Explaining congenital CMV, valganciclovir and hearing surveillance — OSCE

Candidate instructions (8-minute station)

You are the paediatric registrar in the neonatal unit. A 10-day-old term baby has been admitted with prolonged jaundice, petechiae, an enlarged liver and spleen, a platelet count of 45 × 10⁹/L, and a referred newborn hearing screen on the left. The cranial ultrasound shows periventricular calcifications. Congenital cytomegalovirus is the working diagnosis. [10]

Your tasks are: [9]

1. Explain the diagnosis of congenital cytomegalovirus in plain language — what the virus is, how the baby acquired it, and what the findings mean. [10]
2. Explain why a saliva PCR must be done now, within the first 21 days of life, and what it will tell you. [11]
3. Explain the treatment decision — valganciclovir for six months — what it aims to achieve and what monitoring it requires. [8]
4. Explain the long-term hearing surveillance, including why a baby who passed one ear still needs audiology into school age. [13]
5. Address the mother's question about preventing CMV in a future pregnancy. [9]

You are not expected to commit to a prognosis beyond what the evidence supports, or to prescribe without senior review — flag that the final treatment plan will be confirmed by the consultant. [9]

Examiner prompt to the actor (mother)

"Is it my fault the baby has this? I had a flu-like illness early in the pregnancy — could I have prevented it? You're saying he needs medicine for six months — is it really that serious, he's only a bit yellow? And you mentioned his hearing — does that mean he'll be deaf? We were hoping to try for another baby soon — will this happen again?" [9]

Marking domains

• Frame and explanation (3): explains congenital CMV as a common virus (cytomegalovirus) that crossed the placenta during pregnancy, in plain language; reassures that it is not the mother's fault and that primary maternal infection often passes unnoticed; names the findings (jaundice, low platelets, calcifications, hearing referral) as effects of the infection. [10]
• The diagnostic window (2): explains clearly that a saliva PCR must be done within the first 21 days of life to confirm the infection is congenital, because after that window a positive test cannot tell congenital from later-acquired CMV — frames this as time-critical and does it today. [11]
• Treatment decision and monitoring (2): explains that valganciclovir for six months aims to protect hearing and development, that the evidence shows six months is better than six weeks, and that it requires regular blood-count monitoring for a low neutrophil count; sets honest expectations without overwhelming. [8]
• Hearing surveillance and prevention (2): explains that CMV hearing loss can appear or progress months to years later, so audiology continues into school age even if one ear passed; addresses pregnancy prevention with simple hygiene measures (hand-washing, no sharing utensils, no kissing young children on the mouth) and frames a future pregnancy as manageable with monitoring. [13] [9]
• Communication (1): acknowledges the mother's guilt and anxiety without defensiveness, uses plain language, checks understanding, and offers a follow-up conversation with the consultant. [10]

Model answer — the explanatory script

"Thank you for coming in. I want to explain what we've found and what we're going to do about it. The tests and the scan are pointing to an infection called cytomegalovirus, or CMV for short. It's a very common virus — most adults have had it without ever knowing — and it can pass from a mother to her baby during pregnancy. That is almost certainly what happened here, and I want to say straight away that it is not your fault. The flu-like illness you had early in the pregnancy may have been the first time you met the virus, and at that stage there was no reason to test for it. Nothing you did or didn't do caused this." [10]

"The reason your baby is jaundiced, has some small bruises, a low platelet count and the calcium spots on the brain scan, and why one ear didn't pass the hearing test, is that the virus affected him while he was developing. These are the effects of the infection, and the good news is that we have treatments and monitoring that make a real difference to his future." [10]

"The first thing I must do today is confirm the diagnosis, and there's an important reason it has to be now. We test a sample of your baby's saliva, and it has to be done within the first three weeks — twenty-one days — of life. That's because after three weeks, if the test is positive, we can't tell whether the virus came from the pregnancy or whether he picked it up afterwards from breast milk or the birth canal. So we're doing this test today, while we're still in that window. It's quick, it doesn't hurt him, and it gives us the answer we need." [11]

"If the test confirms what we suspect, we'll offer a medicine called valganciclovir, which your baby takes by mouth twice a day for six months. I know that sounds like a long time for a tiny baby. The reason we do it is that a very good study showed that six months of this medicine improves a baby's hearing and development more than a shorter course — so we're giving him the best chance at his hearing and his learning. The medicine can lower his white blood cell count, so we'll do a small blood test regularly to keep an eye on that, and we'll adjust the dose if we need to. It's a commitment, but it's the right one for him." [8]

"Now, about his hearing. The hearing test flagged one ear, and that may be an effect of the CMV. The important thing to understand is that CMV can affect hearing in a way that develops later — it can appear or get worse months or even years from now, even in a baby who seems fine today. So we don't just test once. We'll arrange regular hearing checks all the way through to school age, so that if anything changes we catch it early and can get him the support he needs. He may have perfectly normal hearing — but we watch carefully, because that's how we protect him." [13]

"And your question about another baby is a good one. CMV is common, and having had it once doesn't mean it will definitely happen again, but it doesn't fully protect you either. When you're ready to think about another pregnancy, there are simple things that genuinely reduce the risk — washing your hands carefully after changing nappies or wiping a toddler's nose, not sharing cutlery, food or drinks with young children, and not kissing them on the mouth. These sound small, but they work, because CMV spreads through the saliva and urine of little children. There isn't a vaccine yet, though researchers are working on one. We'll plan your next pregnancy together, with monitoring, so you go into it informed and supported." [9]

"I'll come back with the consultant after the test results, and we'll go through the plan with you in detail. You're asking exactly the right questions, and none of this is your fault — let's take this one step at a time." [10]