Handheld ultrasound systems are portable devices for smartphone or tablet and are increasingly common in emergency, intensive care and veterinary medicine, but also in the pocket of the stationary doctor. This type of ultrasound machine enables immediate diagnoses directly on site (handheld point-of-care-ultrasound / HPOCUS) and quickly provide information regarding the patient's further care. Handheld ultrasound machines fit into a single-use plastic cover and can be easily disinfected, making them particularly useful in infectious environments.
The most striking advantage of handheld POCUS devices is the small footprint. The design is very compact, lightweight (approx. 200 g/0,44 lbs. - 500 g/1,1 lbs) and flexible. Due to this compactness and the necessary technical compression, the quality of the imaging is still limited compared to 'high-end devices', but sufficient to the extent that handheld ultrasound devices are already successfully used in many medical disciplines.
Depending on the model, handheld ultrasound systems run on Android, iOS, Windows or proprietary operating systems. They are connected to the end device via USB cable or wirelessly via Bluetooth or WiFi. The respective end device is used as an ultrasound monitor to display the ultrasound images. The associated app is operated via touchscreen, although some devices have a few buttons, e.g. for recording ultrasound images or freeze images. The images can be stored and managed on the end device itself, the inserted memory card or in the cloud. Theoretically, also a private smartphone can be connected, but this can lead to complications with reimbursement.
See also Portable Ultrasound Machine, Ultrasound Technology, Environmental Protection, Ultrasound Accessories and Supplies and Sonographer.

The prostate is a walnut-shaped gland surrounding the beginning of the urethra in front of the rectum and below the bladder. The prostate can become enlarged (particularly in men over age 50) and develop diseases like prostate cancer or inflammation (prostatitis). A large tumor can be felt by a rectal examination. The most effective way of detecting the early signs of prostate cancer is a combination of a prostate-specific antigen (PSA) blood test and a prostate ultrasound examination.
An abnormally high level of PSA can indicate prostate cancer or other prostate diseases such as benign prostatic hypertrophy or prostatitis. The transrectal sonography is an important diagnostic ultrasound procedure in determining whether there is any benign enlargement of the prostate or any abnormal nodules.
The imaging is performed with a rectal probe, yielding high resolution. High resolution 3D ultrasound provides reliable and accurate determination of the size and the location of cancer. Additionally, ultrasound elastography is a technique in development to improve the specificity and sensitivity of cancer detection. Ultrasound is also used to detect whether cancerous tissue is still only within the prostate or whether it has begun to spread out and to guide a diagnostic biopsy or ultrasound therapy.

See also Brachytherapy, and High Intensity Focused Ultrasound.

An ultrasound couplant is a material that propagates acoustical waves. The couplant eliminates air from the interface and adapts the contours of the transducer to the skin. The used material is an ultrasound gel that mimics the acoustic characteristics of biological tissue.

Urologic ultrasound includes the examination of the kidneys, renal vessels, urinary tract, bladder, prostate, and scrotum.
Usual gray scale ultrasound equipment and standard probes are sufficient to examine the kidney parenchyma and renal pelvis, the urinary tract and bladder. Doppler ultrasound is a useful adjunct to kidney ultrasound. High ultrasound system performance is desirable to show the arterial system, because advanced power Doppler is significantly more sensitive to blood flow than standard color Doppler.
Transurethral sonography may be used to examine the bladder and urethra. Transrectal sonography is used to scan and treat the prostate e.g., with brachytherapy or high intensity focused ultrasound. Very small probes are used for these applications. Reflux sonography is especially used in pediatric ultrasound.

See also Ultrasound Imaging Procedures, Ultrasound Picture, Ultrasound Imaging Modes, Lithotripsy, Thermotherapy, Brachytherapy and Ultrasound Therapy.

Vascular ultrasound obtains images and measures blood flow velocity in the carotids, abdominal aorta, and vessels of kidneys, arms, or legs. Blockages in arteries, blood clots in veins, or abdominal aortic aneurysm can be detected.
These abnormalities in blood flow are usually examined with different Doppler techniques. In addition, the speed and direction of blood flow can be color coded in a color map. Duplex techniques show both, the vessels and the surrounding tissue. The use of ultrasound contrast agents improves the left ventricular opacification in cardiac ultrasound examination. Usually, for a vascular ultrasound no special preparation is needed.

See also Echocardiography, Venous Ultrasound, Adventitia, Intima, Temporal Mean Velocity, and Intravascular Ultrasound.