What are the different types of spontaneous abortion (miscarriage)?

Types of Spontaneous Abortion

Spontaneous abortion is classified into six distinct clinical types: threatened, inevitable, incomplete, complete, missed (retained), and septic abortion, each with specific diagnostic criteria and management implications. 1, 2, 3

Clinical Classification System

Threatened Abortion (Amenaza de Aborto)

• Vaginal bleeding occurs with a closed cervix and viable fetus on ultrasound 1, 2
• The pregnancy may continue successfully or progress to other abortion types 3
• Bleeding is the earliest clinical sign, ranging from spotting to heavier flow 1, 4

Inevitable Abortion (Aborto Inevitable)

• Characterized by vaginal bleeding with cervical dilatation but no tissue expulsion yet 1, 2
• The cervical os is open, making pregnancy loss unavoidable 3
• Cramping abdominal pain typically accompanies the bleeding 1

Incomplete Abortion (Aborto Incompleto)

• Partial expulsion of products of conception with retained tissue in the uterus 1, 2, 3
• Presents with ongoing bleeding that can be profuse and life-threatening 1
• Surgical evacuation has the lowest complication rates: hemorrhage 9.1%, infection 1.3%, retained tissue 1.3% 1

Complete Abortion (Aborto Completo)

• Complete expulsion of all products of conception with an empty uterus 1, 2, 3
• The cervix typically closes after complete expulsion 3
• Rarely requires medical or surgical intervention 1, 3
• Contraceptive counseling should be provided immediately, as ovulation can resume within 2-4 weeks 1

Missed Abortion/Retained Abortion (Aborto Retenido)

• Embryonic or fetal death without spontaneous expulsion of conception products 1, 2, 3, 5
• Modern terminology prefers "embryonic/fetal demise" over outdated terms like "blighted ovum" 1
• Diagnostic ultrasound criteria include: crown-rump length ≥7 mm without cardiac activity, mean sac diameter ≥25 mm without embryo, or absence of embryo ≥14 days after initial sac visualization 1
• Expectant management is absolutely contraindicated due to risks of intrauterine infection, coagulopathy, and maternal sepsis 1
• Active evacuation is required—either medical management with mifepristone plus misoprostol (80% success rate) or surgical evacuation depending on gestational age 1, 5

Septic Abortion (Aborto Séptico)

• Infection complicating any of the above abortion types 1, 2, 3
• Clinical signs include fever, maternal tachycardia, purulent cervical discharge, and uterine tenderness 1
• Do not wait for fever to diagnose infection—maternal tachycardia and purulent discharge are sufficient warning signs 1
• Requires immediate broad-spectrum antibiotics and urgent surgical evacuation 1
• Intraamniotic infection occurs in 38% of cases managed expectantly versus 13% with active abortion care 1

Critical Diagnostic Considerations

Ultrasound Evaluation

• Transvaginal ultrasound is the diagnostic method of choice 1
• Can demonstrate absence of cardiac activity, empty or irregular gestational sac, and placental detachment 1
• The presence of an intrauterine gestational sac rules out ectopic pregnancy 1

Laboratory Assessment

• Serial β-hCG measurements confirm pregnancy loss when levels fail to rise appropriately or decrease 1, 3
• Complete blood count, coagulation parameters, blood typing, and cross-matching are essential in profuse bleeding 1

Essential Management Principles

Rh Immunoprophylaxis

• All Rh-negative women with any type of spontaneous abortion must receive 50 μg anti-D immunoglobulin 1
• Fetomaternal hemorrhage occurs in 32% of spontaneous abortions 1

Expectant Management Risks

• Expectant management carries 60.2% maternal morbidity versus 33% with active abortion care 1
• Postpartum hemorrhage occurs in 23.1% with expectant management versus 11% with active care 1
• Should be avoided in most cases, particularly with missed abortion, infection signs, or significant bleeding 1

Common Pitfalls to Avoid

• Never delay treatment waiting for fever if infection is suspected—initiate antibiotics and evacuate urgently 1
• Do not misdiagnose incomplete abortion as ectopic pregnancy—careful ultrasound evaluation is essential 1
• Avoid using outdated terminology like "blighted ovum" or "pregnancy failure"—use "early pregnancy loss" or "embryonic/fetal demise" 1