CHAPTER 6 One-stop gynaecology
the role of ultrasound in the acute gynaecological patient
Introduction
Acute gynaecological symptoms such as pelvic pain and bleeding occur in pregnant women who have miscarriages, ectopic pregnancies and pregnancies of unknown location, or in women who are not pregnant with ovarian cyst accidents or acute pelvic inflammatory disease. The investigation of the acute gynaecological patient is moving away from the accident and emergency department and operating theatre, and into dedicated emergency gynaecology units (EGUs) located in an outpatient setting (Jones and Pearce 2009). EGUs offer an efficient way of organizing multidisciplinary services for women presenting with acute gynaecological symptoms. These changes have been driven by the demands of the patient and clinician to provide a rapid, accurate diagnosis, with the minimum of investigations and invasive procedures. They are underpinned by national standards and guidelines (Department of Health 2003, Royal College of Obstetricians and Gynaecologists 2006). Furthermore, changing from traditional care pathways to more cost-effective, patient-centred approaches to medical practice lies at the heart of modern health service management (Department of Health 2000, Jones 2008).
In the UK, the majority of gynaecological ultrasound scanning has traditionally been undertaken by radiographers and radiologists in a separate department on a separate day. Transvaginal ultrasonography (TVUS) is a pivotal investigation for the assessment of acute gynaecological patients. Therefore, in order to deliver modern acute gynaecological services, gynaecologists will have to learn these new skills (Jones 2005). TVUS probes, providing high-resolution images of the pelvic organs, have an established role in the characterization of adnexal masses, providing reliable and reproducible information regarding cyst type and probability of malignancy (Granberg et al 1989, 1990, Tailor et al 1997, Timmerman et al 1999a), particularly when they are used in combination with tumour markers (Moore et al 2008). They have superiority over transabdominal probes because of the higher resolution of pelvic anatomy. There is also no need for a full bladder, improving patient acceptability.
TVUS is a pivotal investigation in the delivery of an ‘Ambulatory Gynaecology Service’ (Jones 2008). This is a more comprehensive term which would include the assessment of patients with non-acute gynaecological symptoms such as menstrual disorders, postmenopausal bleeding and chronic pelvic pain. The discussion of these conditions falls outside the scope of this chapter.
Resources for Services
Ultrasound machine
Most gynaecology units will already have an ultrasound machine that can be used within a clinic setting. Minimum requirements are a transvaginal probe (6–7.5 MHz), a 3.5 MHz abdominal transducer and facilities for capturing images, either as a hard copy or digitally. A portable machine can be a wise investment if it is to be shared, for example, with the delivery suite, or to allow for ultrasound-guided procedures in the operating theatre. The ultrasound machine should not be more than 5 years old (Royal College of Radiologists/Royal College of Obstetricians and Gynaecologists 1995).
Reducing the risk of infection transmission
TVUS is a relatively non-invasive procedure. There is, however, a moderate risk of transmission of infection as the probe comes into contact with mucous membranes. The risk of infection is reduced by the use of an appropriate cover for the transducer. It is estimated that up to 7% of covers will sustain perforations, and contamination of the probe may also occur on removing the cover after use (Jimenez and Duff 1997). As a result, appropriate cleaning of the transducer must occur between patients. Sterilization of the probe is not practical, and disinfection using a germicidal (e.g. 70% alcohol) cloth or spray, after first wiping off the gel, is effective. The probe is then left to air dry for at least 5 min. Basic hygiene measures, such as washing hands after each case and ensuring that contaminated gloves do not come into contact with the ultrasound machine, must be used to minimize cross-infection. There is no need for the routine use of antibiotics during ultrasound scanning.
Analgesia
TVUS is a well-tolerated procedure, even in women who present with acute pelvic pain. It does not require the routine use of analgesia. Basama et al (2004) demonstrated that TVUS was considered acceptable, and not painful, embarrassing or stressful in a study of 425 women undergoing TVUS in an emergency setting.
Ultrasound-guided ovarian cyst aspiration
It is important that the ovarian cysts are unilocular and thin walled if the technique is going to be successful and safe. Subtle, superficial, internal mural nodules or small papillary excrescences should be searched for meticulously because these features may indicate a malignant lesion, in particular a borderline tumour. With careful attention to ultrasound surveillance, cyst aspiration can be performed safely (Caspi et al 1996, Troiano and Taylor 1998). In 33–50% of cases, cyst aspiration will constitute definitive therapy. In other cases, cysts will recur and it is important to remember that cytology alone is not sufficiently accurate to exclude malignancy. Cyst recurrence after drainage is higher than if the capsule is removed (Balat et al 1996), but cyst fluid cytology is not always representative of the cyst wall pathology (Dietrich et al 1999).
Cyst aspiration in pregnant women is also feasible, and this technique is useful for functional cysts that become large and symptomatic (Khaw and Walker 1990). Cyst aspiration decreases the risk of rupture or torsion. Cysts that persist into later pregnancy are more likely to be serous or mucinous, and may be malignant. However, in some cases, it may be useful to aspirate the cyst and to remove it post partum. Such treatment may be warranted after careful assessment because surgical treatment for cysts in pregnancy is not without risk, with reported miscarriage rates between 2% and 35%.
The Emergency Gynaecological Unit
The provision of an EGU is now recognized as a gold standard service (Royal College of Obstetricians and Gynaecologists 2006). It provides an easily accessible outpatient area with facilities for ultrasound-based assessment of pregnancy duration, viability and location, This allows the clinician to provide informed management and counselling of the patient in a setting which maximizes her privacy and comfort. The EGU should have a dedicated area for the triage, assessment and initial management of patients presenting with acute gynaecological disorders, including early pregnancy complications. There should be a separate area where the patient can change, a designated waiting area with toilet facility, and bed/trolley spaces to accommodate women who need to recline. An initial assessment of the clinical condition can be made and recorded on a preformed history sheet. The cost benefits of the EPU are well established (Bigrigg and Read 1991) as admission can be avoided in approximately 40% of patients, with a further 20% requiring a shorter stay. Ideally, there should be a dedicated unit for the assessment and investigation of women with suspected complications of early pregnancy. This will be centred around an ultrasound scanning room, run by dedicated ultrasound practitioners. There should be a private area in which the patient can change and also a separate counselling room with access to a counselling service and outside line telephone.
Anti-D immunoglobulin use
Current guidelines (Royal College of Obstetricians and Gynaecologists 2000 & 2006) for the use of rhesus immunoprophylaxis in early pregnancy recommend that anti-D immunoglobulin should be given to all non-sensitized rhesus-D-negative women who have:
Ultrasound Overview
TVUS should be regarded as an extension of a bimanual examination rather than a replacement. A recent prospective comparative trial of endovaginal sonographic bimanual examination versus traditional digital bimanual examination in non-pregnant women with lower abdominal pain has been reported (Tayal et al 2008). The study clearly demonstrated that vaginal examinations combined with TVUS improved confidence in key findings, such as ovarian and uterine size or position irrespective of the patient’s body mass index. The advantages of TVUS over the transabdominal approach are well documented (Gonzalez et al 1988, Mendelson et al 1988). The placement of the ultrasound probe closer to the pelvic organs means that higher frequency ultrasound transducers (6–7.5 MHz) can be used, which produce high-resolution images. TVUS assessment of ovarian volume and morphology correlates closely with subsequent operative findings at laparotomy (Rodriguez et al 1988).
No single ultrasound measurement of the different anatomical features in the first trimester has been shown to have a high predictive value for determining early pregnancy outcome, and Doppler studies are not helpful either (Jauniaux et al 2005). Despite this, high-resolution TVUS has transformed understanding of the pathophysiology and management of early pregnancy failure. The ultrasound findings in both a normal pregnancy and a failing pregnancy are well described (Dogra et al 2005). The intrauterine gestation sac can be visualized from approximately 4 weeks after the last menstrual period using a transvaginal transducer, which is approximately 2 weeks earlier than if using the transabdominal approach (Fossam et al 1988). This is dependent upon a regular 28-day cycle, and hence a more accurate approach to confirming pregnancy viability or failure is dependent upon either changes with time or the presence or absence of fetal cardiac activity. The diameter of the gestational sac increases at approximately 1 mm/day in early pregnancy (Nyberg et al 1985), and can be differentiated from the ‘pseudosac’ of ectopic pregnancy by its thick, echogenic rind surrounding the echo-lucent central chorionic sac and eccentric location to the endometrial midline. The presence of a normal intrauterine gestation sac is associated with β-hCG levels of >1000 IU. Detection at levels greater than this is dependent upon a number of factors, including type of probe and ultrasound machine used, the presence of leiomyomas, operator variations and multiple gestations (Nyberg et al 1985, Bernaschek et al 1988). The absence of a gestation sac should prompt the operator to look for an extrauterine gestation (including a close examination of the cornua and cervix as well as the adnexa). Visualization of the yolk sac is regarded as definitive evidence of an intrauterine pregnancy. The yolk sac can be visualized from 5 weeks’ gestation (Figure 6.1), and the early embryonic pole from approximately 6 weeks. First recognized as a thickening along the yolk sac, it is linear to begin with, subsequently becoming curved in nature. The embryonic growth rate is 1 mm/day. Cardiac activity starts at approximately 5 weeks after the last menstrual period. Cardiac activity not detected in embryos of more than 4 mm is associated with embryonic demise (Brown et al 1990, Levi et al 1990, Goldstein 1992). However, a repeat scan to confirm diagnosis is always indicated. Embryonic bradycardia can be associated with poor outcome (Doubilet et al 1999), and a follow-up scan is warranted to confirm viability.
