Prenatal Diagnostic Ultrasound in Application of Umbilical Cord

台北榮總婦產部 陳志堯洪正修主任指導

2006年中華醫用超音波年會

媽媽的慈繩愛索

What Ultrasound Can Do?

In Diagnosis

• Vessel Number: Normal cord has 3 vessels encased in Wharton jelly. (2A1V)

– Arteries flanking the bladder.

• Cord Coiled: Arteries coil around vein.

• Connections: Abdominal wall & central placenta. (vesa previa, velamentous insertion)

Cord Length (50~60 cm)

• Short cord– Akinesia sequence– Trisomy 21– Body stalk anomalies

• Long cord– Hyperactivity– Increased likelihood of true cord knot

Morphological Abnormalities

Single Umbilical Artery

• 3% in 1st trimester, 1~2% 2nd tri., 0.63% newborn.

• 70% absent LT UA, 30% RT

• Size is larger than 3 vessel cord UA

• Less coiled

• 15% develop IUGR

• Non-isolated SUA: 50% aneuploidy (T18 & 13)

• D/D– Fused UAs.

– Umbilical vessel thrombosis

– Excessive Wharton jelly

Umbilical Cord Cyst (UCC)

• Para-axial (60%), axial (40%), mid-UC (39%)• 2% in 1st trimester, 2nd~3rd trimester: aneuploidy

(T18 & T13)• Single UCC (75%): good prognosis• Multiple UCC (25%): 2/3 aneuploidy & anomalies.• D/D

– Normal yolk sac– UC aneurysm– Resolving UC hematoma (rare)– UC supernumerary vessels (very rare, conjoined twins)

Umbilical Cord Aneurysm (UCA)

• UV varix (UV > 9mm)– May associated with persistent Rt umbilical vein

– Between abdominal insertion site and inferior liver

– May be large

• UA aneurysm– May have A-V fistula to UV

– Associated with multiple anomalies (T18)

– Near placental origin

– More rare than UV varix; wall may be calcified

Umbilical Cord Aneurysm (UCA)

• Careful research for other anomalies• UV varix may be first manifestation of vein

pressure• Monitor impending hydrops• Monitor for anemia• Use color Doppler for checking

• D/D– Normal fluid-filled structures– Abdominal cysts (choledochal cyst, meconium

pseudocyst, ovarian cyst, urachal cyst)– UC cysts

Meconium pseudocyst

Vasa Previa

• Submembranous fetal vessels cross cervical os

• Doppler shows fixed fetal vessels overlying cx os

• From succenturiate lobe: most common etiology

• Best imagine tool: TVS + color Doppler + PW

• D/D– Marginal sinus previa– Cord presentation– Uterine vessel near cervix

Vasa Previa

• Pathology: 1 in 3500 deliveries

• 60~80% fetal mortality if diagnosis missed.

• C/S before onset of labor

Nuchal Cord

• One or more complete loops of UC around fetal neck.– Males>females; 29% at 42wks– Single loop 10.6%, double 2.5%

• Diagnosis best by: Doppler US and 3D ultrasound• Recommendations~

– Look for vascular compromise (S/D ratio)– Fetal growth and movement, amniotic fluid

• D/D– Cord adjacent to neck– Cystic hygroma

Special Topic

Cord Index

OBGYN 2006

• Under coiling is associates with (umbilical coiling index below the 10th percentile)– fetal death– spontaneous preterm delivery– trisomies – low Apgar score at 5 minutes– velamentous cord insertion – single umbilical artery

There was an inverse relationship between the umbilical coiling index and the birth weight percentile.

• Over coiling (umbilical coiling index above the 90th percentile) – asphyxia– umbilical arterial pH < 7.05 – small for gestational age infants – trisomies – single umbilical artery

• Under-coiling may give way to kinking and compression, whereas over-coiling may give way to occlusion in cases with cord entanglement.

• Early second-trimester low umbilical coiling index predicts small-for-gestational-age fetuses.(J Ultrasound Med 20:1183–1188, 2001)

It appears that umbilical cord coiling modulates noticeably blood flow through the umbilical cord.

We speculate that more prominent umbilicalcoiling (higher antenatal UCI values) has a protective effect on blood flow in terms of decreased arterial resistance and higher blood flow velocities, as well as increased venous blood flow.

Abnormal Cord Doppler & Clinical Significance

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The DV blood flow that was corrected for fetal weight was increased significantly in intrauterine growth-restricted fetuses compared with control fetuses (P=0).

In 23 of 30 IUGR, the percentage of umbilical blood flow that was shunted through the ductus was>90th percentile of control fetuses.

DV diameters were significantly greater in growth-restricted fetuses than in control fetuses (P=.0001).

• IVC, DV, and UV Doppler parameters correctly predict acid-base status in a significant proportion of IUGR neonates. Combination, rather than single vessel assessment provides the best predictive accuracy.

We studied 97 gravidas with the diagnosis IUGR and confirmed 61 cases of IUGR with acidemia. The demographic data showed that 24 gravidas had a diagnosis of preeclampsia, and 37 had pregnancies superimposed with chronic hypertension.

Results

• Based on the PI of the umbilical artery and PI for the vein of the ductus venosus, the areas under the receiver operating characteristic curves were 0.7992 and 0.6749, respectively, for predicting growth-restricted neonates with acidemia.

• With a combination of the PIs of the umbilical artery and the PIs for the vein of the ductus venosus, the predictive accuracy of the growth-restricted neonates with acidemia increased, with sensitivity of 0.79 and specificity of 0.79 and an area under the receiver operating characteristic curve of 0.8441.

Conclusions

• Compared with single-vessel assessment, combining the PIs of the umbilical artery and the PIs for the vein of the ductus venosus provides the greatest accuracy in predicting growth-restricted neonates with acidemia.

•婦人生產的時候就憂愁，因為他的時候到了；既生了孩子，就不再記念那苦楚，因為歡喜世上生了一個人。

Train up a child in the way he should go: and when he is old, he will not depart from it.

(Proverb 22:6)

Thanks for attention!Thanks for attention!