I now have comprehensive content from both Rosen's Emergency Medicine and Tintinalli's to deliver a thorough, well-structured response.
Vaginal Bleeding During Pregnancy
Vaginal bleeding complicates approximately 4% of all pregnancies and represents one of the most common obstetric emergencies. The differential diagnosis is strongly shaped by gestational age, and the clinical approach must first determine whether bleeding is occurring in the first or second half of pregnancy. — Rosen's Emergency Medicine, p. [block31]
Approach: First vs. Second Half
| Period | Key Diagnoses |
|---|
| First trimester (0–12 wks) | Threatened/inevitable/incomplete/complete/missed abortion, ectopic pregnancy, molar pregnancy, implantation bleeding |
| Second trimester (12–24 wks) | Placenta previa, abruptio placentae, vasa previa, cervical incompetence, subchorionic haematoma |
| Third trimester (>24 wks) | Abruptio placentae, placenta previa, vasa previa, show of labour, uterine rupture |
Critical rule: All patients with painless second-trimester/third-trimester vaginal bleeding should be assumed to have placenta previa until proven otherwise. Digital or instrumental examination of the cervix must be avoided until this diagnosis is excluded by ultrasound — it may precipitate catastrophic haemorrhage. — Rosen's Emergency Medicine [block31]; Tintinalli's Emergency Medicine [block8]
1. First-Trimester Bleeding
Causes
| Cause | Key Feature |
|---|
| Threatened abortion | Bleeding + closed cervical os; pregnancy may continue |
| Inevitable abortion | Bleeding + open os; cannot be prevented |
| Incomplete/Complete abortion | Partial or full expulsion of POC |
| Missed abortion | Retained non-viable pregnancy, no bleeding, closed os |
| Ectopic pregnancy | Amenorrhoea + pain + bleeding; most dangerous |
| Molar pregnancy | Exaggerated symptoms; "snowstorm" on USS |
| Implantation bleeding | Light spotting ~6–12 days post-conception; benign |
| Cervical pathology | Ectropion, polyp, cervicitis |
Ectopic Pregnancy
- The classic triad is amenorrhoea, abdominal pain, and abnormal vaginal bleeding ("the three A's") — ectopic pregnancy until proven otherwise. — Swanson's Family Medicine Review [block4]
- Risk factors: prior tubal surgery, PID, previous ectopic, IUD use, assisted reproduction.
- β-hCG present but intrauterine gestational sac absent on TVUSS → highly suspicious.
- Tubal rupture = surgical emergency; vasovagal attacks and orthostatic hypotension are strong indicators. — Swanson's Family Medicine Review [block4]
Molar Pregnancy
- Presents with vaginal bleeding, uterus large-for-dates, hyperemesis, early pre-eclampsia, and markedly elevated β-hCG.
- USS shows characteristic "snowstorm" appearance (see image below).
- Up to two-thirds are diagnosed only on pathological specimens after miscarriage; USS is only 58% sensitive.
- Management: uterine D&C + surveillance for gestational trophoblastic disease (invasive mole, choriocarcinoma). — Rosen's Emergency Medicine [block31]
2. Second-Half Bleeding
Bleeding from 14–24 weeks carries a 33% risk of fetal loss; management is supportive and expectant since fetal rescue is not possible before viability. In the third trimester, vaginal bleeding is associated with significant morbidity in ~one-third of cases, and urgent delivery may be required. — Rosen's Emergency Medicine [block31]
A. Abruptio Placentae (Placental Abruption)
Definition: Premature separation of a normally implanted placenta from the uterine lining. Incidence is highest between 24 and 32 weeks. — Tintinalli's Emergency Medicine [block8]
Abruptio placentae: placenta has separated from the superior pole of the uterus. — Tintinalli's Emergency Medicine
Risk factors: abdominal trauma (even minor), cocaine use, oligohydramnios, chorioamnionitis, advanced maternal age/parity, eclampsia, chronic or acute hypertension. — Tintinalli's [block8]
Clinical features (depend on severity):
- Mild: small retroplacental clot; vaginal bleeding may be minimal; no fetal distress
- Moderate: painful uterine contractions + vaginal bleeding; fetal distress present
- Severe: board-like rigid uterus; heavy bleeding (may be concealed); coagulopathy (DIC); fetal death; maternal haemorrhagic shock
Up to 20% of cases have no pain or vaginal bleeding (concealed abruption) — assessment relies on clinical features, coagulation parameters, and fetal monitoring. — Rosen's [block31]
Complications: DIC, haemorrhagic shock, uterine rupture, multiple organ failure, fetal demise.
Diagnosis: primarily clinical; USS confirms in ~50% (retroplacental clot) but a negative USS does not exclude abruption. CTG for fetal wellbeing.
Management:
- IV access × 2; FBC, coagulation studies, blood group + crossmatch
- IV fluid resuscitation; blood transfusion as needed
- Continuous fetal monitoring
- Obstetric consultation urgently
- Delivery timing based on gestational age, severity, and fetal/maternal condition
B. Placenta Previa
Definition: Abnormal implantation of the placenta overlying or adjacent to the internal cervical os.
Clinical presentation:
- Painless, bright red vaginal bleeding — classic hallmark
- Onset typically after 28 weeks (most commonly in the third trimester)
- Uterus non-tender, soft
- Abnormal fetal lie common (placenta occupies lower segment)
- Bleeding may be precipitated by intercourse, examination, or occur spontaneously
Key rule: Never perform a digital or speculum examination until placenta previa has been excluded by ultrasound — mechanical disruption of the placenta can cause catastrophic haemorrhage. When performed by an experienced operator (probe angled against anterior lip of cervix, not advanced into cervix), transvaginal USS is safe and is the preferred diagnostic modality. — Tintinalli's [block8]
Risk factors: previous caesarean section or uterine surgery (placenta accreta spectrum), multiparity, multiple gestation, advanced maternal age, smoking, prior placenta previa.
Grading:
- Complete (total): placenta covers internal os entirely
- Partial: placenta partially covers internal os
- Marginal: placental edge at margin of internal os
- Low-lying: placental edge within 2 cm of os but not covering it
Management:
- Haemodynamically stable + remote from term: expectant management, pelvic rest, hospitalisation (if severe bleeding)
- Haemodynamically unstable or near term: caesarean section
- Rh-negative patients: anti-D immunoglobulin
- Avoid vaginal delivery with complete previa
C. Vasa Previa
Definition: Fetal blood vessels (from velamentous cord insertion or succenturiate lobe) course through the fetal membranes across the internal cervical os, ahead of the presenting part.
Clinical significance: Vessel rupture (often at amniotomy or membrane rupture) causes fetal haemorrhage, not maternal — even small volumes are immediately life-threatening to the fetus.
Features:
- Sudden onset vaginal bleeding coinciding with rupture of membranes
- Rapid fetal bradycardia or sinusoidal CTG pattern
- Maternal haemodynamics may remain stable while fetus exsanguinates
Management: Emergency caesarean section is required immediately. Antenatal diagnosis by Doppler USS allows planned elective caesarean before membrane rupture. — Tintinalli's [block8]
D. Uterine Rupture
- Rare but catastrophic; risk factors: prior uterine scar (caesarean, myomectomy), obstructed labour, oxytocin misuse, grand multiparity.
- Sudden severe abdominal pain + vaginal bleeding + fetal bradycardia/loss of fetal heart tones.
- Loss of uterine contour on palpation; presenting part may retract.
- Emergency laparotomy + caesarean section.
Comparative Summary: Major Second-Half Causes
| Feature | Abruptio Placentae | Placenta Previa | Vasa Previa |
|---|
| Bleeding | Dark, may be concealed | Bright red, painless | Bright red; fetal blood |
| Pain | Severe, constant | None | None (until fetal distress) |
| Uterus | Rigid, tender | Soft, non-tender | Soft |
| Onset | Sudden, often traumatic/hypertensive | Spontaneous, 28+ wks | At ROM |
| Fetal distress | May be present | Less common unless severe | Immediate, severe |
| Who bleeds | Mother | Mother | Fetus |
| USS finding | Retroplacental clot (variable) | Placenta over os | Vessels over os (Doppler) |
| Pelvic exam | Safe after USS | CONTRAINDICATED until USS | CONTRAINDICATED |
Initial Assessment & Emergency Management (All Causes)
- History: gestational age, onset/character of bleeding, pain, trauma, prior USS, placental location, Rh status
- Vitals + fetal heart rate (normal 120–160 bpm)
- Do NOT perform digital/speculum examination until placenta previa/vasa previa excluded by USS
- IV access × 2; bloods: FBC, coagulation studies, blood group + crossmatch, Kleihauer-Betke test (feto-maternal haemorrhage)
- Transvaginal USS by experienced operator to localise placenta
- Continuous CTG (>24 weeks)
- Obstetric consultation — urgent/emergent based on severity
- Anti-D immunoglobulin for all Rh(D)-negative patients
- Resuscitate with crystalloid/blood products as needed; prepare for emergency delivery if haemodynamically unstable
Sources: Rosen's Emergency Medicine: Concepts and Clinical Practice [block31]; Tintinalli's Emergency Medicine [block8]; Swanson's Family Medicine Review [block4]; supplemented with standard obstetric knowledge (Williams Obstetrics; RCOG/ACOG guidelines).