HIV in pregnancy — structured oral station (12 minutes)

Opening prompt — "What is your immediate management?"

Model response, in this order: ^[1][2]

• "I would confirm the diagnosis with the confirmatory testing if not already done, assess the baseline viral load and CD4 count, and start combination antiretroviral therapy as soon as possible. The priority is to suppress the maternal viral load before delivery, because the viral load is the single most important determinant of vertical transmission."^[1]
• "I would involve the multidisciplinary team — the infectious diseases physician, the obstetric team, the paediatric team, and the midwife specialist — and arrange resistance testing and baseline bloods."^[2]
• "The aim is a fully suppressed viral load by delivery, which drives the transmission rate down to under 1%, and as low as 0.1% with a viral load under 50 copies per mL."^[2]

Examiner is listening for: immediate cART, the multidisciplinary team, and the viral-load target. ^[1][2]

Probe 1 — "What vertical transmission rate can she expect with effective intervention?"

• "Without intervention, HIV is transmitted to about 15 to 25% of infants in a non-breastfeeding population. The ACTG 076 trial began the antiretroviral prevention era — zidovudine reduced transmission from 25.5% to 8.3%."^[1]
• "With modern combination antiretroviral therapy and a suppressed viral load, transmission falls to under 1%. In the UK and Ireland surveillance, transmission was 0.46% overall in 2010 to 2011 and 0.09% with a viral load under 50 copies per mL."^[2]
• "So if we suppress her viral load by delivery, her risk is under 1%, and approaching 0.1% if fully suppressed."^[2][3]

Probe 2 — "She asks for a normal birth. How do you decide on the mode of delivery?"

• "The mode-of-delivery decision is viral-load-driven, made on the viral load closest to delivery — typically the 36-week viral load."^[2]
• "If her viral load is fully suppressed — under 50 copies per mL — planned vaginal delivery is acceptable. In the UK and Ireland data, transmission was 0.26% following elective caesarean and 1.1% following planned vaginal delivery in women with a viral load of 50 to 399 copies per mL, a non-significant difference that underpins the vaginal-delivery policy."^[2]
• "If her viral load is detectable near term, a planned caesarean is indicated. The threshold for offering planned caesarean is set by the local guideline and the detectable viral load."^[2]

Probe 3 — "What about the duration of ruptured membranes in labour?"

• "The Peters population-based surveillance study showed that in women delivering at term on combination therapy, rupture of membranes of 4 hours or more was not significantly associated with increased transmission — 0.64% versus 0.34%, and for a viral load under 50 copies per mL, 0.14% versus 0.12%."^[4]
• "This means that in the suppressed woman, I would not mandate expedited delivery purely for the duration of ruptured membranes. The decision turns on the viral load and the clinical progress of labour."^[4]

Probe 4 — "What neonatal prophylaxis will the infant receive?"

• "The infant receives antiretroviral prophylaxis, with zidovudine as the backbone. The regimen is escalated — with additional agents — based on the infant's transmission risk, which is driven by the maternal viral load at delivery, the duration of maternal therapy, and the mode of delivery."^[5]
• "The prophylaxis is typically continued for several weeks, while infant HIV diagnostic testing — HIV RNA PCR — is undertaken at the appropriate intervals."^[5]

Probe 5 — "She asks whether she can breastfeed. How do you answer?"

• "Infant feeding advice is setting-dependent, and I would name the setting first. In a high-income setting like ours, where safe replacement feeding is reliably available, exclusive formula feeding from birth eliminates breastfeeding-related transmission and is recommended."^[5]
• "In a resource-limited setting where replacement feeding is not safe or sustainable, the WHO guidance supports breastfeeding with effective maternal suppression, because the survival benefit of breastfeeding outweighs the residual transmission risk. The advice is genuinely setting-dependent — applying our formula advice in a low-resource setting could cause harm."^[5]

Probe 6 — "Tell the woman what is happening, in language she will understand."

This is scored. Demonstrate it out loud rather than describing it. ^[1]

• Sit down, at her eye level, with her partner or support person present if she wishes. Acknowledge her anxiety first.
• Plain words: "The blood test shows you have HIV. HIV is a virus that, without treatment, can pass from a mother to her baby during pregnancy and birth — in about one in four cases. The good news is that we have very effective treatment that brings that risk down to under one in a hundred, and even lower if we get the virus fully suppressed in your blood before the birth."
• The plan: "I would like to start you on a combination of medicines today that suppress the virus. We will check the level of virus in your blood over the coming weeks, and plan the birth around that. Most women who take the medicines and have the virus suppressed can have a normal vaginal birth. After the birth, the baby will have a short course of medicine too."
• The feeding question: "Because we live in a place where safe bottle feeding is easy to get, I would recommend bottle (formula) feeding from birth — this is the safest option for the baby here, because it removes any chance of the virus passing through breast milk. In some other parts of world advice is different, but here, formula is the safest."
• Outcome honesty: "With all of this, the chance of the baby having HIV is under one in a hundred, and we will test the baby in the weeks after birth to be sure."^[1][2]