Abstract
Ultrasound has been used as a guide during gynaecological operative procedures, in addition to the role in diagnostic testing. In the field of gynaecology, some of the interventions, especially intrauterine procedures, are carried out without imaging guidance or with limited view, and are performed based on clinical skills and experience alone. Operative ultrasound provides concurrent visualization of the structures and contents and, therefore, has the potential to improve efficacy and safety of the operative interventions.
Introduction
Ultrasound has been used as a guide during gynaecological operative procedures, in addition to the role in diagnostic testing. In the field of gynaecology, some of the interventions, especially intrauterine procedures, are carried out without imaging guidance or with limited view, and are performed based on clinical skills and experience alone. Operative ultrasound provides concurrent visualization of the structures and contents and, therefore, has the potential to improve efficacy and safety of the operative interventions.
Application of intraoperative ultrasound will depend on a good understanding of the ultrasound features of the normal female pelvic anatomy. The introduction of intraoperative ultrasound in obstetrics and gynaecology is still progressing at a very slow pace, despite some available evidence that it will help to reduce complication rates. Even with endoscopic procedures like hysteroscopy, the perforation rate or trauma is still high – quoted as 1.7 per cent [1]. The use of ultrasound-controlled operative hysteroscopy will help to reduce this known complication of uterine perforation, especially in women with known intrauterine pathologic factors, thereby avoiding the use of unnecessary laparoscopy [2]. This, in turn, has the potential to reduce operating time and cost, and lower potential morbidity. Performing blind intrauterine procedures such as surgical evacuation of the uterus, intrauterine device placement in the presence of uterine abnormalities or complex cases under ultrasound guidance has the benefit of confirmation of procedure completion and reduced risk of injury to the uterus and internal visceral organs. In assisted reproduction treatment (ART), ultrasound has established its indispensable role in egg collection and embryo transfer, as described in Chapter 11. Ultrasound guidance is also used in cases like ovarian cyst aspiration, hydrosalpinx aspiration prior to in vitro fertilization embryo transfer (IVF-ET) and aspiration of ascitic fluid resulting from ovarian hyperstimulation syndrome.
Ultrasound-Guided Intrauterine Surgery
Most commonly, abdominal ultrasound is used to guide hysteroscopic and intrauterine procedures. It is best for the patient to have a moderately filled bladder, to have a better view of the uterus and cervix. The abdominal probe is covered with a sterile sheath and is positioned to obtain a longitudinal view of the uterus. Transvaginal and transrectal probes are only used if the abdominal ultrasound view is limited, but this may restrict the vaginal access and manipulation of instruments used for the procedure.
The ultrasound probe is positioned at the start of the procedure to provide a clear delineation of cervical canal, endometrial cavity, myometrial depth and boundaries (Figure 12.1). The bladder, if under-filled, can be filled with sterile normal saline to optimize visualization. Insertion of dilators, if cervical dilation is required, is done under ultrasound guidance to ensure the dilation follows the cervical canal and to minimize the risk of perforation or creation of a false passage. Once the procedure is started, the probe is dynamically manipulated to provide real-time images of the instruments, especially at its distal or operative end, operative site, correct plane of dissection and myometrial thickness/depth.
Figure 12.1 Abdominal scan demonstrating the uterus, including the cervix in its longitudinal plane.
Resection of Uterine Septum
Uterine septum, resulting from incomplete septal resorption during embryogenesis, is a protrusion of fibromuscular tissue from the fundal region into the uterine cavity, and it can be partial or complete. While most women with uterine septum have normal reproductive function, some may be affected by adverse reproductive outcomes. Although randomized controlled trials on the efficacy and safety of surgical treatment of septum to improve reproductive outcomes are lacking, controlled studies have indicated that hysteroscopic septal resection reduces miscarriage rates and increases live birth rates. The National Institute for Health and Care Excellence (NICE) has recommended that the evidence on the efficacy of hysteroscopic metroplasty of a uterine septum for recurrent miscarriage is adequate to support the use of this procedure, provided that normal arrangements are in place for clinical governance, consent and audit [3]. However, for management of septum in primary infertility patients, current evidence on efficacy is inadequate, and this procedure should therefore only be performed with appropriate arrangements for clinical governance [4].
Hysteroscopic septal division is not free of complications, although the procedure is technically less challenging in experienced hands. Some of the complications include incomplete resection of the septum and perforation of the uterus and uterine scarring. During hysteroscopic resection of the uterine septum, it is difficult to perceive the depth despite it being done under direct vision, which provides only an estimate of where the fundus is and may result in either partial/incomplete resection or perforation of the uterus. Partial resection is known to cause recurrent miscarriage [5] and uterine rupture in mid-trimester after uterine septal resection has been reported [6]. Pre-operative preparation and measurement of the septal length using 3D ultrasound and subsequent live scanning during the procedure may improve the outcomes and safety of uterine septal resection. With ultrasound, an accurate measurement of the distances, including the thickness of the fundus just lateral to the base of the septum, may be obtained. Contemporaneous sonographic visualization of the top of the fundus will confirm complete resection of the septum and avoid resecting into the myometrium without the subsequent risk of perforation and scarring. The procedure can be considered complete once both ostia are simultaneously visualized and when the fundal myometrial thickness is 8–10 mm [7]. Ultrasound guidance during the procedure has shown a trend towards lower perforation rates and is less expensive than laparoscopic guidance; therefore it has been suggested as the optimal means of intra-operative guidance during hysteroscopic division of septum or adhesions [8].
Resection of Uterine Fibroids
Submucous fibroids can cause menstrual symptoms and are associated with adverse reproductive outcomes, including subfertility and miscarriage. Hysteroscopic resection of fibroids is the standard treatment for submucous myoma to improve menstrual symptoms and to optimize fertility. While removal of type 0 fibroids (100 per cent intracavitary) may not benefit from ultrasound guidance, removal of type 1 and 2 fibroids (<50 per cent and >50 per cent intramural components) may benefit from ultrasound guidance, as this allows identifying the exact locations of fibroids, the portion of fibroids protruding into the cavity, their intramural extension and myometrial free margin. The common intra-operative and immediate post-operative complications when treating type 1 and 2 fibroids are incomplete removal, perforation and fluid overload. Korkmazer et al. described the technique of ultrasound-guided hysteroscopic resection of submucous fibroids with intramural component using the cutting loop of a monopolar or bipolar resectoscope [9]. The intracavitary component is excised by slicing from the top to basal part and from back to front until reaching the plane of the endometrial surface without causing undesired endometrial ablation. Once the cleavage plane between the fibroid and underlying myometrium with fibroid-free myometrial thickness is identified, the intramural part of the myoma is excised using the cavitation technique by slicing the tissue. Once the procedure is completed, the resectoscope is withdrawn back to the cervix, the uterine cavity is filled with distention media and then the margins of the uterus and fibroid are evaluated sonohysterographically. A prospective multicentre study evaluating 64 women undergoing hysteroscopic resection of type 1 and 2 fibroids under ultrasound guidance reported complete resection with no perforations. The authors concluded that ultrasound-guided hysteroscopy is a safe and effective method for resection of submucous fibroids with an intramural component [9].
Treatment of Intrauterine Adhesions
Intrauterine adhesions result from previous infection or uterine surgeries and manifest as hypomenorrhoea or amenorrhoea, infertility or recurrent miscarriage. Hysteroscopic division of adhesions is the treatment of choice to improve the symptoms. In moderate to severe cases, it is difficult to identify where to enter and which part of the uterine cavity is visualized while doing hysteroscopy. Ultrasound guidance allows the accurate localization of the instruments within the cervical canal and uterine cavity and visualization of myometrial depth (Figure 12.2). Abdominal ultrasound is used to guide the cervical dilation process to ensure the dilator is pushed only along the line of the cervical canal, minimizing the creation of false passage or myometrial or uterine perforation. During the procedure the ultrasonographer is able to provide real-time feedback on the plane of dissection and myometrial thickness. A retrospective cohort review has reported a lower perforation rate and better cost-effectiveness for ultrasound-guided hysteroscopic adhesiolysis compared to laparoscopic-guided or unguided hysteroscopic procedures [8].
Figure 12.2 Hysteroscopic uterine instrumentation demonstrating the tip of the scissors. Ultrasound guidance allows the accurate localization of the instruments within the uterine cavity and visualization of myometrial depth.
Other Hysteroscopic-Guided Procedures
Ultrasound guidance can be useful in hysteroscopic retrieval of foreign bodies embedded in the myometrium (e.g. bony fragments embedded following therapeutic abortion) when the foreign body is not evident by direct hysteroscopic vision [10]. In cases of haematometra associated with cervical stenosis or following endometrial ablation, concurrent ultrasound can be used to guide cervical dilation and hysteroscopic directed drainage of the uterine content [11]. Where resection of endometrial polyps is not possible using techniques employing direct visualization, ultrasound guidance may be employed in a similar way as when resection of leiomyomas is carried out.
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