Urinary Tract Infections in Pregnancy Clinical Presentation

Updated: Jul 13, 2023
  • Author: Raisa O Platte, MD, PhD; Chief Editor: Edward David Kim, MD, FACS  more...
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The presentation varies according to whether the patient has asymptomatic bacteriuria, a lower urinary tract infection (UTI; ie, cystitis) or an upper UTI (ie, pyelonephritis).

Burning with urination (dysuria) is the most significant symptom in pregnant women with symptomatic cystitis. Other symptoms include frequency, urgency, suprapubic pain, hematuria, and pyuria in the absence of systemic symptoms. The usual complaints of increased frequency, nocturia, and suprapubic pressure are not particularly helpful, because most pregnant women experience these as a result of increased pressure from the growing uterus, expanding blood volume, increased glomerular filtration rate, and increased renal blood flow.

Pyelonephritis signs and symptoms often include fever (> 38°C), shaking chills, anorexia, nausea, vomiting, and costovertebral angle tenderness. Right-side flank pain is more common than left-side or bilateral flank pain. Pyuria is a common finding. Patients may also present with hypothermia (as low as 34°C). Symptoms of simple cystitis are not always present.


Physical Examination

Physical examination findings should be considered in relation to the duration of pregnancy. The differential diagnoses may change from one trimester to the next, and the increasing size of the gravid uterus may mask or mimic disease findings. A thorough physical examination is recommended, with particular attention to the abdomen. Suprapubic or costovertebral tenderness may be present.

In asymptomatic bacteriuria, no physical findings are typically present. Symptoms may arise intermittently, only to be overlooked because of lack of persistence or severity.

Pelvic examination is recommended in all symptomatic patients (with the exception of third-trimester patients with bleeding) to rule out vaginitis or cervicitis. In patients with cystitis, tenderness can often be elicited with isolation of the bladder on pelvic examination.

Patients with pyelonephritis have fever (usually > 38°C), flank tenderness upon palpation, and an ill appearance. Flank tenderness occurs on the right side more frequently, and is present in more than half of patients. Pain may also be found suprapubically with palpation.

Assessment of the fetal heart rate on the basis of gestational age should be included as part of the evaluation. Often, owing to maternal fever, the fetal heart rate is elevated to more than 160 beats/min.



The primary complication of bacteriuria during pregnancy is cystitis, though the primary morbidity is due to pyelonephritis.

Complications may include the following:

  • Perinephric cellulitis and abscess
  • Renal dysfunction (usually transient, but as many as 25% of pregnant women with pyelonephritis have a decreased glomerular filtration rate)
  • Hematologic dysfunction, including anemia or thrombocytopenia 
  • Hypoxic fetal events due to maternal complications of infection that lead to hypoperfusion of the placenta
  • Preterm labor, and possible subsequent preterm delivery, leading to increased infant morbidity and mortality

Pregnant women with pyelonephritis can become critically ill very quickly. It has been estimated that approximately 20% of pregnant women with severe pyelonephritis develop complications that include septic shock variants. [21] In a prospective study of cases of pregnant women with acute pyelonephritis, complications included anemia (23%), bacteremia (17%), respiratory insufficiency (7%), and renal dysfunction (2%). [17]

Pulmonary injury may also complicate UTI in pregnancy. Approximately 2% of women with severe pyelonephritis during pregnancy have evidence of pulmonary injury due to systemic inflammatory response syndrome and respiratory insufficiency. Endotoxins that alter alveolar-capillary membrane permeability are produced; subsequently, pulmonary edema and acute respiratory distress syndrome develop.