The scan done after an abortion is usually a transvaginal ultrasound (TVS), a pelvic scan with a slim probe placed in the vagina, because it shows the lining of the womb and any retained tissue in far more detail than a probe on the belly. A transabdominal scan with a full bladder is used when a vaginal probe is not acceptable or the pregnancy was beyond the first trimester. Neither is routine: WHO and NICE say a urine pregnancy test or a falling blood hCG can confirm the abortion is complete.
Which ultrasound is done after an abortion?
A transvaginal ultrasound is the scan doctors choose after an abortion in the first trimester. The NHS describes it as an internal ultrasound, where a tube-shaped probe is put inside the vagina, and also calls it a pelvic or transvaginal ultrasound. Cleveland Clinic says providers use transvaginal ultrasound in early pregnancy to confirm the location of the pregnancy, estimate gestational age, measure the heartbeat and identify early complications, and lists signs of ectopic pregnancy or miscarriage among the findings it can show. The same questions arise after an abortion, so the same scan is used.
The research literature confirms the choice. A 2021 scoping review in Acta Obstetricia et Gynecologica Scandinavica of 248 studies on retained products of conception after induced abortion or early pregnancy loss found ultrasound was the assessment tool in 73.4% of observational studies, and the single most used criterion was transvaginal measurement of the endometrial thickness.
A transabdominal scan, with the probe moved over gel on the lower belly, is the alternative. MedlinePlus says the probe goes into the vagina instead in some cases and that this is more likely in early pregnancy; the abdominal route is the default later, when the womb has risen out of the pelvis. In India both are done at the same diagnostic centre on the same machine, and prices are on the ultrasound cost page. The radiologist or gynaecologist decides on the day, and a woman can ask for the abdominal route if she prefers it.
What is the difference between a transvaginal and an abdominal scan?
The difference is where the probe sits and how close it gets to the womb. A transvaginal probe lies a few centimetres from the cervix, so it sees the lining and any tissue in the cavity clearly; an abdominal probe looks through the belly wall and a full bladder, which pushes the bowel away and gives a window to the pelvis.
| Transvaginal (TVS, internal) | Transabdominal (external) | |
|---|---|---|
| Probe | Slim probe in the vagina, covered with a condom and gel (MedlinePlus) | Handheld probe moved over gel on the lower belly (MedlinePlus) |
| Bladder | Empty or partly filled (MedlinePlus) | Full: about 2 to 3 glasses of liquid an hour before, no urinating (MedlinePlus) |
| Time | About 15 to 30 minutes (Cleveland Clinic) | Within the NHS range of 10 to 45 minutes for any ultrasound |
| Comfort | May be uncomfortable but should not be painful (Cleveland Clinic) | Pressure from a full bladder can be uncomfortable (MedlinePlus) |
| Best for | Early pregnancy, lining thickness, small sacs, ectopic clues | Later gestation, women who decline an internal probe |
| Radiation | None (NHS) | None (NHS) |
The NHS says the sound waves used in ultrasound are safe and that scans do not use any radiation, unlike X-rays or CT. MedlinePlus states there are no known harmful effects of transvaginal ultrasound on humans. Both can be repeated as often as needed.
How do I prepare for a post-abortion ultrasound?
Preparation depends on which scan is booked, so ask the centre when you book. For a transvaginal scan MedlinePlus says the test is done with the bladder empty or partly filled, and you undress from the waist down and lie on your back with your knees bent. For an abdominal scan MedlinePlus advises drinking about 2 to 3 glasses of liquid an hour before and not urinating, because a full bladder gives a clearer image. Cleveland Clinic adds that having a full or empty bladder affects the way your organs appear, so follow the instruction you are given.
- Carry the prescription or discharge summary, any earlier scan, and the dates of the mifepristone tablet and of the first bleeding; the report is read against this timeline.
- Remove a tampon if you are using one (Cleveland Clinic). Wear clothing you can take off easily.
- Expect bleeding during the scan to be normal; the NHS says vaginal bleeding can last several weeks after a medical or surgical abortion.
- The NHS says you are in control during an internal scan and can ask the sonographer to stop at any time. If the cervix is tender, say so.
What does 'retained products of conception' mean on the report?
It means the sonographer saw material in the cavity of the womb, or a lining thicker than a chosen cut-off, and suspects that pregnancy tissue is still inside. The term is less precise than it sounds. The 2021 scoping review found no standard definition: across 169 observational studies seven tools were used in 28 combinations with 89 different cut-off values. The most common rule was a transvaginal endometrial thickness of 15 mm or more about 2 weeks after treatment, reported in 58.1% of studies that measured thickness. Other criteria were the presence of a gestational sac, 'intrauterine remains' and a so-called empty uterus. Only three studies tested the 15 mm rule against a reference standard; in those its specificity was 94% or more and its sensitivity 75% to 100%.
Thickness measured early is a weak guide. A 2009 study in Ultrasound in Obstetrics and Gynecology pooled 2,208 women scanned about 7 days after misoprostol. Those who later needed a dilatation and curettage had a mean thickness of 14.5 mm against 10.9 mm in those who did not, but the area under the ROC curve was 0.65 and no threshold had a positive predictive value above 25%. Only 30 women (1.6%) needed surgery.
So a report that says 'retained products, endometrium 16 mm' is a prompt for a conversation with a gynaecologist, not a verdict. A persisting sac, heavy bleeding or fever carry more weight than the millimetres.
What are the alternatives to an ultrasound after an abortion?
Pregnancy hormone tests are the main alternative, and after an uncomplicated early medical abortion they are the recommended check. The WHO summary chart for its 2022 guideline says routine follow-up is not necessary after an uncomplicated medical abortion. NICE recommendation 1.14.2 says women should be given a low-sensitivity or multi-level urine pregnancy test to exclude an ongoing pregnancy.
The tests work because hCG falls once the pregnancy ends. MedlinePlus says hCG appears in blood and urine as early as 10 days after conception and rises rapidly through the first trimester. A 2025 trial protocol in Trials explains that an ordinary chemist's test is high-sensitivity and turns positive at the lowest hCG level, while the low-sensitivity test turns positive only at a high level, is usually done 3 weeks after an early medical abortion, and is negative if the abortion succeeded. The protocol also describes the Canadian and New Zealand blood-test route: a serum hCG on the day of the mifepristone and again 7 days later, checking that the level has dropped as expected.
| Method | When | Result that confirms completion | Needs |
|---|---|---|---|
| Low-sensitivity urine test | About 3 weeks after the pills | Negative | Kit from the provider |
| Serum quantitative hCG | Day 0 and day 7 | Clear fall | Two lab visits |
| Transvaginal ultrasound | When symptoms or a positive test raise doubt | No sac, no significant material | Scan centre and a doctor to read it |
Which scan is right for which situation?
The situation decides the scan, and sometimes a blood test comes first. NICE says that when an abortion was done before a scan showed a yolk sac inside the womb, follow-up may be needed to ensure the pregnancy has ended and to monitor for ectopic pregnancy; a transvaginal scan plus a serum hCG is the pair that answers this. - Bleeding has not started, or a home test is still strongly positive weeks later: transvaginal scan to look for a persisting sac.
- Heavy or prolonged bleeding: transvaginal scan for retained tissue; the NHS says part of the pregnancy remaining may need an operation to remove it.
- Fever, foul discharge, pelvic pain: transvaginal scan plus examination for infection; the NHS warns an untreated womb infection can lead to pelvic inflammatory disease.
- Abortion after 12 to 14 weeks, or a woman who declines an internal probe: transabdominal scan with a full bladder.
- Pain on one side or in the shoulder tip, feeling faint: emergency scan and hCG for ectopic pregnancy.
Go to a hospital emergency department the same day, or call 112, if you are soaking a pad soon after putting it on, have a fever, severe or one-sided pain, shoulder-tip pain, or feel faint or dizzy. These are the NHS warning signs for urgent care in early pregnancy and after an abortion.
This guide is general information from the sources listed below, not medical advice; a registered doctor makes decisions with you.
