Ultrasonography is a medical imaging technique that is also called ultrasound scanning or sonography. High frequency sound waves and their echoes and used in this technique for obtaining images from inside the human body. The echoes of sound waves reflected from the human body are recorded and displayed as a real-time visual image. This technique is similar to the echo location used by bats, whales and dolphins. The sonar used by submarines also operates the same technique. Ultrasound is useful method to examine many of the body's internal organs like heart, liver, gallbladder, spleen, pancreas, kidneys and bladder.
Movement of the internal tissues and organs are captured in ultrasound. Ultrasonography enables the physicians to diagnose a variety of disease conditions and also assess the damage caused to the systems. The ultrasound machine transmits high frequency sound pulses into the human body by using probes. These sound waves that travel into the body hit a boundary between the tissues inside the body and reflect the sound waves to the probe. Some waves travel even further and they reach another boundary and then get reflected back. The waves that are reflected are picked up by the probe and relayed back into the ultrasound machine.
The ultrasound machine in turn calculates the distance from the probe to the tissue or organ by using the speed of sound tissue and the time of each echo's return. The machine displays these distances and intensities of the echoes on the screen. Through the echoes that are produced the sonologist can identify how far away an object is, how large it is, its shape and consistency (fluid, solid or mixed). Two dimensional images are formed and reflected on the screen. Different types of ultrasound are used for different disease conditions. Ultrasound is used in a variety of clinical settings including obstetrics and gynecology, cardiology and cancer detection.
Acardia is a rare and serious malformation that occurs exclusively in monizygous twins - twins developing from a single egg. Acardia represents one of the most severe and rare congenital anomalies. It is characterized by the absence of functioning heart. Acardia results from the artery to artery connections in the placenta, thereby causing a physically normal fetus to circulate blood for itself as well as a severely malformed fetus suffering from heart regression. In other words, fetus acardius is a parasite and it receives blood supply from the donor twin. Because the pump twin heart has to pump for two, there is a high risk of going into heart failure and this would lead to the death of the normal twin.
The most common variety is the acardius acephalus where the head is lacking and so are the upper extremities. Other types are acardius anceps, acardius acormus and acardius amorphous. While in acardius anceps, the most highly developed form, a partly developed head with remnants of cranial bones and brain tissue are present with developed body and extremities, acardius acormus is the rarest form of acardia. The monster is a head without a body. Acardia amorphous is the least developed monster not recognizable as a human form, with minimally developed visceral organs. Since there is no gross human form, the name acardius amorphous.
As to the cause of acardia, the etiology of acardiac monster is still unknown. Genetic defects have been reported to be the cause. Some researchers suggest chromosomal abnormalities to be the reason. Krause and Bejdl suggest that compression of the cephalic pole of the embryo prohibiting curving and fusion of the primitive heart tube to be the basic cause of this anomaly. As a result, the dependant entodermal organs like thyroid, esophagus, trachea, lung, liver and others are also not formed.
A pregnant woman carrying an acardiac twin is unlikely to have any unusual symptoms. An acardiac twin is often found incidentally on prenatal ultrasound. As no two acardiac twins are formed exactly alike, they may present differently. Several improved imaging techniques like 2D ultrasonography, 3D ultrasonography and transvaginal Doppler ultrasonography have made diagnosis of acardia possible even in the first trimester of pregnancy. Such early diagnosis helps to reduce the risk of complications. Fetal echocardiography is also recommended to assist in early detection of heart failure in the normal twin. Chromosome studies are also done on both fetuses.
One line of treatment is watching for the earliest signs of heart failure in the pump twin with frequent ultrasounds. If heart failure is identified and the pregnancy is also far enough, then the pump twin should simply be delivered. Physicians recommend prenatal interruption of the blood vessel connections before heart failure develops in the pump twin, thus sacrificing the acardiac twin.
Specialists use laser, electrical cauterization and electrodes, serial amniocentesis, medications and other treatments successfully. If the acardiac twin is large enough and the amount of blood flow to it can cause heart failure in the healthy twin, then blood flow is stopped with Fetal Image-Guided Surgery. The acardiac or parasitic twin never survives, as it is severely malformed and does not have a functioning heart. The normal twin is at risk for heart failure and complications associated with premature birth. The normal twin is expected to have about 10% risk for malformations.
Scleritis is a serious eye disease that refers to the inflammation of the sclera, the white outer portion of the eye. Sclera is made up of connective tissues and thus helps in protecting the eye. Sclera is also responsible for giving spherical shape to our eyes. When sclera develops inflammation it is termed as scleritis.
Normally scleritis occurs between the age of 30 and 60 and also scleritis affects women more than men. Scleritis is potentially damaging and may even cause permanent vision loss in severe cases. Most often scleritis is associated with other underlying auto immune diseases present in the body such as rheumatoid arthritis, Gout, Wegener granulomatosis to name a few. But in few cases the disease may occur without any underlying condition and in such instances, the cause remains unknown. Scleritis can occur in the front portion of the eye ball or the back part of the eye ball and they are known as anterior scleritis and posterior scleritis respectively. Anterior scleritis is further classified into Nodular scleritis, Diffuse scleritis, Necrotizing scleritis with inflammation and Necrotizing scleritis without inflammation.In Nodular scleritis, tiny tender nodules form on the white portion of the eye. Diffuse scleritis refers to the inflammation of the front half of the sclera. This is the most common type of scleritis compared to other variations. Necrotizing scleritis is a serious form of scleritis and may even lead to vision loss. It is accompanied by severe pain and usually associated with the problem in other organs of the body. The sclera of the eye thins down severely and may occasionally result in perforation of the eye globe. This condition may surface with or without inflammation. Posterior scleritis is the rarest form of scleritis and usually presents itself with the symptoms like double vision, severe pain, retinal detachment, proptosis and restricted eye movement.
Diagnosis of Scleritis
Clinical examination of the eye is the first step towards assessing the scleritis disease. Further some eye tests and blood tests may be conducted to assess the severity and to diagnose the underlying disease that is causing the inflammation. Diagnostic procedures like ultrasonography and MRI may be advised if posterior scleritis is suspected.
Treatment of Scleritis
Firstly, oral anti inflammatory drugs are prescribed to control the inflammation and relieve the patient of the pain. In case of scleritis, topical eye drops alone are not sufficient to cure the inflammation. The main objective of the treatment would be to diagnose and treat the underlying disease that is causing the condition. In chronic cases, graft surgery may be performed to treat the injured portion of the eye.
Scleritis is treatable, but there are chances of this condition recurring again. The success rate of the treatment also depends upon the severity and the type of the scleritis. Necrotizing scleritis has low success rate and the incidence of vision loss is higher with this condition where as diffuse and nodular scleritis are easily treatable.
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Bibliography / Reference
Collection of Pages - Last revised Date: November 22, 2019