Abortus

01Pathophysiology

The fundamental process in all forms of abortion is the premature termination of pregnancy before the fetus reaches viability, defined as before 20 weeks of gestation or fetal weight below 500 grams.

In spontaneous abortion, the most frequent underlying mechanism is a lethal chromosomal abnormality (particularly trisomies, monosomy X, and polyploidy) that prevents normal embryonic development. The defective conceptus fails to progress, triggering an inflammatory and hemorrhagic cascade in the decidua. This leads to separation of the gestational sac from the uterine wall, which manifests clinically as vaginal bleeding and uterine cramping. Prostaglandins released at the site of decidual disruption stimulate myometrial contractions, producing pain and eventually expelling the products of conception.

The cervical os is the single most important physical finding that differentiates one type from another. In threatened abortion, the cervix remains closed because the process is still reversible and the gestational sac has not yet detached fully. Once the cervix dilates, the process becomes irreversible (inevitable abortion). If only part of the tissue is expelled, retained products act as a foreign body that prevents the uterus from contracting effectively, leading to continued bleeding (incomplete abortion). Conversely, if all products pass spontaneously, the uterus contracts down, the cervix closes, and bleeding diminishes (complete abortion).

In missed abortion, the embryo/fetus dies but the body fails to mount a sufficient expulsion response. The uterus neither grows nor contracts to expel, and the cervix stays closed. Over time, pregnancy symptoms regress and previously positive pregnancy tests may become negative.

Septic abortion develops when bacteria, most commonly polymicrobial flora from the lower genital tract, ascend into the uterine cavity through an open cervix or following instrumentation performed without proper aseptic technique. The infection can remain localized to the decidua (infectious abortion) or spread to the myometrium, parametrium, peritoneum, and eventually the bloodstream (septic abortion with sepsis). This is why septic abortion is associated with high-grade fever, tachycardia, foul-smelling vaginal discharge, and uterine tenderness.

02Classification and Clinical Manifestation

03Diagnostic Workup

The best initial test in any woman presenting with first-trimester vaginal bleeding is a thorough history and bimanual pelvic examination. The status of the cervical os is what immediately classifies the type of abortion. A closed cervix with a viable fetus on ultrasound points to threatened abortion; an open cervix with tissue at the os points to inevitable or incomplete abortion.

Ultrasound is the most useful adjunct to confirm the diagnosis and, importantly, to rule out ectopic pregnancy before initiating any medical treatment. The PNPK emphasizes that ultrasound is helpful but not an absolute requirement for establishing the diagnosis. Gestational age can be estimated by uterine size on bimanual exam when ultrasound is unavailable.

After evacuation, tissue inspection should be performed. The operator looks for villi, decidua, and membranes in a clear container with water and backlighting. Absence of villi raises concern for ectopic pregnancy or incomplete evacuation. Grape-like hydropic villi suggest molar pregnancy.

04Management and Treatment

Overview Table (Aligned with PNPK Kemenkes 2020)

Misoprostol Dosing for Evacuation

Operative Management

For uterine size below 13 weeks, the procedure of choice is manual vacuum aspiration (MVA). For uterine size 13 weeks or more, the procedure is dilation and evacuation (D&E), which is essentially MVA preceded by cervical preparation and must be performed by a trained Ob-Gyn specialist at a referral facility.

Sharp curettage (D&C) is obsolete. The PNPK explicitly states that sharp curettage is no longer recommended by WHO or FIGO due to higher complication rates, including a 1.2% risk of Asherman syndrome, which is not observed with MVA or misoprostol.

Cervical Preparation Before Operative Evacuation

For uterine size <13 weeks, cervical priming is not mandatory but can reduce procedural difficulty. If used: misoprostol 400 mcg per vaginam 3-4 hours before the procedure, OR sublingual 2-3 hours before. For uterine size 13 weeks or more, cervical preparation is recommended for all patients with the same misoprostol regimen; laminaria is an alternative especially beyond 20 weeks.

Pain Management

For medical management, NSAIDs are the first-line analgesic (ibuprofen, ketoprofen, mefenamic acid, diclofenac, or ketorolac), given before or when cramping begins. Paracetamol is a second-line option only when NSAIDs cannot be given. For uterine size beyond 12 weeks, epidural anesthesia should also be considered.

For operative management (MVA/D&E), a paracervical block using lidocaine (typically 20 mL of 1% lidocaine) plus NSAIDs is recommended for all patients. General anesthesia is not routinely recommended because it increases morbidity and mortality risk in post-abortion care.

Prophylactic Antibiotics

Antibiotics are recommended before operative procedures (MVA or D&E) only: doxycycline 200 mg oral, OR azithromycin 500 mg oral, OR metronidazole 500 mg oral, given as a single dose before the procedure. Routine prophylactic antibiotics are not recommended for medical management with misoprostol.

Septic Abortion: Antibiotic Regimens

In septic abortion, the first dose of antibiotics is given immediately, and uterine evacuation with MVA should follow as soon as possible. The PNPK emphasizes that in suspected unsafe induced abortion, tetanus prophylaxis (0.5 mL tetanus toxoid IM + 1500 units tetanus antitoxin IM) should be administered if immunization history is unknown.

Post-Procedure

Contraception can begin immediately after operative evacuation. Hormonal contraceptives, IUD insertion (except in septic cases), and barrier methods are all options. After medical management, hormonal methods can start once expulsion is confirmed. Fertility returns in approximately 8 days after a completed abortion. A follow-up visit at 7-14 days is offered but not mandatory.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students lose points on this topic is by confusing the types of abortion based on cervical os status. The exam will give you a vignette with vaginal bleeding in early pregnancy and expects you to classify it based on two key variables: whether the cervix is open or closed, and whether products of conception have been partially or fully expelled. A closed cervix with a viable fetus is threatened; a closed cervix with a dead fetus and no expulsion is missed abortion. An open cervix with tissue still inside is inevitable or incomplete. Memorize the cervical os as the branching point for your entire diagnostic algorithm.

A second trap involves management selection. Students who answer "D&C" for evacuation of retained products are choosing an obsolete method. The current standard per WHO and FIGO guidelines (and the PNPK 2020) is misoprostol or MVA, not sharp curettage. If you see sharp curettage or D&C as an answer choice alongside MVA, it is almost always the distractor.

Third, never forget to rule out ectopic pregnancy before giving misoprostol. Misoprostol has no therapeutic effect on ectopic pregnancy, and a delay in recognizing an ectopic can be fatal. If the vignette includes no intrauterine pregnancy on ultrasound with a positive beta-hCG, the next best step is to investigate for ectopic, not to administer misoprostol.

Finally, for missed abortion at 13 weeks or more, recognize that the PNPK includes the option to give mifepristone 200 mg oral 1-2 days before misoprostol when available. This combination improves expulsion rates and is a testable detail that distinguishes missed abortion management from incomplete/inevitable abortion management, where mifepristone is not part of the standard protocol.