Disease Description (Causes and Symptoms)
- Definition: Single umbilical artery is a condition in which only one artery remains in the umbilical cord, which normally consists of one vein and two arteries. It occurs in less than approximately 1% of all pregnancies.
- Causes·Pathophysiology: Although the exact cause is unknown, it is presumed to occur because one artery fails to form during the embryonic period or degenerates and becomes occluded during pregnancy due to factors such as thrombosis. The remaining artery may enlarge to compensate for the function.
- Main symptoms·Associated findings: The fetus itself does not exhibit symptoms, but the condition is detected on prenatal ultrasound. Approximately 80% are “isolated” cases without accompanying abnormalities and have a good prognosis. However, in some cases, there is an increased risk of other congenital anomalies such as heart or kidney abnormalities, chromosomal abnormalities, intrauterine growth restriction (IUGR), low birth weight, and preterm birth.
Treatment Methods
- Principle: There are no medications or surgeries that treat single umbilical artery itself; after prenatal detection, observation and management according to the presence or absence of complications or accompanying anomalies are key.
- Standard management
- Detailed anomaly screening (mid-pregnancy anomaly ultrasound, at 18–22 weeks) and fetal anatomical assessment.
- Fetal echocardiography is recommended if a fetal heart abnormality is suspected.
- Periodic ultrasound for growth assessment (e.g., growth monitoring at 3–4-week intervals) and Doppler testing when necessary.
- Assessment of the risk of chromosomal abnormalities: If high-risk findings are present (accompanying abnormalities, severe growth restriction, etc.), discuss and consider noninvasive prenatal testing (NIPT) or invasive testing (amniocentesis·chorionic villus sampling) and chromosomal microarray analysis (CMA).
- Delivery planning: Obstetric decisions based on fetal status (growth, fetal movement, decreased fetal movement), the presence or absence of accompanying anomalies, and gestational age (preterm delivery·preparation for multidisciplinary care in cases of severe anomalies, etc.).
- Neonatal evaluation: After birth, a physical examination and, when necessary, neonatal echocardiography, abdominal ultrasound, and other tests are performed to check for kidney, heart, and other abnormalities.
- Medications/Procedures: No specific medication is indicated. If accompanying conditions (e.g., gestational diabetes, hypertension, etc.) are present, standard treatment for those conditions is applied.
- Lifestyle management: Regular prenatal checkups and ultrasound follow-up are recommended, and prompt hospital visits are advised if fetal movement decreases.
- Precautions: Isolated single umbilical artery often has a good prognosis, but the prognosis may be worse when other abnormalities are present; therefore, additional testing and consultation with a specialist are important.
Checklist Before an Outpatient Visit (Including Example Questions)
- Items to prepare (recommended to bring)
- List of medications and supplements currently being taken
- Results of previous prenatal tests (blood tests, ultrasound findings, NIPT/amniocentesis results, etc.) or reports/images
- History of previous pregnancies and deliveries (miscarriage, preterm birth, congenital anomalies, etc.)
- Whether chronic diseases are present (diabetes, hypertension, etc.) and treatment records
- Notes on current symptoms such as changes in fetal movement, weight changes, and edema
- Items useful to record for the consultation
- The first day of the last menstrual period (or the exact year of conception)
- When the single umbilical artery was first detected on ultrasound and the related report
- Results of fetal growth monitoring on previous ultrasounds
- Materials to show the doctor during the outpatient visit
- Previous ultrasound images/reports and NIPT·blood test results
- Example questions (including questions to prepare independently before the outpatient visit)
- “Could you review the recent ultrasound images?”
- “How is the current fetal growth curve (weight trend)?”
- “When will future ultrasounds or additional tests be needed?”
Examples of General Questions to Ask the Doctor
- “How can we determine whether this condition is isolated in our fetus or accompanied by other abnormalities?”
- “What additional tests are recommended (NIPT, amniocentesis, fetal echocardiography, etc.), and what are their advantages and disadvantages?”
- “What immediate action should we take if fetal growth restriction or decreased fetal movement occurs?”
- “What factors affect the timing and method of delivery (vaginal delivery/cesarean section)?”
- “What additional tests will the newborn undergo, and what problems can be expected?”
Examples of Condition-Specific Questions
- “No other structural abnormalities besides single umbilical artery are visible on ultrasound. Is it safe to consider this an ‘isolated’ case? How often should follow-up be performed?”
- “When a single umbilical artery is detected, how likely is a fetal heart abnormality, and when would it be best to perform fetal echocardiography?”
Standard management and recommendations may vary depending on the patient’s individual circumstances (gestational age, accompanying findings, and the mother’s underlying conditions). Please consult your obstetrician-gynecologist for a detailed diagnosis, testing, and management plan.