OSCE Station·Counselling·Posterior urethral valves
A simulated-parent counselling station: explaining antenatally suspected posterior urethral valves to parents after delivery, setting out the immediate plan, and being honest about the long-term kidney outlook.
You are the neonatal registrar. A male infant was born at term this morning. The antenatal scans showed bilateral hydronephrosis, a dilated prostatic urethra and a distended, thick-walled bladder that emptied poorly. Posterior urethral valves are strongly suspected. The baby has been admitted to the neonatal unit and urology have been contacted.
Speak with both parents. Explain what has been found, what will happen over the next hours and days, and answer their questions about the future.
Suggested time: 10 minutesPersona: Mr and Mrs K. Mrs K is exhausted and quiet; Mr K does most of the talking and is frustrated that nobody has given them a straight answer during the pregnancy. Opening line: “Everyone kept saying ‘we’ll see after he’s born’. He’s born now — so what is it?”
Questions they raise:
- “What actually is this — is it a blockage?”
- “Why wasn’t anything done while he was still inside?”
- “What happens today? Does he need an operation right now?”
- “His breathing — the midwife mentioned his lungs. Why would his lungs be involved?”
- “Will his kidneys fail? Be honest with us.”
- “Is there anything we need to watch out for, or avoid?”
Mr K presses hard for certainty on the long-term outlook. He responds well to honesty and poorly to false reassurance.
How do you explain what posterior urethral valves are, and how common they are?
Show model answer
- Posterior urethral valves are an obstructing membranous flap or fold in the lumen of the posterior part of the urethra in males — in plain terms, a flap of tissue blocking the outflow of urine from the bladder.
- It is among the commonest causes of urinary tract obstruction in neonates and is the commonest cause of lower urinary tract obstruction.
- In the United States the incidence is estimated at 1 in 5,000 to 1 in 8,000 births.
- The antenatal findings described — bilateral hydronephrosis, a dilated prostatic urethra, and a distended bladder with a wall thicker than 3 mm emptying poorly over 30 minutes — are the features that raised the suspicion.
The father asks why nothing was done before birth. What is the honest answer?
Show model answer
- Antenatal management is typically deferred because of the high morbidity and mortality associated with intervening before birth.
- What is done antenatally is serial ultrasonography to monitor amniotic fluid levels and assess for renal dysplasia, and fetal urinary electrolytes and β2 microglobulin can be measured to assess fetal kidney function.
- It is also worth acknowledging their frustration directly, rather than defending the antenatal team — the uncertainty they experienced was real.
What do you tell them about today — the immediate management and investigations?
Show model answer
- Initial management is correction of electrolytes and management of possible respiratory distress or urosepsis.
- Urinary catheterisation, often placed by the urology team, may be needed if the baby is in urinary retention.
- Investigations where the diagnosis is of concern include blood tests, imaging and urodynamic studies — renal and bladder ultrasonography, a voiding cystourethrogram, and renal scintigraphy.
- Postnatal presentation can range from lethargy, poor feeding, delayed voiding and a palpable bladder through to urosepsis in the most severe cases, so the team will be watching for these.
The mother asks why the lungs are involved. How do you explain it?
Show model answer
- Posterior urethral valves can cause pulmonary hypoplasia in utero, secondary to low amniotic fluid levels — the lungs need fluid around the baby to develop normally.
- Other complications include urinary retention and chronic kidney disease.
- This is why respiratory support may be needed as part of the initial management.
They ask directly whether his kidneys will fail. What do you say?
Show model answer
- The prognosis depends on the severity of the obstruction and on any damage sustained in utero — so certainty today is not possible, and it is right to say so.
- Many infants go on to develop chronic kidney disease and bladder dysfunction.
- In one study of 75 patients with posterior urethral valves, 21% developed end-stage renal failure by the end of a mean follow-up period of 64 months.
- Several factors were prognostic for kidney function in that study: renal volume below the third percentile, more than three urinary tract infections with fever, decreased eGFR at 1 year of age, elevated renal echogenicity, and pathological corticomedullary differentiation.
- Close observation and monitoring by both urology and nephrology is needed to follow kidney function and manage chronic kidney disease.
They ask whether there is anything to avoid. What is the safety-critical point here?
Show model answer
- Nephrotoxic medications should be avoided where possible — specifically non-steroidal anti-inflammatory drugs and aminoglycosides.
- This should be stated explicitly to the parents and documented, since these are drugs the child may be offered elsewhere.
- Febrile urinary tract infections matter: more than three of them was among the factors prognostic for kidney function, so the parents should know to seek review early if the baby is unwell or feverish.
Based on: Fong J, De Beritto T. Congenital Anomalies of the Kidneys and Urinary Tract. NeoReviews, 2024.
Educational material for teaching and revision. Doses, thresholds and management points are for orientation only — always follow your local guidelines and senior clinical advice.