01OverviewDefinition, clinical context and the essential points that orientate the chapter.
Miscarriage is pregnancy loss before viability, but the immediate clinical task is more precise: assess stability, confirm location, then determine viability and whether tissue remains. Vaginal bleeding and cramping are common in viable pregnancy and cannot diagnose loss. Ask about dates, prior scans, amount and progression of bleeding, pain, passed tissue, fever, discharge, dizziness, pregnancy history and ectopic risks. Check observations and abdominal findings before speculum or bimanual examination in a stable consenting patient.
Threatened miscarriage describes bleeding in a viable intrauterine pregnancy. Ultrasound shows an appropriately located pregnancy with heartbeat when expected; the cervix is generally closed and no tissue has passed. A subchorionic haematoma may be seen but does not determine outcome alone. For no previous miscarriage, NICE advises return if bleeding worsens or persists beyond 14 days and routine antenatal care if it stops. Bed rest does not prevent miscarriage and can increase guilt when loss occurs.
NICE offers micronised vaginal progesterone 400 mg twice daily when ultrasound confirms an intrauterine pregnancy, current vaginal bleeding is present and there has been at least one previous miscarriage. Treatment may start before heartbeat is seen once intrauterine location is confirmed; if fetal heartbeat is subsequently confirmed, continue until 16 completed weeks. Do not prescribe for bleeding without prior miscarriage, prior miscarriage without current bleeding, or a PUL where ectopic pregnancy remains possible.
Missed miscarriage is nonviable intrauterine pregnancy retained in the uterus, sometimes discovered at a routine scan after pregnancy symptoms diminish. Diagnosis must meet safe ultrasound rules: with no heartbeat and CRL below 7 mm, or no embryo and mean sac diameter below 25 mm, repeat transvaginal scanning after at least seven days. At or above those thresholds, seek a second opinion and/or repeat after at least seven days before treatment. Transabdominal uncertainty requires at least 14 days.
Incomplete miscarriage follows partial passage of pregnancy tissue. Bleeding and colicky pain continue; the cervical os may be open and ultrasound can show heterogeneous intrauterine material. Endometrial thickness alone has poor specificity and should not override symptoms and the known pregnancy course. Exclude ectopic and gestational trophoblastic disease where location was not previously documented or hCG and bleeding do not resolve.
Complete miscarriage follows passage of all intrauterine tissue, with decreasing pain and bleeding, a closing cervix and an empty uterus. This label is safe when a previous scan confirmed the pregnancy inside the uterus. If no such scan exists, an empty uterus after bleeding is a pregnancy of unknown location because a tubal pregnancy may still be present. Follow hCG or urine testing to resolution rather than closing care from history of passed tissue.
Speculum examination can identify active cervical bleeding, visible tissue and alternative cervical or vaginal causes. If tissue is removed, follow local histology pathways, especially when diagnosis is uncertain or molar change is possible. Bimanual examination assesses cervical excitation, uterine size and adnexal tenderness but does not establish location. Use intimate-examination consent, a chaperone and trauma-informed pacing.
Blood tests are targeted. FBC evaluates anaemia or infection; group and RhD informs transfusion and updated anti-D care; hCG follows PUL rather than confirming miscarriage subtype. June 2026 NICE guidance says do not offer anti-D through 11+6 weeks for ectopic, miscarriage or threatened miscarriage. At 12+0 to 12+6 weeks, offer at least 250 IU to RhD-negative patients having medical or surgical management, and consider it for threatened miscarriage with heavy or recurrent bleeding.
Use language chosen by the patient: pregnancy, baby, tissue or remains. State clearly when a miscarriage is confirmed and equally clearly when it is not. Explain that most isolated first-trimester losses result from sporadic chromosomal problems and are not caused by ordinary activity, exercise, sex or stress. Provide written options, emergency advice, follow-up, information about pregnancy remains and time for questions.
Key points
- Threatened miscarriage means vaginal bleeding with a confirmed intrauterine pregnancy that remains viable; the cervix is usually closed and many pregnancies continue.
- Missed miscarriage means an intrauterine pregnancy has stopped developing but pregnancy tissue remains, often with little bleeding and a closed cervix.
- Incomplete miscarriage means some intrauterine pregnancy tissue has passed but tissue remains, usually with continuing bleeding, cramping and an open cervix.
- Complete miscarriage means all intrauterine pregnancy tissue has passed and the uterus is empty, but only call it complete when prior imaging documented intrauterine location or ectopic follow-up is complete.
- Transvaginal ultrasound is the diagnostic standard for location and viability; use CRL and mean sac diameter with minimum seven-day repeat scans when findings are uncertain.
- Do not use last menstrual period alone to decide a heartbeat should be visible, and explain that waiting for a repeat scan does not harm pregnancy outcome.
- For threatened miscarriage with scan-confirmed intrauterine pregnancy, bleeding and at least one previous miscarriage, offer micronised vaginal progesterone 400 mg twice daily; if heartbeat is confirmed continue to 16 weeks.
- From June 2026, do not offer anti-D for threatened miscarriage or miscarriage through 11+6 weeks; at 12+0 to 12+6 weeks apply the new bleeding and management-specific recommendations.
02AetiologyUnderlying causes, associations and risk factors, with why each one matters.
Sporadic chromosomal abnormality
Most isolated first-trimester miscarriages reflect random embryonic aneuploidy that prevents normal development and was not caused by routine activity or behaviour.
Maternal medical or anatomical factors
Thyroid disease, antiphospholipid syndrome, uterine anomalies and poorly controlled diabetes can increase loss risk, particularly when miscarriage recurs.
Unexplained loss
Even after appropriate assessment no specific cause may be identified, and absence of a cause does not make the loss imagined or prevent future success.
03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.
- 1Developmental arrest
Embryonic or placental development stops, hCG support falls and pregnancy structures cease growing before tissue is expelled.
- 2Decidual separation
Loss of hormonal and placental support allows gestational tissue to separate from the decidua, opening maternal vessels and causing bleeding.
- 3Cervical passage
Uterine contractions and cervical dilatation expel tissue; complete passage closes the process while retained tissue sustains bleeding and cramping.
- 4Retained-tissue inflammation
Persistent products can maintain hCG and bleeding and occasionally provide a focus for endometritis or systemic infection.
04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.
Vaginal bleeding occurs while ultrasound confirms an ongoing viable intrauterine pregnancy; pain may be present but tissue has not been expelled.
Ultrasound safely confirms absent development or cardiac activity while pregnancy tissue remains and symptoms may be minimal or have quietly regressed.
Partial tissue passage leaves continued bleeding and cramping, often with an open cervix and retained intrauterine material.
Pain and bleeding settle after all tissue passes and the cavity is empty, provided previous imaging proved intrauterine location or PUL follow-up resolves.
Fever, uterine tenderness, offensive discharge, tachycardia or systemic illness with retained tissue indicates infection requiring urgent treatment.
05InvestigationsWhat to request, why it matters and how to interpret it.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
Transvaginal ultrasoundFirst step - Why
- Confirm location, viability, retained tissue and adnexal or free-fluid findings.
- Interpretation and limitations
- Use CRL and mean sac diameter with minimum repeat intervals; an empty uterus without prior intrauterine proof remains PUL.
- 02
Speculum examination - Why
- Localise bleeding, assess cervical os and identify tissue, infection or cervical lesions in a stable patient.
- Interpretation and limitations
- Visible tissue supports miscarriage but does not by itself prove the original location; send tissue according to local histology criteria.
- 03
Full blood count - Why
- Assess anaemia and support infection evaluation when bleeding is heavy or prolonged.
- Interpretation and limitations
- Interpret with observations and trajectory; acute haemorrhage may precede a measurable haemoglobin fall and normal white count does not exclude infection.
- 04
Blood group and RhD - Why
- Prepare transfusion support and apply current gestation-specific anti-D recommendations.
- Interpretation and limitations
- Through 11+6 weeks do not offer anti-D; from 12+0 to 12+6 weeks management type and threatened-bleeding severity determine prophylaxis.
- 05
Serial hCG or timed urine test - Why
- Resolve pregnancy location or persistence when ultrasound history does not securely prove complete intrauterine loss.
- Interpretation and limitations
- Use the PUL pathway when location was never confirmed and a three-week urine test after expectant or medical miscarriage care to detect retained, molar or ectopic pregnancy.
06Differential diagnosisRealistic alternatives and the features that help distinguish them.
Ectopic pregnancy
Pain and bleeding overlap, and an empty uterus without prior intrauterine proof requires PUL follow-up until ectopic is excluded.
Viable early pregnancy
Bleeding can occur with normal ongoing development, while late ovulation may make expected structures too small for one scan.
Gestational trophoblastic disease
Persistent bleeding, unusually high or plateauing hCG and abnormal vesicular tissue require histology and specialist trophoblastic follow-up.
Cervical or vaginal bleeding
Ectropion, polyp, infection, trauma or malignancy can bleed during pregnancy and may be identified on consented speculum examination.
07ManagementImmediate care, first-line treatment, alternatives and escalation.
01First assessmentStabilise, locate and test viabilityFirst stepA patient presents with pain or bleeding in early pregnancy.+
- 1EscalationAssess haemodynamics, bleeding, pain, ectopic and infection features and escalate shock, peritonism, sepsis or uncontrolled bleeding immediately.
- 2Obtain pregnancy testing, expert transvaginal ultrasound and targeted bloods, adding consented speculum examination where it answers bleeding or tissue questions.
- 3Classify only when location and safe viability criteria support it; otherwise use PUL or uncertain-viability follow-up with exact repeat intervals.
02Threatened miscarriageSupport an ongoing intrauterine pregnancyUltrasound confirms intrauterine location and ongoing viability despite bleeding.+
- 1Explain that bleeding increases risk but many pregnancies continue and advise return if bleeding worsens, pain develops or bleeding persists beyond 14 days.
- 2If at least one previous miscarriage exists, offer vaginal micronised progesterone 400 mg twice daily and continue to 16 weeks once heartbeat is confirmed.
- 3Avoid bed-rest prescriptions and blame, continue routine antenatal care when bleeding stops and investigate persistent or recurrent concerning symptoms.
03Confirmed lossName the subtype and offer optionsRepeat-safe ultrasound and clinical findings confirm missed, incomplete or complete miscarriage.+
- 1Explain the diagnosis clearly, pause for the response and discuss what expectant, medical and surgical pathways involve, including bleeding, pain and completion testing.
- 2For apparent complete loss without prior intrauterine proof, retain the PUL pathway until ectopic pregnancy and persistent trophoblast are excluded.
- 3Provide written emergency advice, pregnancy-remains choices, anti-D assessment under the 2026 gestation rule and an optional follow-up appointment.
Key medicines and prescribing safety1 treatment · regimens, roles and cautions+
Micronised vaginal progesterone for threatened miscarriage
Insert 400 mg vaginally twice daily when scan confirms an intrauterine pregnancy, current bleeding is present and at least one previous miscarriage occurred; if fetal heartbeat is confirmed continue to 16 completed weeks.Do not use for PUL, bleeding without prior miscarriage or recurrent miscarriage without current bleeding; confirm location first and reassess worsening pain, bleeding or collapse urgently.
08ComplicationsImportant consequences, why they occur and why they matter clinically.
Haemorrhage and anaemia
Ongoing or rapid blood loss can cause symptomatic anaemia, circulatory shock, transfusion need and urgent uterine evacuation for definitive control.
Infection and sepsis
Retained pregnancy tissue can become infected, causing endometritis, pelvic infection, bacteraemia, coagulopathy, organ dysfunction and potentially life-threatening septic shock.
Retained pregnancy tissue
Incomplete passage causes persistent bleeding, pain and positive testing and may require medical or surgical completion.
Psychological morbidity
Grief, guilt, anxiety, depression, relationship strain and trauma can persist after physical recovery and recur in later pregnancies.
09Monitoring and follow-upTreatment response, safety checks and longer-term review.
- Track every uncertain scan to the minimum seven-day transvaginal or 14-day transabdominal repeat and prevent premature treatment from borderline measurements.
- Review threatened bleeding that worsens or persists beyond 14 days and any new pain, dizziness, fever, offensive discharge or heavier loss sooner.
- After expectant or medical miscarriage treatment, provide a urine pregnancy test at three weeks and review positive results for retained, molar or ectopic pregnancy.
- Follow haemoglobin and symptoms when loss was heavy, and assess persistent bleeding even with a negative test for infection or other pathology.
- Offer follow-up with a healthcare professional of the patient’s choice, including emotional recovery, recurrence questions, future pregnancy and contraception if wanted.
10Special situationsVariants, exceptions and circumstances that change the usual approach.
Threatened does not mean inevitable
The term describes bleeding with continuing viability; language should not imply that loss has begun or was caused by the patient.
Missed refers to retained tissue
It does not mean the patient failed to notice symptoms and should be explained without language that suggests personal omission.
Complete needs a known location
An empty uterus after bleeding closes an intrauterine story only when an earlier scan established that the pregnancy was inside it.
Progesterone has a narrow evidence group
Benefit applies to current bleeding plus a previous miscarriage after scan-confirmed intrauterine location, not every history of loss or every early bleed.
The 2026 anti-D rule changed practice
Surgical treatment no longer triggers prophylaxis before 12 weeks; learners must replace the historic under-12-week surgical exception.
11Common pitfallsFrequent interpretation and management errors.
- 01
Calling any early-pregnancy bleeding a threatened miscarriage before confirming intrauterine location and viability.
- 02
Diagnosing missed miscarriage from one borderline ultrasound or last menstrual period alone.
- 03
Calling an empty uterus complete miscarriage when no prior scan documented intrauterine pregnancy.
- 04
Offering progesterone for a PUL or for bleeding without any previous miscarriage.
- 05
Prescribing bed rest or implying exercise, sex or ordinary stress caused the loss.
- 06
Using the historic anti-D surgical rule instead of the June 2026 gestation-based recommendations.