Subfertility is defined as not being able to conceive after one year of regular unprotected sexual intercourse.

As the leading tertiary healthcare provider for women, KK Women’s and Children’s Hospital (KKH) provides specialised care for a large number of couples presenting with subfertility.

For a female patient undergoing assessment for subfertility, part of the imaging workup includes assessment for fallopian tubal patency. This is traditionally performed via hystero-salpingography (HSG), an X-ray examination where an iodinated contrast is injected into the uterine cavity under fluoroscopic guidance.

Demonstration of free passage of contrast through both fallopian tubes is taken as an indication of tubal patency. Should the patient further undergo assisted reproduction treatment at KKH, additional evaluation via saline sono-hysterography is commonly performed to evaluate the uterine cavity, uterus and ovaries for any abnormalities.

This study is useful for the detection of intrauterine abnormalities in subfertile women. It has been shown to be highly sensitive and specific in the diagnosis of endometrial polyps, submucosal leiomyomas, uterine anomalies and intrauterine adhesions, which may affect fertility.


One-stop complete ultrasound assessment for subfertility

In early 2017, the Department of Diagnostic and Interventional Imaging at KKH introduced a new one-stop diagnostic procedure for patients undergoing assessment for subfertility.

Known as HyFoSy (hystero-salpingo foam contrast sonography), the combined procedure consists of a saline sonohysterography study, followed by a tubal foam contrast sonography study in one sitting. This allows for complete imaging assessment of the female pelvic organs by ultrasound alone.

At KKH, HyFoSy is performed by a multidisciplinary core team comprising of specialists, sonographers and nurses. During the study, the uterine cavity is evaluated for configuration and to identify any intracavitary abnormality, and the uterus is evaluated for any focal lesion.

Morphological assessment and antral follicle count are performed for both ovaries, as well as sonographic evaluation of the adnexal and the pouch of Douglas regions. Subsequently, the tubes are examined for patency, previously part of the HSG examination.

A relatively new type of material, ExEm Foam contrast, consists of a gel component of hydroxyethyl cellulose and glycerol, as well as purified water, and is the contrast used to assess the tubes. The components are combined just prior to usage, resulting in a foam-like liquid containing micro-air bubbles. This is injected through a catheter into the uterine cavity.

Where both fallopian tubes are patent, the foam contrast is seen to flow through the tubes as bright echoes on ultrasound (Figure 1). Figure 2 demonstrates a subfertile patient found to have a subseptate uterus and multiple small endometrial polyps.

A better patient experience

For the patient undergoing assessment for subfertility, the benefits of HyFoSy are several. The key advantage is the need for only one imaging examination with one cervical cannulation to obtain relevant clinical information, previously necessitating two separate studies.



This provides time and cost savings to the patient, as compared with separate HSG and saline sonohysterography studies, which need to be performed during a certain phase of the patient’s menstrual cycle at separate occasions.

During imaging studies for fertility assessment, patients commonly experience pelvic discomfort similar to menstrual cramps. With one rather than two cervical cannulation procedures in HyFoSy, pelvic discomfort associated with distension of the uterine cavity is minimised.

As at October 2017, more than 500 KKH patients have successfully undergone HyFoSy for fertility evaluation, with a proportion finding HyFoSy to be comparatively less uncomfortable than HSG examination.

A randomised controlled trial by VU University Medical Center and Spaarne Hospital in the Netherlands has also found that HyFoSy for tubal patency testing is less painful and less time-consuming for patients, compared with HSG1.

Lastly, the use of HyFoSy obviates the use of X-rays and spares the patient the small dose of ionising radiation associated with HSG. Nevertheless, patients should be educated that the radiation dose received during a HSG study is extremely small (approximately 0.1mSv). This is similar to the amount of radiation received by a passenger on a return flight between Singapore and Hong Kong.

The introduction of HyFoSy in the imaging workup of subfertile female patients enables KKH to offer a one-stop assessment of the female pelvic organs, with no associated radiation and minimal discomfort. We hope to continually provide the most modern and specialised services for our patients, and help more couples in their subfertility treatment journey at KKH in the best way possible.


​Refer a patient

Polyclinics and community healthcare practitioners can contact KKH at +65 6294 4050 to refer patients for consultation and assessment on their suitability to undergo tertiary evaluation for infertility.


Dr Teo Sze Yiun, Senior Consultant, Department of Diagnostic and Interventional Imaging, KK Women's and Children's Hospital

Head of the Breast Imaging Unit at the Department of Diagnostic and Interventional Imaging, KKH, Dr Teo Sze Yiun is also an adjunct assistant professor with Duke-NUS Graduate Medical School. Dr Teo’s subspecialty expertise lies in breast and women’s imaging and she is actively involved in clinical work, research and teaching in these areas.



  1. Dreyer K, Out R, Hompes PG, Mijatovic V. Hysterosalpingo-foam sonography, a less painful procedure for tubal patency testing during fertility workup compared with (serial) hysterosalpingography: a randomized controlled trial. Fertil Steril. 2014 Sep;102(3):821-5.
  2. Loh SF, Argawal R, Chan J et al. Academy of Medicine-Ministry of Health Clinical Practice Guidelines: assessment and management of infertility at primary healthcare level. SMJ 2014; 55(2): 58-66