Article about HSG (long)

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Introduction

Investigation of the intrauterine cavity and tubal patency is indicated for

many clinical conditions in gynaecology. Hysterosalpingography (HSG) is a

conventional radiologic procedure that serves the purpose. The outline of

the intrauterine cavity and tubal lumen is created by radiographic images

using a radio-opaque medium. These images can identify anatomical disorders

and/or lead the clinician to further confirmation. Although many new

procedures such as hysteroscopy (HSC) and sonohysterosalpingography (SHSG)

have been developed, these new techniques require expensive instruments and

operator's expertise. The technique of HSG is quite simple and less

invasive. Moreover, most lesions can be definitely diagnosed by this

procedure provided that the operator performs the procedure and interprets

the results correctly. This article will discuss its current role in

gynaecological conditions, the proper technique and common mistakes.

Indications and Contraindications

HSG is recommended for any conditions that require morphological

demonstration of the endocervical canal, uterine cavity, and uterine tubes

for clinical decision. Commonly, HSG is indicated for early evaluation of an

infertile couple. HSG can assess basic factors, i.e. uterine cavity and

tubal patency that are essential for successful conception. Because it is a

less invasive method, HSG is usually selected before diagnostic laparoscopy

and hysteroscopy.

The other advantage of HSG for infertile couples is the therapeutic effect

of the procedure. It has been recognized that, after a normal HSG finding

(with oil-soluble contrast medium), the infertile patient has a 30% chance

to conceive spontaneously within the first 3 months.1-3 Recently, Cundiff et

al. have shown the com-parable therapeutic effect of this procedure using a

water-soluble medium as well.4 The reasons for the therapeutic effect of the

procedure, particularly the oil dye, may be a) HSG acts as a mechanical

lavage by dislodging mucus plugs or soft debris, it may straighten the

tubes and break down peritoneal adhesions, c) it may stimulate the tubal

cilia, d) it may improve cervical mucus, e) iodine in the contrast medium

exerts a bacteriostatic effect on the mucus membrane, f) when using an oil

dye, the ethiodol may decrease in vitro phagocytosis by peritoneal

macrophages.5

Other indications for HSG relate with the reproductive function of the

uterus. Patients with a history of recurrent abortions, post surgical

evaluation, abnormal uterine bleeding, and secondary amenorrhea should be

considered for HSG.

Contraindications for HSG are active pelvic inflammatory disease, recent

uterine or tubal surgery, active uterine bleeding, pregnancy and

hypersensitivity to the contrast medium.6 Usually, very few cases are really

contraindicated for HSG and with proper timing, most cases can be performed.

Patients with active infection or bleeding should be treated first and an

antibiotic prophylaxis should be considered during the procedure.

Techniques and common mistakes

The procedure should be scheduled during the proliferative phase, 2-5 days

after cessation of a menstrual flow, to avoid early pregnancy.5 The patient

prepares herself similar to having a pelvic examination. Most patients can

tolerate the procedure with minimal discomfort. However, in cases suspicious

for tubal occlusion, the patients may have more pelvic pain requiring a

slower medium injection. Mild analgesic may be used in some selected cases.

An NSAID may be taken 30 minutes before the procedure. In addition, an

antibiotic may be prescribed as well to reduce the chance of postprocedure

infection. The antibiotic of choice is doxycycline (200 mg after the

procedure or 100 mg bid 2 days before, followed by 100 mg bid for 5 days).5

HSG requires fluoroscopy with a 70-90 kilovolt range. Attempts to do HSG

without fluoroscopy are not recommended because the operator cannot control

the injection and proper timing for film shooting. The images can be

recorded on a film-cassette system, spot-film cameras, or videotape.

The contrast medium may be water or oil soluble. The oil-soluble medium

requires additional time for resorption. Some complications may occur with

the oil medium such as oil embolization to the lungs and peritoneal

irritation. Therefore, it is not the best choice for cases with a

questionable risk of infection. Water-soluble medium is now more widely

used. However, the watery medium distends the tubal lumen more quickly than

the oil medium. Therefore, it may be associated with greater pain. The

average amount of contrast medium for a complete examination is about 5-6

ml. Three to four ml of medium may be enough for nulliparous woman, whereas

a big uterus or large hydrosalpinx may need more than 10 ml. However, proper

technique can minimize the amount of medium used.

The instruments for HSG procedure are standard tools for pelvic examination,

i.e. a bivalve speculum, a sponge holder, cotton ball or gauze, a tenaculum,

a uterine sound, and a uterine cannula. A variety of uterine cannulas, from

a pediatric Foley catheter to specially designed cannulas, can be used for

HSG. A commonly used cannula is the Cohen-Eder cannula with a metal tip. All

cannulas have tubular tips that are either rigid or soft for endocer-vical

canal cannulation. The soft cannula usually has balloon at its tip to seal

the cervical os, whereas the metal cannula needs a traction or pressure

applied via a tenaculum to close the os. Proper placement of the cannula is

crucial for medium injection. The exact position/posture of the uterus must

be known to ease the insertion and to prevent accidental perforation of the

uterus and leakage of the contrast medium. A uterine sound may be used in

case of difficult insertion. Another common mistake is negligence to fill

the cannula with medium before insertion. This step is very important

because air bubbles in the cannula can mislead the operator's

interpretation. The air bubbles in the uterine cavity may be misdiagnosed as

an adhesion, submucous myoma, or a polyp.

The operator must remove the speculum before medium injection to prevent the

study field from being masked. All steps of medium injection should be

performed under fluoroscopy. Another pitfall is inadequate observation

during the early stage of medium filling into the uterine cavity. Small

lesions in the cavity can only be detected during this period with slow

injection. The first film should be taken during this period. The second

film should be taken when the uterine cavity is completely filled. The

operator should change the position of the uterus by moving the cannula or

placing adequate traction on the cervix to get a clearer view of the uterine

and tubal image. Some investigators showed better views of HSG when

performed with full bladder.7 Saline-filled bladder or naturally full

bladder is good for anteflexed uterus when only limited traction can be

applied with a soft cannula.

HSG can show the image of tubal mucosa and lumen clearly during the tubal

filling phase. Healthy ampulla can be interpreted from the rugal fold in the

image. At this time, the third film should be taken. The final film should

be shot when both tubes show spillage of the medium. Usually, four films are

necessary for a complete examination. However, 3 films may be adequate;

uterine cavity filling, tubal filling and spillage of dye into the

peritoneal cavity.5 In suspicious case of pelvic adhesion, a late film taken

20 minutes after removal of the cannula may be useful for evaluation of

pelvic dispersion of the contrast medium.8

Interpretation

The most difficult part of HSG is interpreting the 2-dimensional

radiographic image into a complex, 3 dimensional living organ. It is

advisable for the interpretator to perform the procedure himself rather than

to inspect only the finished radiographic images. Fluoroscopy can disclose

some small lesions or abnormalities that need real-time image to detect.

Principles in interpretation of HSG are :

- dividing the images of the whole internal genital organ into endocervix,

uterine cavity and tubal lumen and patency.

- investigating the images of each part regarding these aspects; size or

shape or dilatation, filling defect, border or irregularity and spillage or

collection of medium.

A normal HSG is considered when the following are observed: observation of

an inverted triangle uterine cavity without filling defects, normal

fallopian tubal contour and diameter, and bilateral spillage of contrast

medium without pooling. The following table describes possible diagnoses for

abnormal HSG findings in each part of the internal genital organ.

Many technical problems can occur during the procedure. The most common

problem is leakage of contrast medium. The cervical os may be too large,

e.g. partulous cervix, or stenotic and difficult to cannulate. A larger

cannula tip with forceful traction or a balloon catheter may correct this

problem. In a case of stenotic os, a smaller tip such as a pediatric Foley

catheter may be useful. Gentle insertion of the uterine sound into the

cervical os before cannulation may ease the procedure.

Air bubbles may cause an artifact in the image. Moving the cannula or

aspiration and refilling the uterine cavity can remove the air bubbles.

Observation of the moving filling defects can help the operator to

distinguish bubbles from actual defects. Absence of tubal spillage,

especially unilateral, can be explained in some cases by cornual spasm or

mucous plugging. The operator may maintain constant pressure on the syringe

or stop the operation for a while allowing the patient to rest before gently

starting the procedure again. Administration of 1 mg of glucagon

intravenously can relieve tubal spasm. However, for suspicious cases, the

tubal patency should be confirmed with diagnostic laparoscopy under general

anesthesia.

Abnormal HSG findings and differential diagnoses.6

Endocervix

Narrowing

normal variant, DES exposure, post operative, neoplasm

Dilatation normal variant, incompetent os, postoperative

Filling defects air bubble, mesonephric remnant, synechiae, neoplasm

Irregularity normal variant, diverticulum, perforation, neoplasm

Uterus

Small

hypoplasia, nulliparity, DES exposure, synechiae

Large multiparity, pregnancy, molar pregnancy, neoplasm

Shape arcuate uterus, septate uterus, unicornuate uterus, bicornuate uterus,

other congenital abnormalities DES exposure, synechiae, neoplasms,

postoperative

Filling defects congenital fold, air bubble, blood clot, mucoid material,

pseudoadhesions, leiomyoma, polyp, synechiae, adenomyoma, septate uterus,

IUD, postoperative, endometrial carcinoma, pregnancy, molar pregnancy,

retained conceptus

Irregularity s ynechiae, DES exposure, intrava- sation, neoplasm, normal

variant, endometrial hyperplasia, adenomyo- sis, tuberculosis,

postoperative, embedded IUD, uterine fistula, Gartner's duct remnant.

Uterine tubes

Absent visualization

technical, cornual spasm, mucosal pluging, obstruction, postoperative

Partial visualization technical postoperative, obstruction, congenital

Dilatation obstruction (hydrosalpinx), peri- fimbrial adhesions, tubal

pregnancy

Filling defect air bubble, polyp, neoplasm, silicone implants, tubal

pregnancy

Irregularity salpingitis isthmica nodosa, tubal diverticula, tuberculosis,

endometriosis, postoperative

Risks and complications of hysterosalpingography

Pain and pelvic discomfort is the most common complication of HSG. However,

most patients can tolerate the pain with no medication. Only 6 percent of

women undergoing HSG with a water-soluble medium had significant pain.9

Difficult cannulation or false insertion of the cannula can result in

bleeding or perforation of the uterus. The injury may involve other organs

such as bladder and large bowel. Therefore, the proper and gentle

cannulation is the first thing to be emphasized in order to avoid any

serious complications. Infection of the upper genital tract can occur after

the procedure ranging from 1 to 11 % of cases.10,11 The operator must pay

attention to the sterile technique to reduce the chance of contamination.

The antibiotic is reserved for high risk cases; previous pelvic inflammatory

disease, broken aseptic technique, dilated tubes, and traumatic procedure.

Contrast medium allergy may be occasionally encountered. Patient with

history of iodine or sea food allergy should be excluded from the procedure.

The vascular or lymphatic intravasation of the contrast medium can occur

frequently in cases of tubal disease or obstruction, recent uterine surgery,

synechiae, uterine anomalies, misplacement of the cannula tip and excessive

injection pressure. Oily media can cause embolization and be responsible for

a small number of deaths from HSG, whereas water soluble medium can be

dissipated more quickly.

Radiation exposure is an unavoidable risk to patients. The amount of

radiation exposure depends on the equipment and exposure factors used,

duration of fluoroscopy, number of films, and size of the patient. A serious

concern is gonadal exposure. The ovarian dosage in most cases are less than

0.6 rad 6, ranging from 0.075-0.55 rad. For the 67 KVP, 1.9 mA and tube

target-to-entrance skin distance of 18 inches fluoroscope, the permissible

rad time limit will be approximately 35 minutes provided that the radiation

exposure to the ovary is limited to 10 rad.12 The ovarian dose and entrance

surface dose of HSG can be reduced more with a C-arm, digital fluoroscopic

system equipped with an image capture system to obtain hard copy film stored

digital images without need for further patient exposure.13

Predictive value of hysterosalpingography

Value of HSG depends on the experience of the operator or interpretator.

False positive rates of HSG are reported as 20% to 57%.14-16 Most reports

used the findings from hysteroscope (HSC) for uterine status and the

findings from laparoscopy for tubal and pelvic peritoneal status as gold

standard. The uterine cavity receives higher false positive rates. Gaglione

et al. compared HSG to HSC in 70 infertile patients and found a sensitivity

of 79.1%, a specificity of 81.8%, 18.1% false positive rate, and 18.9% false

negative rate of HSG.17 HSG may miss some small lesions such as little

synechiae, sessile polyp or submucous myoma, and endometrial inflammation

which can be detected by HSC. HSG is superior to HSC, however, for a lesion

penetrating into myometrium, congenital and acquired partition of the

uterine cavity, and for evaluation of the uterine scar.8 Pellerito et al.

found that HSG was accurate in diagnosing only 20% of uterine anomalies.18

Although HSG can diagnose uterine synechiae, it needs further evaluation for

other cavity defects.16

Compared to laparoscopy regarding tubal patency and peritoneal assessment,

HSG is highly predictive for normal and frankly abnormal cases with a

sensitivity of 89% and a specificity of 98.8%.19 But for the suspicious

group (unilateral tubal occlusion, proximal tubal occlusion, and peritubal

loculation), HSG has a high false positive rate (36.9%) and a low positive

predictive value (63%). HSG can diagnose patency of both tubes clearly only

when the image shows media spillage of both tubes. In contrast, when there

is no filling of contrast medium in one or both tubes the diagnoses need

further confirmation with diagnostic laparoscopy. Glucagon administration

can reduce tubal spasm in some cases, but only with a demonstration of tubal

patency can a diagnosis be concluded.

lthough there is considerable variability in the interpretation of HSG, it

usually occurs in the cases of minor uterine defects and pelvic

adhesion.20,21 The missing lesions may be very small and suspicious for

their clinical significance.22 Therefore, normal HSG do not require any

further evaluation, except after a failed expectant period in infertile

cases (6-10 months).23 Laparoscopy and hysteroscopy should be placed as

complementary techniques for HSG with proper indications and interval in

order to offer the best advantage to the patient.

New methods have been recently introduced for upper genital tract

evaluation. HSG is modified to use radionuclide solution (RN-HSG) instead of

radio-opaque medium.24 The image can inform about the active transport

mechanism of the genital tract, but not the actual anatomy. Therefore, its

clinical application has not been approved yet. The

sonohysterosalpingography (SHSG) is a new method developed with the advanced

ultrasonography technology. The modern ultrasound with vaginal approach can

reveal clear images of the uterus and both ovaries without risk from

radiation. However, ultrasonography alone cannot provide adequate data of

the organs. The echo-enhancing or echo-contrast agents are instilled

intrauterinely to improve the intracavity image and to show tubal patency.

SHSG has a high sensitivity and specificity when compared to hysteroscopy

and laparoscopy.25-27 SHSG gives a results concordant result with HSG.26

Although SHSG can avoid radiation, it needs more experienced operator and

sophisticated machine. In addition, SHSG costs the patients a more than HSG,

particularly when the echo-enhancing agent is utilised.

Conclusion

HSG is still an essential part of an upper genital tract evaluation for

intrauterine abnormalities and tubal patency. The procedure can be performed

easily, less invasively and with less cost than other methods. With correct

techniques, the HSG can provide the clinician complete data regarding the

uterotubal anatomy. Furthermore, HSG has shown its valuable therapeutic

effect in cases with normal findings. To receive full advantages of HSG, the

operator must perform the procedure himself correctly and interpret the

image carefully.

References

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