Urinary Tract Infection (UTI) in pregnancy
UTI in pregnancy is commonly caused by an ascending infection of the urinary tract from existing gastrointestinal and genitourinary tract flora. It is defined as the presence of ≥ 100,000 organisms/mL of urine if asymptomatic or > 100 organisms/ml of urine with pyuria (> 7 WBC/mL) in symptomatic women. The most common cause is Escherichia coli. Others include Klebsiella, Proteus, GBS etc. The risk of UTI increases in pregnancy mainly due urinary stasis (elevated progesterone relaxes the detrusor muscles and the gravid uterus makes it difficult to void), dehydration and **glycosuria. Ureteral dilatation and stasis commonly occurs on the right due to compression by a dexrorotated uterus. UTI is associated with adverse fetal risk and the biggest risk for development of symptomatic UTI is asymptomatic bacteriuria (carries a 20-30x increased risk; hence it is screened and treated during first ANC visit and third trimester visit).
Summary of UTI during pregnancy
| Asymptomatic bacteriuria | Acute cystitis | Pyelonephritis | |
|---|---|---|---|
| Urine culture | Positive | Positive | Positive |
| Urgency, frequency, burning | No | Yes | Yes |
| Fever | No | No | Yes |
| CVA tenderness | No | No | Yes |
- Primary prevention of UTI in pregnancy
- Avoid bathing. Shower instead
- Wash hands before using toilet
- Wipe front to back
- Use liquid soap (less likely to have bacteria growing on it)
- Clean urethral meatus area first
Urinary tract change in pregnancy
- Renal pelvis and ureters
- Progesterone reduces ureteral tone, peristalsis and contraction pressure → vesicoureteral reflux
- The gravid uterus applies pressure on the bladder and compresses the ureters
- Compression of ureters by enlarged vessels in the suspensory ligaments of the ovary
- Relative immunosuppression
- Right ureter is more affected than the left because it is affected by dextrorotation of the uterus by the sigmoid colon, as well as kinking as it crosses the right iliac artery
- Bladder
- Edematous and hyperemic mucosa
- Progesterone induces bladder wall relaxation and increases the capacity
- The enlarged uterus displaces the bladder superiorly, anteriorly and flattens it, which can decrease capacity
- Increased incidence of microhematuria
- Intermittent vesicoureteral reflux
- Due to incompetence of the vesicoureteral valve from bladder flaccidity
- Increased intravesical pressure
- Decreased intraureteral pressure
- Postpartum changes from trauma during labor and delivery
- Mucosal congestion and submucosa haemorrhage
- Decreased bladder sensitivity/ sensation
- Detrusor atony
- Postvoidal residual volume
- Bladder overdistension
- Urinary retention
- Impaired tubular function
- Reduced fractional reabsorption of glucose, amino acids, and beta microglobulin
Asymptomatic bacteriuria (ASB)
All women are screened for bacteriuria at their first ANC visit.
Approximately 10% of women have positive urinary culture. 30-50% with ASB will develop symptomatic UTI (Pyelonephritis) if not treated.
- Risk factors
- Lower socioeconomic status
- Diabetes
- History of urinary tract infection
- Multiparity
- Anatomic or functional urinary tract anomalies
- Sickle cell trait
- Signs and symptoms
- None…it is asymptomatic
- Physical exam
- Unremarkable
- Investigation
- Urinalysis and urine culture
- Treatment
- Nitrofurantoin
- Repeat culture after treatment and q1mos thereafter
- Daily suppression treatment with nitrofurantoin or cephalexin if it persists after two courses
Acute cystitis
- Symptoms
- Burning urination
- Sensation of incomplete voiding
- Urinary urgency
- Frequency
- Suprapubic discomfort
- Physical exam
- Tenderness on pelvic exam with manipulation of bladder
- Investigation
- Urinalysis and urine culture
- Positive nitrites
- Positive esterase
- Increased WBCs, RBCs
- Proteinuria
- +/- bacteria
- Positive culture
- Urinalysis and urine culture
- Treatment
- Nitrofurantoin 100mg BD 7-10 days
- Repeat culture after treatment
- Daily suppression treatment for women with two or more UTIs and for women with increased risk of UTIs e.g. diabetes, sickle cell trait
Pyelonephritis
Women with pyelonephritis are generally sick-looking
- Signs and symptoms
- Malaise
- Fatigue
- Chills
- Anorexia
- Fever
- Symptoms of acute cystitis (burning urination, sensation of incomplete voiding, urinary urgency, frequency and suprapubic discomfort)
- Physical exam
- Sick-looking
- Costovertebral angle (CVA) tenderness
- Flank tenderness
- Investigations
- Urinalysis and culture
- Blood culture
- Complete Blood Count
- Urea, Electrolytes and Creatinine
- Treatment
- Admit
- IV antibiotics
- 2nd or 3rd generation cephalosporin (ceftriaxone) or ampicillin + gentamicin
- Transition to oral medications after afebrile for 24-48 hours (try not to give antipyretics to monitor fever)
- Daily suppression therapy for remainder of pregnancy
- Control nausea with doxylamine/B12 (if woman is dehydrated will put fetus at risk)
- Judicious use of IV fluids (inflammatory response puts the patient at risk of ARDS)
- Complications of pyelonephritis
- Systemic Inflammatory Response Syndrome (SIRS)
- Acute Respiratory Distress Syndrome (ARDS): pulmonary edema, injury
- Renal dysfunction
- Septic shock → hypoxic fetal events
- Spontaneous abortion
- Preterm delivery
- Intrauterine Growth Restriction (IUGR) and Low Birth Weight (LBW) infant
