eMedicine Specialties > Urology > Infections and Related Inflammatory Conditions

Urinary Tract Infections in Pregnancy: Follow-up

Author: Leticia A Jones, MD, Clinical Instructor, Department of Obstetrics and Gynecology, Indiana University Hospital, Clarian Health Partners
Coauthor(s): Patrick J Woodman, DO, Assistant Director, Urogynecology (FPMRS) Fellowship, Associate Clinical Professor, Indiana University School of Medicine; Consulting Staff, Department of Obstetrics and Gynecology, Methodist Hospital; Henry E Ruiz, MD, Chief, Reconstructive Urology and Urodynamics, Urology Associates of South Texas, PA and Radiation Oncology Center
Contributor Information and Disclosures

Updated: Oct 9, 2008

Follow-up

Further Inpatient Care

• In addition to appropriate antibiotic and antipyretic therapy, include antepartum management of pyelonephritis through rehydration and tocolytic therapy, if appropriate.
• The most important complication of pyelonephritis is respiratory insufficiency due to bacterial endotoxin damage to the alveoli, causing pulmonary edema; therefore, fluid overload (>3 L over outputs in 48 h) must be avoided and tocolytics used sparingly. Frequent clinical evaluation allows identification of pulmonary injury early. Clinical signs include dyspnea, tachypnea, and hypoxemia and findings on a chest radiograph that are consistent with pulmonary edema ARDS. Prompt recognition can be addressed with oxygen, intubation, and mechanical ventilation, as necessary, to prevent adverse maternal and fetal outcomes. Central hemodynamic monitoring is helpful to guide fluid therapy and oxygen delivery, especially when mechanical ventilation is necessary.
• Renal dysfunction typically resolves with hydration; however, nephrotoxic medications should be dose-adjusted for changes in creatinine clearance. Likewise, maternal anemia usually resolves with the infection if iron stores are adequate.
• Clinical improvement is usually rapid after the initiation of antimicrobial therapy, although fevers may wax and wane. Most (85%) fevers resolve within the first 48 hours (ie, 90% within 72 h). Women who do not improve in 72 hours should undergo testing for other sources of infection, including renal ultrasonography to rule out obstructive nephrolithiasis. Continue intravenous antibiotic therapy for 24-48 hours after defervescence.
• If conservative treatment fails or if an infected obstructed system is suspected, imaging studies are indicated. Renal ultrasonography is often performed initially, but the findings are often inconclusive. A limited IVP (ie, a KUB and a 30-min shot following injection of contrast) can be helpful in delineating the site of obstruction.
• ESWL is contraindicated in pregnancy.

Further Outpatient Care

• Generally, women are discharged with 1-2 weeks of oral antibiotic therapy. Because acute pyelonephritis places the pregnant patient at risk for recurrent antepartum urinary tract infection (UTI) (38%) and recurrent antepartum pyelonephritis (7-8%), continue antibiotic prophylaxis for the remainder of the pregnancy. Although this approach has not been definitively proven to prevent preterm labor and low birth weight in infants, the significant recurrence of asymptomatic bacteriuria (ASB), UTI, and pyelonephritis supports the prudence of prophylaxis. Both continuous (daily) and postcoital prophylaxis regimens are effective. The agents of choice during pregnancy include nitrofurantoin (50-100 mg) and cephalexin (250 mg).
• For simple cystitis and bacteriuria, a test-for-cure urine culture should be performed approximately 1-2 weeks after the completion of therapy. Cases that are persistent (positive culture results) or recurrent (positive culture results after 2 wk) should be treated with a sensitive antibiotic and continued on a low-dose suppressive (prophylactic) antibiotic until 6 weeks postpartum.
• Possible nonpharmacologic recommendations include early postcoital voiding (type II-3 evidence), pushing fluids (type II-3 evidence), and drinking cranberry juice (type I evidence in elderly women). The patient’s hygiene should be reviewed to determine if certain practices predispose her to infection.

Inpatient & Outpatient Medications

• Aside from the antibiotics prescribed for UTI and ancillary medications, no medications are required. The administration route is dictated by the patient's diet.
• Tylenol is the preferred medication for fever.
• Most antiemetics can be used for adverse effects caused by antibiotics, but doxylamine, Emetrol (class A), dimenhydrinate, and metoclopramide (class B) are preferred.

Transfer

The general obstetrician/gynecologist or family practitioner should be able to manage even a complicated case of pyelonephritis. However, a urologist should be consulted if the patient is not responding to treatment, if the patient has a protracted course, or to rule out other factors such as perinephric abscess or obstruction. In addition, cases involving a known stone or indwelling ureteral stent also should include consultation with a urologist. Only the most complicated cases (ie, ARDS, renal failure, septic shock) require consultation or transfer to the appropriate specialist.

Deterrence/Prevention

• Untreated ASB progresses to pyelonephritis in 25-30% of cases; therefore, routine screening for bacteriuria is recommended throughout pregnancy. The most cost-effective and cost-beneficial screening method depends on the local prevalence of ASB. Rouse and colleagues (1995) described the use of leukocyte esterase-nitrite dipsticks, treating the patients with positive results, and retesting using dipsticks.⁸ A urine culture is unnecessary unless the retest result is positive. If the culture result is positive, the patient is re-treated and placed on suppressive therapy; however, if the prevalence of ASB is high, screening and treatment based on urine culture with reculture (used as test of cure) are also cost-benefit effective.
• Because the prevalence increases with sexual activity, limited activity or postcoital antibiotic prophylaxis may be prudent. Investigate untreated pathologies. UTI before pregnancy or antepartum is predictive of bacteriuria at the first prenatal visit. Avoid in-dwelling catheterization during labor and after delivery.
• Suppressive antibiotic therapy should be instituted in patients who develop acute cystitis or pyelonephritis during pregnancy. Patients treated for ASB during pregnancy who have recurrent or persistent ASB upon retest should also receive prophylactic antibiotics. Penicillins (including ampicillin and clavulanic acid), cephalosporins, and nitrofurantoin are safe in pregnancy. Some warn against the use of nitrofurantoin in women with G-6-PD deficiency because of the possibility of hemolytic anemia; however, data do not support this. Sulfonamides are associated with fetal kernicterus and should be avoided during the third trimester. Similarly, quinolones are class C drugs, and no controlled human data regarding their safety in pregnancy have been published. In fact, pregnant animal studies using quinolones in the first trimester resulted in major fetal malformations; therefore, quinolones should not be used in pregnancy.
• Pregnant women with sickle cell hemoglobinopathies are at increased risk for UTI, as are patients who have undergone renal transplantation or orthotopic diversions. Patients with these high-risk conditions may benefit from more aggressive screening (culture vs dipstick) and antibiotic prophylaxis.
• A possible immunization for UTI: Uehling et al described a study in which repeated immunization with a vaginal mucosal vaccine prolongs the time to reinfection in women susceptible to UTIs.⁹ Women who received 6 doses of a vaginal vaccine remained infection-free significantly longer than patients who received 3 doses or placebo only. The study was a double-blind phase 2 trial of suppositories that contain Urovac, which contains 10 heat-killed uropathogens. Women who were given the vaccine developed significantly fewer UTIs than those in the control group. Phase 3 clinical trials are ongoing.

Complications

• Pyelonephritis
  • The most important primary complication of bacteriuria in pregnancy is pyelonephritis. Other rare, but serious, complications include septic shock, respiratory failure, and death. As many as 25-30% of women with untreated ASB in pregnancy eventually develop symptomatic cystitis or pyelonephritis. Antepartum UTI is also a risk factor for adverse perinatal outcomes, including low birth weight and preterm delivery. Adverse maternal outcomes include premature labor, maternal anemia, amnionitis, and hypertension or preeclampsia.
  • Acute pyelonephritis occurs in 1-2% of all pregnancies. The incidence varies depending on the local prevalence of ASB and whether it is treated. Women with urinary tract abnormalities, such as renal calculi, anomalies, or a history of pyelonephritis, are at increased risk. Most (73%) cases are discovered antepartum, with 8% identified intrapartum and 19% postpartum. Ninety percent of antepartum cases are diagnosed in the last 2 trimesters.
  • Complications associated with pyelonephritis are serious and are due primarily to bacterial endotoxin damage. Ten percent to 15% of pregnant women with pyelonephritis develop bacteremia. Respiratory insufficiency due to endotoxin alveolar damage and pulmonary edema occurs in 2-8% of patients. Respiratory compromise can be exacerbated by iatrogenic fluid overload and tocolytics. Renal dysfunction occurs in as many as 25% of antepartum cases but is usually self-limited. Maternal anemia (hematocrit <30%) due to endotoxin-induced hemolysis occurs in 25-66% of cases and typically resolves.
  • Pyelonephritis is associated with preterm birth and low birth weight; however, this association is compounded by low socioeconomic status. The strength of the association is unknown and has recently been questioned.
• Preeclampsia: Women who develop preeclampsia during pregnancy seem to be predisposed to UTI. A retrospective review of the perinatal database at a major tertiary center revealed a UTI rate of 16.2% in normotensive patients, but this increased to 27.3% in women with mild preeclampsia and 35.9% in women with severe preeclampsia. The authors hypothesize that underlying renal damage weakens the patients' systemic defense mechanisms against ascending infection.
• Effects on the fetus: Maternal UTI has few direct fetal sequelae because fetal septicemia is rare; however, uterine hypoperfusion due to maternal dehydration, maternal anemia, and direct bacterial endotoxin damage to the placental vasculature may cause fetal cerebral hypoperfusion.

Prognosis

• In most cases of bacteriuria and UTI in pregnancy, the prognosis is excellent; however, most long-term sequelae are due to complications associated with septic shock, respiratory failure, and hypotensive hypoxia (ie, extremity gangrene).

Patient Education

• Specimen collection
  • Since Kass described the criteria for ASB in the 1950s, physicians have struggled to prevent female patients from contaminating their own specimens. The most accepted development has been the introduction of the midstream-voided specimen after urethral and perineal cleansing.
  • The patient must be instructed on how to execute the following:
    1. With one hand, spread the labia.
    2. With the other hand, use a Castile soap-moistened towelette to wipe the urethral meatus downward towards the rectum and discard the towelette.
    3. Void the initial portion of the bladder contents into the toilet.
    4. Catch the middle portion of the bladder contents in the sterile collection container, while keeping the labia spread with the first hand.
  • Unfortunately, a recent study on pregnant adolescents suggests the cleansing process does not prevent contamination.
• For excellent patient education resources, visit eMedicine's Kidneys and Urinary System Center and Pregnancy and Reproduction Center. Also, see eMedicine's patient education articles Urinary Tract Infections, Pregnancy, Bladder Control Problems, and Blood in the Urine.

Miscellaneous

Medicolegal Pitfalls

• Because 25% of untreated asymptomatic bacteriuria (ASB) cases progress to pyelonephritis, failure to treat documented ASB followed by a complication from pyelonephritis might result in medicolegal liability.

Special Concerns

• Beta streptococci
• Beta streptococci are important pathogens in pregnancy because early and late complications of neonatal beta-streptococcal infection are well-documented. Incidental documentation of beta-streptococcal bacteriuria suggests a higher colonization count than revealed by a screening vaginal or rectal culture. Beta-streptococcal colonization in the urine warrants immediate treatment and antibiotic prophylaxis when the patient presents in labor.
• Whether beta streptococci are associated with preterm labor is controversial. McKenzie and colleagues (1994) prospectively found no relation of beta-streptococcal bacteriuria to preterm labor, but they describe the use of urinary antibodies to identify at-risk women.¹⁰ In 2043 consecutive women, those with E coli antibodies at initial visit and at 28 weeks' gestation and women with beta-streptococcal antibodies at 28 weeks' gestation had a significantly higher chance of preterm delivery.
• Caesarean delivery: Cesarean delivery is associated with urinary tract infection (UTI) (2.7 times more likely), but this association may be confounded by bladder catheterization or prolonged rupture of membranes (PROM). The incidence of symptomatic UTI is 9.3% and ASB is 7.6%.
• Orthotopic continent urinary diversion: Many women who, in the past, would have been counseled against pregnancy are now attempting pregnancy. In orthotopic continent diversion (OCD), an ileal-ascending colon conduit is made (OCD, Kock pouch) and reattached to the in situ urethra (OCD) or a continent abdominal stoma (Kock pouch). Typical candidates are patients born with congenital exstrophy of the bladder in whom primary reconstruction has failed. Recurrent UTI and hydronephrosis are common because of outflow obstruction of the orthotopic stoma secondary to uterine compression or uterine prolapse. In this exceedingly rare case, a percutaneous nephrostomy tube or antegrade passage of a ureteral stent may be indicated.
• Outpatient treatment of pyelonephritis in pregnancy
• In 1995, Millar and colleagues reported on a randomized, controlled trial of outpatient treatment of pyelonephritis in pregnancy.¹¹ They concluded that outpatient therapy is as safe and effective as inpatient care in the treatment of pyelonephritis before 24 weeks' gestation. However, the prevailing attitude still dictates that aggressive inpatient hydration and parenteral antibiotics are necessary. In early pregnancy, pyelonephritis places the patient at risk for spontaneous abortion and, after 24 weeks' gestation, preterm labor.
• In their study, Millar et al (1995) treated outpatients with 2 doses of intramuscular ceftriaxone and 10 days of oral cephalexin.¹¹ Initial outpatient therapy and traditional inpatient therapy failed to cure equal numbers of patients. Benefits include the obvious cost savings and psychosocial benefits for the patient. Risks include septic shock or respiratory insufficiency at home during outpatient therapy. Strict guidelines for an observation period before emergency department discharge, patient education, and home nursing have been discussed. In addition, approximately two thirds of the outpatient treatment group did not complete the study because the subjects developed one or more complications. If outpatient therapy is considered, only selected patients in their second trimester should be considered. More study is necessary before a change in the physician's practice pattern is considered.

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