The Saline Sonogram, also called Saline Infusion Sonohysterography (SIS) or Sonohysterography (SHG), is a standard diagnostic tool used during a fertility evaluation. This specialized ultrasound procedure provides a detailed view of the uterine cavity, which is crucial when investigating potential causes of difficulty conceiving. While primarily diagnostic, clinical observation suggests a temporary increase in spontaneous conception rates in the months following the procedure. This unexpected effect raises the question of whether the sonogram functions as a treatment rather than just a screening test.
Understanding the Saline Sonogram Procedure
The Saline Sonogram is an outpatient procedure designed to enhance the clarity of a standard transvaginal ultrasound examination of the uterus. It involves inserting a thin catheter through the cervix into the uterine cavity. A sterile saline solution is then gently injected through the catheter, acting as a negative contrast agent.
The saline solution distends the uterine walls, separating the endometrial lining and allowing for clearer visualization of the cavity’s contours. This technique permits assessment of the uterine shape and the identification of subtle structural abnormalities not visible on a regular ultrasound. The procedure detects intrauterine lesions such as endometrial polyps, submucosal fibroids, or scar tissue, which can interfere with embryo implantation. By outlining these potential physical barriers, the Saline Sonogram informs the patient’s fertility treatment plan.
Clinical Observations on Post-Procedure Conception
Despite being performed for diagnostic purposes, clinical data suggests the Saline Sonogram is associated with a short-term, elevated chance of natural conception. This phenomenon has been observed across various fertility centers, with studies noting spontaneous pregnancies occurring in the three to six months immediately following the procedure. This increase occurs even in patients whose sonogram did not reveal major structural issues requiring intervention.
The temporary rise in spontaneous pregnancy following SIS is often compared to the established effect seen after a Hysterosalpingography (HSG), which uses contrast dye and X-rays to check for open fallopian tubes. While the evidence for SIS is less robust than for HSG, some data suggests comparable or superior post-procedure pregnancy rates, especially when higher pressure saline is used. For instance, one study of women with unexplained infertility found the pregnancy rate following a specialized high-pressure SIS technique was statistically higher than in a control group who underwent HSG.
The increased conception rate is also attributed to subsequent treatment prompted by SIS findings. A study evaluating women with unexplained infertility who had polyps found on SIS and subsequently removed showed a four-fold increase in the odds of conception compared to those who did not undergo removal. The overall clinical benefit is a combination of the procedure’s direct effect and its ability to guide the removal of subtle uterine pathology.
Proposed Mechanisms for Enhanced Conception
The leading theory for the unexpected fertility increase following a Saline Sonogram centers on the mechanical action of the fluid itself, often termed the “flushing” or “washout” hypothesis. As the sterile saline solution is pushed through the uterine cavity and into the fallopian tubes, it clears out minor, non-pathological debris. This debris includes microscopic particulate matter, cellular fragments, or thick mucus plugs that impede the passage of sperm or the egg.
The mechanical force of the fluid effectively “cleanses” the reproductive tract, creating an optimized environment for fertilization and early embryo transport. The transient distension of the uterine cavity and minor manipulation of the reproductive tract also enhance endometrial receptivity. This minor mechanical stimulation triggers a localized biological response that makes the uterine lining more welcoming to an implanting embryo in subsequent menstrual cycles.
When the saline successfully passes through the fallopian tubes, the process indirectly confirms tubal patency, a prerequisite for natural conception. The cumulative effect of clearing minor obstructions and improving the uterine environment contributes to the observed, temporary elevation in the chances of achieving a spontaneous pregnancy.