2.1 Causes of Proximal Tubal Blockage

The causes of proximal tubal blockage include the following:

1. 
   

   1. Tubal spasm

   
   

   This is one of the commonest causes of proximal tubal blockage diagnosed particularly at the time of hysterosalpingogram, where considerable pain can lead to tubal spasm and a false diagnosis of tubal occlusion. These women should proceed to have laparoscopic inspection under a general anaesthetic and with the pain no longer a confounding factor, often these tubes are found to easily fill with dye.

   
   
2. 
   

   2. Mucous plug

   
   

   This is a common cause of proximal tubal blockage. The presence of a small amount of mucous or endometrial debris can lead to a temporary occlusion of the proximal fallopian tube. Injection of dye under laparoscopic guidance often relieves the problem. In these cases, if necessary, tubal cannulation is quite successful at dislodging the obstructing mucous plug.

   
   
3. 
   

   3. Preferential tubal flow

   
   

   This is often the case during hysterosalpingogram or even during laparoscopy when the dye will pass preferentially through one fallopian tube rather than the other. This can be excluded by gently blocking the proximal end of the patent tube using an atraumatic instrument followed by injection of the dye. The dye can then be seen to flow freely through the contralateral fallopian tube previously thought to be obstructed.

   
   
4. 
   

   4. True proximal tubal occlusion

   
   

   This may be as a result of a number of tubal and pelvic pathologies, such as endometriosis and pelvic inflammatory disease. Chronic inflammation and nodular thickening of the proximal tube is sometimes seen at laparoscopy and is known as salpingitis isthmica nodosa. This is a particular pathology that surgeons should look for, as its presence is a poor prognostic factor for attempted tubal surgery.

   
   
5. 
   

   5. Intrauterine pathology

   
   

   Proximal tubal obstruction may occasionally be caused by the presence of endometrial pathology such as intrauterine adhesions or an endometrial polyp, which overlies the tubal ostium. Hysterosalpingogram may give rise to suspicion by showing an irregular endometrial cavity as is often the case in Asherman’s syndrome, or the presence of a filling defect as in the presence of a polyp. Performing combined hysteroscopic and laparoscopic examination will diagnose and often allow treatment of the cause.

2.2 Diagnosis of Proximal Tubal Disease

1. 
   

   1- Hysterosalpingogram

   
   

   This is the usual initial screening test performed in the absence of high risk factors for tubal disease as recommended by the NICE guidelines [6]. Hysterosalpingogram correlates with laparoscopic findings in about 75% of cases, with a false positive rate of 6–25% and a false negative of 8–24% [7]. Although a good test for excluding proximal tubal disease, failure of the dye to pass into the fallopian tubes is often a result of a false positive test due to, as indicated above, a mucous plug, tubal spasm or preferential flow. The presence of proximal tubal blockage on hysterosalpingogram is an indication for further assessment of the tube using laparoscopy.

   
   
2. 
   

   2- Laparoscopy and chromotubation

   
   

   Diagnostic laparoscopy will allow a detailed examination of the fallopian tube. False positive diagnoses, as a result of preferential flow, mucous plug or tubal spasm are easily excluded during laparoscopic assessment. Combined laparoscopic and hysteroscopic assessment will also allow exclusion of intrauterine factors which may be obstructing the tubal ostium. If true proximal tubal obstruction is diagnosed then laparoscopic assessment of the remainder of the tube as well as assessment of other relevant pelvic pathologies is essential to determine the feasibility of surgical correction. The presence of bipolar tubal disease (proximal and distal blockage), the presence of salpingitis isthmica nodosa or significant pelvic pathology such as grade IV endometriosis would be a contraindication for proximal tubal cannulation and may be an indication to proceed with IVF treatment.

   
   
3. 
   

   3- Hysterosalpingocontrastsonography

   
   

   Although a recent meta-analysis showed that hysterosalpingocontrastsonography (HyCoSy) was comparable to hysterosalpingogram for diagnosis of proximal tubal disease, the study noted that there was no differentiation between proximal versus distal tubal disease in individual reports [7]. It remains, however, that in well-trained hands, hysterosalpingosonography can be a useful diagnostic tool for diagnosing proximal tubal disease with a potential advantage of avoiding exposure to radiation.

   
   
4. 
   

   4- Fluoroscopic guided salpingography

   
   

   Proximal tubal cannulation can also be performed under fluoroscopic control and several studies have reported encouraging results [7,4]. In addition, fluoroscopic balloon tuboplasty can be performed [8]. However, hysteroscopic tubal cannulation does offer several advantages over performing the procedure under only fluoroscopic control as a full evaluation of the endometrial cavity can be performed. This allows the option to deal with any adhesions or endometrial polyps. Furthermore, performing the procedure only under fluoroscopic control does lead to the potential of missing significant pathologies such as bipolar tubal disease, which would be achieved using a combined hysteroscopic and laparoscopic approach.

2.3 Treatment of Proximal Tubal Obstruction by Hysteroscopic Tubal Cannulation

A 5 mm saline hysteroscopy is performed allowing inspection of the uterine cavity. This also allows exclusion of any intrauterine adhesions or endometrial polyps. A dedicated tubal catheter is then passed through the hysteroscope into the tubal ostium. In our Unit the Cook Novy^® catheter is used. This has an outer sheath that curves towards the cornu and hence facilitates placement of the inner catheter and guide wire that are used to cannulate the tube. The procedure should be performed under laparoscopic guidance to avoid undue trauma and perforation of the fallopian tube (occurring in rare cases). The catheter should only be introduced a few millimetres through the tubal ostium. This usually results in the treatment of the blockage. Dye can then be injected (selective salpingography) and free flow of the dye can be observed laparoscopically. The process of hysteroscopic tubal cannulation is a simple procedure with a short learning curve, requires only basic diagnostic hysteroscopic skills and when successful can be highly rewarding to both the patient and the surgeon.

2.4 Microsurgical Tubal Anastomosis/Cornual Reimplantation

In the presence of significant proximal tubal blockage where tubal cannulation has either been unsuccessful or is deemed to have a low success rate such as in women with salpingitis isthmica nodosa or fibrosis and obstruction affecting a long segment, then microsurgical reanastomosis is a valid option. The surgeon first excises the occluded portion of fallopian tube, taking extreme care not to extend the dissection into the broad ligament where troublesome bleeding may occur. After identification of the patent proximal and distal portions of the fallopian tube, 7/0 or 8/0 of a monofilament delayed absorbable sutures can be used to reinsert the tube into the uterine cornua or reanstomose the two ends of the tube. This is best achieved using the operative microscope for correct placement of the sutures. The fallopian tube is approximated in two layers, seromuscular and serosal while avoiding the tubal lumen. A tubal stent of Prolene 0 or 1 suture can be used at the time to facilitate correct approximation of the tubal lumen. The procedure should, of course, be carried out using microsurgical principles to minimise trauma and ensure a moist, relatively blood-free operating field with minimal tissue handling and the use of anti-adhesion agents at the end of the procedure. With adequate training and careful patient selection, intrauterine pregnancy rate following tubal anastomosis can be extremely encouraging reaching between 38 and 68% [12].

2.5 Distal Tubal Disease

Distal tubal disease is one of the most significant tubal disorders faced by the reproductive medicine specialist as it can have a serious impact on the results of the fertility treatment, in particular, assisted conception treatment. Distal tubal disease can vary from partial to complete occlusion of the distal end of the fallopian tube. This may be associated with a wide spectrum of damage to the remainder of the fallopian tube and can be combined with proximal tubal disease (bipolar disease).

Distal tubal disease is commonly caused by pelvic inflammatory disease as a result of chlamydial infection. Women with at least one previous attack of chlamydia have a 30% increased risk of pelvic inflammatory disease, ectopic pregnancy and tubal factor infertility over their lifetime [13]. Other causes of distal tubal disease include pelvic adhesions as a result of previous pelvic surgery, endometriosis and inflamed pelvic organs such as appendicitis. Distal tubal disease can result in complete occlusion and distension of the fallopian tube with fluid leading to a hydrosalpinx.

2.6 Effect of Hydrosalpinges on the Results of Assisted Conception

The negative effect of hydrosalpinges and the significant improvement in pregnancy rates after treatment has been clearly demonstrated in many studies including a Cochrane meta-analysis which has shown that treatment of a hydrosalpinx by salpingectomy, salpingostomy or occlusion can result in almost doubling the chance of conceiving [14].

Hydrosalpinges can impair pregnancy chances by several mechanisms including embryo toxicity, decreasing endometrial receptivity or mechanical flushing of the embryos from the uterine cavity [[15,16,17]. Hydrosalpingeal fluid has an effect on cytokines and integrins essential for successful implantation. Studies have shown that leukaemia inhibitory factor (LIF) expression is reduced in the mid-luteal endometrium of women with a hydrosalpinx and improved following salpingectomy or salpingostomy [18,19]. Furthermore, alteration of HOXA10 and HOXA11 expression has been associated with decreased implantation in women with a hydrosalpinx. HOX genes are essential for endometrial development and receptivity [20].

Another study demonstrated impaired endometrial and ovarian blood flow in women with hydrosalpinges, which may have an effect on endometrial receptivity and oocyte quality [21].

The effect is so significant that the suspicion of a hydrosalpinx during fertility investigations should almost always be investigated further to either confirm or refute the diagnosis. In this context it is important to remember that ultrasound is not an accurate method for diagnosing hydrosalpinges and furthermore hydrosalpinges can be intermittent and therefore may not always be seen on ultrasound scan. Therefore, if a hydrosalpinx is suspected then a laparoscopy should always be considered.

2.7 The Diagnosis of Distal Tubal Disease

Similar to proximal tubal disease, laparoscopy is the gold standard for diagnosis of distal tubal disease and is usually the first line of investigation in women with significant risk factors such as previous chlamydial infection [6]. This offers the opportunity to both diagnose and treat at the same time. It is imperative at laparoscopy that a full assessment of the degree of tubal damage is performed. The presence of a hydrosalpinx is significant regardless of whether it is partial or complete, unilateral or bilateral. The thickness of the wall, the presence of peri-tubal adhesions and intraluminal adhesions should be assessed and the presence of bipolar disease should be excluded. A proper assessment of the extent of tubal damage by an experienced surgeon is fundamental to planning future management and deciding whether to undertake surgical correction or proceed directly with IVF after removal of the hydrosalpinx.

A hydrosalpinx may also be seen when a hysterosalpingogram has been performed. This should usually be followed by a laparoscopy to evaluate further and decide the best approach for treatment (salpingectomy, salpingostomy or occlusion).

Some studies have advocated the use of chlamydial antibody testing as a screening method for tubal disease. However, evidence for the efficacy of this approach remains controversial; while some studies have shown a strong correlation between tubal factor and fertility and anti-chlamydial antibody testing [22], others have shown doubtful value [23]. Similarly centres that perform HyCoSy may identify possible hydrosalpinges but again the opportunity to fully assess the fallopian tube and its suitability for restorative surgery versus excisional treatment is lost except by performing a laparoscopy.