• Screen for asymptomatic bacteriuria on the first antenatal visit by sending urine for culture. If asymptomatic bacteriuria is found, send a second urine sample for culture.
• If the second urine culture confirms asymptomatic bacteriuria, treat for 7 days with an antibiotic to which the organism is sensitive.
• Preferred options when sensitivities are known are (in order of preference):
• Amoxicillin: 250 mg three times daily, for 7 days.
• Nitrofurantoin: 50 mg four times daily, or 100 mg (modified-release) twice daily, for 7 days.
• Trimethoprim: 200 mg twice daily, for 7 days (unless the woman is folate deficient or taking a folate antagonist).
• Cefalexin (500 mg twice daily, or 250 mg 6-hourly, for 7 days) may be used but is less preferred.
• After treatment, send urine for culture to screen for asymptomatic bacteriuria at every antenatal visit until delivery.
• If a group B streptococcus is isolated, inform the antenatal care service, as prophylactic antibiotics may be indicated during labour and delivery.

In depth

• Convey a positive approach and reassure the woman that treatment with an antibiotic will prevent any harm to her baby, and will shorten the duration of symptoms.
• If the women has fever or loin tenderness, suspect upper urinary tract infection and admit or seek urgent specialist opinion.
• Offer paracetamol for symptomatic relief. Do not recommend urine alkalinizing agents or cranberry products. Do not recommend urine alkalinizing agents or cranberry products.
• Send a urine sample for culture before starting antibiotic treatment.
• Prescribe an antibiotic empirically. If local guidelines are not available, suitable first-line antibiotics are (in order of preference):
• Nitrofurantoin 50 mg four times daily, or 100 mg (modified-release) twice daily, for 7 days.
• Trimethoprim 200 mg twice daily, for 7 days (if the person is not folate deficient or taking a folate antagonist, and has not been treated with trimethoprim in the past year).
• Cefalexin 500 mg twice daily, or 250 mg 6-hourly, for 7 days.
• Follow up after 48 hours (or according to the clinical situation) to check response to treatment and the urine culture results.
• Amoxicillin 250 mg three times daily, for 7 days, is recommended only if the organism is reported to be susceptible on the culture results.

In depth

• Review culture results when available and, if necessary, change to an antibiotic that the organism is sensitive to.
• Send urine cultures to screen for asymptomatic bacteriuria 7 days after completion of treatment, and at every antenatal visit until delivery.
• If a group B streptococcus is isolated, inform the antenatal care service, as prophylactic antibiotics may be indicated during labour and delivery.

In depth

• Admit, or seek urgent specialist opinion, if upper urinary tract infection is suspected (fever, loin tenderness, and pain).
• Seek specialist advice if symptoms fail to respond to antibiotic treatment guided by urine culture results, and if other causes have been excluded — see Differential diagnosis.

In depth

• Check compliance with antibiotic treatment.
• Continue symptomatic treatment with paracetamol or, in the first or second trimesters, ibuprofen.
• Send a urine sample for culture.
• If symptoms are troublesome, offer a different antibiotic (nitrofurantoin or trimethoprim) while waiting for the culture results — see Managing suspected acute cystitis during pregnancy.
• If infection is confirmed on culture, treat with an antibiotic to which the organism is sensitive.
• If infection is not confirmed on culture, consider other possible causes for the symptoms — see Differential diagnosis.
• If cystitis symptoms fail to respond to a second antibiotic shown by urine culture results to be appropriate treatment, seek specialist advice.

In depth