Colour Doppler studies have added lot of colour to the grim- grey world of ultrasound. On 25th May 1852, at a meeting of the royal Bohemian society of sciences in Prague, a gentleman, Christian doppler presented a paper "on the coloured light of double stars and certain other are stars of the heavens" about the redshift in light from stars. through this has the letter been refuted, this effect is described by him state on and has been named after him. It has found a place of greater prominence in non- invasive vascular studies in the human.
I have often been asked by a student whether the red colour vessel seen during a Doppler study are the arteries and the blue ones the veins. Well no!
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| Doppler velocimetry of uterine artery |
Let us assume that we are sitting inside a
moving train which is moving at high speed and blowing its whistle. Another train is coming towards it on a track alongside at a similar speed and also blowing its whistle. When these two
trains cross each other the sound volume of the whistle will have a higher frequency and we hear it louder. Similar is the case in the Doppler effect.
Moving RBCs there will be an additive frequency shift which looks red and if they moving away from one or another the frequency change will be longer given a blue colour on Screen. For turbulent flows, there are various shades of green yellow between these two.
over the last decade, Doppler ultrasound has become a routine mode of study through a lot of research. The commonly measured parameters are the peak systolic flow S (in cm/sec), end-diastolic flow D (also in cm/sec), and flow indices pulsatility index
PI, given as an S-D/A (mean frequency shift in one cardiac cycle)
RI (resistance index) given as S-D/S.
The indices are given an idea about downstream resistance to flow or distal haemodynamics, e.g. umbilical artery flow gives an idea about placental function. As they are measured in a single cardiac cycle they are virtually independent of angle of insonation. However, sample volume and wall filter adjustments are often required.
Fetal Study (Doppler ultrasound)
After implantation, the embedding trophoblast erodes maternal spiral arteries to set-up the fetomaternal circulation.
However, of during this stage, improper vascularization occurs, later development of foetal growth retardation and for maternal hypertension has been reported to occur. In a large series, we have reported how Doppler can detect this "Vascular Fetomaternal crosstalk as early as 5th week of menstrual age.
In fetoplacental circulation, progressive lowering of index values takes place to allow continuous flow to grow organs of a foetus to cause Uninterrupted perfusion to vital organs.
The pulsatility, i.e. the difference between maximum systolic and end-diastolic flow progressively diminishes with advancing gestation. In normal pregnancies the diastolic component in the cerebral artery is lower than in the umbilical arteries throughout pregnancy; i.e. the resistance in cerebral vessels is higher than the placental vessels and thus the ratio of resistance - Cerebroplacental ratio (CPR) is greater than 1. In case of flow redistribution, as in foetal growth retardation, the CPR becomes less than 1.
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| Ectopic trophoblast with blood flow within fallopian tube |
Being a ratio of resistance in two vessels in the same cardiac cycle, this value is independent of heart rate. With maternal inhalation of most oxygen and correction of flow redistribution, CPR has been reported to become normal. The two umbilical arteries together carry approximately 40% of foetal stroke volume.
As of now the major foetal vessels being studied include the descending aorta, umbilical arteries, renal vessels, pulmonary vessels, and intracerebral vessels like internal carotid, anterior and middle cerebral arteries. Maternal arteries studied for foetal well-being are the uterine arteries, which are easy to locate at the level of the internal os.
Foetal 'brain-sparing effect' by vascular flow redistribution has long been studied. Lately, the 'heart sparing effect' has been reported in growth-retarded foetuses. Brain sparing phenomenon has been shown to precede the late deceleration of foetal heart by several weeks. However, preceding death in such cases normalization of PI and RI in cerebral vessels has also been seen. Pulsatile flow in the umbilical vein with absent or reversed end-diastolic flow in the umbilical artery is the last sign of atal asphyxia before foetal demise. this has now been reported to be accompanied by increased vascular flow in coronary arteries which has been attributed to dilation of coronary arteries in case of extreme foetal hypoxaemia.
In abnormal gestation such as Ectopic pregnancy, when ordinary 2D ultrasound is not so efficient to detect an Ectopic back in the early stage of gestation, the typical flow high-velocity low impedance and of high diastolic flow in the adnexa is helpful for confirmation. As a concomitant feature, this floor will be absent within the uterus in Ectopic gestation, unless it is a rare case of hydro topic pregnancy which however has gone up after the advent of various infertility management procedure and can be as high as 1 in 6,000 in contrast to a previous incidence of 1 in 30,000. And Ectopic pregnancy can be similar in flow pattern to the luteal cyst, cystic ovarian malignancy, tubo ovarian abscess, related fibroid with high vascularity.
In Gynaecology (Doppler scan)
Doppler study has made it possible not only to study the pelvic anatomy but the physiology throughout the menstrual cycle by studying the various pelvic vessels and thus get information regarding vascular-functional pathophysiology. Torsion of ovarian mass result is distributed blood flow which can be studied well.
In the detection of ovarian malignancy is early-stage Doppler plays an important role. Being a leading cause of gynecologic cancer molarity, the 5-year survival rate has only increased from 36 % in 1975 to 39% in 1990 it is disturbing the note that over 90% of patients with stage I ovarian malignancy can be given abettor prognosis with early diagnosis. Doppler has stepped in here, since another screening method like CA 125 and antigenic determinant on high molecular weight glycoprotein, that is recognised by the monoclonal antibody OC-125, choose a value of 35U/ml or more in majority 80% of patient with advanced epithelial ovarian carcinoma, is elevated in only 23 to 50% of a stage I disease. CA 125 is also elevated in other being condition like endometriosis, pelvic inflammatory disease coma uterine fibroids, pregnancy and psoriasis. It is also elevated in other malignant condition of pancreas, breast, lung and endometrium and hence is not specific. But a tumour vessel of neoangiogenesis having no muscular media Court gives a typical Doppler waveform and over 90% diagnostic accuracy has been reported by several workers in differentiating being from the malignant ovarian lesson. The PI in such lesson is less than 1.
In Infertility (Doppler)
Many groups have reported a large series of pelvic Doppler study in a normal and stimulated cycle for treatment of infertility.
Before a pelvic a study, it has to be appreciated that unlike any other organ of the body, the pelvis structure involved in reproductive function undergoes a cyclical hormone-related morphological and functional change which also affects the vascular function.
New vessel formation or neoangiogenesis formation takes place during follicle growth/maturation, corpus luteum formation and endometrium proliferation and layering. During follicular growth, angiogenesis takes place in the thecal layer while the granulosa layer remains avascular. After ovulation, the thecal vessel vascularise the corpus luteum formation. Spiral arteries from the basal endometrium grow throughout the proliferative phase II supply the functional layer. Transvaginal sonography can detect the detailed stage of the follicle growth, endometrium proliferation and measure in cm/sec, the blood flowing within them. The steady blood supply in both phase of cardiac cycle viz. systolic and diastolic is essential for growth sustenance and this is evident in a normal cycle in all related vessels.
It has been reported that detection of blood flow at a particular site in a growing follicle denotes healthy cumulus growth and is followed with a 70% chance of producing good (grade I or II) embryo in IVF.
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| Blood flow in controlled ovarian stimulation |
Before seeds are sown the nursery bed in prepared with a careful stop for implantation to be successful the rose- bed, here the endometrium needs to be checked and prepared carefully. Growth in mm; measured between anterior and posterior Mayu material endometrium interface usually in monitor throughout the follicular phase. This endometrium, divided into five zones, is capable of supporting implantation when the spiral arteries coil up along the glandular elements of the endometrium from D7. Blood flow can be measured within these vessels from D7.
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| Pulsatile flow in endometrium |
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| Circadian variation in uterine flow |
Implantation vascularity has been a study very early by us and followed by, later larger series. It can be seen as early as the D6/7 of implantation. absence of such flow result is restricted growth of sac, blighted ovum and IUGR letter on. Simultaneous corps lutal blood flow which has a "Ring of Fire" appearance when healthy, rule out nonfunctioning CL or luteal phase defect.
The value of the symmetric pattern is characteristics in polycystic ovarian disease a very high stromal blood flow is seen in basal studies and this is thought by some workers to be the initiating factor for the higher incidence of ovarian hyperstimulation syndrome (OHSS) in such patients. However such a conclusion can be reached after more detail report come in from workers.
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| Poor uterine flow in women with unexplained requirement pregnancy loss |
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| Umbilical artery |
The blood flow of uterine, ovarian and endometrial vasculature in poor responder also has a characteristic pattern. in fact, each vessel in the body shows a typical flow pattern.
Related topic #doppler ultrasound!
1. Doppler in pregnancy?
2. Doppler to study the effect of vasoactive drugs in pregnancy?
3. Doppler studies on obstetric, analgesia and anaesthesia?
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