GYNAECOLOGY

CLINICAL USE OF SONOHYSTEROGRAPHY IN THE EVALUATION OF INFERTILITY Allison M. Case, MD, FRCSC, Roger A. Pierson, MS, PhD Department of Obstetrics, Gynaecology and Reproductive Sciences, Saskatoon SK

Abstract: Assessment of tubal patency and evaluation of the uterine cavity should be part of all infertility investigations. Sonohysterography (SHSG), also referred to as saline-enhanced ultrasonography, is being used with increasing frequency for investigation of infertility and other gynaecological indications. Sonohysterography is similar to hysterosalpingography (HSG) in its effectiveness for evaluating tubal patency, and superior to HSG for assessing intrauterine abnormalities. Advantages of SHSG over HSG include the ability to assess extrauterine structures, lack of ionizing radiation, and often better tolerability by the woman being examined. Sonohysterography can offer detailed assessment of the female pelvis, and has the potential to replace HSG as a routine, first-line infertility investigation. This paper discusses the technique and indications for SHSG, and reviews its use in infertility investigation, in particular in the assessment of the uterine cavity and tubal patency.

INTRODUCTION

Assessment of tubal patency and evaluation of the uterine cavity are part of basic infertility investigations. Structural abnormalities causing anatomic distortion of the uterus and endometrial cavity may adversely affect reproductive outcome by causing implantation failure, spontaneous abortion, or complications in the third trimester of pregnancy, such as preterm labour, premature rupture of membranes, or malpresentation.1 It is estimated that up to 10% of infertility may be related to uterine abnormalities,2 with the incidence being possibly higher in secondary infertility.3 In one study, 32% of women with secondary infertility were found to have intrauterine abnormalities, compared to 8.1% of women with primary infertility. Of the 8 women with secondary infertility, 2 had endometrial polyps, 3 had submucous myomas, and 3 had uterine anomalies.3 Couples who are infertile, especially the female partners, undergo many tests and procedures. It is important to determine which investigations will provide the most useful information, while causing the least discomfort and risk. Sonohysterography (SHSG), also known as saline-enhanced ultrasonography, is increasingly being used for infertility investigation and other gynaecological indications. Many clinicians are unsure, however, when this test should be used. This paper discusses the technique and indications for SHSG, and reviews its use in infertility investigation.

Résumé : Toute enquête sur les causes de la stérilité devrait comprendre l’évaluation de la perméabilité tubaire et de la cavité utérine. La sonohystérographie (SHSG), aussi appelée échographie rehaussée par solution saline, s’emploie de plus en plus pour rechercher les causes de la stérilité et de nombreux autres problèmes. La SHSG est semblable à l’hystérosalpingographie (HSG), du point de vue de son efficacité pour évaluer la perméabilité tubaire, mais elle lui est supérieure pour l'évaluation des anomalies intra-utérines. Les avantages de la SHSG, par rapport à l’HSG, sont la possibilité d’évaluer les structures extra-utérines, l’absence de rayonnement ionisant et, souvent, une meilleure tolérance de la part de la femme examinée. La SHSG permet une évaluation détaillée du pelvis de la femme et offre la possibilité de remplacer l’HSG en tant que technique de référence habituelle pour la recherche des causes de stérilité. Cet article examine la technique de la SHSG et les indications pour son utilisation. Il passe aussi en revue son utilisation pour la recherche des causes de la stérilité, particulièrement en ce qui a trait à l’évaluation de la cavité utérine et de la perméabilité tubaire.

METHODS

English-language journals indexed in MEDLINE and PubMed were searched for relevant articles addressing methods of assessing the uterine cavity and tubal patency in the investigation of women with infertility. Search terms included “sonohysterography,” “infertility,” “hysterosalpingography,” “hysteroscopy,” ”uterine polyps,” “uterine fibroids,” “congenital uterine anomalies,” and “tubal patency.” The references in retrieved articles were also reviewed for potentially relevant articles not identified through database searches. Hand searches of library holdings, books, and other related publications were used to trace references not available on-line.

J Obstet Gynaecol Can 2003;25(8):641–8.

Key Words Sonohysterography, infertility, hysterosalpingography, hysteroscopy, uterine polyps, uterine fibroids, congenital uterine anomalies, tubal patency Competing interests: None declared. Received on January 6, 2003 Revised and accepted on June 5, 2003

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without using a tenaculum, so that the procedure is typically more comfortable for the woman. A pediatric Foley catheter is less rigid than the SHSG catheter, and often requires the use of a tenaculum on the anterior cervix to ease transcervical catheter insertion. A study of 610 women undergoing SHSG found no significant difference, in relation to tolerability and reliability, between specifically designed SHSG catheters and a pediatric Foley catheter, the latter being less expensive, but more difficult to position correctly.7 The transvaginal ultrasound probe is then inserted into the vagina, and balloon placement confirmed just above the internal cervical os in a sagittal plane (Figure 2A). Normal saline that has been processed for intravenous use is slowly instilled into the cavity while the cavity is being examined in both sagittal and transverse planes (Figure 2B). The tip of the SHSG catheter is easily visualized once the saline has been instilled (Figure 3). The entire procedure usually takes less than 5 minutes. Documentation of findings is done either by print images for the woman’s chart, electronic acquisition and storage of digital images, or video recording. Figure 4 shows a normal uterine cavity.

RESULTS QUALITY OF EVIDENCE

The quality of evidence of the articles retrieved on SHSG and its ability to assess the uterine cavity and tubal patency was predominantly Level II-2 for the well-designed, mostly prospective, cohort studies, and Level III for the descriptive studies, the levels determined using the criteria described by the Canadian Task Force on the Periodic Health Examination.4 TECHNIQUE OF SONOHYSTEROGRAPHY

Sonohysterography involves the instillation of physiologic saline into the uterine cavity through a narrow catheter, such as a specially designed SHSG catheter, pediatric feeding tube, or pediatric Foley catheter.5 Saline, a negative (hypoechoic) contrast medium, distends the cavity and outlines the endometrial lumen, while the cavity is evaluated by continuous transvaginal ultrasonography. The procedure is best performed in the follicular phase of the menstrual cycle, after menstruation is completed.4 This timing avoids the possibility of dislodging an early pregnancy, and reduces false positive results due to endometrial sloughing or blood clots that may occur in the late luteal phase of the cycle.6 An experienced transvaginal ultrasonographer is an important component of a successful SHSG. SHSG is ideally performed with the woman in a semiupright lithotomy position. A speculum is inserted into the vagina, and the cervix visualized and cleansed with antiseptic solution. A specially designed SHSG catheter (H/S catheter set, Ackrad Laboratories, Inc., Cranford, NJ, USA) or a #8 gauge pediatric Foley catheter may be used for saline instillation. The tray set-up used for SHSG in our centre is shown in Figure 1. The catheter is inserted into the cervix 3 cm to 4 cm beyond the distal aspect of the insufflation balloon, to ensure that the balloon is just beyond the internal cervical os. The balloon is inflated with approximately 1 mL of normal saline to stabilize the catheter and prevent leakage of fluid back through the cervix. The speculum is then removed, with the catheter left in place. Catheters designed for SHSG can usually be inserted

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B Figure 2. Sagittal views of a normal uterine cavity on sonohysterography showing balloon placement just above the internal cervical os before infusion of saline (A) and immediately after the first bolus of saline (B).

Figure 1. Tray set-up for sonohysterography.

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Figure 3. Image of normal uterine cavity following saline infusion. Note the tip of the catheter protruding from the tip of the balloon.

Figure 5. Image of intrauterine synechia extending between the anterior and posterior uterine walls.

endometrial polyps. Submucosal and intramural fibroids may also distort the endometrial contours. Congenital anomalies, such as septate or bicornuate uteri, are frequently observed (Figure 8). Particulate matter free-floating in the uterine lumen

INTRAUTERINE ABNORMALITIES

Sonohysterography may be used to identify a variety of intrauterine abnormalities. Acquired anomalies include intrauterine adhesions (Figure 5) or single (Figure 6) or multiple (Figure 7)

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Figure 4. Transverse and sagittal views of uteri containing flocculently distributed particulate matter (A) and semiorganized matter (B) within the lumen of a normal cavity.

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Figure 6. Images of endometrial polyps taken in transverse (A) and sagittal (B) planes.

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is likely to be artifact, such as air bubbles or fragments of endometrium (Figure 4). Three-dimensional ultrasound has the potential to greatly improve diagnosis of congenital uterine anomalies, but definitive studies await the widespread availability of calibrated intervaginal three-dimensional probes.

AIR AND SALINE With this technique, air is injected through the SHSG catheter, followed by saline, which disturbs the air bubbles. A methodical scan is then carried out, assessing the proximal, interstitial, and distal portions of the tubes.9

ASSESSMENT OF TUBAL PATENCY

Sonohysterography is useful for the evaluation of tubal patency. A variety of contrast media have been described to facilitate visualization of the tubes, including normal saline, air, and positive contrast media. NORMAL SALINE Tubal distension and flow from the fimbriated end of the oviduct is often observed and is indicative of a patent fallopian tube (Figure 9). Fluid collection in the cul-de-sac is also indicative of at least one tube being open (Figure 9). Agitation of the saline prior to infusion can further facilitate tubal visualization, as the increased proportion of air bubbles in the saline makes it appear hyperechoic.8 Saline agitation should only be done after the uterine cavity has been thoroughly assessed, as the bubbles will make uterine imaging detail much more difficult to visualize.

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B Figure 8. Transverse views of septate uteri showing different degrees of septation upon saline infusion. The double nature of the uterine cavity is clearly demonstrated.

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B Figure 7. Images demonstrating midsagittal views of multiple small endometrial polyps (A, B). Polyps of this nature are not readily appreciated without the addition of saline enhancement.

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Figure 9. Image of the oviductal fimbrae, visualized in a fluid pocket following saline infusion, demonstrating tubal patency.

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POSITIVE CONTRAST MEDIA Several different manufacturers produce positive contrast media. The only positive contrast medium licensed for use in Canada consists of a stabilized mixture of microbubbles and microparticles of a galactose that are highly echoic. Other positive contrast agents, at time of writing not available in Canada, consist of air-filled microspheres, also hyperechoic. The purpose of contrast agents is to increase the delineation and identification of anatomic structures in the ultrasonographic image by enhancing visualization of the fluid.10

DISCUSSION

Evaluation of the uterus and fallopian tubes has traditionally been performed by hysterosalpingography. HSG requires exposure of women to radiographic contrast medium and ionizing radiation. In some women, assessment of the uterine cavity is suboptimal because a very anteverted or retroverted uterus may make adequate visualization of the full cavity difficult. Although HSG allows general identification of most intrauterine abnormalities, it is difficult to make a definitive diagnosis using this technique alone. Differential diagnoses of intrauterine filling defects on HSG include anatomic abnormalities such as endometrial polyps, submucosal fibroids, and intrauterine adhesions, as well as artifacts such as air bubbles, cervical mucus, and blood clots.13 A significant limitation of HSG is that visualization of the uterine cavity is in only the anterior-posterior plane, rendering the location and size of abnormalities more difficult to determine. Sonohysterography allows evaluation of the size, shape, and contour of the uterine cavity in both the sagittal and transverse planes, in addition to identification and localization of filling defects such as polyps, fibroids, and adhesions.14 Ultrasonography also allows visualization of other intrapelvic structures, particularly the ovaries, which cannot be assessed with routine HSG. Hysterosalpingography is also useful in diagnosing congenital uterine anomalies. Differentiation between a bicornuate uterus and a septate uterus, 2 of the most commonly identified abnormalities, is difficult, however, due to the inability to evaluate the serosal surface of the uterus. Further investigations such as an MRI or laparoscopy or hysteroscopy are usually required to confirm the diagnosis. Transvaginal ultrasonography, in conjunction with SHSG, can be used to evaluate the external uterine contour, allowing differential diagnosis of these abnormalities without the use of more expensive or invasive diagnostic tests.15,16 In cases where a uterine septum is identified, the thickness of the septum and its relationship to fundal myometrium can be measured by SHSG. The anatomical details are useful when performing a hysteroscopic septum resection.3 Another important advantage of SHSG is that it avoids exposure to the iodine-containing contrast medium and ionizing radiation used during HSG, which may be a concern for some women. From studies assessing the tolerability and complications of SHSG compared to HSG,11,12,17-19 SHSG generally appeared to be better tolerated, with women experiencing less discomfort, and, when pain occurred, it seemed to be present for a shorter duration.12 Infectious morbidity with SHSG is minimal.11 Diagnostic hysteroscopy is considered the gold standard for evaluating the integrity of the uterine cavity. Disadvantages of hysteroscopy as a primary diagnostic test are that general anaesthesia is required, surgical or anaesthetic complications may occur, the cost related to the equipment and support personnel required is considerably higher than with HSG or SHSG, and in many cases,

PATIENT CONSIDERATIONS

Premedication with acetominophen or ibuprofen approximately 1 hour before the scheduled procedure is recommended, as women will usually experience mild discomfort when the catheter is inserted beyond the internal os, and again when the balloon is inflated. Uterine cavity distension can also cause menstrual-type cramping in some women. In general, women report less discomfort with SHSG than with hysterosalpingography (HSG).11,12 INDICATIONS FOR SONOHYSTEROGRAPHY

Sonohysterography is used in our centre for the indications summarized in Table 1. Initial evaluation of the uterine cavity and tubal patency in a woman with primary infertility is performed by either HSG or SHSG, depending on availability and physician preference or experience. Any abnormality of the uterine cavity identified on HSG, such as a filling defect or congenital abnormality, is subsequently re-evaluated with SHSG. SHSG is often performed as a first-line investigation in women with secondary infertility because of the higher incidence of uterine cavity abnormalities.3 The technique is also frequently performed in women who are considering in vitro fertilization treatment, to ensure a normal uterine cavity into which embryos may eventually be transferred. Any woman with infertility and a history of menorrhagia, intermenstrual or premenstrual spotting, or previous uterine surgery, due to a higher index of suspicion for an acquired intrauterine abnormality, also undergo SHSG at our centre.

TABLE 1 CLINICAL INDICATIONS FOR SONOHYSTEROGRAPHY* 1. An abnormal uterine cavity on HSG 2. Secondary infertility 3. Pre-IVF assessment of the uterine cavity 4. History of menorrhagia, intermenstrual or premenstrual spotting, or previous uterine surgery *HSG:

hysterosalpingography; IVF: in vitro fertilization.

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Dueholm and colleagues21 evaluated SHSG and hysteroscopy for diagnosis of benign intrauterine pathology (polyps and fibroids) in 106 women undergoing hysterectomy. Hysteroscopy and SHSG were found to be equivalent with a sensitivity of 83% and 84%, and a specificity of 90% and 88%, respectively, when results were correlated with intrauterine findings at hysterectomy. Sonohysterography appears to be fully capable of replacing HSG for assessment of the uterine cavity, and a normal SHSG is almost as reliable as a diagnostic hysteroscopy.3,11,17,20 Endometrial polyps or adhesions measuring