| 2D / B-Mode Probe | Approximately 2–15 MHz, depending on probe geometry and examination depth | Two-dimensional real-time imaging | General abdominal, obstetric, gynecological, musculoskeletal, vascular, and point-of-care examinations | B-mode; often available with color and spectral Doppler when supported by the probe and system | Versatile, widely used, and suitable for routine anatomical assessment | Image quality depends on frequency, aperture, acoustic coupling, and penetration requirements |
| 3D / 4D Volume Probe | Typically about 2–9 MHz for abdominal, obstetric, and gynecological volume imaging | Volumetric acquisition; 4D provides real-time or near-real-time volume imaging | Fetal face and anatomy, fetal cardiac assessment, pelvic imaging, gynecology, and selected abdominal studies | 2D, 3D, 4D, color Doppler, and volume-rendered imaging, depending on system capabilities | Provides multiplanar views and spatial anatomical information from a captured volume | Requires appropriate volume acquisition, patient cooperation, adequate acoustic windows, and compatible software |
| Doppler Probe | Approximately 2–10 MHz; continuous-wave probes may use dedicated lower-frequency elements | Directional flow and velocity assessment; may be integrated with 2D imaging | Peripheral vascular studies, carotid assessment, obstetric fetal heart-rate checks, cardiac examinations, and blood-flow evaluation | Color Doppler, power Doppler, pulsed-wave Doppler, and continuous-wave Doppler where supported | Assesses flow direction, relative velocity, vascularity, and hemodynamic patterns | Angle, sample-volume placement, aliasing, wall-filter settings, and scale selection affect measurements |
| Linear Array Probe | Approximately 5–18 MHz, with high-frequency models used for superficial structures | Rectangular or trapezoidal field of view | Thyroid, breast, tendons, muscles, nerves, small parts, superficial vessels, and ultrasound-guided procedures | B-mode, color Doppler, power Doppler, elastography, and needle-enhancement functions on compatible systems | High spatial resolution and excellent near-field detail | Higher frequencies generally provide less penetration; the relatively narrow footprint may limit coverage of deep or broad anatomy |
| Convex / Curvilinear Probe | Approximately 1–7 MHz for deeper abdominal and obstetric examinations | Curved, sector-like field of view with a broad far field | Abdomen, pelvis, obstetrics, urology, emergency assessment, and general deep-organ imaging | B-mode, color Doppler, pulsed-wave Doppler, harmonic imaging, and selected 3D/4D applications | Good penetration and wide coverage for deep organs and large anatomical regions | Lower frequencies provide depth but less superficial resolution; rib, bowel gas, and body habitus can reduce image quality |
| Endocavity Probe | Approximately 4–12 MHz, depending on endovaginal, endorectal, or other specialized design | Compact endocavitary field of view; commonly curved or sector-shaped | Transvaginal pelvic imaging, early pregnancy assessment, follicular monitoring, prostate imaging, and selected endocavitary procedures | B-mode, color Doppler, spectral Doppler, 3D volume imaging, and elastography on compatible systems | Close proximity to target anatomy supports high-detail imaging with a compact footprint | Requires strict infection-control procedures, protective covers where applicable, approved high-level disinfection, and trained operators |
| Phased Array / Cardiac Probe | Approximately 1–5 MHz for adult cardiac and deeper thoracic examinations; higher-frequency options may be used in pediatrics | Narrow sector field of view with electronic beam steering | Adult and pediatric echocardiography, emergency cardiac assessment, lung imaging, and intercostal examinations | 2D, M-mode, color Doppler, pulsed-wave Doppler, and continuous-wave Doppler where available | Small footprint fits between ribs and supports imaging of moving cardiac structures | Lower frequency favors penetration, while sector geometry may provide less near-field detail than a linear probe |