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. 2008 Nov;18(4):326-44.
doi: 10.4103/0971-3026.43848.

Fetal environment

Arun Kinare  1
Affiliations

Fetal environment

Arun Kinare. Indian J Radiol Imaging. 2008 Nov.

Abstract

The intrauterine environment has a strong influence on pregnancy outcome. The placenta and the umbilical cord together form the main supply line of the fetus. Amniotic fluid also serves important functions. These three main components decide whether there will be an uneventful pregnancy and the successful birth of a healthy baby. An insult to the intrauterine environment has an impact on the programming of the fetus, which can become evident in later life, mainly in the form of cardiovascular diseases, diabetes, and certain learning disabilities. The past two decades have witnessed major contributions from researchers in this field, who have included ultrasonologists, epidemiologists, neonatologists, and pediatricians. Besides being responsible for these delayed postnatal effects, abnormalities of the placenta, umbilical cord, and amniotic fluid also have associations with structural and chromosomal disorders. Population and race also influence pregnancy outcomes to some extent in certain situations. USG is the most sensitive imaging tool currently available for evaluation of these factors and can offer considerable information in this area. This article aims at reviewing the USG-related developments in this area and the anatomy, physiology, and various pathologies of the placenta, umbilical cord, and the amniotic fluid.

Keywords: Amniotic fluid; placenta; ultrasound (USG); umbilical cord.

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Conflict of interest statement

Conflict of Interest: None declared.

Figures

Figure 1
Figure 1
Implantation site of placenta; 8-weeks' sac. A hyperechoic focus can predict the implantation site (arrow)
Figure 2
Figure 2
Placenta. Reliable confirmation of location is seen at 11 weeks; in this case an anterior placenta (arrow)
Figure 3 (A-B)
Figure 3 (A-B)
25-weeks' gestation with a rather bulky placenta. Note the focal hyperechoic areas (arrows in A) in an anteriorly located placenta. Color Doppler is not of great help but power Doppler (B) demonstrates the abnormal vascularity in this chorioangioma (image on the right)
Figure 4 (A-B)
Figure 4 (A-B)
A case of significant IUGR detected at 22 weeks. A small but globular anterior placenta (arrow in A) is seen with multiple subamniotic cysts (arrow in B). Multiple anomalies were confirmed at termination)
Figure 5 (A, B)
Figure 5 (A, B)
Placental lakes. Cystic foci (arrows in A) are seen in the placenta. Color Doppler (B) helps to exclude molar changes or a tumor
Figure 6 (A, B)
Figure 6 (A, B)
Subchorionic bleeds in two different patients. A small bleed (BL) is seen related to the fundal end of the placenta (A). A small bleed is seen involving most of the anterior placenta (arrow in B). Both bleeds are somewhat old as they are quite echofree in nature
Figure 7
Figure 7
Acute placental abruption. Note the bulky heterogenous placenta (arrows) in this hypertensive, 29-weeks pregnant patient
Figure 8 (A, B)
Figure 8 (A, B)
Placental abruption in two different patients. Sagittal section (A) shows an echogenic bleed (CLOT) close to the fetal surface of the placenta in this case of abruption. The bleed is relatively fresh. (B) Another case of acute placental abruption, in which USG shows a few small hypoechoic areas of bleed (Bleed) in the retroplacental bed
Figure 9
Figure 9
Anterior placenta previa. The placenta (arrow) has covered the internal os completely (arrowhead)
Figure 10
Figure 10
Placenta accreta. The arrow indicates loss of definition of the normal hypoechoic myometrium. The uterine and bladder wall demarcation is also poor
Figure 11
Figure 11
Velamentous cord insertion. The cord insertion is seen along the membranes (arrow). Extension of these splayed vessels into the cervix is not seen in this illustration (Image courtesy Dr Manoj Chinchwadkar)
Figure 12
Figure 12
Twin gestation. Molar changes are seen in the first placenta. Sagittal image shows both placentae to be anterior. A typical bunch-ofgrapes appearance (arrow) is present in the first placenta. The second placenta (arrowhead) is normal
Figure 13 (A,B)
Figure 13 (A,B)
Hydatidiform mole. In this patient with a 6-weeks' gestation presenting with vaginal bleeding, transvaginal USG (A) shows a gestational sac (white arrow) on the first examination. Follow-up examination after 2 days (B) shows focal cystic changes (arrow) with loss of normal definition of the gestational sac, suggesting the possibility of molar changes. Investigations confirmed triploidy
Figure 14 (A–C)
Figure 14 (A–C)
(A) Invasive mole. Extensive cystic foci (arrows in A) are seen in the uterine cavity; the lesion also shows intense vascularity on color Doppler (B) and almost complete filling of the uterus with color on power Doppler (C)
Figure 15 (A,B)
Figure 15 (A,B)
(A) Posterior placenta. The echodense foci (arrows in A) in this case of pregnancy-induced hypertension with IUGR were considered to be likely infarcts, better defined on the chroma image (arrows in B)
Figure 16
Figure 16
Fibrin deposits. Echo-rich foci (arrows) in the placenta are a normal finding and the peripheral location is typical. These should not be confused with calcifications
Figure 17
Figure 17
Normal umbilical cord – fetal insertion (arrows). This is the preferred area for morphometry
Figure 18
Figure 18
A transverse section of the cord (arrow) is the best to show the number of vessels
Figure 19
Figure 19
A tranverse section of the cord (arrow) shows a four-vessel cord
Figure 20
Figure 20
Coiled cord loops (arrows) are well-visualized
Figure 21 (A,B)
Figure 21 (A,B)
Transverse images through the cord show the method of estimation of the cross-sectional area (A) of the cord and of the umbilical vein (B)
Figure 22
Figure 22
Transverse image through the cord shows the method of measurement of the maximum cord diameter
Figure 23 (A,B)
Figure 23 (A,B)
Grey-scale (A) and color Doppler (B) images of the cord suggest the presence a thick cord (arrow). The fetus had megacystis. Follow-up after a week revealed a cystic hygroma around the fetal skull; IUD occurred 1 week later
Figure 24 (A, B)
Figure 24 (A, B)
A short cord (arrow in A) is seen. The length is 1.7 cm with a CRL of 3.9 cm corresponding to a gestation of around 10 weeks and 5 days of growth. Note evidence of a cranial anomaly (arrow in B)
Figure 25
Figure 25
The cord insertion (arrow) in the first trimester is shown
Figure 26
Figure 26
The large cystic structure (arrow) in the amniotic cavity, separate from the yolk sac, was thought to be a pseudocyst of the cord in this patient with an 8 weeks' gestation. The cyst regressed completely at 13 weeks
Figure 27
Figure 27
An umbilical cord cyst is seen (arrow in A) associated with hydrops (arrows in B)
Figure 28 (A,B)
Figure 28 (A,B)
A well-defined anechoic umbilical cord cyst (c) is seen (A). Other associated findings in this case (B) include hydramnios (arrow) and arthrogryposis (arrowhead)
Figure 29
Figure 29
Allantoic cyst. Color Doppler helps differentiate between an allantoic cyst (A) and an umbilical cord aneurysm
Figure 30
Figure 30
An umbilical vein varix (v) is seen, intrahepatic in location
Figure 31
Figure 31
Two-vessel cord. Transverse section through the cord (arrow) shows one vein and one artery
Figure 32
Figure 32
Nuchal cord. Color Dopper is excellent for demonstrating the number of loops
Figure 33
Figure 33
An amniotic fluid pocket (arrow) is seen containing loops of cord (arrowheads). The cord should be excluded when measuring amniotic fluid volume
Figure 34
Figure 34
Myometrial contraction (arrow) causes underestimation of the amniotic fluid volume
Figure 35
Figure 35
Demonstration of the technique to measure a single vertical pocket of liquor. Hydramnios is present in this case
Figure 36
Figure 36
Echoes (arrows) are seen in the amniotic fluid. In this case, they were due to desquamation of the fetal skin. The postnatal diagnosis was aplasia cutis congenita. (Illustration: courtesy Dr S.T. Ambardekar)
See this image and copyright information in PMC

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