Asymptomatic Bacteriuria in Pregnancy: Causes, Symptoms, and Treatment

Asymptomatic bacteriuria is a condition where bacteria are present in the urine without causing any symptoms of urinary tract infection (UTI). It is common in early pregnancy and can be diagnosed by urine tests. It can lead to serious complications such as pyelonephritis, low birth weight, and premature labor if untreated. Antibiotic treatment can reduce these risks.

What causes asymptomatic bacteriuria in pregnancy?

The causes of asymptomatic bacteriuria in pregnancy are not fully understood, but some factors may increase the risk of developing it, such as:

History of previous UTI

Diabetes mellitus

Sickle cell disease

Anemia

Low socioeconomic status

Multiparity

Sexual activity

Use of spermicides or diaphragms

The normal changes in the urinary tract during pregnancy may also contribute to the development of asymptomatic bacteriuria. These changes include:

Increased urinary volume and frequency

Decreased bladder tone and ureteral peristalsis

Increased urinary stasis and reflux

Altered pH and glucose levels in the urine

Decreased immune response in the urinary tract

These changes create a favorable environment for bacterial growth and colonization in the urine.

What are the symptoms of asymptomatic bacteriuria in pregnancy?

Asymptomatic bacteriuria does not cause any symptoms of UTI, such as:

Burning or pain during urination

Frequent or urgent urination

Blood or pus in the urine

Lower abdominal or back pain

Fever or chills

However, asymptomatic bacteriuria may progress to symptomatic UTI or pyelonephritis if left untreated. Pyelonephritis is a serious infection of the kidneys that can cause:

High fever and chills

Nausea and vomiting

Flank pain or tenderness

Costovertebral angle tenderness

Pyelonephritis can also cause complications for the mother and the baby, such as:

Preterm labor and delivery

Low birth weight or intrauterine growth restriction

Preeclampsia or eclampsia

Sepsis or septic shock

Acute respiratory distress syndrome

Renal failure or chronic kidney disease

How is asymptomatic bacteriuria diagnosed in pregnancy?

Asymptomatic bacteriuria is diagnosed by urine tests that detect the presence and type of bacteria in the urine. The current guidelines recommend screening for asymptomatic bacteriuria in the first trimester of pregnancy or at the first prenatal visit, using a urine culture or a dipstick test 3.

A urine culture is a test that grows bacteria from a urine sample in a laboratory and identifies the type and number of bacteria present. A urine culture is considered positive for asymptomatic bacteriuria if it shows more than 100,000 colony-forming units (CFU) per milliliter of one or two types of bacteria 3.

A dipstick test is a test that uses a strip of paper with chemical indicators that change color when exposed to certain substances in the urine. A dipstick test can detect nitrites, leukocyte esterase, blood, protein, glucose, and pH in the urine. A dipstick test is considered positive for asymptomatic bacteriuria if it shows nitrites or leukocyte esterase 3.

How is asymptomatic bacteriuria treated in pregnancy?

Asymptomatic bacteriuria should be treated with antibiotics to prevent the development of symptomatic UTI or pyelonephritis and their complications. The treatment of choice is a short course of antibiotics that are safe and effective for both the mother and the fetus 4.

The choice of antibiotics depends on several factors, such as:

The type and sensitivity of bacteria causing the infection

The local patterns of antibiotic resistance

The availability and cost of antibiotics

The potential side effects and interactions of antibiotics

Some examples of antibiotics that are commonly used to treat asymptomatic bacteriuria in pregnancy are 4:

Nitrofurantoin (Macrobid) for 5 days

Amoxicillin-clavulanate (Augmentin) for 3 to 7 days

Cephalexin (Keflex) for 7 days

Fosfomycin (Monurol) as a single dose

Some antibiotics that should be avoided or used with caution to treat asymptomatic bacteriuria in pregnancy are 4:

Trimethoprim-sulfamethoxazole (Bactrim) due to the risk of birth defects, especially in the first trimester

Fluoroquinolones (such as ciprofloxacin or levofloxacin) due to the risk of cartilage damage and arthropathy in the fetus

Tetracyclines (such as doxycycline or minocycline) due to the risk of tooth discoloration and bone growth inhibition in the fetus

Aminoglycosides (such as gentamicin or tobramycin) due to the risk of ototoxicity and nephrotoxicity in the mother and the fetus

The treatment of asymptomatic bacteriuria should be confirmed by a repeat urine culture after completing the antibiotic course. If the urine culture remains positive, a different antibiotic should be used based on the sensitivity results. If the urine culture becomes negative, no further treatment is needed 4.

How can asymptomatic bacteriuria be prevented in pregnancy?

The prevention of asymptomatic bacteriuria in pregnancy may involve some lifestyle modifications, such as:

Drinking plenty of fluids, especially water, to flush out bacteria from the urinary tract

Urinating frequently and completely to empty the bladder and prevent urinary stasis

Wiping from front to back after urination or defecation to avoid spreading bacteria from the anus to the urethra

Avoiding douching or using perfumed products in the genital area that can alter the normal flora and pH of the vagina and increase the risk of bacterial overgrowth

Wearing cotton underwear and loose-fitting clothes that allow air circulation and prevent moisture and heat buildup in the genital area

Changing sanitary pads or tampons regularly during menstruation to prevent bacterial growth and infection

Practicing good hygiene and safe sex to prevent sexually transmitted infections that can cause UTI

Asymptomatic bacteriuria in pregnancy is a common and potentially serious condition that requires timely diagnosis and treatment. By following the screening and treatment guidelines and adopting some preventive measures, pregnant women can reduce their risk of developing complications from asymptomatic bacteriuria and ensure a healthy pregnancy and delivery.

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