Obstetrics and Gynecology Now

uBMILICAL cORD dOPPLER

2009-02-12T01:38:00.001-08:00

Doppler of the Umbilical
Cord
Holly Hollis RT(R)

Abstract
The use of spectral and color Doppler, and ultrasound, are extraordinary noninvasive tools to evaluate the well - being of a fetus. The umbilical cord contains blood flow that may have a correlation with the fetus’ health. A wide range of studies have been done to evaluate the reliability of Doppler of the umbilical cord. Five articles will be discussed on this topic. One study compares the umbilical cord Doppler of fetuses with true intrauterine growth retardation (IUGR) with the Doppler of fetuses that are small for gestational age. Another study uses Doppler on umbilical arteries adjacent to the fetal bladder and cross section views of the umbilical cord to evaluate a two vessel cord (2VC). Color and spectral Doppler evaluation of the umbilical cord of a dead twin is also used. Studies have been done to compare chromosomally normal and abnormal fetuses and their Doppler flow. Methods of achieving the correct Doppler flow has also been studied. This study compares multigate spectral Doppler with traditional pulsed Doppler.

Key words: Two vessel cord (2VC), intrauterine growth restriction (IUGR), color Doppler, spectral Doppler, umbilical cord, ultrasound

Introduction
There is a wide range of reasons for using color and spectral Doppler on the umbilical cord of a fetus. Five articles have been reviewed to reveal the importance in Doppler of the umbilical cord. Getting the correct Doppler signal is important for proper results. The Doppler signal can be used to compare chromosomally normal and abnormal fetuses. Evaluation of a dead twin can be done with Doppler of the umbilical cord. Doppler can be done on the umbilical arteries adjacent to the fetal bladder to evaluate a two – vessel cord (2VC). It can also compare fetuses that are small for gestational age to fetuses that have true intrauterine growth retardation (IUGR). The umbilical cord is sampled because it is has better reproducibility than the thoracic aorta, abdominal aorta and internal carotid artery of the fetus.[1]

Body
The flow velocity is different at various positions in the flow of the same vessel, such as the umbilical cord. A comparison between traditional pulsed Doppler and multigate spectral Doppler was done to evaluate the differences in the pulsatility index (PI), resistive index (RI), and the systolic to diastolic ratio (S/D ratio). The study was done at Yale University in Connecticut by Prapas et al. There were 32 participants in this study, who were at 29 – 42 weeks gestation. Two of these were excluded because of maternal obesity and fetal body movements, which caused poor quality Doppler signals. A 4.o MHz convex probe was used and all patients were placed in a semi recumbent position. The same researcher performed all of the exams, which were limited to 15 minutes for each patient. The multigate spectral Doppler was performed by taking multiple samples along the length of the umbilical cord vessel. The traditional pulsed Doppler was then performed. When multigate spectral Doppler and pulsed Doppler were compared, the average differences were close to zero. The differences in the PI, RI, and S/D ratio ranged from .2 to 1.9. Even though there was only a little difference between the two systems, the traditional pulsed Doppler was the most reliable technique with the highest reproducibility. However, pulsed Doppler displayed only the Doppler signal at the point of the sample volume, and the velocity was variable at different points within the vessel. Multigate spectral Doppler opened the view of an area instead of one point and allowed insight about the hemodynamic changes in that area.

A study was done in London at the King's College Hospital School of Medicine to compare umbilical venous flow in chromosomally normal and abnormal fetuses. The wave form of the umbilical vein was documented as a pulsatile or continuous flow pattern. Brown et al stated that cardiac failure may be the reason for the pulsatility of the venous flow.[2] Maternal age and nuchal thickening were used as the screening for fetal chromosome abnormalities. Fetal karyotype was performed for all of the fetuses, which showed that 88 % was normal and 12 % was abnormal. A 3.5 MHz curvilinear sector array transducer was used for the examinations. A loop of umbilical cord was found and the Doppler gate was positioned over it to obtain a wave- form. Out of the normal group, pulsatile flow was found in 24 % of the cases. Pulsatile flow was found in 63 % of the abnormal cases. The umbilical vein Doppler wave form of the normal fetuses was not significantly different from the fetuses with Trisomy 21. However, the fetuses with Trisomy 18 and 13 had a significantly greater difference in Doppler wave forms than the normal fetuses. Pulsatile venous flow may result from an increased reversal of flow in the IVC during atrial contraction, associated with heart failure and abnormal cardiac filling. Figure 1 demonstrates umbilical Doppler wave forms with the venous wave form below the baseline.[2] The image on the left shows continuous venous flow while the image on the right shows pulsatile venous flow.

Figure 1

Laurel P. Messina, RDMS and Sabrina Craigo, MD from South Shore Hospital in Massachusetts performed umbilical cord Doppler to evaluate the death of a twin. The mother was 32 years old with monochorionic, diamniotic twins at 16 weeks gestation. Twin A had no abnormalities and measured at 16 weeks while twin B had a femur measurement of 13.5 weeks. Abnormalities such as a cystic hygroma, a two vessel cord, unidentifiable intracranial structures, and unidentifiable upper extremities existed in twin B. The dead twin, twin B, had retrograde flow of the umbilical cord. Figure 2 demonstrates a transverse image showing the acardiac twin (B) with a cystic hygroma (arrow) above the normal pump twin (A).[3] Figure 3 demonstrates a longitudinal image of the acardiac twin.[3] A large cystic hygroma (curved arrow) and abnormal intracranial anatomy ( arrow) were seen.

Figure 2

Figure 3

The parents were given three options. They could continue the entire pregnancy with close monitoring. Another option would be attempting cord ligation of the dead twin, which is done under ultrasound guidance. This is accomplished by tying a knot around the umbilical cord. The last option would be to terminate the pregnancy of the dead twin. The parents decided to terminate the abnormal fetus for the safety of the normal twin. There was an arterial-to-arterial anastamosis in the placenta. One twin receives oxygenated blood from the placenta while the other twin receives poorly oxygenated blood. This is called a twin reversed arterial perfusion, or TRAP sequence. This occurs in 1 in 35,000 monochorionic pregnancies. The mortality rate for the abnormal trapped twin is obviously 100 %, while the rate for the normal twin is 50 – 75 %. The retrograde flow in the umbilical cord confirmed the diagnosis of the dead twin.

Figure 4

One percent of pregnancies have only one umbilical artery present. Figure 4 is a cross-section image of a two vessel umbilical cord with one artery and one vein.[4] This abnormality is associated with fetal anomalies. If the umbilical cord is not visualized, color Doppler may be used to locate the umbilical arteries as they course adjacent to the bladder of the fetus. A study at the University of Washington Medical Center has been done to answer three questions about the two vessel cord.

The first question to answer was if the two umbilical arteries are found adjacent to the fetal urinary bladder, does this validate that there is a three vessel umbilical cord? The second question asked was if only one umbilical artery was present, was there a certain side affected? The third question asked was there any anomalies associated with the side of the absent umbilical artery? Out of 35 cases of fetuses with a 2VC, 49 % of fetuses with the abnormality had an absent left umbilical artery, while 37% had an absent right umbilical artery. Fourteen percent of the fetuses had both umbilical arteries present adjacent to the bladder. When looking for the two umbilical arteries adjacent to the fetal bladder, some problems could occur in searching for them. The artery could be identified incorrectly, mistaking the femoral artery for the umbilical artery. Even if both umbilical arteries are seen adjacent to the fetal bladder, they could possibly fuse distal from the bladder to form one artery. The 2VC may also be seen too close to the placenta, where the two arteries sometimes anastamose at the placenta end of the umbilical cord. Therefore, just because the two umbilical arteries are found adjacent to the fetal bladder does not validate that there are two umbilical arteries present in the umbilical cord. There was no correlation observed between the side of absent umbilical artery and associated anomalies. The conclusion of the study states that the diagnosis of a 2VC may be missed by relying solely on color Doppler views of the umbilical arteries adjacent to the fetal bladder. [4]

A retrospective study was performed to compare the difference between the umbilical cord Doppler study of fetuses with IUGR and fetuses that were small for gestational age. The study was performed by William J Ott, MD at St. John's Mercy Medical Center in St. Louis, Missouri. The Doppler study was done within two weeks of delivery. The fetal weight was also recorded two weeks before delivery. The small for gestational age fetuses with a normal Doppler study had about the same outcome as the fetuses that were average for their gestational age with normal Doppler studies. Both the "average for gestational age" and the "small for gestational age" infants with an abnormal Doppler study had increased neonatal morbidity, with the small for gestational age infants having the poorest prognosis.

Conclusion

In conclusion, spectral and color Doppler of the umbilical cord is important in the field of ultrasound. The experiments and research that has been discussed proves that Doppler of the umbilical cord can help with the diagnosis of abnormalities. The articles discussed also prove that Doppler of the umbilical cord can not be relied on for some diagnosis. The artery and vein of the umbilical cord will continue to be tested in the future for helpful insights in diagnosing abnormalities.

REFERENCE
1. Prapas, MD, Nikos, et al: Assessment of Doppler Velocimetry of the Fetal Umbilical Artery by Multigate Spectral Doppler Scanning and Traditional Pulsed Doppler Ultrasonography Plus Color Flow Mapping. J Ultrasound Med 18:831,1999

2. Brown, MD, MRCOG, Richard N, et al: First Trimester Umbilical Venous Doppler Sonography in Chromosomally Normal and Abnormal Fetuses. J Ultrasound Med 18:543 1999

3. Messina, RDMS, Laurel P., Craigo MD, Sabrina : Prenatal Diagnosis of Twin Reversed Arterial Perfusion Sequence 16 65 2000
4. Bornemeier, BA, BS, Shaun, et al: Sonographic Evaluation of the Two Vessel Umbilical Cord. Journal of Diagnostic Medical Sonography 12:260 1996

5. Ott MD, William J.: Intrauterine Growth Restriction and Doppler Ultrasonography 19:660 2000

uBMILICAL cORD dOPPLER

2009-02-12T01:38:00.000-08:00

myomectomy .... is it logical postnatally?!

2008-08-18T14:17:00.001-07:00

Red degeneration in a uterine fibroid
A case file
Few days ago, my resident called me for consultation of a referred case from the surgical department. She was a young lady who delivered per vagina four days ago. An acute abdomen was there with severe pain. Ultrasonography revealed "An Ovarian mass" with tissue texture measuring seven by six centimeters. That mass was actually palpable under the skin and severely tender.
I decided to open the case. A vertical skin incision done. After opening the peritoneum, I noticed a large fibroid loosely attached to the right side of the uterus near the fundus. I made the diagnosis of red degeneration of a fibroid. During all my professional life, I did not remove such a fibroid, but I did not know why I decided to do it that time!
After removing the mass, a profound bleeding happened from its bed. I did not enter the uterine cavity and hardly had I controlled the bleeding. Since I left the OR, I still blame myself. Have you had an experience like this before? Please tell something that helps me relieving my sense of being guilty!

myomectomy .... is it logical postnatally?!

2008-08-18T14:17:00.000-07:00

To All Gynecologist

2008-08-13T13:20:00.001-07:00

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