UTIs in pregnancy: Managing urethritis, asymptomatic bacteriuria, cystitis, and pyelonephritis
Lower urinary tract infections typically pose minimal risk to mother and fetus with proper treatment; however, acute pyelonephritis may be dangerous. The author outlines diagnostic procedures and antibiotic treatment, particularly which medications should be avoided during pregnancy.
Treatment failure
Obstetric patients with pyelonephritis usually respond promptly to antibiotics. More than 75% will be afebrile within 48 hours, and more than 90% will be afebrile within 72 hours. When patients fail to respond promptly, 2 major causes should be considered. The first is antibiotic resistance, and this problem can be corrected on the basis of the sensitivity studies. The second is ureteral obstruction, secondary either to the effect of the gravid uterus or a urinary stone. If obstruction is suspected, renal ultrasonography should be performed. Depending upon the cause of the obstruction, a procedure such as a percutaneous nephrostomy or cystoscopic removal of the stone may be necessary.
Recurrence is possible. Following an initial episode of pyelonephritis, approximately 20% of patients will experience a recurrent lower or upper tract infection.1 Because of this recurrence rate, I recommend that these patients receive suppressive doses of antibiotics for the remainder of pregnancy. An ideal agent for suppression is nitrofurantoin (100 mg at bedtime). An alternative agent is trimethoprim-sulfamethoxazole double strength (800 mg/160 mg) once daily. Amoxicillin and cephalexin are less desirable for prophylaxis because of their adverse effects on vaginal and bowel flora and their propensity for precipitating yeast infection and/or diarrhea.
CASE Resolved
The most likely diagnosis in this patient is acute cystitis. An in-out catheterization should be performed to obtain an uncontaminated urine specimen. A portion of the specimen should be forwarded to the laboratory for urine culture and sensitivity. Another portion should be used for assessment by dipstick. If the nitrite and leukocyte tests are positive, the diagnosis of acute cystitis is confirmed. Since this infection is the patient’s first episode, a reasonable antibiotic regimen would be oral nitrofurantoin (100 mg twice daily) for 3 days. The course should be extended to 7 days if symptoms persist at the end of 3 days. ●
