Ectopic pregnancy: Clinical sciences

An ectopic pregnancy is a pregnancy that develops outside of the uterine cavity. Now, in an intrauterine pregnancy, embryonic tissue implants within the decidualized endometrium at or near the top of the uterus. However, in ectopic pregnancy, the embryonic tissue typically implants in the fallopian tube, most commonly in the ampulla, but it can also occur in the isthmus or interstitial areas of the tube. Other sites of abnormal implantation include the abdomen, cervix, or c-section scar. Rarely, an ectopic pregnancy can be present along with an intrauterine pregnancy, which is called a heterotopic pregnancy.

Your first step in evaluating a patient presenting with a chief concern suggesting an ectopic pregnancy is to assess their CABCDE to determine if they are unstable. An ectopic pregnancy can rupture at any time leading to extensive intraperitoneal hemorrhage. Because of this, start your management with type and cross for possible packed red blood cell transfusion. Then, stabilize their airway, breathing, and circulation. Also, consider intubation as clinically indicated, obtain IV access, and continuously monitor vital signs.

Next, obtain a focused history and physical exam, and check labs, including CBC, CMP, and hCG, or human chorionic gonadotropin. Additionally, perform an ultrasound to assess pregnancy location and evaluate for the presence of free fluid in the abdomen or cul-de-sac of the pelvis.

Alright, the patient might report delayed or missed menses, syncope, abdominal or pelvic pain, and vaginal bleeding. On physical exam, you’ll find signs of hemodynamic instability like hypotension and tachycardia, altered mental status, and pale and clammy skin. Next, you’ll usually see signs of acute abdomen like abdominal tenderness, guarding, and rebound pain indicating intraperitoneal bleeding is present. Lastly, on pelvic exam, you may observe bleeding from the cervical os. As for the labs, they usually reveal a positive hCG and probably anemia. Finally the ultrasound will show an empty uterus without signs of an intrauterine pregnancy, possible free fluid in the abdomen or posterior cul-de-sac of the pelvis, and sometimes an adnexal mass.

So, if your patient is of childbearing age, the hCG is positive, there’s free fluid present, and no intrauterine pregnancy; the patient has a ruptured ectopic pregnancy until proven otherwise.To manage these patients, immediately start IV fluid resuscitation. Be prepared to initiate a blood transfusion even if initial labs are reassuring, as they don’t always reflect the true extent of anemia. Immediately obtain a gynecologic surgical consult, as all ruptured ectopic pregnancies must be removed surgically. This can often be accomplished with a minimally invasive or laparoscopic approach. However, laparotomy should be considered if the patient is extremely unstable or there’s a high suspicion for extensive intraperitoneal hemorrhage that would impede visualization. Finally, if the patient is Rh-negative, administer Rh immune globulin.

Now that unstable patients are taken care of, let’s talk about stable ones. Your first step is to obtain a focused history and physical exam, as well as a urine hCG pregnancy test. The patient may report a delayed or missed period, abdominal or pelvic pain, and vaginal bleeding. Be sure to go over risk factors for ectopic pregnancy, such as a history of prior ectopic pregnancy, history of pelvic inflammatory disease, and prior pelvic or tubal surgery. Also consider a history of conditions that may have caused damage to the fallopian tube and prevent an embryo from traveling to the uterus, like endometriosis or a history of ruptured appendicitis. Remember that approximately half of all patients with an ectopic pregnancy will have no known risk factors.

On physical exam, the patient may have abdominal or pelvic tenderness, bleeding from the cervical os, or adnexal fullness or tenderness. Be gentle when performing your exam and don’t palpate too forcefully, as you can rupture the ectopic pregnancy! Lastly, if hCG is negative, consider an alternative diagnosis. However, if hCG is positive, suspect an ectopic pregnancy.

Next, obtain a quantitative hCG and pelvic ultrasound. An important thing to know about the quantitative hCG is something called the discriminatory level. The idea is that there’s an hCG value above which signs of a viable intrauterine pregnancy should be visible on ultrasound. An hCG level of 3500 is usually used as the cutoff. This means that when the hCG is 3500 or greater, the absence of a gestational sac on ultrasound is strongly suggestive of a non-viable pregnancy. This can either be an ectopic pregnancy or an early pregnancy loss.

Okay, let’s put this into practice! If the hCG is below 3500 and you don’t see evidence of an intrauterine pregnancy on ultrasound, repeat the quantitative hCG in 48 hours and the ultrasound in one week to make a final diagnosis. In a normal pregnancy, the hCG will rise at an expected rate, whereas it may rise minimally or fall in an abnormal one. Be sure to keep a close eye on these patients, and counsel them to call with any symptoms suggesting a ruptured ectopic pregnancy.

Now, let’s switch gears and talk about another scenario. In this case, hCG is 3500 or more. The ultrasound shows no evidence of an intrauterine pregnancy, but it might show signs of a pregnancy in the adnexa, such as a gestational sac with or without a yolk sac, an embryo, or a mass with a hypoechoic area separate from the ovary. With either or both of these findings, you can confirm your diagnosis of ectopic pregnancy.

Here’s a high-yield fact! A quantitative hCG and ultrasound findings can be used to diagnose ectopic pregnancy together or separately. If you see an adnexal mass in patients with a positive hCG, even if it’s below 3500, that’s an ectopic pregnancy until proven otherwise. The 3500 cut-off value for hCG is used for stable patients with pregnancy of unknown location, meaning that the ultrasound shows neither intrauterine pregnancy nor an adnexal mass.