Vaginal ultrasonography (synonyms: transvaginal ultrasonography, vaginal ultrasound, vaginal echography) is a diagnostic imaging procedure used in gynecology and obstetrics – to visualize the uterus (womb), ovaries (ovaries), uterine tube (fallopian tube), Douglas space (lat. Excavatio rectouterina or Excavatio rectogenitalis; this is a pocket-shaped protrusion of the peritoneum between the rectum (rectum) and uterus (uterus) that extends to the posterior vaginal vault), the urinary bladder and the urethra (urethra) – in which the ultrasound probe is inserted transvaginally (through the vagina). Examination of the pelvic organs using vaginal ultrasonography is a standard diagnostic procedure for all gynecological diseases, infertility diagnosis and in early pregnancy (1st trimester/third trimester). Moreover, the procedure can also be seen as a preventive measure for mother and child in the case of an existing pregnancy. Sonographic examination offers the possibility of achieving high-resolution imaging of the pelvic organs and is a more accurate procedure than transabdominal sonography. Thus, vaginal sonography represents an accurate, painless, and low-risk method.
Indications (areas of application)
- Gravidity (pregnancy)
- Suspicion of tubal (ectopic) pregnancy or peritoneal/abdominal (abdominal) pregnancy, respectively
- Suspicion of abortus imminens (threatened abortion – threatened miscarriage).
- Missed abortion (miscarriage in which the amniotic sac has died but is not spontaneously expelled from the uterus)
- Abortus incompletus (incomplete abortion, ie, placental parts remained in the uterus).
- Multiple pregnancy
- High-risk pregnancy
- Uterine malformations (malformations of the uterus).
- Ovarian cysts (ovarian cysts)
- Tubal changes (changes in the fallopian tube) such as saktosalpinx, hematosalpinx.
The procedure
The principle of vaginal ultrasonography is the emission of ultrasound waves via crystal elements in the ultrasound probe, which are reflected and scattered by the tissue structures of the organs to be examined. Due to the reflection from the tissue structures in the pelvis, the ultrasound waves are partially received by the crystal elements located in the ultrasound probe. Only specially shaped ultrasound heads are used for vaginal sonography. To the procedure of vaginal sonography:
- The sonographic examination does not require any preparatory measures, except that the sonography should be performed when the bladder is empty. During vaginal ultrasound, the patient lies on the gynecological examination chair.
- The attending gynecologist covers the ultrasound probe with a condom-like rubber cover containing a special gel to prevent the formation of air spaces to reduce the impedance phenomenon. Impedance represents a phenomenon that is of concern in the propagation of all sound waves and describes the resistance that opposes the propagation of ultrasound waves. Possible air pockets between the ultrasound probe and the tissue surface increase the characteristic impedance, thus reducing the resolving power of the procedure and lowering the diagnostic significance.
- The use of the cover with the included contact gel, in addition to reducing the impedance phenomenon, also serves to improve hygiene.
Vaginal sonography is predestined for imaging the following structures and organs:
- Cervix uteri (called cervix for short; cervix): the cervix uteri can be imaged by sonographic examination in full length, so that in the case of an existing pregnancy a precise representation (length and width) of the cervix is feasible. Furthermore, the length of the cervical canal to the internal cervix and its condition (closed or open) as well as the inferior pole of the ovary can be precisely visualized. Also volume increases, as they occur, for example, in cervical carcinoma can be well represented.
- Corpus uteri (uterine body incl. endometrium / endometrium): In addition to the cervix uteri, the corpus portion of the uterus (size and position determination) can also be depicted with vaginal sonography.Vaginal sonography offers the possibility of reliably detecting pregnancy at an early stage. Cardiac actions of the embryo can be reliably detected from the fifth to sixth week of pregnancy. The determination of the gestational age can be made primarily by measuring the chorionic diameter (amniotic sac diameter). Likewise, the nidation site (implantation site) of the embryo can be identified, so that extrauterine pregnancy (pregnancy outside the uterus) or tubal pregnancy (ectopic pregnancy) can be ruled out at an early stage. Both the cavum uteri (uterine cavity), the endometrium and the myometrium and their possible pathological (pathological) changes can be easily differentiated. Myomas (benign muscular tumors), regardless of whether they are submucosal, intramural, subserosal or pedunculated, are easily visualized by vaginal sonography. Accurate size determination and thus any growth tendency during check-ups are usually possible.
- Tuba uterina (fallopian tube): imaging of the tubes is indicated in cases of thickening of the salpinx, which may be due to fluid accumulation such as a saktosalpinx (sac-shaped deformed fallopian tube (tuba uterina), which is closed at the ampulla end and cystically expanded) or a hematosalpinx (fallopian tube filled with blood). Sonographic examination is particularly important in detecting tubal pregnancy (tubaria; ectopic pregnancy). Note: The tubes (fallopian tubes) cannot be visualized in normal cases. Pathological structures can be detected from a size of > 1 cm.
- Ovary (ovary): the ovaries (ovaries) are visible – if necessary, a corpus luteum cyst (corpus luteum cyst), which produces the pregnancy-maintaining hormone progesterone, is detectable in one of the ovaries. Vaginal sonography is an important procedure in the diagnosis and treatment of benign (benign) or malignant (malignant) changes in the ovaries. Occasionally, it is possible to detect ovarian carcinomas (ovarian cancer) at a very early stage. The differentiation of solid and fluid-filled cystic parts is optimally achieved with the procedure. In addition to this classification, it is possible to accurately distinguish whether the fluid accumulation is clear or cloudy fluid. The presence of an accumulation of turbid fluid indicates hemorrhage.
Currently, there is a call for the introduction of vaginal ultrasonography as a routine procedure in all patients in early pregnancy, specifically to reduce maternal risk (maternal risk) in the presence of extrauterine pregnancy. Early detection provides the option of performing organ-preserving laparoscopic surgery. Evidentiary factors for ectopic (outside the uterine cavity) pregnancy on sonographic examination include the following:
- The exclusion of a nonpathologic intrauterine (inside the uterus) chorionic structure on a positive pregnancy test.
- Extrauterine (outside the uterus) chorion-like structures.
- The perception of cardiac actions from an extrauterine structure.
- The enlargement of the uterus (womb) and the appearance of fluid accumulation in the Douglas space (ascites/abdominal fluid)
Other indications
- Frequency and duration of prenatal ultrasound examinations were not associated with autism spectrum disorders in children in a case-control study
