Vaginal bleeding in early pregnancy is a common problem affecting approximately 25 % of all clinically diagnosed pregnancies. Of these about 50 % will be due to a failed pregnancy.

Bleeding in early pregnancy is commonly defined as vaginal bleeding during the first trimester, however some definitions extend this to an arbitrary figure of 20 weeks.

Ectopic pregnancy must always be considered in the first instance.

Clinical examination alone is unreliable in the modern assessment of the stable patient with mild early pregnancy bleeding. It is best assessed by ultrasound and quantitative beta HCG levels. 1

Patients with heavy bleeding, circulatory shock or vagal shock will need speculum examination as part of their resuscitative management. 1

The following refers to threatened miscarriage.

A threatened miscarriage is defined as any vaginal bleeding other than spotting, that occurs before 20 weeks of gestation.

See also:

  • Bleeding in Early Pregnancy – Miscarriage
  • Ectopic Pregnancy
  • Anti D


The causes of bleeding in early pregnancy include:

1.         Ectopic pregnancy.

2.         Abortion (miscarriage):

●          Threatened.

●          Failed pregnancy:

●          Incomplete (or inevitable).

●          Complete

●          Septic

3.         Trophoblastic disease (or “molar” pregnancy)

4.         Incidental:

            ●          This is due to non pregnancy related pathology, (see non-pregnancy           related vaginal bleeding document).

Clinical Features

The principle clinical features of a threatened abortion include:

Important points of History:

1.         Pain:

            ●          Mild crampy abdominal pain only

2.         Minimal bleeding:

●          Estimating the amount of vaginal bleeding is somewhat subjective.

            More objective measures include:

♥          The presence of clots, (suggests a relatively heavy bleed)

♥          Number of pads used.

♥          Bleeding of a degree which is greater than a woman’s normal period carries a worse prognosis

3.         POC (products of conception):

●          A history of the passage of the “POC” is unreliable in making a definitive statement about the viability of a pregnancy.

Blood clots or decidual cast may be misinterpreted as the POC.

Additionally the correct identification of the POC does not exclude the possibility of a live twin (or of the rare situation of a coexistent ectopic twin pregnancy).     

Important points of Examination:

1.         Abdominal examination:

●          Significant abdominal tenderness is not a feature of uncomplicated             threatened abortion.

2.         PV examination:

Traditionally the finding that the os was closed was taken as being supportive of a diagnosis of threatened abortion. 

Clinical assessment of the state of the os however is imprecise and subjective with poor inter-observer agreement.

It does not definitively define the state of a pregnancy. In any case it can be better assessed by ultrasound examination.

With the ready availability of beta HCG and ultrasound testing, the diagnostic yield for clinical vaginal pelvic examination is so low by comparison that its routine performance is no longer considered necessary by many. 1,3

This is provided:

●          The patient is not in circulatory shock

●          The patient is not in cervical shock

●          Bleeding is mild

●          There is not a history of abnormal PAP smear, or recurrent bleeding.

This is essentially due to the unreliability of clinical assessment of the state of viability of the pregnancy (with respect to both sensitivity and specificity) when compared to the use of ultrasound and the quantitative measurement of beta HCG.  

Furthermore, the causes of bleeding unrelated to the pregnancy are rare, and a short delay in the diagnosis of non-pregnancy-related bleeding (until follow up) is unlikely to be clinically significant. 3

Vaginal examination however is essential in cases of circulatory compromise as a resuscitative measure, (clearing the os)

Ultrasound in fact is by far the best “examination”.

●          Ultrasound is better able to determine the state of the os1, 2 as well as the state of the pregnancy.

●          It may also detect unexpected tubo-ovarian pathology


Blood tests:

These should include:

1.         FBE

2.         Beta HCG:

●          Beta HCG should be consistent with dates in cases of threatened abortion.

It should be noted that the half life of beta HCG is approximately 48 hours, and so the beta HCG level can remain at an elevated level for a week or two after a miscarriage.

A single beta HCG level therefore may be non-diagnostic of the viability of a pregnancy and so a series of tests will be required to confirm a normally rising level.

See Appendix 1 below.

3.         Blood group (for the determination of the need for the administration of anti-D).


Ultrasound examination is desirable but is not immediately urgent, and can in most circumstances be done next “working day”.

 Ultrasound is used to assess:

●          The viability of the pregnancy.

●          The age of the pregnancy.

●          The location of the pregnancy

♥          Note thatwhen no pregnancy can be identified on ultrasound, yet the beta HCG is elevated, a pregnancy of unknown location is diagnosed i.e it             could be intrauterine but the pregnancy is too early to be seen on            ultrasound, or it could be an ectopic, that again is too early to be identified             on ultrasound.


1.         Analgesia/ sedation

●          Mild analgesia may be given if required.

●          If pain is significant however the diagnosis of threatened abortion needs to             be reassessed. 

2.         Anti-D:

There is diversity of opinion about whether anti-D should be given for first trimester threatened miscarriage.

The British Blood Transfusion Society and the RWH give the following advice: 4,5

●          Anti-D is not indicated for threatened miscarriage before 12 weeks gestation but “consider” giving Anti D if there is heavy or repeated      bleeding or associated abdominal pain, especially if gestation is close to       12 weeks.

In cases of multiple (i.e. twins or more) pregnancies where a sensitizing event occurs in the first trimester, the 625 IU dose should be given (rather than the 250 IU dose).

3.         Explanation and reassurance are important for the patient.


Patients with a threatened miscarriage and an ultrasound that confirms a live intrauterine pregnancy have an 85- 90 % chance of the pregnancy progressing to term.

Indictors of a worse prognosis include:

  • Advanced maternal age
  • Ultrasound finding of an enlarged yolk sac and foetal bradycardia after 7 weeks gestation.

Best rest has not been proven to be beneficial  


Referral for investigation of an underlying cause is not generally indicated until after a third consecutive miscarriage.

Conditions looked for will include:

  • Uterine abnormalities
  • Thrombophilic disorders
  • Autoimmune disorders
  • Hormonal disorders
  • Infection
  • Environmental factors.
  • Chromosomal abnormalities.




Fellowship Notes

Dr Jessica Hiller LITFL Author

Doctor at Sir Charles Gairdner Hospital in Western Australia. Graduated from Curtin University in 2023 with a Bachelor of Medicine, Bachelor of Surgery. I am passionate about Obstetrics and Gynaecology, with a special interest in rural health care.

Dr Lucy J Yarwood LITFL author

MSc, MBChB University of Manchester. Currently doctoring in sunny Western Australia, aspiring obstetrician and gynaecologist

Physician in training. German translator and lover of medical history.

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