Kehamilan Ektopik

01Pathophysiology

Ectopic pregnancy occurs when a fertilized ovum implants in a location other than the uterine endometrium. The vast majority implant within the fallopian tube, most frequently in the ampullary segment. Other less common sites include the isthmus, fimbriae, ovary, cervix, cesarean scar, and the abdominal cavity.

The underlying mechanism is impaired ovum transport. Any condition that damages the tubal epithelium or disrupts normal tubal motility delays passage of the fertilized egg into the uterus. This is why prior PID (especially from Chlamydia trachomatis), tubal surgery, and smoking are such strong risk factors. PID causes chronic tubal inflammation and scarring, which physically obstructs or slows transport. Smoking impairs ciliary function within the tube, producing a similar effect through a different mechanism.

Once the embryo implants in the tube, the thin tubal wall cannot accommodate trophoblastic invasion and growth the way the endometrium can. As the gestational tissue expands, it stretches and erodes through the tubal wall, causing unilateral pelvic pain. Disruption of local blood vessels leads to vaginal bleeding, which is often irregular and lighter than a normal period. If the tube ruptures, bleeding into the peritoneal cavity produces hemoperitoneum, leading to peritoneal signs, shoulder pain (due to diaphragmatic irritation from blood), and potentially hemorrhagic shock.

A key concept for vignettes: the decidual reaction in the endometrium still occurs under the influence of progesterone from the corpus luteum, even though the pregnancy is ectopic. When progesterone levels fall as the ectopic pregnancy fails, the decidual tissue sheds. This is why the vaginal bleeding in ectopic pregnancy can sometimes be mistaken for a normal period or early miscarriage.

02Classification and Clinical Manifestation

Clinical Manifestation

03Diagnostic Workup

The diagnostic approach begins with confirming pregnancy via urine beta-hCG in any reproductive-age woman presenting with abdominal pain and/or vaginal bleeding. Once pregnancy is confirmed, obtain a serum quantitative beta-hCG and perform a transvaginal ultrasound.

The critical concept here is the discriminatory zone: a serum beta-hCG level (typically 1,500-2,000 mIU/mL, depending on the institution) above which a normal intrauterine pregnancy should be visible on TVUS. If the beta-hCG is above this threshold and no IUP is seen, ectopic pregnancy is the leading diagnosis until proven otherwise. This is one of the most frequently tested principles.

If the beta-hCG is below the discriminatory zone and the patient is hemodynamically stable, the correct next step is serial beta-hCG measurements 48 hours apart. In a normal early IUP, beta-hCG approximately doubles (rising at least 49% over 48 hours). An abnormally slow rise, a plateau, or a decline suggests either ectopic pregnancy or a failing intrauterine pregnancy. The distinction often requires repeat TVUS once the beta-hCG reaches the discriminatory zone.

TVUS findings suggestive of ectopic pregnancy include an empty uterus (no gestational sac), an adnexal mass separate from the ovary, a tubal ring sign (hyperechoic ring surrounding the ectopic gestational sac), and free fluid in the cul-de-sac (suggesting hemorrhage).

The gold standard for definitive diagnosis is direct surgical visualization (laparoscopy), but this is reserved for cases requiring operative intervention. In practice, the combination of beta-hCG trends and TVUS findings is sufficient to establish a working diagnosis in most cases.

04Management and Treatment

Acute stabilization is the first priority. If the patient presents with signs of rupture (hypotension, tachycardia, peritoneal signs), the next best step is emergent surgical intervention, not imaging or lab workup. Large-bore IV access, fluid resuscitation, and blood product preparation are performed simultaneously.

For stable, unruptured ectopic pregnancies, methotrexate is the first-line medical therapy. It works by inhibiting dihydrofolate reductase, which blocks DNA synthesis in rapidly dividing trophoblastic cells. The single-dose protocol uses 50 mg/m${}^2^2$ intramuscularly. After administration, beta-hCG is measured on day 4 and day 7. A decline of at least 15% between day 4 and day 7 indicates adequate response. If the decline is insufficient, a second dose may be given. Serial weekly beta-hCG monitoring continues until the level falls to < 5 mIU/mL.

Methotrexate has absolute contraindications that are commonly tested: immunodeficiency, hepatic or renal disease, active pulmonary disease, peptic ulcer disease, breastfeeding, and blood dyscrasias (leukopenia, thrombocytopenia, anemia). Patients receiving methotrexate must also avoid folate supplements, NSAIDs, alcohol, and sexual intercourse until beta-hCG reaches undetectable levels.

Surgical management is indicated when methotrexate criteria are not met, when medical therapy fails (persistent or rising beta-hCG after treatment), or when the patient presents with rupture. Salpingectomy (removal of the affected tube) is standard, particularly if the tube is severely damaged. Salpingostomy (incision and removal of the ectopic tissue while preserving the tube) is considered when future fertility is a priority and the contralateral tube is absent or compromised, though it carries a small risk of persistent trophoblastic tissue requiring postoperative beta-hCG monitoring.

All Rh-negative patients with ectopic pregnancy should receive anti-D immunoglobulin (RhoGAM) to prevent Rh alloimmunization.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common trap on this topic is the student who sees vaginal bleeding in early pregnancy and immediately jumps to "threatened abortion" without checking whether an intrauterine pregnancy has been confirmed. The exam consistently tests whether you understand that a positive pregnancy test with an empty uterus on ultrasound is ectopic until proven otherwise. Never assume the pregnancy is intrauterine just because the patient is bleeding vaginally.

A second classic pitfall is ordering further diagnostic tests in a hemodynamically unstable patient. If the vignette describes a pregnant woman with hypotension, tachycardia, and peritoneal signs, the answer is emergent surgery, not "obtain an ultrasound" or "check serial beta-hCG." Test-writers use this to assess whether you can prioritize stabilization over workup.

Another frequently tested concept is the discriminatory zone logic. Students sometimes select "ectopic pregnancy" as the diagnosis when the beta-hCG is still below the discriminatory zone and no IUP is seen on TVUS. At that stage, a normal early IUP is also possible and simply too small to visualize. The correct answer in that scenario is serial beta-hCG monitoring, not immediate treatment.

Finally, remember that the presence of a visible IUP on ultrasound does not completely exclude ectopic pregnancy in patients who underwent assisted reproduction. Heterotopic pregnancy (simultaneous intrauterine and ectopic pregnancy) is rare in spontaneous conceptions but occurs at a meaningfully higher rate after IVF. If the vignette mentions fertility treatments and the patient has persistent adnexal pain despite a confirmed IUP, consider this diagnosis.

The core competency being tested is the ability to integrate beta-hCG values with ultrasound findings to make a timely and accurate diagnosis, and to recognize when surgical intervention takes priority over further workup.