Hysterosalpingography

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Chapter 29 Hysterosalpingography

ACCURACY

HSG should be considered a screening test; as such, it should have a high sensitivity so as not to miss the opportunity to treat an abnormality but with a low false-positive rate to prevent unnecessary additional testing and treatments. The accuracy of an HSG is highly dependent on technique and interpretation. The technical quality of the HSG is important to limit misinterpretations (i.e., eliminating air bubbles that may be confused with a polyp or myoma or using inadequate contrast volume or injection pressure to demonstrate tubal patency). In one study 50 HSG films were reviewed by five reproductive endocrinologists. There was considerable variability in the interpretation as well as the recommended clinical management.4 In another study, three reproductive endocrinologists and three radiologists reviewed 50 HSGs on two occasions. The intrareader and inter-reader reliability was high for the detection of normal uterus and tubes, as well as tubal obstruction, but low for the detection of hydrosalpinges, uterine adhesions, pelvic adhesions, and salpingitis isthmica nodosa. Clinicians more reliably diagnosed hydrosalpinges and tubal obstruction; radiologists more reliably detected salpingitis isthmica nodosa and uterine adhesions.5

Diagnosing Uterine Cavity Abnormalities

HSG has a high sensitivity but a low specificity for the diagnosis of uterine cavity abnormalities.6 HSG and diagnostic hysteroscopy performed on 336 infertile women showed that HSG had a sensitivity of 98% but a specificity of only 35% due to difficulties distinguishing between polyps and myomas. False-negative results were mild intrauterine adhesions of doubtful clinical significance.7 Thus, HSG fulfills the requirements as a good first-line screening test for revealing abnormalities of the uterine cavity, although any abnormalities found will likely need further evaluation to make a definitive diagnosis. Sonohysterography or diagnostic hysteroscopy can distinguish between polyps and submucous myomas, which appear similar on HSG (Fig. 29-2). A uterine septum and a bicornuate uterus cannot be differentiated on an HSG (Fig. 29-3). Evaluation of the external fundal contour by laparoscopy, magnetic resonance imaging (MRI), or three-dimensional ultrasonography is required to make a definitive diagnosis. The arcuate uterus has a mild convex fundal margin and is a normal variant. Extrinsic compression from an intramural fundal myoma may give a similar appearance and is easily recognized on routine transvaginal ultrasonography.

Other conditions visualized on HSG are adhesions, changes caused by diethylstilbestrol (DES), and adenomyosis. Adhesions appear as irregular filling defects and may be very mild or completely obliterate the cavity (Fig. 29-4). DES was used from the 1940s up to 1971 as prophylaxis for spontaneous abortions. The classic appearance associated with in utero DES exposure is a hypoplastic T-shaped cavity. (Fig. 29-5). Adenomyosis can occasionally be diagnosed by HSG as a cavity with shaggy borders (Fig. 29-6). The sensitivity for detecting this condition is unknown because it is uncommon in younger women and is definitely diagnosed histologically after hysterectomy.

Diagnosing Tubal Abnormalities

An evidence-based study found HSG to be “a valid and accurate diagnostic test to be applied in a general population of subfertile couples to assess tubal patency but an unreliable test for diagnosing tubal occlusion.” Tubal blockage on HSG is not confirmed by laparoscopy in up to 62% of patients, but if HSG suggests patent tubes, tubal blockage is highly unlikely. Laparoscopy is needed to confirm or exclude tubal occlusion on HSG.8 It should be noted that laparoscopy is not the perfect gold standard; 2% of patients with bilateral tubal occlusion subsequently conceived spontaneously.9 One study noted that 60% of patients with proximal tubal occlusion on HSG were patent on repeat HSG 1 month later.10

Surprisingly, hydrosalpinges may be both overdiagnosed and underdiagnosed by HSG. They may be only mildly dilated with preservation of mucosal folds or massively dilated with complete loss of the normal intratubal architecture (Fig. 29-7). HSG can also diagnose salpingitis isthmica nodosa. This condition, which predisposes to tubal occlusion and ectopic pregnancy, is similar to adenomyosis of the uterus in that there are diverticuli from the mucosa into the muscularis (Fig. 29-8). HSG is also not an ideal test for diagnosing pelvic adhesions because it detects them in only half of the cases in which they are present.2 Adhesions are usually diagnosed on HSG by the presence of loculated spill of contrast medium (Fig. 29-9).

CONTRAINDICATIONS

Pregnancy

HSG is scheduled immediately after menses to prevent performing the procedure in the presence of an unrecognized pregnancy due to the concerns of disrupting the pregnancy as well as radiation exposure. Before the advent of pregnancy testing and ultrasonography, HSG was performed specifically to diagnose pregnancy, with no untoward effects.2 HSG during inadvertent pregnancy is uncommonly reported. In a recent case report the calculated dose to the embryo was 3.7 mGy. The authors state that the teratogenic risk with less than 20 mGy during the first trimester does not justify pregnancy termination.17 The possibility of spontaneous abortion should be discussed with the patient.

TECHNICAL CONSIDERATIONS

Types of Cannulas

Rigid metal cannulas have been the standard device for performing HSG because they are inexpensive, reusable, and readily available. A balloon catheter can be employed in rare cases when cervical stenosis or an inadequate cervical seal prevent completion of the study with the rigid cannula. In addition to the cost of the disposable balloon catheter, it is more difficult to manipulate the uterus compared to a rigid cannula with a tenaculum. Also, the balloon obscures the lower uterine segment. One study reported that the balloon catheter caused significantly greater pain after the procedure.24 However, a randomized study found that HSG performed with a balloon catheter required less contrast and fluoroscopy time, produced less patient discomfort, and was easier for senior residents to perform. It has the additional advantage of allowing the clinician to perform immediate selective salpingography and transcervical tubal catheterization for proximal tubal occlusion without the need to replace the cannula or reschedule the patient.25

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