A 28-year-old woman presented to the emergency department (ED) via ambulance at 3 a.m., reporting severe abdominal pain that had awakened her from sleep just 30 minutes prior. The pain, localized in her lower abdomen and radiating to her rectum, was unlike anything she had experienced before. She denied pregnancy, stating her last menstrual period was a month prior, and reported no urinary or vaginal symptoms.
Upon arrival, the patient was visibly in distress, doubled over in pain with signs of a peritonitic abdomen (though not explicitly peritoneal), tachypneic at 32 breaths per minute, and hypotensive with a blood pressure of 90/60 mm Hg. Her heart rate was within normal limits at 96 bpm. Her medical history included previous treatment for gonorrhea and chlamydia, but was otherwise unremarkable, and she was not currently taking any medications. Given the critical combination of hypotension and acute abdominal pain, a bedside ultrasound was immediately performed to rapidly narrow the differential diagnosis and guide immediate management.
What could be the cause of this patient’s critical presentation?
Unveiling the Diagnosis: Heterotopic Pregnancy
The focused assessment with sonography for trauma (FAST) exam revealed the presence of free fluid in the patient’s abdomen. Further examination identified not only an approximately 10-week intrauterine pregnancy with fetal cardiac activity but also an extrauterine pregnancy alongside a large corpus luteal cyst. Following the administration of blood products, her blood pressure showed improvement; however, her heart rate paradoxically decreased to 56 bpm, and her abdominal pain intensified. Pain management was escalated, and the patient was swiftly transferred to the operating room (OR) within 20 minutes of her arrival at the ED.
The diagnosis was heterotopic pregnancy, a rare condition defined by the simultaneous presence of both intrauterine and extrauterine pregnancies. Before the widespread use of assisted reproductive technology (ART), heterotopic pregnancies were exceedingly rare, occurring in approximately 1 in 30,000 pregnancies. However, with the advent and increasing utilization of ART, this incidence has risen significantly to about 1 in 3,900 pregnancies. Several factors associated with ART contribute to this increased risk, including pre-existing tubal disease, elevated hormone levels, and the transfer of multiple embryos.
Alt text: Bedside ultrasound image revealing an intrauterine pregnancy, a key finding in the heterotopic pregnancy diagnosis.
In this particular patient’s case, her history of multiple episodes of pelvic inflammatory disease (PID) and subsequent tubal adhesions likely contributed to her risk. Intraoperatively, perihepatic lesions consistent with Fitz-Hugh-Curtis syndrome were noted, further supporting a history of PID. While the vast majority of heterotopic pregnancies involve a single intrauterine pregnancy (IUP) and a single extrauterine pregnancy – with approximately 90% of ectopic pregnancies located in the fallopian tube – the diagnostic challenge remains significant. A crucial factor contributing to missed diagnoses is confirmation bias; once an intrauterine pregnancy is identified, the possibility of a concomitant ectopic pregnancy is often overlooked. This diagnostic oversight frequently leads to delayed diagnoses, typically made later in gestation when rupture-related symptoms such as severe abdominal pain or vaginal bleeding manifest.
In this case, the patient’s abdominal pain at presentation was not clearly differentiated, complicated by her hypotensive state. The emergency physician’s immediate decision to perform a bedside ultrasound proved to be the pivotal step in rapidly clarifying the clinical picture and guiding subsequent management. The ultrasound examination revealed free fluid in Morison’s pouch, a critical finding suggestive of hemoperitoneum. Deviating slightly from the standard FAST exam protocol, the physician extended the scan to include the pelvis to evaluate for alternative etiologies, such as acute bladder rupture (particularly relevant given the presentation after waking from sleep with a potentially full bladder) or pregnancy-related complications. The intrauterine pregnancy, along with the concurrent extrauterine pregnancy and corpus luteal cyst, were rapidly identified. Had only the IUP been visualized, the ectopic component of the heterotopic pregnancy might have been inadvertently excluded from the differential diagnosis, potentially leading to a significant delay in appropriate diagnosis and timely treatment.
Alt text: Ultrasound FAST exam image demonstrating free fluid in Morison’s pouch, a critical indicator of intra-abdominal bleeding.
Differential Diagnosis of Abdominal Pain and Hypotension in Women of Reproductive Age
When a woman of reproductive age presents to the emergency department with the concerning combination of abdominal pain and hypotension, a broad differential diagnosis must be considered. This clinical picture signals potentially life-threatening conditions requiring rapid assessment and intervention. Key considerations in the differential include:
- Ruptured Ectopic Pregnancy: While intrauterine pregnancy was confirmed in this case, ectopic pregnancy, particularly ruptured ectopic pregnancy, is a leading cause of abdominal pain and hemorrhagic shock in women of reproductive age. Heterotopic pregnancy, though rarer, must also be considered, especially in patients with risk factors like prior PID or ART.
- Hemorrhagic Ovarian Cyst: Rupture of an ovarian cyst, particularly a hemorrhagic corpus luteum cyst, can cause significant abdominal pain and, if bleeding is substantial, hypotension.
- Ovarian Torsion: Twisting of the ovary can lead to acute, severe abdominal pain and, in some cases, can progress to hypotension due to pain and potential vascular compromise.
- Pelvic Inflammatory Disease (PID) and Tubo-ovarian Abscess (TOA): While typically associated with fever and vaginal discharge, severe PID or a ruptured TOA can present with peritonitis and sepsis, leading to hypotension. Fitz-Hugh-Curtis syndrome, as seen in this case, is a complication of PID that can cause right upper quadrant pain.
- Appendicitis: While classic appendicitis pain is often periumbilical migrating to the right lower quadrant, atypical presentations, especially in women, can mimic gynecologic emergencies. Ruptured appendicitis can lead to sepsis and hypotension.
- Uterine Rupture: In pregnant women, particularly those with prior uterine scars, uterine rupture is a catastrophic event presenting with severe abdominal pain, vaginal bleeding, and hypotension.
- Abruptio Placentae/Placenta Previa: These pregnancy complications can cause abdominal pain and vaginal bleeding, and in severe cases, lead to maternal hypotension.
- Gastrointestinal Causes: Conditions like bowel perforation, mesenteric ischemia, or severe gastroenteritis can also present with abdominal pain and hypotension, though less common in this demographic as primary considerations.
- Urinary Tract Infection/Pyelonephritis with Sepsis: Severe UTI progressing to pyelonephritis and urosepsis can cause abdominal pain (flank pain radiating to abdomen) and hypotension.
- Trauma: Blunt or penetrating abdominal trauma should always be considered, especially in younger patients.
Diagnostic Approach and the Role of Bedside Ultrasound
In the hypotensive patient with acute abdominal pain, a rapid and systematic diagnostic approach is crucial. Initial resuscitation with intravenous fluids and blood products, as indicated, should be initiated concurrently with diagnostic evaluation. Bedside ultrasound, as expertly utilized in this case, is an invaluable tool for rapid assessment in the emergency setting.
In the context of abdominal pain and hypotension in a woman of reproductive age, bedside ultrasound allows for:
- Rapid identification of free fluid: Suggestive of hemoperitoneum from ruptured ectopic pregnancy, hemorrhagic cyst, or trauma.
- Visualization of intrauterine pregnancy: To confirm or exclude intrauterine pregnancy, and in this case, to identify the IUP alongside the ectopic pregnancy.
- Evaluation for ectopic pregnancy: Although challenging to visualize directly in early gestation, ultrasound can detect signs suggestive of ectopic pregnancy, such as an adnexal mass or absence of IUP in a pregnant patient.
- Assessment for ovarian pathology: Ovarian cysts, torsion, or TOA may be visualized.
- Guidance for further management: Ultrasound findings can rapidly triage patients for surgical intervention or further diagnostic imaging, such as CT scan if other intra-abdominal pathology is suspected.
Alt text: Ultrasound image clearly demonstrating a heterotopic pregnancy with both intrauterine and extrauterine gestational sacs.
Alt text: Intraoperative image showing the extrauterine component of the heterotopic pregnancy during surgical intervention.
Management and Outcome
The definitive treatment for a ruptured heterotopic pregnancy, as in the case presented, is surgical intervention. In this case, a salpingectomy was performed to remove the fallopian tube containing the ectopic pregnancy, along with evacuation of one liter of blood from the abdomen. Preservation of the intrauterine pregnancy is the primary goal when surgically managing heterotopic pregnancies. Methotrexate, a medical treatment option for some ectopic pregnancies, is contraindicated in heterotopic pregnancies with a viable IUP due to the desire to maintain the intrauterine gestation.
Postoperatively, patients require close monitoring, including repeat ultrasounds to assess the viability of the IUP. It is important to note that patients with heterotopic pregnancies, even after successful surgical management of the ectopic component, have a higher risk of spontaneous abortion of the intrauterine pregnancy. In this case, the patient had a reassuring obstetric ultrasound showing continued cardiac activity of the IUP at her two-week follow-up appointment.
Conclusion: The Power of Bedside Ultrasound in Critical Diagnoses
This case underscores the critical importance of considering heterotopic pregnancy in the differential diagnosis of abdominal pain and hypotension in women of reproductive age, particularly those with risk factors for ectopic pregnancy. Furthermore, it highlights the indispensable role of bedside ultrasound as a rapid, readily available, and highly effective diagnostic tool in the emergency department. The astute utilization of bedside ultrasound in this case facilitated a swift diagnosis, expedited blood product administration, and prompted immediate surgical activation, ultimately contributing to the positive outcome for this patient and her intrauterine pregnancy. For emergency physicians, maintaining a broad differential, especially in high-risk presentations like abdominal pain and hypotension, and leveraging bedside ultrasound are paramount for optimal patient care and timely, life-saving interventions.
Disclaimer: This case study is for educational purposes and does not constitute medical advice. Always consult with qualified healthcare professionals for diagnosis and treatment.
