O23.03 Infections of kidney in pregnancy, third trimester

Name of the Condition

• Infections of kidney in pregnancy, third trimester
• ICD-10 Code: O23.03

Summary

Infections of the kidney during the third trimester of pregnancy, also known as pyelonephritis, involve bacterial infection of the renal parenchyma and collecting system. This condition is a serious complication of urinary tract infections (UTIs) and requires prompt medical attention to prevent maternal and fetal harm.

Causes

Pyelonephritis in the third trimester typically results from ascending bacterial infection, most commonly caused by Escherichia coli. Hormonal and anatomical changes during pregnancy, such as ureteral dilation and reduced urinary flow, increase susceptibility to UTIs that can progress to kidney infection.

Risk Factors

• Previous history of UTIs or pyelonephritis.
• Asymptomatic bacteriuria during pregnancy.
• Structural urinary tract abnormalities.
• Diabetes mellitus.
• Immunosuppression.
• Prolonged labor or catheterization.

Symptoms

• Fever, chills, or flank pain (unilateral or bilateral).
• Costovertebral angle tenderness.
• Nausea, vomiting, or abdominal pain.
• Dysuria, frequency, or urgency.
• Cloudy or foul-smelling urine.
• Fatigue or malaise.

Diagnosis

Diagnosis is confirmed through urinalysis (showing pyuria, bacteriuria, or positive nitrites), urine culture (to identify the causative organism and guide antibiotic therapy), and blood tests (to assess for systemic involvement). Imaging may be used cautiously to evaluate for complications.

Treatment Options

Treatment typically involves hospitalization for intravenous antibiotics, followed by oral antibiotics to complete the course. Close monitoring of maternal and fetal status is essential. Hydration and pain management may also be provided.

Prognosis and Follow-Up

With prompt treatment, most cases resolve without long-term complications. Follow-up includes repeat urine cultures to ensure eradication of infection and monitoring for recurrence, especially as pregnancy progresses.

Complications

Untreated or severe infections can lead to sepsis, preterm labor, low birth weight, or maternal renal damage. Rarely, abscess formation or chronic kidney disease may occur.

Lifestyle & Prevention

• Maintain good hydration.
• Practice proper hygiene.
• Urinate promptly when needed.
• Treat asymptomatic bacteriuria if identified.
• Avoid irritants like harsh soaps.

When to Seek Professional Help

Seek care immediately for fever, severe flank pain, or signs of systemic illness. Prompt evaluation is critical to prevent progression and complications.

Tips for Medical Coders

Document the trimester (third) and specify kidney involvement. Ensure clinical documentation supports the diagnosis and any associated complications. Code O23.03 is specific to the third trimester; verify no other trimester codes apply.