The clinical aspects of this guideline (Indications, Specifications of the Examination, and Equipment Specifications) were developed collaboratively by the American Institute of Ultrasound in Medicine (AIUM), the American College of Radiology (ACR), and the American College of Obstetricians and Gynecologists (ACOG). Several sections of this guideline (Qualifications and Responsibilities of Personnel; Documentation; and Quality Control and Improvement, Safety, Infection Control, and Patient Education and Concerns) vary among these organizations and are addressed by each separately.
This guideline has been developed to assist physicians performing sonographic studies of the female pelvis. Ultrasound of the female pelvis should be performed only when there is a valid medical reason, and the lowest possible ultrasonic exposure settings should be used to gain the necessary diagnostic information. In some cases, additional or specialized examinations may be necessary. While it is not possible to detect every abnormality, adherence to the following guideline will maximize the probability of detecting most of the abnormalities that occur.
Indications for pelvic sonography include but are not limited to:
Dysmenorrhea (painful menses)
Menorrhagia (excessive menstrual bleeding)
Metrorrhagia (irregular uterine bleeding)
Menometrorrhagia (excessive bleeding irregularly)
Follow-up of previously detected abnormality (eg, hemorrhagic cyst)
Evaluation and/or monitoring of infertile patients
Delayed menses or precocious puberty
Abnormal pelvic examination
Further characterization of a pelvic abnormality noted on another imaging study (eg, computed tomography or magnetic resonance imaging)
Evaluation of congenital anomalies
Excessive bleeding, pain, or fever after pelvic surgery or delivery
Localization of an intrauterine contraceptive device
Screening for malignancy in patients with an increased risk
III. QUALIFICATIONS AND RESPONSIBILITIES OF PERSONNEL
See the AIUM Official Statement Training Guidelines for Physicians Who Evaluate and Interpret Diagnostic Ultrasound Examinations and the AIUM Standards and Guidelines for the Accreditation of Ultrasound Practices.
IV. SPECIFICATIONS OF THE EXAMINATION
The following guideline describes the examination to be performed for each organ and anatomic region in the female pelvis. All relevant structures should be identified by the transabdominal or transvaginal approach. In many cases, both will be needed. A transrectal or transperineal approach is useful in patients who cannot tolerate a vaginal probe (eg, virgins and postmenopausal women).
A. General Pelvic Preparation
For a pelvic sonogram performed transabdominally, the patient's urinary bladder should, in general, be distended adequately to displace the small bowel and its contained gas from the field of view. Occasionally, overdistention of the bladder may compromise evaluation. When this occurs, imaging may be repeated after the patient partially empties the bladder.
For a transvaginal sonogram, the urinary bladder should preferably be empty. The patient, the sonographer, or the physician may introduce the vaginal transducer, preferably under real-time monitoring. When possible, a female member of the physician's or hospital's staff should be present as a chaperone in the examining room if a male examiner is performing the examination.
The vagina and uterus provide anatomic landmarks that can be used as reference points for the remaining normal and abnormal pelvic structures. In evaluating the uterus, the following should be documented: (1) the uterine size, shape, and orientation; (2) the endometrium; (3) the myometrium; and (4) the cervix. The vagina may be imaged as a landmark for the cervix and lower uterine segment.
Uterine length is evaluated in the long axis from the fundus to the cervix (the external os, if it can be identified). The depth of the uterus (anteroposterior dimension) is measured in the same long axis view from its anterior to posterior walls, perpendicular to the length. The width is measured from the transaxial or coronal view. If volume measurements of the uterine corpus are performed, the cervical component should be excluded from the uterine measurement.
Abnormalities of the uterus should be documented. The endometrium should be analyzed for thickness, focal abnormality, and the presence of fluid or a mass in the endometrial cavity. Assessment of the endometrium should allow for variations expected with phases of the menstrual cycle and with hormonal supplementation. If the endometrial stripe is difficult to image or ill defined, a comment should be added to the report. The myometrium and cervix may be evaluated for contour changes, echogenicity, and masses. Masses, if identified, should be measured in at least 2 dimensions and their locations recorded.
C. Adnexa (Ovaries and Fallopian Tubes)
When evaluating the adnexa, an attempt should be made to identify the ovaries first since they can serve as a major point of reference for assessing the presence of adnexal pathology. The ovaries should be measured, and ovarian abnormalities should be documented. Ovarian size can be determined by measuring the ovary in 3 dimensions (width, length, and depth), on views obtained in 2 orthogonal planes. It is recognized that the ovaries may not be identifiable in some women. This occurs most frequently after menopause or in patients with a large leiomyomatous uterus.
The normal fallopian tubes are not commonly identified. This region should be surveyed for abnormalities, particularly dilated tubular structures.
If an adnexal mass is noted, its relationship to the ovaries and uterus should be documented. Its size, echogenicity, and internal characteristics (cystic, solid, or complex) should be determined. Doppler or color Doppler ultrasound may be useful in select cases to identify the vascular nature of pelvic structures.
The cul-de-sac and bowel posterior to the uterus may not be clearly defined. This area should be evaluated for the presence of free fluid or a mass. If a mass is detected, its size, position, shape, echogenicity, internal characteristics (cystic, solid, or complex), and relationship to the ovaries and uterus should be documented. Differentiation of normal loops of bowel from a mass may be difficult if only a transabdominal examination is performed. A transvaginal examination may be helpful to distinguish a suspected mass from fluid and feces within the normal rectosigmoid.
Adequate documentation is essential for high-quality patient care. A permanent record of the ultrasound examination and its interpretation should be included in the medical record. Images of all appropriate areas, both normal and abnormal, should be recorded. Variations from normal size should be accompanied by measurements. Images are to be appropriately labeled with the examination date, facility name, patient identification, image orientation, and, whenever possible, the organ or area imaged. Relevant history for each patient should include obstetric history and/or relevant menopausal history. Retention of the permanent record of the sonographic examination should be consistent with both clinical needs and the relevant legal and local health care facility requirements.
Reporting should be in accordance with the AIUM Standard for Documentation of an Ultrasound Examination.
VI. EQUIPMENT SPECIFICATIONS
The sonographic examination of the female pelvis should be conducted with a real-time scanner, preferably using sector, curved linear, or endovaginal transducers. The transducer or scanner should be adjusted to operate at the highest clinically appropriate frequency, realizing that there is a trade-off between resolution and beam penetration. With modern equipment, studies performed from the anterior abdominal wall can usually use frequencies of 3.5 MHz or higher, while scans performed from the vagina should use frequencies of 5 MHz or higher.
VII. QUALITY CONTROL AND IMPROVEMENT, SAFETY, INFECTION CONTROL, AND PATIENT EDUCATION CONCERNS
Policies and procedures related to quality, patient education, infection control, and safety should be developed and implemented in accordance with the AIUM Standards and Guidelines for the Accreditation of Ultrasound Practices.
Equipment performance monitoring should be in accordance with the AIUM Standards and Guidelines for the Accreditation of Ultrasound Practices.
This guideline was developed by the American Institute of Ultrasound in Medicine (AIUM) in collaboration with the American College of Obstetricians and Gynecologists (ACOG) and the American College of Radiology (ACR), according to the process described in the ACR Practice Guidelines and Technical Standards Book.