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OverviewAetiologyPathophysiologyClinical features and red flagsInvestigationsDifferential diagnosisManagementComplicationsMonitoring and follow-upSpecial situationsCommon pitfallsQuestionsSources
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Educational draft · awaiting clinical reviewThe full textbook explains uncertainty but does not replace live national or local guidance, specialist advice, or current prescribing information.

Threatened, missed, incomplete and complete miscarriage

Obstetrics and gynaecology · UK scope · Sources checked 27 Aug 2026 · Clinical review pending

RapidFull
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Stabilise bleeding and exclude ectopic

Haemodynamic compromise, syncope, severe unilateral pain, peritonism, fever, offensive discharge or uncontrolled bleeding requires urgent emergency assessment rather than classification of miscarriage subtype alone.

Action: Use ABCDE, obtain IV access and bloods, involve senior gynaecology, resuscitate haemorrhage or sepsis and confirm pregnancy location before assuming an intrauterine loss.

Overview

Distinguish early-pregnancy bleeding with ongoing viability from missed, incomplete and complete miscarriage using safe ultrasound criteria while continuing to exclude ectopic pregnancy.

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.

Practice

Two practice questions

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Obstetrics and gynaecologyOriginal SBA

Who should receive progesterone

A patient has vaginal bleeding, one previous miscarriage and a scan-confirmed intrauterine pregnancy. No heartbeat is visible yet because the pregnancy is very early. What does NICE recommend?

Choose one answer, then submit
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Sources and review status4 sources · checked 27 Aug 2026 · clinical review pending+
Sources

Sources and review status

National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.

  • NICE NG126 miscarriage managementThreatened miscarriage progesterone and management pathways.
  • NICE NG126 location and viability diagnosisSafe ultrasound criteria and complete-loss caution.
  • NICE NG126 anti-D prophylaxisJune 2026 gestation-based prophylaxis update.
  • NHS miscarriageSymptoms, causes, care and recovery.

Editorial contact: Doctor’s Passport editorial team. Source-check date is separate from clinical approval. Report a content problem · Content changes

Authoring stateComplete draftClinical stateAwaiting reviewJurisdictionUnited Kingdom
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.

Aetiology

01

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.

02

Maternal medical or anatomical factors

Thyroid disease, antiphospholipid syndrome, uterine anomalies and poorly controlled diabetes can increase loss risk, particularly when miscarriage recurs.

03

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.

Pathophysiology

  1. 1
    Developmental arrest

    Embryonic or placental development stops, hCG support falls and pregnancy structures cease growing before tissue is expelled.

  2. 2
    Decidual separation

    Loss of hormonal and placental support allows gestational tissue to separate from the decidua, opening maternal vessels and causing bleeding.

  3. 3
    Cervical passage

    Uterine contractions and cervical dilatation expel tissue; complete passage closes the process while retained tissue sustains bleeding and cramping.

  4. 4
    Retained-tissue inflammation

    Persistent products can maintain hCG and bleeding and occasionally provide a focus for endometritis or systemic infection.

Clinical features and red flags

Threatened miscarriage

Vaginal bleeding occurs while ultrasound confirms an ongoing viable intrauterine pregnancy; pain may be present but tissue has not been expelled.

Missed miscarriage

Ultrasound safely confirms absent development or cardiac activity while pregnancy tissue remains and symptoms may be minimal or have quietly regressed.

Incomplete miscarriage

Partial tissue passage leaves continued bleeding and cramping, often with an open cervix and retained intrauterine material.

Complete miscarriage

Pain and bleeding settle after all tissue passes and the cavity is empty, provided previous imaging proved intrauterine location or PUL follow-up resolves.

Septic miscarriage

Fever, uterine tenderness, offensive discharge, tachycardia or systemic illness with retained tissue indicates infection requiring urgent treatment.

Red flags requiring action

  • A positive pregnancy test with unilateral pain, shoulder-tip pain, collapse or an empty uterus may be ectopic pregnancy even if tissue or clots have passed.
  • Heavy ongoing bleeding with tachycardia, hypotension, pallor or syncope requires emergency haemorrhage care and may need urgent uterine evacuation.
  • Fever, uterine tenderness, offensive discharge or systemic illness suggests infected miscarriage or retained tissue and needs urgent antibiotics and source control.
  • A single borderline scan without the NICE repeat interval cannot safely diagnose miscarriage and risks treatment of a viable pregnancy.

Investigations

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.

Differential diagnosis

01

Ectopic pregnancy

Pain and bleeding overlap, and an empty uterus without prior intrauterine proof requires PUL follow-up until ectopic is excluded.

02

Viable early pregnancy

Bleeding can occur with normal ongoing development, while late ovulation may make expected structures too small for one scan.

03

Gestational trophoblastic disease

Persistent bleeding, unusually high or plateauing hCG and abnormal vesicular tissue require histology and specialist trophoblastic follow-up.

04

Cervical or vaginal bleeding

Ectropion, polyp, infection, trauma or malignancy can bleed during pregnancy and may be identified on consented speculum examination.

Management

01First assessmentStabilise, locate and test viabilityFirst stepA patient presents with pain or bleeding in early pregnancy.+
  1. 1EscalationAssess haemodynamics, bleeding, pain, ectopic and infection features and escalate shock, peritonism, sepsis or uncontrolled bleeding immediately.
  2. 2Obtain pregnancy testing, expert transvaginal ultrasound and targeted bloods, adding consented speculum examination where it answers bleeding or tissue questions.
  3. 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.+
  1. 1Explain that bleeding increases risk but many pregnancies continue and advise return if bleeding worsens, pain develops or bleeding persists beyond 14 days.
  2. 2If at least one previous miscarriage exists, offer vaginal micronised progesterone 400 mg twice daily and continue to 16 weeks once heartbeat is confirmed.
  3. 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.+
  1. 1Explain the diagnosis clearly, pause for the response and discuss what expectant, medical and surgical pathways involve, including bleeding, pain and completion testing.
  2. 2For apparent complete loss without prior intrauterine proof, retain the PUL pathway until ectopic pregnancy and persistent trophoblast are excluded.
  3. 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+
Increases live-birth likelihood in the NICE-defined threatened-miscarriage group with current bleeding and previous pregnancy loss.

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.

Complications

01

Haemorrhage and anaemia

Ongoing or rapid blood loss can cause symptomatic anaemia, circulatory shock, transfusion need and urgent uterine evacuation for definitive control.

02

Infection and sepsis

Retained pregnancy tissue can become infected, causing endometritis, pelvic infection, bacteraemia, coagulopathy, organ dysfunction and potentially life-threatening septic shock.

03

Retained pregnancy tissue

Incomplete passage causes persistent bleeding, pain and positive testing and may require medical or surgical completion.

04

Psychological morbidity

Grief, guilt, anxiety, depression, relationship strain and trauma can persist after physical recovery and recur in later pregnancies.

Monitoring and follow-up

  • 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.

Special situations

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.

Common pitfalls

  1. 01

    Calling any early-pregnancy bleeding a threatened miscarriage before confirming intrauterine location and viability.

  2. 02

    Diagnosing missed miscarriage from one borderline ultrasound or last menstrual period alone.

  3. 03

    Calling an empty uterus complete miscarriage when no prior scan documented intrauterine pregnancy.

  4. 04

    Offering progesterone for a PUL or for bleeding without any previous miscarriage.

  5. 05

    Prescribing bed rest or implying exercise, sex or ordinary stress caused the loss.

  6. 06

    Using the historic anti-D surgical rule instead of the June 2026 gestation-based recommendations.