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    UTI Special Circumstances – Pregnancy (Complicated UTI) Diagnosis & Treatment

    Cardinal Presentations / Presenting Problems, Infections, Obstetrics and Gynecology, Urological

    Last Updated Dec 05, 2021
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    UTI is common in pregnancy. Rates of pyelonephritis are higher than in the general population.

    Patients can present with:

    Asymptomatic Bacteriuria

    • 2-7% of pregnant women, mostly in the 1st trimester
    • Risk factors include:
      • History of UTIs.
      • Diabetes.
    • High rates of cystitis or pyelonephritis without treatment.
    • Increased risk of preterm birth, low birth weight, and preeclampsia.
    • Urine culture generally performed as a screening test (part of antenatal care in community).
    • Diagnosis:
      • Urine culture with 10^5 colony-forming units (CFU)/mL.
      • Asymptomatic clinically.

    Acute Cystitis

    • 1-2 % of pregnant women.
    • Similar symptoms to non-pregnant women.
      • Suspect in cases of dysuria.
      • Urgency and frequency can be normal in pregnancy.
      • Perform urinalysis and urine culture.
        • Pyuria usually present.
        • Diagnosis with cultures 10^3CFU/mL.
        • Empirically treat with antibiotics.
    • Consider in your differential:
      • STD/STI

    Acute Pyelonephritis

    • 5-2% of pregnant women.
    • Mostly 2nd or 3rd trimester.
    • Physiological changes in pregnancy, such as smooth muscle relaxation and enlarging uterus increase rates of pyelonephritis.
    • Similar symptoms to non-pregnant women.
      • Includes flank pain, nausea/vomiting, fever, CVA tenderness +/- cystitis symptoms.
      • Perform urinalysis and urine culture.
      • Depending on severity consider blood cultures, lactate, and imaging with renal ultrasound (R/O obstruction or abscess).
    • Consider differential for fever and/or flank/back pain:


    • E. coli is the most common. Others are Klebsiella, Enterobacter species, Proteus.
    • Group B Streptococcus (7 – 30 percent of pregnancy-associated asymptomatic bacteriuria).
    • Extended-spectrum beta-lactamases (ESBL) rates increasing.


    A.  Asymptomatic Bacteriuria

    • Treatment with antibiotics lowers rates of pyelonephritis and adverse pregnancy outcomes.
    • Choice of antibiotics based on urine culture susceptibility results (will be available at time of diagnosis). Options can include:
      • Nitrofurantoin 100 mg PO BID x 5-7 days.
        • Don’t use if suspect pyelonephritis.
        • Avoid in 1st trimester; contraindicated near term (causes hemolytic anemia in mother and newborn with G-6PD deficiency).
      • Amoxicillin 500 mg PO TID or 875 mg PO BID x 5-7 days.
      • Amoxicillin-clavulanate 500 mg PO TID or 875 mg PO BID x 5-7 days.
      • Cephalexin 500 mg PO q 6 h x 5-7 days.
      • Fosfomycin 3 g PO x 1 dose.
        • Don’t use if suspect pyelonephritis.
      • Trimethoprim-sulfamethoxazole 800/160 (one double strength tablet) BID x 3 days.
        • Shorter courses preferred.
        • Avoid during the 1st trimester because of the antifolate effect associated with neural tube defects.
        • Avoid at term.
      • Follow-up urine culture 1 week from completion of therapy recommended for test of cure.
        • If negative, no need for repeat urine cultures.
        • If positive, use susceptibilities to guide treatment. Do not repeat any further urine cultures (based off expert opinion; insufficient data).
          • Do not recommend suppressive or prophylactic antibiotics for persistent or recurrent asymptomatic bacteriuria.

    B. Acute Cystitis

    • Principles:
      • Obtain urine cultures, empirically treat, perform follow-up cultures.
      • Empiric Antibiotics – ensure drug safety and note stage of pregnancy:
        • Recommend oral amoxicillin-clavulanate or fosfomycin à safe in pregnancy and offers broad spectrum coverage (same doses as above).

    Can also use amoxicillin, cephalexin, nitrofurantoin or trimethoprim-sulfamethoxazole (see above).

      • For ESBL concerns, oral options include nitrofurantoin or fosfomycin.
      • Typically can treat for 3-7d, as long as no symptoms of pyelonephritis.
      • Obtain follow up cultures, 1 week post completion of antibiotics.
    • If your patient has recurrent cystitis?
      • Antibiotic prophylaxis for duration of pregnancy is an option to discuss with your patient (consider infectious disease, OBGYN opinion).
        • Choice of agent depends on susceptibilities.

    C. Acute Pyelonephritis

    • Principles: Perform urine cultures and sensitivities, hospital admission for empiric IV antibiotics, consider oral conversion if clinical improvement. Following treatment consider suppressive antibiotics for remainder of pregnancy as recurrence prevention.
    • Empiric Antibiotics:
      • Note: Generally prefer broad spectrum beta lactams as empiric treatment.
        • Mild to moderate pyelonephritis.
          • Ceftriaxone 1 g IV once daily.
          • Cefepime 1 g IV BID (fourth-generation cephalosporin).
          • Aztreonam 1 g IV TID (restricted use – Int Med or Inf Disease consult).
          • Ampicillin 1-2 g IV q6 h + gentamicin 1.5 mg/kg IV TID*.
            • *Note: only use if other options not available as aminoglycosides associated with fetal ototoxicity.
        • Severe pyelonephritis.
            • Piperacillin-Tazobactam 3.375 g IV q 6h.
            • Meropenem 1 g IV TID.
            • Ertapenem 1 g IV once daily.
      • Consider MRSA and add antibiotic coverage if concerned.
      • If concerns for ESBL, treat with meropenem or ertapenem.
    • Clinical Course and follow-up:
      • Improvement usually within 24-48h of treatment.
      • If afebrile for 48 h, can be discharged on appropriate oral antibiotics (10-14d) guided by susceptibility.
        • Beta-lactams.
        • Trimethoprim-sulfamethoxazole if in 2nd trimester.
      • However, if symptoms continue beyond first 24-48h of antibiotics, repeat urine culture and perform a renal ultrasound to rule out stone/abscess.
    • Preventing recurrence
      • 6-8 % of women experience recurrent pyelonephritis.
        • Consider low dose antibiotic preventative therapy (use agent based on susceptibility) for remainder of pregnancy.
        • Perform a later urine culture to screen for breakthrough bacteriuria, which can occur despite preventative therapy (if positive treat with course of antibiotics based on susceptibility and then adjust preventative therapy as needed).

    D. Group B streptococcal (GBS) infection

    • Treatment guided by urine culture susceptibility results.
    • Intrapartum Chemoprophylaxis is an additional consideration after treatment of confirmed GBS infection.
      • Note: at time of delivery, intrapartum chemoprophylaxis recommended for all GBS bacteriuria (regardless of colony count) as it prevents neonatal infection.  This is because GBS bacteriuria is marker for anogenital colonization which persists despite bacteriuria treatment.
    • Asymptomatic bacteriuria with GBS.
      • Bacteriuria >= 10^5 CFU/mL.
        • Generally can use amoxicillin, penicillin, or cephalexin for 5-7 days (safe in pregnancy).
        • Clindamycin is alternative oral option if allergy to penicillins or cephalosporins.
      • Bacteriuria < 10^5 CFU/mL.
        • Do not treat.
    • Cystitis with GBS.
      • Should be able to treat with same oral antibiotics as per asymptomatic GBS bacteriuria. Repeat urine culture post-treatment for clearance.
    • Pyelonephritis with GBS.
      • Treat with Penicillin G for 10 days (tailor duration to clinical response).
        • Penicillin G (Lexicomp):
          • “Usual dosage range: 12 to 24 million units/day IV/IM in divided doses every 4 to 6 hours”.
        • For uncomplicated patients, if resolving severe symptoms (eg fever), can switch to oral antibiotic (eg. penicillin or cephalexin).
      • If allergic to penicillin and cephalosporins, use vancomycin until both clinical response and negative urine culture. Can then use oral clindamycin, if susceptible, to complete therapy.
        • Perform repeat culture after treatment to ensure clearance.
        • Again, duration of antibiotics (can range from 10-14 days) is based on clinical improvement.

    Antibiotic Safety in Pregnancy

    • Penicillins (+/-beta-lactamase inhibitors), cephalosporins, and aztreonam are generally safe.  Aztreonam is restricted – consult internal medicine/infectious diseases.
    • Meropenem and ertapenem are the preferred carbapenems.
    • Fosfomycin is safe. Not to be used in pyelonephritis.
    • Trimethoprim-sulfamethoxazole should be avoided in 1st trimester and near term.
    • Nitrofurantoin should be avoided in the 1st trimester, near term, and for pyelonephritis.
    • Aminoglycosides are ototoxic.
    • Tetracyclines and fluoroquinolones should not be used.
    • data is lacking and the current safe standard is avoiding use and using established safe antibiotics.

    Related Information


    Quality Of Evidence?


    The above summary is taken from recent literature reviews on emergency department diagnosis and management of UTI’s.


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