Baseline Ultrasound

A baseline ultrasound is a transvaginal pelvic scan (TVS) performed on Day 2, 3, or 4 of the menstrual cycle, before starting IVF, IUI, or ovulation induction. It checks: antral follicle count (AFC — small follicles 2–10mm in both ovaries), absence of functional cysts (which could delay cycle start), uterine cavity (for fibroids, polyps, or fluid), and endometrial thickness (should be <5mm at baseline). It is the essential clinical starting point for any fertility treatment cycle.

AFC is the total number of small follicles (2–10mm) visible in both ovaries on the Day 2–4 baseline TVS. It is one of the two primary ovarian reserve markers (alongside AMH). AFC 10–20 = normal response expected. AFC <5 = poor ovarian reserve — expect lower egg numbers from IVF stimulation, higher dose gonadotropins needed. AFC >20 = high responder — OHSS risk if stimulated too aggressively. AFC directly determines the gonadotropin starting dose for IVF.

A functional cyst (>14–18mm) on the baseline scan usually represents a residual dominant follicle from the previous cycle. If present, the IVF cycle start is typically delayed 2–4 weeks until the cyst regresses spontaneously. Simple cysts >25mm may be aspirated under TVS guidance to allow the cycle to proceed. Endometriomas (chocolate cysts) require a separate management plan — usually not aspirated before IVF as recurrence is rapid and aspiration may reduce ovarian reserve.

Yes. TVS at baseline identifies: submucosal fibroids (protrude into the uterine cavity — associated with significantly lower IVF implantation rates; hysteroscopic resection recommended before IVF), intramural fibroids >4cm (debated but often managed before IVF), endometrial polyps (hyperechoic foci in the cavity — removed by hysteroscopy before IVF), and intrauterine fluid/adhesions. All of these, if identified and treated before IVF, improve implantation rates.

A hydrosalpinx is a fluid-filled, blocked fallopian tube. If visible on baseline TVS (or diagnosed on HSG), it significantly reduces IVF success rates by approximately 50% — the toxic fluid leaks into the uterine cavity, impairing endometrial receptivity and embryo implantation. Treatment before IVF: salpingectomy (surgical removal of the affected tube) or cornual occlusion (laparoscopic or hysteroscopic blocking of the tube at the uterine junction) is recommended before embryo transfer. Leaving an untreated hydrosalpinx before IVF is a significant preventable cause of IVF failure.