An ectopic pregnancy is any pregnancy which implants outside the uterus. Given its incidence of approximately 2% of all pregnancies (Cline et al, 2013) and the devastating consequences of missing the diagnosis, ectopic pregnancy is a commonly tested condition.
This diagnosis must be considered in the differential of any child bearing age female presenting with abdominal pain.
The presentation of ectopic pregnancy can be highly variable. Clinically, patients may present with vague abdominal discomfort, or in the setting of rupture, can be hemodynamically unstable.
The classic triad of abdominal pain, vaginal bleeding, and amenorrhea is not commonly seen, but can serve as clues to the diagnosis. A focused gastrointestinal, gynecologic, and obstetrical history can guide the clinician toward the diagnosis.
A thorough history to narrow the differential diagnosis is important.
Of note, if the patient is hemodynamically unstable or signs of shock are present, the clinician should obtain a brief history but prioritize resuscitation. In stable patients, assessing the last menstrual period is paramount. Amenorrhea is an important clue. The presence of vaginal bleeding should be assessed.
The clinician should attempt to categorize the degree of bleeding which can be intermittent or continuous in nature. Degree of blood loss will dictate the patient’s accompanying symptoms.
Abdominal pain in the setting of an unknown last menstrual period and vaginal bleeding should alert the condition to an ectopic pregnancy. Early in the condition, abdominal pain may be one-sided depending on location of the pregnancy. It is more likely to be pelvic in nature.
As the condition progresses, pain may become diffuse. Radiation to the shoulder is an ominous sign that may alert the clinician to peritoneal irritation from a rupture. Other symptoms that are indicative of a progressing EP include vertigo, dizziness and syncope which can indicate instability.
The physical exam should begin by assessing vital signs. Vital signs may be normal if the presentation is early. Later presentations may include decreased systolic blood pressure, tachycardia and positive orthostatic vital signs, depending on volume of blood loss.
Fever can point to an infectious cause. Abdominal exam may have focal or diffuse tenderness. Rebound tenderness and guarding are ominous signs. A pelvic exam should be performed, which may reveal blood in the vaginal vault.
Other findings may include cervical motion tenderness. Bimanual exam should be carefully performed and may demonstrate a full uterus or a palpable mass.
The clinical signs and symptoms above can be supportive of the diagnosis. However, the mainstays of diagnosis include the serum HCG and transvaginal ultrasound.
A point of care bedside urine HCG is an excellent first step, however the serum HCG is paramount. The quantitative value will determine further management. A serum HCG of zero rules out the disease. Any other value cannot rule out the disease.
Other pertinent lab work includes a CBC to assess for anemia, CMP, type and cross, and Rh status.
A supplement to a serum HCG is the transvaginal ultrasound. Of note, it is important to consider the discriminatory zone. This is the value of HCG in which a transvaginal ultrasound should visualize a gestational sac.
This is generally accepted as 1500 mIU/mL (Cline et al), but can be institution dependent. A transvaginal ultrasound should be performed to determine the presence of an intrauterine pregnancy.
A normal ultrasound cannot rule out ectopic pregnancy. An ultrasound that demonstrates an empty uterus and an HCG above the discriminatory zone suggests an ectopic pregnancy.
Evidence of any cardiac activity outside of the uterus clinches the diagnosis. In presentations that are inconclusive, the serum HCG should be monitored. A serum HCG that does not increase by 53% every two days can suggest EP.
Stable patients can be closely followed over a period of a few days to assure that the HCG regresses to zero. Unstable patients should have surgical intervention.
The diagnosis of ectopic pregnancy remains an imperative concern for all female patients of reproductive age presenting with abdominal pain.
The presentation can vary quite widely based on the progression of disease. Regardless, prompt recognition and diagnosis remains paramount for this potentially life threatening disease.