This chapter should be cited as follows:
Petrovic M, Naftalin J, Glob Libr Women's Med
ISSN: 1756-2228; DOI 10.3843/GLOWM.418513

The Continuous Textbook of Women’s Medicine Series – Gynecology Module

Volume 4

Benign gynecology

Volume Editor: Professor Shilpa Nambiar, Prince Court Medical Centre, Kuala Lumpur, Malaysia

Chapter

Office Ultrasound in Gynecology

First published: March 2025

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INTRODUCTION

The first description of the use of ultrasound in gynecology was published in 1958, when it was used to determine the risk of malignancy of abdominal masses.¹ This involved a large rudimentary transabdominal ultrasound machine that was developed with the help of an engineer from the Glasgow shipyards. In recent decades, there have been major advances in the field of gynecology, but few have as wide an impact across the specialty, particularly in the outpatient setting, as that of the developments in ultrasound. Advances in ultrasound include the advent of the transvaginal probe, increasing resolution of ultrasound images, Doppler assessment and 3D scanning. These have led to significant improvements in the diagnostic accuracy of ultrasound for most gynecological conditions. Beyond diagnosis, ultrasound guidance has also been shown to improve the effectiveness and safety of outpatient procedures, as well as emergency and elective gynecological operations. Ultrasound is relatively cheap, non-invasive, acceptable to most patients and already the primary diagnostic tool for most women presenting with gynecological symptoms. Furthermore, while some still consider MRI to be the gold standard in gynecological imaging, increasing numbers of studies show that the performance of high-quality ultrasound is equivalent to that of MRI in diagnosing most gynecological conditions.

More widespread use of high-quality ultrasound would have a broad range of benefits to office gynecologists and their patients, including same-day diagnosis, reduced need for diagnostic procedures, efficient resource allocation and facilitation of outpatient procedures.

Same-day diagnosis

One-stop outpatient clinics that incorporate initial assessment and point-of-care ultrasound facilitate same-day diagnosis. This can expedite treatment initiation, provide reassurance when no treatment is needed, and, in cases in which management can also be completed as an outpatient, can allow the entire patient journey to be started and concluded in one visit. This reduces social disruption for the patient and is likely to be more cost-effective for healthcare organizations, because it reduces the number of outpatient appointments required by an individual patient, thereby opening up slots for new referrals.

Diagnostics

Accurate diagnosis obtained by detailed clinical and ultrasound examination is essential in general gynecology for assessment of women presenting with early pregnancy complications, subfertility, menstrual disorders (dysfunctional bleeding, irregular bleeding, prolonged bleeding, amenorrhea, etc), pelvic pain and suspected cancer. Moreover, bimanual manipulation during a transvaginal scan allows assessment of the mobility of pelvic structures (e.g. sliding of tissue layers, adherence to surrounding organs, pain mapping), which can facilitate improved diagnostic accuracy in the context of a patient’s symptoms and ultrasound findings.²

Reduced need for diagnostic procedures

High quality leads to improved diagnostic accuracy, thereby reducing the need for diagnostic procedures and operations. Diagnostic operations carry both a clinical risk to the patient as well as a financial cost to healthcare providers. There is also an associated opportunity cost to performing large numbers of diagnostic procedures: the limited surgical time that highly trained gynecological surgeons have available is better used in performing complex therapeutic operations than potentially unnecessary diagnostic operations.

Right operation, right surgeon, right hospital, right time

With increasing sub-specialization of gynecological surgery, not all gynecological surgeons are able to perform all operations. For example, with poor-quality diagnostics, a gynecologist may discover on diagnostic laparoscopy advanced endometriosis that they are either not trained to excise or not prepared to excise because they do not have adequate support from colorectal or urological colleagues. High-quality ultrasound that can map deep infiltrating endometriosis drastically reduces the likelihood of this occurring, while facilitating referral of such a patient to centers or multidisciplinary teams with the appropriate surgical expertise to manage such cases. With appropriate diagnostics and counseling, a proportion of these patients may not be scheduled for surgery at all.

Facilitating outpatient procedures

Use of ultrasound guidance during outpatient procedures improves safety by enabling better visualization of anatomy in real-time. Recent evidence also suggests a better pain tolerance of such procedures when performed under ultrasound guidance.³ This reduces the need to perform such procedures under general anesthetic, which is more risky and disruptive for the patient and less cost-effective for healthcare providers.

In this chapter, we outline recent advances in ultrasound, discuss and illustrate their use in diagnosing common gynecological conditions, and make the case that there is no more important tool that a gynecologist could have in their office than an ultrasound machine on which they are trained to provide high-quality ultrasound.

TYPES OF ULTRASOUND EXAMINATION IN GYNECOLOGY

Transvaginal ultrasound is the first-line imaging modality in gynecology. It can provide a detailed visualization of the pelvic organs and surrounding soft tissues. Where a complete gynecological ultrasound examination would once have included just the uterus and ovaries, high-quality ultrasound can now be used to assess the upper vagina, cervix, endometrium, endometrial–myometrial junction, myometrium, parametrium, Fallopian tubes, pouch of Douglas, rectovaginal space, anterior wall of the rectum and sigmoid colon, bladder, pelvic ureters and urethra.

Transabdominal ultrasound is a useful and sometimes essential addition to transvaginal ultrasound. It may also be the primary method in situations in which transvaginal ultrasound may be inappropriate (e.g. pediatric patients, virginal introitus, severe vaginismus, patient preference) or when gynecological organs are either located entirely outside of the pelvis or are sufficiently large that they cannot be completely assessed within the field of a transvaginal probe. Examination usually requires that the bladder is filled to above the uterine fundus to optimize visualization. Adequate visualization may be affected by increased subcutaneous adipose tissue (high body mass index) or abdominal structures (e.g. enteric gas shadowing). The additional distance from the pelvic structures and reduced frequency of the transabdominal probe limits the evaluation of certain pathologies such as deep infiltrating endometriosis and adenomyosis.

Transrectal ultrasound is an alternative option in carefully selected and properly counseled patients when transvaginal ultrasound is not possible, and the images obtained are comparable to those obtained with transvaginal ultrasound.⁴

ADJUNCTS TO ULTRASOUND ASSESSMENT

Endometrium assessment

Saline infusion is an adjunct to transvaginal ultrasound that involves instillation of saline into the uterine cavity while performing an ultrasound examination. The saline delineates the cavity, which enables the detection and assessment of intracavitary pathology (e.g. endometrial polyps, submucous fibroids, intrauterine adhesions, congenital defects and malignancy) (Figure 1).

Fertility assessment

Hysterosalpingo-contrast sonography (HyCoSy) is an accurate, safe and well-tolerated test for evaluation of the uterine cavity morphology and tubal patency. The procedure involves a transvaginal ultrasound assessment with concurrent injection of a contrast agent.

ULTRASOUND-GUIDED PROCEDURES

Ultrasound guidance is essential for office procedures such as insertion of an intrauterine contraceptive device (IUCD), endometrial biopsy, drainage of a pelvic cyst/abscess/pseudocyst, and manual vacuum aspiration. It can be also beneficial in selected outpatient hysteroscopy cases.

Insertion of an IUCD under ultrasound guidance minimizes the risks of the procedure, including misplacement and uterine perforation. Furthermore, recent evidence has shown that ultrasound guidance during IUCD insertion decreases pain, procedure time and rates of complications, with better patient satisfaction.³

Use of ultrasound guidance during endometrial biopsy enables targeted rather than blind sampling, and may reduce the need for subsequent hysteroscopy. Visualization may be further improved by simultaneous saline infusion sonography.

Pelvic cyst/abscess/pseudocyst drainage under ultrasound guidance can provide symptom relief in the outpatient setting without the requirement for a general anesthetic and surgery, while manual vacuum aspiration under ultrasound guidance is a management option for patients who wish to have surgical management after a miscarriage but want to avoid the risks of general anesthesia. The total blood loss volume is lower with manual vacuum aspiration,⁵ and it provides a quicker recovery, shorter hospital stay, reduced waiting time and lower costs to healthcare providers, while the rate of complications (retained tissue, etc) is similar to that when the procedure is performed under sedation/general anesthetic. Manual vacuum aspiration is also useful in an emergency setting as it can be performed safely and quickly, thereby avoiding the need for emergency surgery under general anesthetic.

Outpatient hysteroscopy is a safe, well-tolerated procedure that involves direct visualization of the uterine cavity without the need for an operating room and anesthesia. Ultrasound guidance may be used in certain cases (e.g. removal of intrauterine fibroids or adhesions) to minimize the risks of complications, including cervical trauma, uterine perforation, extended procedure time and blood loss.

ULTRASOUND ASSESSMENT OF COMMON GYNECOLOGICAL CONDITIONS

Endometrial polyps

Endometrial polyps are common uterine lesions that are present in 5.8% of premenopausal women and 11.8% of postmenopausal women.⁶ They are mostly benign, localized protrusions of the endometrial tissue. Histologically, endometrial polyps comprise stroma, thick-walled vessels and endometrial glands.⁷

Ultrasound findings include thickened endometrium (hyperechoic, heterogeneous, presence of cystic spaces), a focal echogenic area within the endometrium, an intracavitary lesion surrounded by fluid, a lesion with the ‘bright-edge sign’⁸ (Figure 2), and, on color Doppler, the ‘single pedicle artery sign’⁹ (Figure 3). Use of saline infusion sonography further increases the accuracy of diagnosis of endometrial polyps,¹⁰ and should be considered in all inconclusive cases.

Accurate diagnosis is important as endometrial polyps are a possible cause of irregular and heavy periods, intermenstrual bleeding, subfertility, postcoital bleeding and postmenopausal bleeding. In many cases, surgical removal is the treatment of choice; however, expectant management is increasingly being offered. Reasons for pursuing expectant management may include patient preference, lack of symptoms, failed hysteroscopic polypectomy, cervical stenosis or the presence of multiple comorbidities. Ultrasound findings can play a crucial role in determining in which women this is a safe management option. A recent study showed that cystic appearance and a mean diameter ≤ 13 mm were both associated with benignity in postmenopausal women.¹¹ Furthermore, when the polyp mean diameter was combined with the presence of intralesional cystic spaces and the patient’s body mass index, the overall accuracy in predicting premalignant or malignant postmenopausal polyps was 92%.¹²

Uterine fibroids

Uterine fibroids (leiomyomas) are the most common gynecological pathology, being found in over 70% of women over the course of their lives.¹³ They are smooth muscle tumors that may be located within the uterine cavity (submucosal), myometrium (intramural) or uterine surface (subserosal), or they may be attached to it by a thin or broad stem (pedunculated fibroids). The International Federation of Gynecology and Obstetrics (FIGO) classifies leiomyomas as submucosal (Figure 4), other or hybrid.¹⁴ Submucosal leiomyomas are subcategorized as type 0 (submucosal, pedunculated intracavitary), type 1 (submucosal, < 50% intramural) or type 2 (submucosal, > 50% intramural). Other leiomyomas are further subcategorized as type 3 (100% intramural but in contact with the endometrium), type 4 (100% intramural), type 5 (subserosal, ≥ 50% intramural), type 6 (subserosal, < 50% intramural), type 7 (subserosal pedunculated) or type 8 (other e.g. cervical, parasitic). Hybrid leiomyomas affect both the endometrium and the serosa.

On ultrasound, fibroids commonly appear as discrete, round or ovoid lesions and are often heterogeneous. They may be hypoechogenic, isoechogenic or hyperechogenic, with circumferential flow and minimal internal vascularity on Doppler examination. Shadowing is often seen, either from the edge of the lesion or from the internal structure.

Transabdominal ultrasound, 3D ultrasound and saline infusion sonography are used in addition to non-enhanced transvaginal ultrasound for ‘fibroid mapping’ – a precise assessment of the location and size of every visible fibroid. Fibroid mapping is essential for the gynecologist to determine the clinical significance of each fibroid. There are an increasing number of treatment options for fibroids, including expectant management, medical treatment (non-hormonal or hormonal) or surgical/therapeutic management, including transcervical resection, radiofrequency ablation and high-intensity focused ultrasound. The route and technique used for surgery are also variable (laparoscopic, robotic, open, vaginal). Fibroid mapping may help to determine the most effective management strategy and help individualize care.

Adenomyosis

Adenomyosis is a benign pathology that is associated with menorrhagia, dysmenorrhea, dyspareunia, pelvic pain and possibly subfertility. Histologically, it is characterized by the presence of endometrial glands and/or stroma within the myometrium.¹⁵ Historically, it could be diagnosed only by histological examination of hysterectomy specimens, and its estimated incidence in retrospective studies varied between 5% and 70% due to significant variation in the criteria used.¹⁶ With the evolution of imaging, adenomyosis can now be easily diagnosed without recourse to surgery.¹⁷ This has also greatly advanced our understanding of the condition.

In 2021, the international Morphological Uterus Sonographic Assessment group revised its definitions of the features of adenomyosis into direct or indirect.¹⁸ Direct features include the presence of ectopic endometrial tissue beyond the subendometrial layer, such as myometrial cysts (Figure 5), hyperechogenic islands (Figure 6), echogenic subendometrial lines and buds. Indirect features are those that are secondary to the presence of ectopic endometrial tissue within the myometrium: asymmetrical thickening of the myometrium (Figure 7), fan-shaped shadowing (Figure 8), globular uterus, irregular endometrial–myometrial junction (Figure 9) or interrupted endometrial–myometrial junction.

Diagnosis of adenomyosis requires the presence of at least one direct sign. Symptom severity appears to increase with the number of direct and indirect features identified (i.e. the extent of adenomyosis). Studies have demonstrated a statistically significant association between the ultrasound features of adenomyosis and the volume of menstrual loss¹⁹ and the severity of menstrual pain.²⁰

Uterine cavity morphology

Use of 3D ultrasound to reconstruct the coronal plane of the uterus allows unparalleled assessment of uterine cavity morphology.²¹ Nowadays, 3D ultrasound is the method of choice to diagnose uterine cavity malformations (Figure 10). There are many classification systems for uterine cavity malformations, with those of the American Society of Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE)/European Society for Gynaecological Endoscopy (ESGE) being the most widely accepted and utilized. The ASRM Müllerian Anomalies Classification 2021 classifies Müllerian anomalies into nine categories: Müllerian agenesis, cervical agenesis, unicornuate uterus, uterus didelphys, bicornuate uterus, septate uterus, longitudinal vaginal septum, transverse vaginal septum and complex anomalies.²¹ The ESHRE/ESGE consensus classifies anomalies into the uterine classes normal (U0), dysmorphic (U1), septate (U2), bicorporeal (U3), hemiuterus (U4), aplastic (U5), unclassified malformations (U6), with co-existent cervical and vaginal classes.²² The main classes are divided into sub-classes describing anatomical variations with clinical significance.

Ovarian cysts and adnexal pathology

Ovarian cysts are a common finding during pelvic ultrasound examination, and their etiology varies from physiological to complex, benign or malignant. Furthermore, they may result in acute conditions such as cyst rupture and ovarian torsion. Accurate diagnosis determines the type of further management, including any requirement for emergency surgery and/or referral to specialized teams (reproductive unit, endometriosis team, gynecology oncology team), or expectant management with or without the need for follow-up appointments.

Lesions may be divided into:

• physiological cysts: follicular cyst, corpus luteum cyst
• those with ovarian pathology: serous cystadenoma, mucinous cystadenoma, cystadenofibroma, dermoid cyst (Figure 11), endometrioma, ovarian fibroma
• those with adnexal pathology: paraovarian and fimbrial cysts, peritoneal pseudocyst, hydrosalpinx or pyosalpinx (Figure 12), hematosalpinx, tubo-ovarian abscess
• borderline ovarian tumors (Figure 13): serous, mucinous, seromucinous
• ovarian tumors

Standardized terminology to describe the sonographic features of adnexal tumors proposed by the International Ovarian Tumor Analysis (IOTA)²³ group includes the following descriptions:

• unilocular, unilocular–solid, multilocular, multilocular–solid, solid
• content: anechoic, low level (‘ground glass’), hemorrhagic, mixed echogenicity
• solid material, papillary projections (presence, number, size > 3 mm) (Figure  14), wall irregularity
• acoustic shadows
• vascularity (1 = no flow, 2 = minimal flow, 3 = moderate flow, 4 = strong flow)
• presence of ascites

If the above descriptors are not applicable, then the IOTA simple rules can be used for malignancy prediction:²⁴

• if one or more M features (M1, irregular solid tumor; M2, presence of ascites; M3, at least four papillary structures; M4, irregular multilocular–solid tumor with largest diameter ≥ 100 mm; M5, very strong blood flow [color score 4]) are present in the absence of B feature(s), the mass is classified as malignant
• if one or more B features (B1, unilocular cyst; B2, presence of solid components with largest diameter < 7 mm; B3, presence of acoustic shadows; B4, smooth multilocular tumor with largest diameter < 100 mm; B5, no blood flow [color score 1]) are present in the absence of M feature(s), the mass is classified as benign
• If both M features and B features are present, or if no M or B features are present, the result is inconclusive, and a second-stage test is recommended

For women in whom the nature of the ovarian/adnexal lesion is uncertain, and in particular for establishing the diagnosis of borderline ovarian tumor, ‘pattern recognition’, i.e. the subjective evaluation of ultrasound findings by an experienced ultrasound operator, can be utlized with high accuracy.²⁵ This can determine whether the management can be fertility-sparing rather than radical, which is important as borderline ovarian tumors are more prevalent in women of reproductive age.

Furthermore, various risk models have been developed to differentiate benign and malignant neoplasms, such as the risk of malignancy index (RMI),²⁶ which is a product of the ultrasound scan score, menopausal status and serum CA 125 level, and the ADNEX model (assessment of different neoplasias in the adnexa).²⁷ However, although the algorithms may help with diagnosis, none of them approaches the accuracy of expert pattern recognition.

Endometriosis

Endometriosis is a chronic benign condition that is characterized by the presence of endometrial glands and/or stroma outside the uterus. It affects approximately 10% of women of reproductive age and girls globally, and it may be associated with severe, life-impacting pain during periods, sexual intercourse, bowel movements and/or urination, chronic pelvic pain, abdominal bloating, nausea, fatigue, and sometimes depression, anxiety and infertility.²⁸ Accurate diagnosis of endometriosis is important for effective management, including tailored fertility counseling. Furthermore, accurate imaging provides detailed information to help determine the surgical approach (diagnostic surgery with/without minimal treatment [i.e. ablation] under a general gynecology team or complex surgery by an experienced endometriosis specialist).

In cases of suspected endometriosis, ultrasound is the first-line tool to evaluate the etiology of the woman’s symptoms and to map and determine the extent of the disease. The International Deep Endometriosis Analysis (IDEA) group has published a systematic approach to evaluate sonographically the pelvis in patients with suspected endometriosis.²⁹ A four-step system was introduced, including routine evaluation of the uterus and adnexa, site-specific tenderness, assessment of the pouch of Douglas using the 'sliding sign' and the presence of deep endometriosis nodules compartmentally throughout the pelvis (Figure 15).³⁰ The use of ultrasound for diagnosis of endometriosis requires advanced scanning skills and carefully planned timing of clinic appointments for detailed evaluation of this complex condition.

CONCLUSION

Improvement in ultrasound has transformed diagnosis and care within gynecology. Ultrasound is acceptable to patients, non-invasive and cost-effective, and remains the primary diagnostic tool for the office gynecologist. Moreover, it allows accurate diagnosis and disease mapping, which enables appropriate triaging, counseling and management. For the office gynecologist, ultrasound provides point-of-care diagnosis and facilitates same-day treatment and safer outpatient procedures.

PRACTICE RECOMMENDATIONS

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