Incomplete Abortion
The most likely diagnosis is incomplete abortion. This patient presents with the classic triad: severe lower abdominal pain, heavy vaginal bleeding with passage of tissue and clots, and a dilated cervix with active bleeding on examination, combined with an empty uterus on ultrasound—all pathognomonic features of incomplete abortion at 11 weeks gestation 1.
Diagnostic Reasoning
The clinical presentation definitively excludes other diagnoses:
Ectopic pregnancy is ruled out because the patient had documented passage of tissue material, indicating that pregnancy tissue was intrauterine and is now being expelled 1. Additionally, if a previous ultrasound had demonstrated an intrauterine pregnancy (IUP), an empty uterus on follow-up ultrasound is definitive proof of a nonviable IUP that is no longer present 1. In general, for a woman with a spontaneously occurring pregnancy, identification of an IUP excludes a coexisting ectopic pregnancy with near complete certainty 1.
Missed abortion is excluded because the cervix is dilated with active bleeding and tissue passage 1. In missed abortion, the cervix remains closed, and the nonviable pregnancy is retained in utero without expulsion 1.
Molar pregnancy is unlikely given the clinical scenario. Complete molar pregnancy typically presents with a hyperechoic area in the endometrium with multiple cystic spaces on ultrasound, not an empty uterus 1. The classic "snowstorm" appearance would be expected if molar tissue were present 1.
Threatened abortion is definitively ruled out because the cervix is dilated 1. By definition, threatened abortion requires a closed cervical os; once the cervix dilates, the abortion becomes inevitable or incomplete 1.
Key Diagnostic Features Supporting Incomplete Abortion
Clinical findings that confirm this diagnosis:
- Passage of tissue and large clots over the past 4 hours indicates partial expulsion of pregnancy tissue 1
- Dilated cervix with active bleeding indicates ongoing expulsion process 1, 2
- Empty uterus on ultrasound confirms that the gestational sac has been expelled, but retained products of conception (RPOC) may still be present 1
- Cramping pain and vaginal tissue passage are clinical findings that help support the diagnosis of nonviable IUP 1
Critical Diagnostic Considerations
Ultrasound findings in incomplete abortion:
After the diagnosis of a nonviable IUP, continued bleeding or persistent elevation of serum hCG may suggest retained products of conception 1. An endometrial mass, focal endometrial thickening, or marked diffuse thickening is suggestive of RPOC, particularly when flow is detected within the endometrial abnormality by Doppler imaging 1. Transvaginal sonography with a bilayer endometrial thickness of more than 8 mm has 100% sensitivity and 80% specificity for detecting retained products of conception 3.
The patient's vital signs warrant attention:
- Heart rate of 112/minute indicates mild tachycardia, consistent with blood loss and pain 4
- Blood pressure of 108/64 mmHg suggests the patient is currently hemodynamically stable but requires close monitoring 4
- Temperature of 98.9°F is reassuring, making septic abortion less likely at this time 2
Common Pitfalls to Avoid
Do not assume "empty uterus" means complete abortion. Even with an empty-appearing uterus on grayscale ultrasound, RPOC may be present 1. Use Doppler imaging to assess for vascularity within any endometrial thickening, as this significantly increases the likelihood of RPOC requiring intervention 1, 3.
Do not overlook cervical vasovagal shock. Products of conception lodged in the cervical os can cause reflex bradycardia and hypotension through vagal stimulation 2. If the patient develops sudden bradycardia with hypotension, perform immediate speculum examination to remove any tissue from the cervical os using sponge-holding forceps 2.
Monitor for continued bleeding. Approximately 50% of patients with clinically diagnosed incomplete abortion actually have retained products requiring intervention 3. Serial hCG monitoring and repeat ultrasound may be necessary if bleeding persists or hCG levels plateau or rise 1.