Fertility Scans · Cycle Monitoring

Follicle Tracking Scan in London

A short series of pelvic ultrasounds across one cycle that follows your follicles and womb lining in real time — so ovulation timing stops being a guess and becomes a measurement.

  • 30-minute appointments — unhurried, where most clinics allow 20
  • Typically 2 to 4 scans across a single cycle
  • Findings at the scan; written report usually within two hours
  • No GP referral required — self-refer today
  • Reports written for your fertility clinic to act on the same day
£159per scan · report and images included, no hidden fees
Book Your Follicle Tracking Scan
Call 0203 051 6506

CQC-registered clinic · Provider ID 1-2775844974 · HCPC-registered sonographers

30Minutes · Per Appointment
£159Per Scan · Report Included
4.9 ★476 Google Reviews
0Radiation · Completely Safe
The Basics

What is a follicle tracking scan?

Follicle tracking is not one scan but a short series — usually two to four across a single cycle. Each is a standard pelvic ultrasound, and together they follow one thing: the growth of the follicles in your ovaries and the thickening of the lining of your womb.

Follicles are small fluid-filled sacs, each holding an immature egg. Every cycle a group begins growing, one normally takes the lead, and at around 18 to 25 mm it releases its egg. Because follicles are easy to see and simple to measure, ultrasound can show exactly where in that sequence you are — and, on a follow-up scan, confirm that release has actually happened.

That is the difference between tracking and predicting. An app estimates from an average; a tracked cycle measures yours.

Indications

Why might I need follicle tracking?

The fertile window is short — roughly the five days before ovulation plus the day itself — and ovulation sits about 14 days before your next period, not 14 days after the last one. In a 35-day cycle that puts it around day 21, a week later than the day-14 rule most apps assume.

If your cycles are irregular, prediction gets worse still, because there is no fixed pattern to project forward. Tracking answers it directly: whether a follicle is developing, how fast, when it releases, and whether the lining is thickening to match.

Transvaginal ultrasound being performed to track follicle development at IUS London

Common reasons to track

  • Trying to conceive and wanting the fertile window measured, not estimated
  • Irregular or unpredictable cycles
  • Ovulation predictor kits giving unclear or repeated negative results
  • Known or suspected PCOS
  • Timed intercourse or IUI cycles
  • A medicated cycle your fertility clinic is directing
What we measure at each visit

  • Every visible follicle in both ovaries, in millimetres
  • Which follicle is dominant, and its growth rate between scans
  • Endometrial thickness and pattern
  • Confirmation of release once it has occurred
  • Ovarian appearance, including a polycystic pattern
  • Any cyst or finding that needs explaining
When tracking is not the first step

If your periods have stopped altogether, if you are bleeding between periods, or if you have severe pelvic pain, see your GP first — those need assessment in their own right before a tracking series is worth booking. Fertility assessment also belongs with both partners: sperm factors contribute in roughly a third of couples, and semen analysis is arranged through your GP or fertility clinic. We do not offer it.

Suitability

Is follicle tracking suitable for me?

A tracked cycle is a good fit if any of these sound like you:

  • ✓You have been trying to conceive and want the timing confirmed rather than estimated
  • ✓Your cycles vary enough that apps and kits disagree with each other
  • ✓You want to know whether you are ovulating at all, not just when
  • ✓Your fertility clinic has asked for monitoring scans
  • ✓You are on a medicated cycle and need follicle sizes reported the same day
  • ✓You would rather start with the least invasive assessment available

And when it is not the right booking

You want to know your egg quality — no scan or blood test measures it. Tracking shows maturity and timing, not quality.

You need to know if your tubes are open — that requires a specific tubal test through a fertility clinic. Ultrasound cannot answer it.

The open question is sperm — semen analysis goes through your GP or fertility clinic. We will tell you that before you book, not after.

Book your first tracking scan — £159Not sure? Call 0203 051 6506

If follicle tracking is not the right test for you, we will say so before you book — not after.

Your Cycle

What a tracked cycle looks like

  1. 1
    Tell us your cycle length when you bookTracking usually starts around day 8 to 10, but that shifts with cycle length. If a fertility clinic has set your dates, we follow theirs.
  2. 2
    Scan one — the baselineBoth ovaries measured, the developing follicles identified, and the lining recorded. This is the reference every later scan is read against.
  3. 3
    Scan two — growth rateUsually two to three days later. A dominant follicle typically grows 1 to 2 mm a day; the rate matters as much as the size.
  4. 4
    Scan three — approaching releaseAs the lead follicle nears 18 to 25 mm, scans may move to daily. Your clinic uses these measurements to time a trigger injection if you are having one.
  5. 5
    ConfirmationA follow-up scan after release shows the follicle has collapsed and the corpus luteum has formed — direct evidence that ovulation happened, not an assumption that it did.
  6. 6
    Reports the same dayEach appointment is explained on screen as we scan, with the written report usually with you within two hours — ready to forward to your fertility clinic.
A single measurement is a snapshot. What makes tracking useful is the growth between two scans — which is why a series answers questions a one-off pelvic scan never can.

A transvaginal scan gives the clearest view of the ovaries and is the standard approach; a transabdominal scan is available if you prefer. A female chaperone is present during intimate scans, and you may stop the examination at any point.

Clinical Education

Understanding the cycle we are tracking

Three stages, each visible on ultrasound — which is what makes timing measurable rather than estimated.

Recruitment and selection

Each cycle a group of small antral follicles begins to grow. By around day 5 to 7 one becomes dominant and outpaces the rest — the point at which tracking starts to become informative.

The growth phase

The dominant follicle adds roughly 1 to 2 mm a day, reaching maturity between 18 and 25 mm. Oestrogen rises alongside it, and the womb lining thickens in step.

Release and after

The LH surge triggers release, usually within about 24 to 36 hours of starting. The emptied follicle becomes the corpus luteum, which supports the lining until the next period or an early pregnancy.

Your Results

What tracking tends to show

A follicle developing and releasing on scheduleThe lining thickening in step, and a follow-up scan confirming release. Your fertile window identified for this cycle — and a pattern you can plan around in future ones.

Slower growth, or no dominant follicle yetCommon, and frequently just a longer cycle than expected rather than a problem. Usually answered by continuing the series a few more days rather than concluding anything from one scan.

No ovulation across the cycle, or a finding needing follow-upAn anovulatory cycle, a polycystic pattern, or a cyst that needs assessing. One such cycle is common and often means little; a repeating pattern is worth taking to your GP or fertility clinic, and the report is written for them.

Follicle size indicates maturity, not egg quality. A 22 mm follicle is not “better” than a 19 mm one, only further along — and no scan or blood test measures quality directly. Our guide to follicle size by cycle day sets out the normal ranges in full.

Stop guessing your fertile window

Two to four short scans across one cycle, each explained on screen as we scan, with reports your fertility clinic can act on the same day.

Book Your Tracking Scan — £159Call 0203 051 6506
From Our Practice

How we run a tracked cycle

Scanned by the person reporting it

The sonographer who scans you writes your report. Nothing is passed to a remote reader who never met you.

Timed around your cycle, not our diary

Tracking only works if the scans land on the right days. We build the series around your cycle length and your clinic’s dates.

Reports your clinic can use

Every follicle measured in millimetres with endometrial thickness, in the format a fertility unit expects — usually with you within two hours.

Honest about the limits

Tracking answers whether and when you ovulate. It says nothing about egg quality, tubes or sperm, and we will tell you so plainly.

FAQs

Follicle tracking — your questions answered

How many scans will I need?
Usually two to four across one cycle. It depends on your cycle length and how quickly the dominant follicle grows — if it is close to maturity we may scan daily for a short stretch, and if the cycle is running long we may space them out.
When in my cycle does tracking start?
Typically around day 8 to 10, counting day one as the first day of full flow. Longer cycles start later, because ovulation sits about 14 days before your next period rather than a fixed number of days after the last one.
Is it a transvaginal scan?
Usually, yes — it gives much the clearest view of the ovaries and follicle measurements need to be accurate. A transabdominal scan is available if you prefer. A female chaperone is present during intimate scans, and you can stop at any point.
Can I have tracking if I have irregular cycles?
Yes, and it is one of the situations where it helps most. Prediction tools rely on a pattern; if you do not have one, measuring directly is the only way to know what your ovaries are actually doing.
Does it work with PCOS?
It can, though a polycystic ovary often shows many small follicles with no clear dominant one, and cycles may be anovulatory. Tracking will show that honestly — which is itself useful information for your GP or fertility clinic.
Can you confirm I actually ovulated?
Yes. A scan after the expected release shows the follicle has collapsed and the corpus luteum has formed. That is direct evidence, rather than inference from a temperature chart or a kit.
Will this tell me about my egg quality?
No. Follicle size shows maturity and timing only. Egg quality is not measured by any scan or blood test, and anyone suggesting otherwise is overselling.
Do I need a referral from a fertility clinic?
No — you can book directly. If a clinic is directing your cycle we will follow their dates and write reports in the format they need.
What if my clinic wants specific measurements?
Tell us when you book. We routinely report every follicle in both ovaries in millimetres plus endometrial thickness and pattern, which covers what fertility units typically ask for.
How much does it cost?
£159 per scan, with report and images included. Most cycles need two to four scans, and we will be straight with you about how many yours is likely to need rather than booking them open-endedly.
Related Services

Other fertility scans we offer

Ovarian ReserveAntral Follicle Count (AFC) Scan

A single early-cycle count of the resting follicles in both ovaries.

See the scan →
PelvicPelvic Ultrasound Scan

Womb, lining and ovaries assessed in full — the structural baseline.

See the scan →
FertilityAll Fertility Scans

The full range of fertility ultrasound we offer.

See scans →

Further reading: follicle size by cycle day and the basics of follicular tracking.

Location

Where can you get follicle tracking in London?

Our clinic is at 5a Lucerne Mews, Kensington, London W8 4ED — a quiet mews three minutes on foot from Notting Hill Gate, serving Kensington, Notting Hill, Holland Park, Bayswater and central London.

Because tracking depends on landing scans on the right days, we hold short-notice slots for cycles already in progress. Call 0203 051 6506 and tell us which day of your cycle you are on.

Getting here

By tube: Notting Hill Gate — three minutes’ walk.

By bus: Routes along Notting Hill Gate and Kensington Church Street stop nearby.

By car: On-street parking nearby — full options in directions & parking.

Book Your Scan

Timing measured, not estimated

Every follicle in both ovaries measured in millimetres with your womb lining, across the days that actually matter — explained on screen as we scan, with reports your fertility clinic can act on the same day.

Book Online0203 051 6506
£159
Per tracking scan · 30 minutes

Book Now

5a Lucerne Mews
Kensington, London W8 4ED
3 mins from Notting Hill Gate
CQC Registered
HCPC Sonographers
No GP Referral Needed
Report Within 2 Hours
No Radiation

Written and clinically reviewed by the HCPC-registered sonographers who perform this scan at IUS London — a CQC-registered diagnostic ultrasound clinic (Provider ID 1-2775844974). Your own findings are explained to you at the scan and set out in your report.

Author: Yianni Kiromitis, Senior Sonographer, HCPC RA38415 — over 20 years’ experience in NHS and private ultrasound · Reviewed 10 August 2026