Spieldoch, Rachel L. MD; Winter, Tom C. MD; Schouweiler, Calisa MS; Ansay, Susan; Evans, Michael D. MS; Lindheim, Steven R. MD
The instillation of saline and potentially other echogenic ultrasound contrast agents, including air bubbles, into the uterine cavity during ultrasonography has been known by many names, including sonohysterography, hysterosonography, transvaginal sonography with fluid contrast augmentation, saline infused sonography, and finally as saline infusion sonohysterography.1,2 Although primacy is notoriously difficult to accurately assess, saline infusion sonohysterography appears to have been first described in 1981 by Nannini et al.3
Saline infusion sonohysterography has greatly aided the diagnostic evaluation of the uterine cavity for a number of clinical conditions, including abnormal uterine bleeding, evaluation of an endometrium that is thickened, irregular, immeasurable, or poorly defined on conventional transvaginal ultrasonography, discordance between transvaginal ultrasonography and endometrial biopsy, infertility, retained products of conception, and recurrent abortion.4 Compared with the hysterosalpingogram (HSG), endometrial biopsy, and abdominal and transvaginal ultrasonography, saline infusion sonohysterography has improved diagnostic accuracy and better defines cavitary defects, including more correct assessment of submucosal compared with intramural involvement for uterine myomas.5–8
Saline infusion sonohysterography also compares favorably with the “gold standard,” hysteroscopy, in many ways. “[Office saline infusion sonohysterography] is as good as diagnostic hysteroscopy under general anesthesia at detecting focal lesions in the uterine cavity of women with postmenopausal bleeding. … It is better tolerated [than office hysteroscopy], and cheaper.”9 “Routine use of [saline infusion sonohysterography instead of hysteroscopy] in the primary investigation of patients with bleeding disorders would potentially lead to 2 in 3 hysteroscopies being avoided.”10 A randomized controlled series has shown that saline infusion sonohysterography is better tolerated, requires less medical intervention, and provides cost savings when compared with ambulatory office hysteroscopy.11
Saline infusion sonohysterography is not a difficult study to perform; one trial noted no differences in true-positive rates when saline infusion sonohysterography was performed by nurse practitioners, postgraduate year (PGY)2 trainees, PGY4 trainees, and fellows,12 and another10 stated that “routine use of [saline infusion sonohysterography] even in non-expert hands implies a low number of undiagnosed lesions.”
Nonetheless, saline infusion sonohysterography and other intrauterine investigations may cause significant discomfort, uterine cramping, and pain despite the routine use of preprocedural nonsteroidal anti-inflammatory agents. Pain appears to occur as the catheter is introduced into the endometrial cavity, just after passing the internal os. Pain and a vasovagal response are exacerbated if the fundus of the uterus is touched with the tip of the catheter, if there is overdistension of the balloon on the catheter system in an attempt to prevent egress of the saline, and if saline is infused too rapidly into either the balloon or the endometrial cavity. In addition, it has been anecdotally reported that inadvertent infusion of air bubbles (when the catheter system has not been adequately primed with saline) may cause discomfort.
Previous studies have attempted to address techniques that minimize pain and discomfort with hysteroscopy, HSG, and saline infusion sonohysterography,13 including paracervical block,14,15 topical cervical anesthesia,16,17 intrauterine anesthesia,18–21 and even catheter type.22 None of these have been found to consistently reduce pain and discomfort, including two randomized clinical trials that failed to demonstrate that intrauterine lidocaine was effective in decreasing pain during HSG.19,20 Studies evaluating differences between various catheter systems have shown that some devices are better tolerated than others,22 whereas others have reported anecdotally that placement of any balloon catheter system in the cervix is a comfortable method for patients and allows superior visualization of the entire endometrial cavity throughout the procedure.23
The primary objective of this investigation was to estimate whether the location of placement of the saline infusion sonohysterography balloon into either the uterine cavity or the cervical canal affected discomfort perceived during the examination. Our secondary objectives were to estimate whether the location of the balloon placement affected the time and volume of distension media required to successfully perform the saline infusion sonohysterography.
MATERIALS AND METHODS
Patients undergoing saline infusion sonohysterography for diagnostic uterine cavity evaluation at our university's Reproductive Endocrine Infertility Program were recruited to participate in this prospective randomized clinical study. Institutional Review Board approval was obtained from the University of Wisconsin. Exclusion criteria included previous hysterectomy, current pregnancy, active pelvic inflammatory disease, and a patulous or stenotic cervical os noted on previous history or physical examination.
After written informed consent was obtained, patients were assigned to either cervical or intrauterine catheter balloon placement according to a computer-based randomization. Providers were told the designated catheter position just before the procedure. Saline infusion sonohysterography was performed, either during the follicular phase of a spontaneous menstrual cycle or after a progestin withdrawal bleed. All patients were instructed to take preprocedure nonsteroidal anti-inflammatory drugs (NSAIDs) 1 hour before the saline infusion sonohysterography. After speculum examination and cervical cleansing,13 a 2 lumen 5 French balloon catheter (Cooper Surgical Inc., Trumbull, CT) was placed either in the cervical canal (vide infra) or into the lower uterine segment according to the randomization; the balloon was then distended to 1 mL in both cases. Before cavitary distension, routine transvaginal sonography of the endometrium, myometrium, and adnexa was performed. This was followed by instillation of sterile saline through the catheter until an adequate evaluation of the uterine cavity was obtained. If catheter placement was in the endometrial cavity, the balloon was deflated at the end of the procedure to allow for proper sonographic assessment of the lower aspect of the uterine cavity (“pull-out imaging”). Transvaginal sonographic images in orthogonal planes were recorded.
The following technique was used for intracervical placement of the balloon. The cervix is approximately 2.5 cm long in an adult nonpregnant woman.24 The catheter was advanced approximately 1 cm into the cervical canal, that is, until the balloon just disappeared behind the external os. After balloon distention, the catheter was gently tugged to ensure that it was firmly seated. In the rare event in which the catheter popped out into the vagina with this gentle test traction, the process was repeated with the catheter advanced slightly farther into the cervical canal. The speculum was then removed, and saline infusion sonohysterography was performed in the usual fashion.
Patients were asked to assess their level of pain using a 10-point visual analog pain scale. This pain assessment was performed at the time the balloon catheter was initially inflated and then after deflation at the completion of the saline infusion sonohysterography. Because the balloon could move from intracervical to intrauterine position and vice versa, if the balloon was in the incorrect position as visualized on transvaginal ultrasonography (according to the randomization assignment) after completing the initial visual analog scale, the balloon was then deflated and another attempt was made to place the balloon based upon the randomization assignment. At this time another visual analog scale was administered. Regardless of the placement after the second attempt, a full saline infusion sonohysterography was then performed, and outcome measures were assessed based on the intent-to-treat principle.
Baseline demographics recorded included age, gravidity, parity, saline infusion sonohysterography indication, and the use of preprocedure NSAIDs. The primary outcome measure was subjective assessment of discomfort for both intracervical and intrauterine balloon catheter placement using the 10-point visual analog pain scale. Secondary outcome measures included time required for saline infusion sonohysterography, total volume of infused fluid necessary, saline infusion sonohysterography findings, and complications, including vasovagal reactions.
A target enrollment of 68 patients (34 per group) was chosen to provide adequate (80%) power to detect a difference in pain scores of 2 points at the two-sided 5% significance level, assuming within-group standard deviations of 2 points. The sample size calculation included adjustment for expected crossover rates from cervical group to uterine placement (25%) and uterine group to cervical placement (5%). Analyses were carried out using the intent-to-treat principle. The two-sample t test, χ2 test for association, and Fisher exact test were used to assess differences between groups. Relationships between pain scores and patient age, volume of infused saline, and procedure duration were examined using Spearman rank correlation coefficient. Statistical analyses were performed using R (R Foundation for Statistical Computing, Vienna, Austria).
Between December 2004 and August 2005, 69 women enrolled; 35 were randomized to cervical balloon placement and 34 to uterine balloon placement. There were no differences in gravidity (P=.73), parity (P=.86), indication for saline infusion sonohysterography (P=.96), or findings (P=.79) on saline infusion sonohysterography between the two groups (Tables 1 and 2).
In one patient randomized to the uterine placement group, the balloon was defective and would not inflate. There were three patients in each group where catheter placement occurred opposite to the randomized intended position. Two patients experienced complications. One patient assigned to the cervical group experienced 9/10 pain 1 hour after the procedure. A second patient assigned to the uterine group experienced dizziness and lightheadedness after the procedure. Both of these patients were successfully treated with basic supportive, conservative measures.
After initial inflation of the balloon, patients randomized to the cervical group reported less pain than patients in the uterine group (1.8±2.1 compared with 3.0±2.3, P=.02). Upon completion of the saline infusion sonohysterography and after balloon deflation, perceived pain did not differ between groups (cervical compared with uterine: 2.2±2.4 and 2.0±2.4, respectively, P=.66) (Fig. 1). When patients were compared by actual balloon placement (as treated), the results were similar (cervical compared with uterine: inflation pain 1.5±1.9 and 3.1±2.6, respectively, P=.007; deflation pain 2.2±2.4 and 2.0±2.4, respectively, P=.63).
The total volume of infused saline necessary to adequately perform a saline infusion sonohysterography was significantly lower with cervical placement than uterine placement (as treated: 19±16 and 40±32 mL, respectively, P=.001). Total procedure time was not different between these two groups (cervical compared with uterine: 5.0±2.7 and 4.3±2.8 minutes, respectively, P=.30, Table 3).
Among the whole cohort, pain scores were not associated with patient age (inflation: rank correlation coefficient r=–0.14, P=.26; deflation: r=0.05, P=.70), saline volume (r=0.06, P=.63; r=–0.21, P=.08), procedure time (r=0.11, P=.35; r=–0.14, P=.27), use of NSAIDs (Yes 2.4±2.3 compared with No 2.2±2.4, P=.77; 2.1±2.3 compared with 2.4±2.7, P=.73), and presence of intrauterine pathology (Yes 2.4±2.4 compared with No 2.4±2.2, P=.99; 2.4±2.7 compared with 1.9±2.1, P=.36).
Grouping intracervical and intrauterine placements together, a separate analysis revealed that nulliparous women had significantly more pain than did parous women, both after initial balloon inflation (2.7±2.4 compared with 1.6±1.9, P=.04) and at completion of the saline infusion sonohysterography (2.5±2.5 compared with 1.3±1.7, P<.05). Among nulliparous patients (n=47), those randomized to cervical placement reported less pain upon inflation than did those in the uterine group (1.4±1.7 compared with 3.6±2.5, P=.001) and similar pain upon deflation (2.6±2.7 compared with 2.4±2.5, P=.84). Parous patients (n=22) exhibited a somewhat similar pattern, although in this smaller group the differences were not significant (cervical compared with uterine: inflation 2.3±2.6 and 1.2±1.4, respectively, P=.47; deflation 1.5±1.6 and 1.0±1.9, respectively, P=.22).
This randomized clinical trial demonstrates that intracervical placement of the balloon catheter for saline infusion sonohysterography results in significantly less pain after initial placement than does intrauterine balloon placement, although these differences did not persist at the completion of the saline infusion sonohysterography. The time required to perform the saline infusion sonohysterography was similar in both groups, but significantly more distension media was required with intrauterine balloon placement. Balloon catheter placement caused significantly more pain in nulliparous than parous women. Looking at just the subset of nulliparous women, there was more pain with intrauterine than with intracervical balloon catheter placement.
The etiology for the pain experienced with hysteroscopy, HSG, saline infusion sonohysterography, and endometrial sampling has been thought to be related to the following: cervical manipulation from placement of a single-tooth tenaculum, pain from uterine distention with the infused media which may release local prostaglandins and initiate uterine cramps, and peritoneal irritation as a result of spill of the infused medium from the fallopian tubes.16,19,25,26 Additional mechanisms seen with respect to saline infusion sonohysterography may include catheter irritation and/or balloon distension in the cervical canal or uterine cavity.
A number of studies have attempted to evaluate different methods (ie, not related to the specific position of the balloon) to minimize the discomfort that is often experienced during hysteroscopy, HSG, endometrial sampling, and saline infusion sonohysterography, including the use of anesthetics applied as topical anesthetic gel to the cervix, via a paracervical block, or with intrauterine instillation, with inconsistent results.
With respect to topical local anesthetic to the cervix during HSG or office hysteroscopy, some have reported reduced pain.16,17 The benefits in these trials were limited to the cervix where the topical anesthetic was applied before placement of the tenaculum and cervical traction.
Conflicting reports for paracervical blocks include a randomized trial that demonstrated that paracervical block in those undergoing HSG with a metal cannula resulted in significantly less pain,27 whereas other investigators have found no differences in pain when using a paracervical block for outpatient hysteroscopy and endometrial biopsy when compared with controls.14,15 Furthermore, a paracervical block can be painful in and of itself and may result in bleeding and intravasation.
Investigators have also looked at the effects of intrauterine anesthetic instillation, again with mixed results. Two randomized trials in women undergoing HSG found no difference in pain after instillation of intrauterine lidocaine.19,20 Costello et al19 actually noted an increase in discomfort in the lidocaine group 10 minutes after completion of the HSG. In contrast, others have shown a benefit using instilled intrauterine 2% lidocaine in preventing pain associated with endometrial biopsy.28 Cicinelli et al18 and Zupi et al21 demonstrated that intrauterine instillation of 2% mepivacaine solution resulted in significant reductions in pain, as well as vasovagal reactions during diagnostic hysteroscopy and endometrial biopsy, although these findings have not been corroborated when using intrauterine lidocaine.17 Possible explanations for these contrasting results include selection biases introduced when using older patient populations with greater likelihoods of cervical stenosis; differences between the nature of the procedures with hysteroscopy, endometrial biopsy, and HSG; and the agents and doses used. Thus, the potential benefits of instilled intrauterine anesthetic agents have yet to be fully understood and require further investigation.
The use of a balloon catheter alone for HSG has been compared with the traditional technique of a metal cannula for HSG. In a randomized clinical trial, Tur-Kaspa et al29 showed that a double-balloon catheter inserted into the cervical canal was superior to the traditional metal cannula and resulted in significantly less pain. In another randomized trial comparing the use of the metal cannula, a single balloon catheter, and a metal cannula with a paracervical block, there was significantly less pain in the latter two groups. This study, however, failed to identify if the balloon was inflated at the level of the cervix or uterine cavity and used both 7-French or 5-French catheter sets.27
The relative benefits of various catheter systems for saline infusion sonohysterography were evaluated by Dessole et al.22 In their prospective study, six different catheter types were randomly assigned to determine which offered the best compromises between reliability, patient satisfaction, and cost. Devices studied included catheters with a balloon close to the tip and one without a balloon but, instead, with a movable stopper that is placed against the external os of the uterus. The latter catheter was best tolerated by patients (likely secondary to absence of a balloon), but because of the high saline backflow into the vagina required larger volumes of saline for adequate evaluation of the endometrial cavity. Hence, a balloon catheter may prevent egress of the infused distension fluid by ensuring a good seal at the level of the internal os and/or cervix, whereas a nonballoon catheter will require more fluid but be more comfortable.
With all of this in mind, we sought a different approach in an attempt to minimize perceived discomfort during saline infusion sonohysterography. Given that nerve innervation to the cervix and uterus are known to be different, we postulated that experienced pain might be minimized with different balloon placement sites. The afferent nerves from the cervix enter the spinal cord in the nerve roots of S2-S4.28,30 In contrast, the nerves of the fundus and body of the uterus ascend through the inferior hypogastric plexus and enter the spinal cord at T10-L1. Furthermore, the uterus is primarily muscle, whereas the cervical stroma is fibromuscular with only approximately 15% smooth muscle. Therefore, sympathetic fibers to the uterus cause vasoconstriction and muscle contraction, unlike the effects in the fibrous tissue of the cervix; this difference may exacerbate pain perception with uterine aggravation.24,31 These anatomical differences provide a model to explain the differences in pain demonstrated in our study between intrauterine and intracervical placement of the catheter balloon.
Our saline infusion sonohysterography study demonstrates that intracervical balloon placement results in significantly less pain compared with intrauterine placement only after initial inflation. No differences were noted between these two groups at completion of the saline infusion sonohysterography. A greater volume of infused saline was required with intrauterine balloon catheter placement (40 mL compared with 19 mL, P=.001), but this did not translate into longer procedural times or more pain after the initial balloon inflation.
The finding of more pain in nulliparous women compared with parous women innately seems reasonable, given that previous pregnancy-induced uterine distension may lead to desensitization of nerve pathways. Because the study was not adequately powered to assess just parous women, the lack of differences in pain between intrauterine and intracervical balloon placement in this group may merely represent an inadequate sample size. Further research is warranted to assess for any potential differences in pain with different balloon locations in parous patients.
Intrauterine balloon placement required double (40 mL compared with 19 mL) the volume of infused saline when compared with intracervical balloon positioning. Although the clinical significance of positive peritoneal cytology in patients with stage I endometrial cancer is controversial,32,33 there is theoretical concern about the potential upstaging of endometrial cancer in patients who undergo hysteroscopy or saline infusion sonohysterography before definitive surgical therapy (eg, seeding tumor cells out the Fallopian tubes into the peritoneal cavity as fluid is pushed into the endometrial cavity). Hysteroscopy, in particular, may be associated with an increased rate of malignant cytology after controlling for confounders of stage and grade.34 It is doubtful that viable malignant cells are disseminated intraperitoneally via saline infusion sonohysterography (Berry E, Lindheim S, Conor J, et al. The incidence of disseminated endometrial cancer cells during sonohysterography and their functional viability: a prospective study [abstract]. Gynecol Oncol 2006;101S:34.), but if washings are positive due to the presence of nonviable malignant cells, more aggressive medical and surgical management might possibly take place than is necessary, with concomitant associated morbidity. Because significantly more fluid is spilled with hysteroscopy than saline infusion sonohysterography and because this trial has shown that intracervical balloon placement for saline infusion sonohysterography requires about half the volume of infused fluid as does intrauterine balloon placement, one might postulate that intracervical balloon placement for saline infusion sonohysterography leads to more optimal care in patients with endometrial cancer. Whether this proposed theoretical benefit is real or not requires further research.
Although our study was randomized, one study limitation relates to the fact that three different physicians performed the saline infusion sonohysterography; differences in patient pain scores between physicians were not evaluated. However, inclusion of multiple operators may serve as an advantage with respect to generalizing the study results. Another study limitation is secondary to sample size; perhaps several of the nonsignificant differences noted throughout the paper might be real and detectable with larger numbers of enrolled patients. Finally, intracervical balloon placement is more technically challenging than intrauterine placement, particularly for beginners. Intracervical balloon placements may “pop out” into the vagina during saline infusion sonohysterography, necessitating reinsertion of the speculum and recanalization of the cervix, but we did not experience this difficulty in our trial, possibly because all three operators were very experienced. Placement in the nonintended position did occur in slightly less than one in 10 patients (three of 35 intracervical and three of 34 intrauterine placements went to the other location).
In conclusion, saline infusion sonohysterography is a valuable tool for evaluating potential intrauterine pathology. Although saline infusion sonohysterography may result in cramping and pain, intracervical balloon placement (as opposed to the more conventionally taught intrauterine balloon placement) results in less pain during the initial part of the procedure. This decreased pain was particularly significant in nulliparous woman. Intracervical placement required half the volume of infused saline when compared with intrauterine placement. There was no difference in overall procedural duration between intracervical and intrauterine placements. For these reasons, we suggest that intracervical balloon placement should be considered during saline infusion sonohysterography to improve overall patient satisfaction and to minimize perceived discomfort and pain.
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© 2008 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.