Definition
A.Pyelonephritis is an infection in one or both kidneys, usually involving the entire urinary tract.
Pyelonephritis may evolve into acute respiratory distress syndrome (ARDS) in pregnancy.
Incidence
A.The incidence of pyelonephritis in pregnancy is 1% to 2%. Most cases develop as a consequence of undiagnosed or inadequately treated lower urinary tract infection (UTI). Approximately 75% to 80% of pyelonephritis cases occur on the right side, with a 10% to 15% incidence on the left side. A small percentage of cases are bilateral.
Pathogenesis
A.Escherichia coli is the main pathogen in pyelonephritis, though Klebsiella pneumoniae and Proteus species are also important causes of infection. Occasionally highly virulent Gram-negative bacilli, such as Pseudomonas, Enterobacter, and Serratia, are responsible (more commonly noted in immunocompromised patients). Gram-positive group B strep (GBS) may also be responsible. Anaerobes also are unlikely pathogens in pyelonephritis except in cases of chronic obstruction or instrumentation.
Predisposing Factors
A.Pregnancy: Because of pregnancy-related anatomic changes in the urinary tract, such as dilated ureters caused by smooth muscle relaxation and pressure on the bladder from the enlarging uterus. The immunosuppression of pregnancy may also contribute.
B.History of UTI, cystitis, and pyelonephritis.
C.Sickle cell disease.
Common Complaints
A.Fever.
B.Chills.
C.Flank pain or tenderness.
D.Urinary frequency or urgency.
E.Hematuria and dysuria.
Other Signs and Symptoms
A.UTI is associated with urinary frequency, urgency, and dysuria; hematuria; and suprapubic pain:
1.Chemical reactions to deodorant or douches can affect urination.
2.Patients with frequent pyelonephritis do not complain of frequency and dysuria.
B.Pyelonephritis is associated with fever, palpitations, dizziness, backache, and urinary frequency:
1.Hematuria may be present, especially if the patient has a history of a previous stone.
2.Dysuria is not always present in upper tract infections.
C.Abdominal pain and uterine contractions, risk of preterm labor (PTL) and birth.
D.Shortness of breath.
Potential Complications
A.Sepsis and septic shock.
B.ARDS: Mortality rate 50% to 70%.
C.Pulmonary embolus, usually presents as sudden-onset costovertebral angle (CVA) tenderness.
Subjective Data
A.Elicit information on the onset, duration, and progression of symptoms.
B.Elicit problems with voiding. Ask the patient about urinary frequency, urgency, and dysuria.
C.Ask the patient if she has experienced preterm contractions.
D.Ask if the patient is complaining of fever or chills.
E.Ask the patient if her urine has a bad odor.
F.Ask the patient if she has felt more tired than usual.
G.Ask the patient if she has felt more nauseated than usual or if she has been vomiting.
H.Does she have a backache? Note location (unilateral or bilateral) and what, if anything, makes the backache better or worse.
I.Review the patient’s history for sickle cell disease, if appropriate; has she been tested?
J.Review prenatal history for recurrent UTIs, previous pyelonephritis, and any abnormalities of the genitourinary (GU) tract.
Physical Examination
A.Check temperature, pulse, respirations, and blood pressure (BP): Fever more than 100.4°F, tachycardia, tachypnea, hypotension associated with sepsis, septic shock, and ARDS.
B.Inspect: Note general appearance for respiratory distress.
C.Palpate:
1.Back: Check CVA tenderness (right CVA tenderness is more common in pregnancy).
2.Abdomen:
a.Palpate for uterine tenderness and contractions.
b.Palpate for suprapubic tenderness.
D.Auscultate:
1.The lungs and heart.
2.The fetal heart rate (FHR).
E.Bimanual exam: Check for cervical dilation.
Diagnostic Tests
A.Complete blood count (CBC) with differential or white blood cell (WBC): Leukocytosis with left shift on differential seen.
B.Blood culture, if indicated.
C.Respiratory function:
1.Arterial blood gases (ABGs), if indicated.
2.Pulse oximetry, if indicated.
D.Renal function:
1.Urinalysis:
a.Check urinalysis for WBCs, red blood cells (RBCs), leukocyte esterase, and/or nitrites.
b.Glucosuria may be normal in pregnancy because of decreased tubular capacity to reabsorb glucose. If it is consistently noted, further testing is needed.
c.Proteinuria is not normal during pregnancy. All cases warrant further investigation.
2.Urine culture and sensitivity: Bacterial count greater than 100,000 colonies/mL indicates a UTI and should be treated. The consensus is unclear whether GBS bacteriuria less than 100,000 colonies/mL should be treated prior to 35 weeks to prevent pyelonephritis, preterm delivery, and postpartum endometritis. Currently the American Congress of Obstetricians and Gynecologists (ACOG) recommends treating GBS bacteriuria greater than 100,000 colonies/mL even if the patient is asymptomatic.
3.Intravenous pyelogram (IVP), if indicated.
4.Renal ultrasonography, if indicated.
Differential Diagnoses
A.Pyelonephritis.
B.Cystitis.
C.Urethritis.
D.Urethral stricture.
E.Urolithiasis.
F.Genital infection.
G.Chorioamnionitis.
H.Septic abortion.
I.Postpartum endometritis.
J.Muscular strain.
K.Pulmonary embolus.
L.Severe upper respiratory tract infection.
M.Postprocedural dysuria or urinary frequency (i.e., following bladder catheterization or cystoscopy).
N.Chemical irritants.
O.Postpartum septic pelvic thrombophlebitis.
P.Renal calculi.
Plan
A.General interventions:
1.Rule out other sources of infection.
2.Assess for PTL.
B. 
See Section III: Patient Teaching Guide “Pyelonephritis in Pregnancy.”
C.Dietary management:
1.Advise the patient to eat a regular diet as tolerated.
2.Encourage her to drink 8 to 10 glasses of water a day.
3.Warn the patient to avoid beverages with caffeine. 100% cranberry juice and cranberry and blueberry capsules are good for urinary tract problems.
D.Pharmaceutical therapy:
1.Broad-spectrum antibiotic coverage until cultures and sensitivity results are back.
2.Drug of choice:
a.Nitrofurantoin (Macrobid) 100 mg orally every 12 hours for 7 days.
b.Amoxicillin 500 mg orally every 12 hours for 10 days or 250 mg orally every 8 hours for 10 days.
c.Augmentin 500 mg orally every 8 hours for 7 days or 875 mg orally every 12 hours for 7 days.
3.If dysuria is present: Phenazopyridine (Pyridium) 200 mg orally three times daily after meals for 3 days. Warn the patient that phenazopyridine (Pyridium) turns urine orange.
4.Alternative medications:
a.Cephalexin (Keflex) 500 mg orally every 12 hours for 7 days.
Follow-Up
A.Once antibiotic therapy is initiated, most patients have a decrease in symptoms within 48 hours. By the end of 72 hours, almost 95% of patients are afebrile and asymptomatic. Stress to patients the importance of completing the course of antibiotics regardless of the absence of symptoms.
B.The most likely causes of treatment failure are a resistant microorganism or obstruction; common causes of obstruction in pregnancy are urolithiasis or compression of the ureter by the gravid uterus.
C.Repeat a urine culture at a 2-week follow-up visit.
D.Recurrence rates are very high. After the initial antibiotic therapy course is completed, start a prophylactic dose of an antibiotic that is to be taken daily till delivery, such as nitrofurantoin (Macrodantin) 50 to 100 mg by mouth at bedtime for recurrent infections.
E.Patients receiving prophylactic antibiotics should have their urine screened for bacteria at each subsequent office visit and be questioned about the recurrence of symptoms.
F.If no prophylactic treatment is undertaken, obtain a urine culture if symptoms recur or if urine dipstick is positive for leukocyte esterase or nitrites.