Patient's question:
How much impact does a single umbilical artery have on my baby? Are the rest of the findings normal? What follow-up tests are needed?Fetal single umbilical artery: BPD 50mm (21w+2d), HC 204mm (22w+4d), AC 183mm (23w+2d), FL 35mm (21w+2d), Humerus length 32mm (21w+0d), Cerebellar transverse diameter 23mm, Cerebellomedullary cistern depth 3.6mm, Lateral ventricle width 3.1mm.
Color Doppler flow imaging: Fetal heart rate is regular, fetal heart rate 146 bpm, bladder view shows only the right umbilical artery, left umbilical artery is not visible, umbilical artery...
Doctor's answer:
Analysis of the Condition: Single umbilical artery is not uncommon, and reference books suggest an increased likelihood of fetal chromosomal abnormalities. After discovering a single umbilical artery, it is important to carefully examine the other systems and structures of the fetus for any abnormalities. Its significance itself is not significant. The absence of one umbilical artery (single umbilical artery) is relatively common, occurring in 0.46% of liveborn singletons, 0.8% of multiple pregnancies, and 6.1–11.3% of chromosomally abnormal newborns. Trisomy 13 and trisomy 18 are most commonly affected, while trisomy 21 and sex chromosome abnormalities rarely present with a single umbilical artery. In most non-disomic fetuses with a single umbilical artery, other structural abnormalities can be detected by ultrasound, and karyotype analysis should be performed. Fetuses with only a single umbilical artery and no other structural abnormalities should not be considered indications for prenatal fetal chromosome testing but should be regarded as "high-risk" pregnancies requiring close obstetric evaluation and follow-up, as these fetuses have an increased risk of preterm birth and low birth weight. A single umbilical artery disrupts blood supply during embryonic development, which can lead to developmental abnormalities in the fetal cardiovascular system, central nervous system, gastrointestinal tract, skeletal system, urogenital system, and fetal limbs. The incidence of single umbilical artery varies among reports. Foreign reports indicate an incidence of 0.27%–1.13% in newborns, while domestic reports suggest 0.59%. Obstetric reports range from 0.2%–1.2%, and pathological autopsies report 2.7%–12%. The systolic peak velocity (S) to diastolic end velocity (D) ratio (S/D value) is slightly higher than normal. Since a single umbilical artery disrupts blood supply to the lower part of the early embryo, it can lead to cardiovascular malformations, central nervous system defects, gastrointestinal, skeletal muscle system, urogenital system, and lower limb developmental abnormalities, as well as affecting the formation of the abdominal wall below the umbilical cord, leading to visceral herniation. The types of abnormalities associated with a single umbilical artery are diverse, with a high incidence of lethal malformations and mortality. It is closely related to intrauterine growth restriction (IUGR) and preterm birth, and some cases are associated with chromosomal genetic factors. The umbilical cord is the main pathway for material exchange between the fetus and the mother. At term, the blood flow through the umbilical cord is approximately 125 ml/kg.min. The umbilical arteries radiate from the root of the placenta and branch into several branches that enter the chorionic plate, then further divide into villous arteries distributed in various villi, forming capillaries within the villi, which finally merge into the umbilical vein. The venous blood of the fetus is transported from the umbilical arteries to the capillaries of the villi, and then the arterial blood is returned to the fetus by the umbilical vein, participating in the fetal circulation. Due to the severe obstruction caused by a single umbilical artery in fetal circulation, the amount of blood returning to the placenta is reduced, leading to fetal hypoxia and subsequent developmental abnormalities, IUGR, preterm birth, and miscarriage. Foreign reports indicate a malformation rate of 25%–30%, while domestic reports suggest 16.7%. Some abnormalities may only become apparent during postnatal follow-up.Advice: Based on your current test results, no other abnormalities were found, so there should not be a major issue, as long as it does not exceed the expected circumference. Amniocentesis can still be considered. Due to the inability to conduct a face-to-face consultation, please visit the hospital to see the doctor. Wishing your baby health!
Doctor's Inquiry: