Perinatal TB

Introduction And Pathogenesis

• Mycobacterium tuberculosis is the etiologic agent responsible for tuberculosis (TB).
• Perinatal TB is the preferred clinical term because it encompasses both true congenital and neonatal forms of the disease.
• Transplacental transmission forms a primary complex in the liver with secondary hematogenous spread.
• Aspiration or ingestion of infected amniotic fluid leads to a primary focus in the lungs or the gastrointestinal tract.
• Postnatal acquisition commonly occurs through the inhalation of infectious droplet nuclei from a contagious caregiver.

Classification And Diagnostic Criteria

Congenital Versus Postnatal Tuberculosis

Cantwell's Diagnostic Criteria

• The diagnostic criteria for congenital TB require proven tuberculous lesions and at least one of the following:
  • Lesions appearing in the first week of life.
  • A primary hepatic complex or a caseating hepatic granuloma.
  • Tuberculous infection of the placenta or maternal genital tract.
  • Exclusion of postnatal transmission by thorough investigation of contacts.

Clinical Presentation

• The infant must be evaluated for perinatal TB if the mother has possible TB disease, even if the infant is asymptomatic.
• Hepatosplenomegaly and respiratory distress are the two most common clinical signs.
• Fever is another common presentation.

Investigations

Infant Evaluation

• Gastric aspirate is utilized for the isolation of tubercular bacilli in neonates.
• Nucleic acid amplification test (NAAT) is the most recommended first-line diagnostic test.
• Xpert Rif is a cartridge-based nested NAAT that detects M. tuberculosis and Rifampicin resistance.
• Chest radiography is usually abnormal.
• Half of the affected neonates exhibit a miliary disease pattern, which may take days to weeks to develop.
• Other radiographic findings include adenopathy and parenchymal infiltrates.
• Cerebrospinal fluid (CSF) must be examined because TB meningitis occurs in one-third of perinatal TB cases.

Maternal And Placental Evaluation

• The placenta must be examined by a pathologist and cultured for M. tuberculosis.
• If the placenta is unavailable, consider uterine dilation and curettage for endometrial specimens.

Management

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    B -->|Present| D[Chest X-ray;
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    C --> F[Evidence of TB]
    
    D --> G[Start treatment]
    F --> D
    
    E --> H[Give BCG and start INH]
    H --> I[Evaluate for clinical evidence of
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Treatment Of Perinatal Tuberculosis Disease

• Treatment must be initiated promptly if congenital or postnatal TB is suspected.
• The total duration of treatment is 9 to 12 months.
• The intensive phase includes an initial four-drug regimen for the first 2 months.
• These drugs are Isoniazid (INH), Rifampicin (RIF), Pyrazinamide (PYZ), and Ethambutol (EMB) or Streptomycin.
• The continuation phase includes INH, RIF, and EMB for an additional 7 to 10 months.
• Fixed-drug combinations (FDC) based on weight categories are recommended for infants weighing more than 4 kg.

• If TB meningitis is suspected, administer 2 mg/kg/day of prednisone (or equivalent) for the first 4 weeks.
• Taper the corticosteroid dose over the subsequent 4 weeks to prevent hydrocephalus or infarcts.

Management Of An Asymptomatic Exposed Neonate

• If a neonate is exposed to active TB, immediately evaluate for the presence of disease.
• If active disease is excluded, start INH preventive therapy (IPT) at a dose of 10 mg/kg/day for 6 months.
• Pyridoxine (10 mg) must also be given to the newborn.
• IPT is not effective and is not recommended if the exposure is to multidrug-resistant (MDR) tuberculosis.
• Administer the BCG vaccine at birth to all neonates.

Infection Control And Breastfeeding

• Suspected neonates should be placed in airborne isolation due to the risk of extensive pulmonary involvement.
• A mother with active untreated TB does not need to be isolated from her newborn if her therapy has started and the baby is on IPT.
• Isolation is required if the mother has MDR-TB or is noncompliant with treatment.
• Breastfeeding is safe and must be continued, provided the mother practices strict cough hygiene.

Prognosis

• The prognosis of perinatal TB is guarded.
• The mortality rate ranges from 25% to 50% even with effective treatment.
• Delays in diagnosis are common because congenital TB is rare.
• Survivors often suffer from growth delay and severe pulmonary damage.
• Neurologic complications, including hearing loss, visual impairments, seizures, and cognitive abnormalities, can occur if TB meningitis is present.