Bleeding in Early Pregnancy

Causes

• ROSEN's Emergency Medicine, p. 333

Miscarriage - Classification

• Embryonic/fetal demise: CRL 5-40 mm, no cardiac activity
• Anembryonic pregnancy (blighted ovum): Gestational sac mean diameter 16-45 mm, no fetal pole
• Swanson's Family Medicine Review, p. 434

Ectopic Pregnancy

• Implants most commonly in the fallopian tube; accounts for ~1-2% of all pregnancies
• Prevalence in ED patients with 1st-trimester bleeding or pain: up to 10-16%
• Half of women with ectopic pregnancy have no identifiable risk factors

• Pelvic inflammatory disease (PID) - raises risk 3-fold
• Prior ectopic pregnancy (subsequent risk up to 22%)
• Previous tubal surgery or sterilization
• Intrauterine device (IUD) in situ
• Assisted reproductive technologies (especially IVF with multiple embryo transfer - also raises risk of heterotopic pregnancy)
• Smoking, infertility, advanced age

• ROSEN's Emergency Medicine, p. 3350

Investigation

1. Urine / serum beta-hCG

• Confirm pregnancy first in any woman of reproductive age
• Serial quantitative beta-hCG: In a normal IUP, hCG doubles approximately every 48 hours in early pregnancy; a failing or ectopic pregnancy typically shows a slower rise or plateau
• A single hCG level cannot diagnose viability or location - serial measurements are needed
• There is no hCG level at which ectopic pregnancy can be completely excluded

2. Transvaginal Ultrasound (TVUS) - First-line imaging

• Discriminatory zone: Traditionally 2,000 IU/mL, but ACOG now recommends using 3,500 IU/mL to avoid inadvertently disrupting a viable IUP
• Pregnancy of Unknown Location (PUL): Positive pregnancy test with neither IUP nor ectopic seen on USS - requires serial hCG + repeat TVUS in 48 hours

3. Other bloods (in haemodynamically unstable patients)

• Full blood count
• Blood group and Rh status
• Crossmatch
• Coagulation screen

Diagnostic Algorithm

Management

Haemodynamically unstable patient

• Immediate resuscitation: IV access, crystalloid, then blood (use Rh-negative blood if Rh status unknown)
• Urgent obstetric/gynaecology consultation
• If confirmed or suspected ectopic or IUP with haemorrhage: operative management

Miscarriage - Stable patient

Ectopic Pregnancy - Stable patient

• Medical: Methotrexate (folic acid antagonist) - suitable for haemodynamically stable, unruptured ectopic with hCG typically <5,000 IU/mL, no fetal cardiac activity on USS
• Surgical: Salpingostomy or salpingectomy (laparoscopic preferred); mandatory for ruptured ectopic or failed methotrexate

Rh-negative patients

• Anti-D (RhoGAM 50 mcg) should be given to all Rh-negative women with early pregnancy bleeding to prevent Rh sensitisation
• Swanson's Family Medicine Review, p. 434

Key Points to Remember

1. Pregnancy status is the single most important determination in any woman of reproductive age presenting with vaginal bleeding.
2. Ectopic pregnancy must be actively excluded in every case - it can present identically to threatened miscarriage.
3. A single beta-hCG level cannot confirm or exclude ectopic pregnancy or viability; serial measurements + USS are required.
4. When fetal cardiac activity is confirmed on TVUS, the subsequent miscarriage risk drops to only 3-6%, though bleeding remains a high-risk indicator.
5. Women who bleed but do not miscarry are still at increased risk for preterm PROM, abruption, previa, stillbirth, and congenital abnormalities.
6. All Rh-negative women with any early pregnancy bleeding should receive anti-D prophylaxis.
7. Patients with PUL (no pregnancy visible on USS) should return in 48 hours for repeat TVUS and hCG.

Conditions Causing Bleeding in Early Pregnancy

A. Obstetric Causes

1. Miscarriage (Spontaneous Abortion)

• 80% of miscarriages occur in the first trimester
• Most are caused by chromosomal abnormalities or uterine malformations
• Fetal death often precedes clinical symptoms by several weeks
• Symptoms most common 8-12 weeks; USS shows death usually before 8 weeks

• ROSEN's Emergency Medicine, p. 3348-3350

2. Ectopic Pregnancy

• Fallopian tube (most common - ~90%): ampulla > isthmus > fimbrial end
• Ovary
• Abdominal cavity (peritoneal implantation after fimbrial expulsion)
• Cornual/interstitial (uterine horn) - particularly dangerous; can grow to 10-14 weeks before rupture
• Cervix (rare)

1. Spontaneous involution
2. Tubal abortion (expulsion into peritoneal cavity or vagina)
3. Rupture - catastrophic, sudden severe abdominal pain, haemorrhagic shock

• Classic triad: amenorrhoea + abdominal pain + vaginal bleeding
• BUT: 15-20% have no missed period; bleeding may be mild; pain is variable
• Adnexal mass palpable in only 10-20%
• Cervical motion tenderness if peritoneal irritation
• Half of patients have no identifiable risk factors

• Pelvic inflammatory disease (raises risk ~3-fold; 50% of cases)
• Prior ectopic pregnancy (subsequent risk up to 22%)
• Tubal surgery (sterilization or prior ectopic)
• Intrauterine device (IUD)
• Assisted reproduction / IVF
• Smoking, advanced age, infertility

• Robbins & Kumar Basic Pathology, p. 703 | ROSEN's Emergency Medicine, p. 3350

3. Implantation Bleeding

• Occurs at the time of blastocyst implantation into the endometrium (~6-12 days post-conception)
• Can also occur at the time of the first missed menstrual period
• Typically light spotting, self-limiting
• Diagnosis of exclusion - all serious causes must be ruled out

4. Subchorionic Haemorrhage (SCH)

• Blood collects between the chorion and the uterine wall
• Occurs in the first half of pregnancy (1st/early 2nd trimester)
• Incidence: approximately 1.7% of pregnancies
• Presents with vaginal bleeding only (not the dramatic presentation of abruption)
• Diagnosed by TVUS (retroplacental blood clot visible)
• Most SCHs resolve and result in a healthy infant
• Associated with slightly increased risk of: miscarriage (OR 2.18), abruption (OR 5.71), preterm delivery, PPROM

Large (6.5 cm) subchorionic haemorrhage at 12 weeks 6 days - Creasy & Resnik's Maternal-Fetal Medicine

• Creasy & Resnik's Maternal-Fetal Medicine, p. 3465-3474

5. Molar Pregnancy (Gestational Trophoblastic Disease - GTD)

• Complete mole: empty ovum fertilized by one sperm that duplicates, or by two sperm (dispermy)
• Partial mole: normal ovum fertilized by two sperm

• Vaginal bleeding (usually late 1st / early 2nd trimester)
• Uterus "large for dates"
• Markedly elevated hCG
• No fetal heart sounds
• "Snowstorm" appearance on USS (complete mole)
• May pass grape-like vesicles per vaginum

Complete hydatidiform mole - numerous swollen hydropic villi - Robbins & Kumar Basic Pathology

• Invasive mole: locally aggressive, penetrates uterine wall, risk of life-threatening haemorrhage
• Choriocarcinoma: highly invasive, frequently metastatic; highly responsive to chemotherapy
• Placental site trophoblastic tumour (PSTT): produces HPL rather than hCG; treated surgically
• Robbins & Kumar Basic Pathology, p. 703-704

6. Corpus Luteum Cyst Rupture

• The corpus luteum (formed from the ruptured follicle after ovulation) becomes cystic and can rupture or bleed
• Causes intraperitoneal haemorrhage + vaginal bleeding
• Can mimic ectopic pregnancy clinically
• Diagnosed by USS; managed conservatively in most cases

B. Non-Obstetric Causes

7. Cervical Lesions

• Cervical ectropion (erosion): Columnar epithelium everts onto the ectocervix; highly vascular in pregnancy due to increased oestrogen and blood flow; bleeds easily on contact (postcoital bleeding common)
• Cervical polyps: Benign pedunculated lesions; bleed easily, especially in pregnancy
• Cervicitis / STI: Chlamydia, gonorrhoea cause friable, inflamed cervix with contact bleeding
• Cervical carcinoma: Rare but must be excluded; typically presents with painless contact bleeding

8. Vaginal Lesions / Trauma

• Vaginal lacerations (most common mechanism: coitus)
• Foreign bodies
• Trauma (falls, interpersonal violence) - particularly dangerous in pregnancy due to fetal/placental risk

9. Lower Genital Tract Infection / Vaginitis

• Inflamed vaginal mucosa can bleed
• Associated with discharge, odour, dyspareunia

Summary Table