) whereas Escherichia coli, Klebsiella pneumoniae and Enterococcus faecalis were found 7.4%. There was a pregnant woman in water group had positive culture for Streptococcus agalactiae, also known as Streptococcus agalactiae. Others organism were presented in table (Tables 2 and 3).

Table 2: Urine culture results of the study population.

Table 3: Organisms of asymptomatic bacteriuria in study population.

Nowadays, the urine culture is still gold standard for diagnosis asymptomatic bacteriuria in pregnancy [1,10-13]. Mid-stream urine void was the simple method for urine culture collection which pregnant women could do by them self. However, there are many contaminations in our institution. It is possible that cleansing external genitalia before urine collection by water may not be enough. Many studies have reported about urine culture results in the difference method of urine collection, but there were no previous studies similar to our research (comparison between antiseptic solution and water) [15]. This study showed that using antiseptic (4% chlorhexidine) solution which was low concentration and safe for cleansing urethral meatus had less contamination rate in urine culture than cleansing by water. However, there was also contamination in antiseptic group more than we expected that maybe due to some participants unable to follow the correct steps even though they repeated their understanding before collecting. In addition, most of our participants were overweight and pregnant in second or third trimester so there is difficulty to clean and collect the urine sample from a large size uterus.

The prevalence of asymptomatic bacteriuria in our study was 9 percent which was similar to previous studies, 10-11 percent in Thailand [16,17]. Gardnerella vaginalis was the most common organism in our study, which was inconsistent with previous studies that were Lactobacillus species and Escherichia coli [16,18]. Because we could not control some factors for example vaginal douching or frequent sexual intercourse these were the risk factor of Gardnerella vaginalis infection [19]. The second and third pathogens in our study were Streptococus mitis and Escherichia coli, respectively. All participants with asymptomatic bacteriuria were treated by an antibiotic that was specific to each organism as sensitivity reported by the Microbiological Laboratory. Those antibiotics that we selected were safe in pregnancy such as metronidazole for Gardnerella vaginalis, amoxycillin for Streptococcus mitis and Escherichia coli [8,19]. Streptococcus agalactiae was treated by Fosfomycin [8]. Then urine cultures were repeated in all pregnant women after completed treatment and showed negative results.

Our study showed the benefit for using antiseptic solution in the process of mid-stream urine voided collection and can be used for all pregnant women to screen asymptomatic bacteriuria at antenatal care unit especially those who have high risk for preterm labor or in case symptomatic preterm labor. The less contamination and corrected results were useful for immediate treatment to decrease risk for preterm labor and adverse pregnancy outcomes. Furthermore, reducing the cost from repeated samples. The strength of this study was the randomized controlled trial with a suitable sample size and excluded any condition that may have affected the result of urine culture. At the same time, the limitation of our study was we could not completely control the process of urine collection in all pregnant women thus there were more contaminations than expected.

Cleansing the urethral meatus with antiseptic solution had less contamination rate in urine culture than water and the prevalence of asymptomatic bacteriuria in pregnancy was 9 percent.

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