Vaginal Swab Test During Pregnancy

Vaginal Swab Test During Pregnancy


Vaginal Microflora and its Diagnosis

Female genital tract are in constant interaction with the environment, thus, they need reliable protection from viruses and bacteria. Many micro-organisms on the genital tract’s mucous membranes are excreted with mucus, urine, activity of epithelium, therefore, they are transitory.

Mechanisms of normal microflora maintenance:

1. Anatomical and physiological:

  • The vagina is protected from the environment with muscles’ hypertonicity contracting the vulvar ring, big and small labia;
  • Distinction between upper and lower vagina greatly restricts the spread of infection;
  • Hormonally induced cyclical changes of epithelium.

2. Hormonal mechanisms. Estrogen and progesterone induce proliferation of mulitilayer squamous epithelium, glycogen synthesis and secretion of mucosa in the cervix. Mucus is rich in carbohydrates that bind receptors in bacteria, preventing them from attaching to the cells of the epithelium. Mucous contains lysozyme, lactoferrin, defensins-substances with a wide range of antimicrobial activity.

3. Immune mechanisms represented by components of complement, lysozyme and secretory immunoglobulin A (Ig A).

4. Symbiosis is mutually beneficial coexistence of microorganisms and the female body. Normal microflora bacteria create colonization protection from pathogens in the genital tract. They got nutrients and assistance from macro-organisms to fight the concurrent flora.

What Happens to Vaginal Microflora During Pregnancy

During pregnancy under the influence of hormonal changes, increase vaginal epithelial cells and glycogen accumulation. Glycogen is the main substrate used by lactic bacteria to produce lactic acid. It helps to maintain acid environment into the vagina (pH 3.8-4.5) necessary for growth of optimal microflora and suppression of pathogens. While the pregnancy progresses, healthy women increase lactobacteria production and reduce colonization of the cervix compared to non-pregnant women. This is necessary to protect the baby from pathogens during its passage on the birth canal.

The vagina contains a very large number of bacteria:108-109 bacterial bodies per 1 gram of liquid, 5-12 different species of microorganisms. The main representative of normal microflora is Doderlein's bacillus. They make up 95-98 % of the total number of microorganisms. This name regroups four kinds of Lactobacillus: Lactobacillus acidophilus, L. casei, L. Fermentum, L. Cellobiosus. They look like straight or curved sticks located by one or in chains. As a rule, they don’t move.

Lactobaceria are able to produce hydrogen peroxide, create an acidic environment in the vagina contributing to a high concentration of lactic acid, compete with other microbes for adhesion to vaginal epithelial cells, as well as boost female immune system. In addition to Doderlein's bacillus, the vagina contains bifidobacteria, ัarine-bacteria, coagulase-negative staphylococci, prevotella and bacteroids. Candida yeast-like fungi may be also found in swab test of a healthy woman, if they aren’t numerous and there are no signs of inflammation.

Swab Test Periods During Pregnancy

In case of normal pregnancy flow, swab tests are taken at the first visit, at 30 weeks and before the birth. However, if a woman has had spontaneous miscarriages, if there is a threat of termination of pregnancy, intrauterine fetal infection, hydramnios, chorioamnionitis, the doctor may assign you with additional tests as well as introduce additional diagnostic methods to detect the pathogen.

Swab test is taken during an ordinary gynecological examination, it’s taken with sterile or disposable tool from the urethra (urinary canal), the side vaginal wall and cervix and then spread over a marked glass and sent to the laboratory. The doctor estimates quantity, color and odor of the mucous secretions, and condition of vaginal walls and the cervix. In the laboratory the swab is Gram stained to examine its bacterial content, presence of erythrocytes, leukocytes and clue cells (epithelial cells covered with round bacteria).

There are the following stages of vaginal purity:

  • First degree (normocenosis) is characterized by an acidic environment, big number of Doderlein's bacillus , low content of optional flora. Small contents of red blood cells and white blood cells per field of vision.
  • Second degree (intermediate type). Acidic environment, the number of Lactobacilli predominate over other microbial cells, WBCs number increases to 15 in the field of vision (during pregnancy the threshold is 20 in the absence of inflammation).
  • Third degree (dysbiosis) is observed in case of a bacterial vaginosis. Lactobacteria are almost absent, the swab features plenty of gram-positive cocci, gram-negative bacilli, anaerobic bacteria genera.
  • The fourth degree (vaginitis). Lactobacilli are absent, alkaline environment, a large number of erythrocytes and leukocytes as well as presence of clue cells and pathogens.

It’s recommended to abstain from sex for one or two days before swab test. You’d better avoid douching, use of vaginal suppositories and local disinfectants. The day of the test avoid using soap during hygienic procedures.

Deviations from the Norm

The absence of squamous epithelium indicates decrease in estrogen contents, while high contents of epithelium are observed in a case of a severe inflammation. The same condition is characterized by gonococci, trichomonads, yeast-like fungi and clue cells contents (at a concentration of more than 104 cfu/ml). Excessive mucus secretion also indicates inflammation.

Any deviations from normal require additional tests. Bacteriological study of vaginal discharge is carried out to define a pathogen or antibiotic resistance. A STIs (sexually transmitted infections) test is required. A treatment is assigned upon the test’s results.

During pregnancy you’d better opt for local treatment such as candles and creams without antibiotics. But if you need a systematic therapy, admission of antibiotics is possible starting from the second trimester. Some infections may be hidden, but still they are dangerous for the normal fetal development, so when planning a pregnancy all women are encouraged to take STD tests.

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