Prevalence:

• 1 in 100 pregnancies.

Ultrasound diagnosis:

• Visualization of only one artery around the fetal bladder.

Associated abnormalities:

• Chromosomal abnormalities, mainly trisomy 18, 13 and triploidy, are found in 5% of cases.
• Fetal growth restriction (<5th percentile) occurs in 10% of cases. Stillbirth, usually in association with growth restriction is twice as common as in the general population.
• Abnormalities affecting cardiovascular, skeletal, gastrointestinal, genitourinary and central nervous systems, are found in 20% of cases.

Investigations:

• Detailed ultrasound examination.
• Fetal karyotyping in non-isolated cases.

Follow up:

• Serial scans at 28, 32 and 36 weeks’ gestation to assess fetal growth and well-being.

Delivery:

• Standard obstetric care and delivery.

Prognosis:

• In isolated cases the prognosis is normal.

Recurrence risk:

• Isolated: no increased risk of recurrence.
• Part of trisomies: 1%.