Congenital and perinatally acquired infections: SAQ

This infant presents the classic cytomegalic inclusion disease phenotype of congenital CMV: microcephaly with periventricular calcifications, petechiae and a 'blueberry muffin' rash of dermal haematopoiesis, and hepatosplenomegaly. The maternal flu-like illness at 10 weeks gestation is consistent with primary CMV infection in the first trimester - the highest-risk period for severe fetal disease. Rubella, syphilis, HIV, and hepatitis B are effectively excluded by the documented negative screens. [2]

Question 1 (10 marks)

Outline your diagnostic approach and the investigations you would perform to confirm congenital cytomegalovirus. [2]

The priority is to confirm congenital CMV within the diagnostic window. The gold standard is detection of CMV by polymerase chain reaction in urine or saliva collected within the first three weeks of life; after this window, postnatally acquired CMV (including from breast milk) cannot be distinguished from congenital infection. Send urine and saliva PCR now, and request CMV PCR on blood and cerebrospinal fluid as adjuncts. [1]

Perform a targeted broader workup to stage disease severity and exclude mimics: a complete blood count for thrombocytopenia and anaemia, liver function tests for hepatitis, and coagulation studies. Perform a lumbar puncture for CSF cell count, protein, glucose, and CMV PCR if the infant is stable. Obtain cranial ultrasound and, for better delineation of cortical and cerebellar involvement, a cranial MRI. Arrange an ophthalmology review for chorioretinitis, and audiology referral for diagnostic auditory brainstem response testing. If the diagnosis is considered after the three-week window, retrospective testing of the stored neonatal blood spot (Guthrie card) is the only reliable retrospective method, though it is less sensitive. [2]

Question 2 (10 marks)

Discuss the management of this infant, including the role of antiviral therapy, and outline the long-term surveillance plan. [1]

This infant has symptomatic congenital CMV with central nervous system involvement, which meets the criteria for antiviral therapy. The standard of care established by the Kimberlin et al randomised trial is six months of oral valganciclovir at 16 mg per kg per dose twice daily, which improves long-term hearing and neurodevelopmental outcomes compared with six weeks of therapy. The principal adverse effect is neutropenia, so a full blood count must be monitored during treatment, and the family must be supported to complete the prolonged course. [1]

Supportive care runs in parallel: treat thrombocytopenia, anaemia, and seizures as they arise, and ensure adequate nutrition. The long-term surveillance plan is critical and must be explicit. Arrange audiology assessment at diagnosis and then regularly - at least every six months - through the first six years, because CMV-related sensorineural hearing loss can be late-onset and progressive. Establish developmental surveillance and early intervention, with neurological review. Repeat neuroimaging and ophthalmology follow-up as indicated. Counsel the family honestly about the uncertainty of prognosis: we cannot fully predict which children will develop hearing loss or developmental problems, which is precisely why close multidisciplinary follow-up is essential. [1]