Asymptomatic bacteriuria in pregnancy co

asymptomatic bacteriuria in pregnancy

1. Asymptomatic bacteriuria

2. Incidence ■ This affects 4%–7% of pregnant women, of whom up to 40% will develop symptomatic UTI and 30% acute pyelonephritis if untreated in pregnancy. ■ Women who have a history of previous UTI and are found to have bacteriuria have a tenfold increased risk of developing cystitis or acute pyelonephritis in pregnancy.

3. Pathogenesis ■ About 75%–90% of bacteriuria in pregnancy is due to Escherichia coli , probably derived from the large bowel. ■ Colonization of the urinary tract results from ascending infection from the perineum and may be related to sexual intercourse

4. Diagnosis ■ Most women with asymptomatic bacteriuria are infected during early pregnancy. Very few subsequently acquire asymptomatic bacteriuria. ■ Bacteriuria is only considered significant if the colony count exceeds 100,000/ mL on a mid-stream urine (MSU) specimen. ■ Urine culture resulting in a non-significant or mixed growth should be repeated on a fresh MSU specimen. ■ Dipsticks for nitrites and leukocyte esterase may be used to help exclude UTI.

5. Management ■ Because dilation of the upper renal tract during pregnancy increases the risk of pyelonephritis (see later), asymptomatic bacteriuria should be treated. ■ Treating asymptomatic bacteriuria reduces the risk of preterm delivery and low birthweight babies. ■ The choice of antibiotic depends on the sensitivities of the causative organism. ■ Amoxycillin and the cephalosporins are safe and appropriate antibiotics for use in pregnancy. Treatment with cefalexin 500 mg b.d. is effective against the majority of urinary pathogens.

6. ■ Nitrofurantoin 100 mg thrice daily and trimethoprim 200 mg B Dare safe alternatives. Nitrofurantoin used in the last few weeks of pregnancy carries a theoretical risk of neonatal hemolytic anaemia . Trimethoprim should be avoided in the first trimester due to its anti-folate action. ■ Long-acting sulphonamides should be avoided in the last few weeks of pregnancy because they increase the risk of neonatal kernicterus.

7. ■ Treatment for 3 days is sufficient for asymptomatic bacteriuria. Regular urine cultures should be taken following treatment to ensure eradication of the organism. About 15% of women will have recurrent bacteriuria during their pregnancy and require a second course of antibiotics