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Empty uterus + adnexal mass + free fluid in Morison's pouch -> Emergent OR
NO DIGITAL PELVIC EXAM until transabdominal ultrasound excludes placenta previa
Magnesium Sulfate 4–6g IV load over 15–20 min, then 1–2g/h continuous infusion
Labetalol 20 mg IV (repeat 40, 80 mg) OR Hydralazine 5–10 mg IV (target SBP 140–150)
Initiate hysterotomy at 4 min of maternal arrest; deliver baby by 5 min (>= 20 weeks)
Bottom-Line Clinical Pearl
Any female of reproductive age with abdominal pain, vaginal bleeding, or syncope has an ectopic pregnancy until proven otherwise; bedside ultrasound and qualitative urine/serum hCG are mandatory. Never perform a digital pelvic examination on a patient with 3rd-trimester bleeding until placenta previa is ruled out by ultrasound. In severe preeclampsia/eclampsia, administer Magnesium Sulfate (4–6g IV over 20 min). In maternal cardiac arrest >= 20 weeks, perform a Resuscitative Hysterotomy (perimortem cesarean delivery) if no ROSC within 4 minutes.
Ectopic pregnancy occurs when a fertilized blastocyst implants outside the endometrial cavity (95% in the fallopian tube, most commonly the ampulla). It remains the leading cause of first-trimester maternal mortality. Every female of childbearing age presenting with abdominal pain, pelvic pain, amenorrhea, vaginal spotting, or unexplained syncope must be evaluated for ectopic pregnancy.
| Diagnostic Modality | Key Findings & Thresholds | Clinical Utility & Action |
|---|---|---|
| Urine Point-of-Care hCG | Qualitative detection of beta-hCG (threshold 20–25 mIU/mL) | Immediate bedside screen; sensitivity > 99%. A negative urine hCG essentially excludes pregnancy. |
| Serum Quantitative beta-hCG | Serum concentration in mIU/mL | Discriminatory Zone: 1,500–2,000 mIU/mL. At this level, a normal intrauterine pregnancy (IUP) MUST be visualized on transvaginal ultrasound (TVUS). |
| Transvaginal Ultrasound (TVUS) | Definitive IUP requires: Gestational sac containing a yolk sac OR fetal pole with cardiac activity | A simple fluid collection without a yolk sac is a 'pseudogestational sac' (seen in 20% of ectopics). An adnexal mass with 'tubal ring sign' or fetal pole confirms ectopic. |
| Bedside POCUS (Morison's Pouch) | Anechoic fluid in the hepatorenal space | Indicates massive hemoperitoneum (> 500–1000 mL blood). In a pregnant patient with acute abdominal pain, positive Morison pouch mandates IMMEDIATE LAPAROTOMY. |
| Rh(D) Immune Globulin (RhoGAM) | Administer to all Rh-negative mothers with vaginal bleeding | Dose: 50 mcg IM in first trimester (< 12 weeks); 300 mcg IM if >= 12 weeks gestation. Prevents maternal alloimmunization. |
Third-trimester vaginal bleeding (gestation > 20 weeks) is an obstetric emergency carrying high maternal and fetal mortality. Distinguishing between placenta previa and placental abruption dictates whether emergency delivery or expectant management is indicated:
| Clinical Feature | Placenta Previa (Abnormal Implantation) | Abruptio Placentae (Premature Separation) |
|---|---|---|
| Pain Characteristics | PAINLESS bright red vaginal bleeding | PAINFUL dark red vaginal bleeding with severe abdominal/back pain |
| Uterine Tone & Palpation | Soft, relaxed, non-tender uterus; normal resting tone | Firm, rigid, exquisitely tender uterus ('woody uterus') with high-frequency contractions |
| Fetal Heart Rate Tracing | Usually normal unless maternal hemorrhagic shock occurs | Fetal distress early: prolonged bradycardia, repetitive late decelerations, loss of variability |
| Etiologic Risk Factors | Prior Cesarean delivery, multiparity, advanced maternal age, prior previa | Maternal hypertension, preeclampsia, abdominal trauma, cocaine use, tobacco smoking |
| Coagulopathy Risk | Rarely associated with coagulopathy | HIGH RISK for Disseminated Intravascular Coagulation (DIC) via tissue factor release |
| PHYSICAL EXAM RULE | DIGITAL PELVIC EXAM IS ABSOLUTELY CONTRAINDICATED (causes massive digital tear of placenta) | Digital exam deferred until ultrasound confirms placenta location; speculum exam after ultrasound |
Preeclampsia is new-onset hypertension (SBP >= 140 or DBP >= 90 mmHg on two occasions >= 4 hours apart) presenting after 20 weeks of gestation (or up to 6 weeks postpartum) combined with proteinuria or end-organ dysfunction. Eclampsia is the development of generalized tonic-clonic seizures in a preeclamptic patient.
| Severe Feature/Complication | Diagnostic Criteria | Immediate Emergency Pharmacotherapy | Clinical Target |
|---|---|---|---|
| Severe Hypertension | SBP >= 160 mmHg OR DBP >= 110 mmHg | Labetalol 20 mg IV over 2 min (repeat 40, 80 mg q10min; max 300 mg) OR Hydralazine 5–10 mg IV (repeat q20min; max 20 mg) OR Nicardipine 5 mg/h IV infusion | Lower SBP to 140–150 mmHg and DBP to 90–100 mmHg to prevent maternal hemorrhagic stroke while preserving placental perfusion. |
| Seizure Prophylaxis & Treatment (Eclampsia) | Generalized tonic-clonic seizure in pregnancy/postpartum | Magnesium Sulfate 4–6g IV loading dose in 100 mL D5W over 15–20 minutes, followed by 1–2g/hour continuous IV maintenance infusion | Drug of choice for eclamptic seizures (superior to phenytoin and diazepam). If seizure recurs, give additional 2g IV bolus over 5 minutes. |
| Magnesium Toxicity Antidote | Loss of deep tendon reflexes (patellar), respiratory depression (< 12/min), cardiac arrest | Calcium Gluconate 1g IV (10 mL of 10% solution) slow IV push over 5–10 minutes | Immediately stop magnesium infusion; administer IV calcium; support airway and ventilation. |
| HELLP Syndrome | Hemolysis (schistocytes, LDH > 600), Elevated Liver enzymes (AST/ALT > 2x normal), Low Platelets (< 100,000) | Magnesium sulfate + Dexamethasone 10 mg IV q12h + Emergency OB consult for delivery | High risk of subcapsular liver hematoma rupture; manage in ICU with blood product readiness. |
In a pregnant patient at or beyond 20 weeks of gestation (uterine fundus at or above the umbilicus) who suffers cardiac arrest, the gravid uterus compresses the inferior vena cava and abdominal aorta, reducing cardiac output by 60–80% during CPR. Resuscitative hysterotomy is primarily a maternal resuscitation procedure: relieving aortocaval compression restores maternal venous return and significantly increases maternal survival, while also saving the viable fetus.
| Phase | Time Benchmark | Execution Checklist | Clinical Rules |
|---|---|---|---|
| Maternal Cardiac Arrest | Time 0 min | Standard ACLS chest compressions + Manual Left Uterine Displacement (LUD) | Manually push uterus 30 degrees to patient's left side to relieve IVC compression during CPR. |
| Decision Threshold | Time 4 min | If NO return of spontaneous circulation (ROSC) by 4 minutes, INITIATE HYSTEROTOMY | Do NOT transport to OR; do NOT wait for surgical prep or fetal heart tones. Pick up scalpel at bedside. |
| Surgical Execution | Time 4 to 5 min | 1) Rapid vertical midline skin incision from below umbilicus to pubic symphysis with #10 scalpel; 2) Incise fascia; 3) Make vertical lower uterine segment incision; 4) Extend with bandage scissors; 5) Deliver infant | Deliver infant by 5 minutes of arrest; clamp and cut umbilical cord; hand infant to neonatal team; deliver placenta; pack uterus; continue maternal CPR. |
| Post-Delivery ROSC | Post-delivery | Spontaneous maternal circulation often returns immediately upon delivery of the fetus due to instantaneous restoration of venous return | Continue maternal resuscitation; administer Oxytocin 20–40 units/L IV; transport to operating room for formal surgical closure. |
Critical Pitfall / Contraindication
The 4-Minute Rule in Maternal Cardiac Arrest: Do not hesitate to perform a perimortem cesarean delivery. If standard resuscitation does not achieve ROSC within 4 minutes in a pregnant patient with fundal height at or above the umbilicus, initiate the incision immediately. Survival for both mother and infant plummets dramatically if delivery is delayed beyond 5 minutes.
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