UTI and Stones in Pregnancy
Bacteruria in Pregnancy
Considerations
- Prevalence: 2-7%, similar to general population
- Resolution: less likely to spontaneously resolve compared to non-pregnant patients
- Timing: pyelonephritis most common in 3rd trimester, occurs 15-45% patients with untreated bacteruria
- Management: treatment of asymptomatic bacteruria decreases morbidity and complications, screen for bacteruria at 12-16 weeks, admit patients with pyelonephritis for treatment
Antibiotics in pregnancy
- Penicillins: ampicillin 500mg QID, amoxicillin 250mg TID, penicillin 500mg QID
- Cephalosporins: cephalexin 500mg QID, cefaclor 500mg QID
- Nitrofurantoin: 100mg BID (avoid after 35 weeks due to neonatal hemolytic anemia)
- Other antibiotics: aminoglycosides, clindamycin, erythromycin (after 12wks, risk of cholestatic jaundice)
Antibiotics to AVOID
- Fluoroquinolones: cause cartilage damage
- Chloramphenicol: cause gray baby syndrome
- Trimethoprim: inhibit folic acid metabolism
- Tetracyclines: inhibit new bone growth
Algorithm for stone management in pregnancy, from Dai 2021
Stones
Pathophys
- Incidence: occur in 1:200-1:1500 pregnancies, similar incidence of laterality despite more prevalent right sided hydronephrosis
- Complications: increases risk for preterm delivery, preeclampsia, placenta previa, and PPROM
- Stone type: calcium phosphate more common due to combination hypercalciuria and elevated pH
- UTI: consider looking for a stone if recurrent infections with urease-producing organisms
Presentation
- Symptoms: flank pain most common, then hematuria and UTI
- US: first line imaging, may show resistive index > 0.7, RI differential > 0.06, ureteral dilation past iliac vessels (normally not dilated), or absence of ureteral jets
- Transvaginal US: may be more accurate for diagnosing distal stones
- CT: consider for surgical planning or if US non-diagnostic, discuss risks/benefits but overall radiation dose is negligible
- MRU: gadolinium considered safe in pregnancy, can consider to avoid radiation dose
Management
- Observation: 50-80% will spontaneously pass with hydration and analgesia
- NSAIDs contraindicated in pregnancy (causes closure of ductus arteriosus)
- a-blockers: safe for pregnancy, can also use tylenol and narcotics (except codeine)
- Acute intervention: stents and PCNs can be used but rapidly encrust and require exchange q4-6 weeks, may also increase risk for preterm labor
- Ureteroscopy: best performed during 2nd trimester (lowest anesthesia risk), no difference in complications from nonpregnant patients, preterm labor rates ~4%
- Other options: ESWL contraindicated, avoid PCNL due to prolonged anesthesia and XRT exposure
References
- AUA Core Curriculum
- Cooper, K. L., G. M. Badalato, and M. P. Rutman. "Infections of the urinary tract." Campbell-Walsh-Wein Urology. 12th ed. Elsevier (2020): 1129-1201.
- Dai, Jessica C., et al. "Nephrolithiasis in Pregnancy: Treating for Two." Urology 151 (2021): 44-53.
- Kaufman, M. "Urologic Considerations in Pregnancy." Campbell-Walsh-Wein Urology. 12th ed. Elsevier (2020): 1129-1201.
- Wieder JA: Pocket Guide to Urology. Sixth Edition. J.Wieder Medical: Oakland, CA, 2021.