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This page describes products and general use; it is not medical advice.
An endocavity ultrasound probe (also called an endocavitary probe) is an ultrasound transducer built to be placed in a body cavity, most commonly for transvaginal or transrectal imaging. This page is for clinic staff, buyers and students who need to know what the term covers, how to read a probe’s specification sheet, and which documents the FDA expects to accompany one. Use it as a reference for the product class, not as a procedure guide.
What an endocavity ultrasound probe is
An endocavity probe is an invasive ultrasound probe in the FDA’s sense: the agency’s guidance on diagnostic ultrasound systems and transducers defines an invasive probe as one “intended to contact tissue other than intact skin or the surface of the eye,” and lists transvaginal, transesophageal, transrectal, transurethral, intravascular and intraoperative probes as examples. In practice, “endocavity” most often refers to the transvaginal and transrectal probes. It is the opposite end of the spectrum from the surface probes described in types of ultrasound probe.
Who uses it: clinicians and sonographers who image through a natural orifice, and the infection-prevention and purchasing staff who maintain and source the equipment. Because these probes touch mucous membranes, they are handled as semi-critical devices (see below).
Transvaginal, transrectal and other variants
The names people search for (endocavitary, transvaginal, transrectal, and the informal search term “hockey stick ultrasound probe”) are covered together here, because the FDA guidance groups the transvaginal and transrectal probes together as invasive probes. The informal “hockey stick” term is not defined in the FDA guidance. The table shows what the FDA guidance and a manufacturer product page state.
| Probe type | What the source says | Source |
|---|---|---|
| Transvaginal | Named by the FDA as an invasive probe; the guidance says endoscopic, rectal and transvaginal probes “should be used with a single-use sterile sheath.” | FDA guidance, definitions and Appendix E |
| Transrectal | Named by the FDA as an invasive probe; listed with transvaginal probes among those used in semi-critical applications. | FDA guidance, definitions and labeling section |
| Combined gynecological and rectal model (one example) | The GE HealthCare E10C4 is described by its maker as an endocavity transducer for gynecological examinations, transvaginal imaging and transrectal imaging. | GE HealthCare product page, checked 2026-11-01 |
| Other invasive probes | Transesophageal, transurethral, intravascular and intraoperative probes are also in the FDA’s invasive-probe list; they are different products from the endocavity probes above. | FDA guidance, definitions |
The CDC and HICPAC disinfection guideline treats “a vaginal probe and all endocavitary probes without a probe cover” as semicritical devices because they have direct contact with mucous membranes (for example vagina and rectum).
Reading an endocavity probe spec sheet
A specification sheet gives the numbers that decide whether a probe suits an application and a machine. The worked example below is one manufacturer’s model, shown to illustrate the fields, not as a typical or recommended probe.
| Field on the sheet | GE HealthCare E10C4 value | What the field tells you |
|---|---|---|
| Frequency range | 10 – 4 MHz | The operating frequency band of the transducer. |
| Sector (field of view) | 150 degrees | The angular width of the image. |
| Focal range | 3 – 60 mm | The depth range over which the probe focuses. |
| Contact surface | 22 x 18 mm | The footprint of the part that touches the patient. |
| Weight | 140 g | The handling weight of the probe. |
| Imaging modes | B, M, CFM, Doppler, THI, strain elastography | The modes the probe supports, when the system also supports them. |
| Compatible systems | bkSpecto, bk3000, bk5000, bkActiv | The ultrasound systems the probe is listed for. |
The compatible-systems line matters most for procurement: a probe is specified for named systems, so the system model has to appear on the probe’s list. The mode list should be read together with the machine’s own capabilities (see what an ultrasound machine is).
What FDA labeling should include
The FDA guidance “Marketing Clearance of Diagnostic Ultrasound Systems and Transducers” (checked 2026-11-01) sets out labeling expectations for endocavity devices. Section 5.1.2.9 states: “If the device is for endocavity use, the labeling includes validated cleaning/disinfecting instructions and identifies the appropriate sleeves, if available.” The guidance also says:
- for semi-critical and critical applications (including transrectal and transvaginal), labeling should recommend, when appropriate, the use of sterile, legally marketed probe sheaths;
- the operator manual should identify compatible accessories and kits with their specifications;
- where sheaths are recommended, the probe labeling should discuss natural rubber issues in line with 21 CFR 801.437.
Covers and reprocessing: what the sheath does not replace
A sheath does not change how the probe is reprocessed. Appendix E of the FDA guidance says semi-critical probes should be sterilized whenever feasible, that “high level disinfection is minimally acceptable,” and that a sterile sheath is recommended for every semi-critical use. It adds that “the use of sheaths does not change the type of processing that is recommended” and that “Sheaths can fail during use and the level of resulting contamination may not be easily visible.”
For probes with a built-in needle-guide channel, the guidance warns the channel can create a contamination risk unless it is thoroughly cleaned and the probe sterilized before use on another patient. Biopsy accessories should be sterile, and reusable ones reprocessed. The CDC guideline gives a cover-failure comparison of 1.7% for condoms against 8.3% for commercial probe covers. For cover types and their limits see ultrasound probe covers; for the classification behind “semi-critical” see high-level disinfection and the Spaulding classification.
Documents to request from the supplier
Each item below follows from the FDA labeling statements above; nothing here is a price or brand recommendation.
- Validated cleaning and disinfecting instructions for that probe model.
- The sleeves or sheaths the manufacturer identifies for the probe, with the natural rubber discussion where sheaths are recommended.
- The list of compatible ultrasound systems, with your system model on it.
- The operator manual’s list of compatible accessories and kits, including needle guides and biopsy accessories if you plan to use them.
- The specification sheet fields in the table above.
Common mistakes
- Treating a sheath or condom as a substitute for disinfecting or sterilizing the probe; the FDA guidance says it does not change reprocessing.
- Assuming a probe works with any system without checking the manufacturer’s compatible-systems list.
- Reading one manufacturer’s spec values as the norm for the whole class.
FAQ
What is an endocavity ultrasound probe?
It is an invasive ultrasound transducer designed to contact tissue inside a body cavity, most often used for transvaginal or transrectal imaging. The FDA lists transvaginal and transrectal probes among invasive probes.
Is an endocavitary probe the same as a transvaginal or transrectal probe?
Endocavitary is another spelling of the same term. Transvaginal and transrectal describe the route; some models, such as the GE E10C4, are described for both.
Does an endocavity probe need a cover?
The FDA guidance says endoscopic, rectal and transvaginal probes should be used with a single-use sterile sheath, and that the sheath does not replace reprocessing of the probe.
How is an endocavity probe classified for reprocessing?
The CDC guideline treats vaginal and other endocavitary probes used without a cover as semicritical devices because they contact mucous membranes.
Sources
- FDA, Marketing Clearance of Diagnostic Ultrasound Systems and Transducers, checked 2026-11-01.
- CDC and HICPAC, Guideline for Disinfection and Sterilization in Healthcare Facilities, checked 2026-11-01.
- GE HealthCare, E10C4 endocavity transducer, checked 2026-11-01.
