A 29-year-old female presents late in the evening to your rural emergency department, accompanied by her husband, with a chief complaint of right flank pain for approximately 3 days. It’s busy and she’s been waiting in triage for over two and a half hours, probably because she looks so good.
She states that the pain is mild and there has been no fever, vomiting, weakness or urinary symptoms. She did have some vaginal bleeding about a week ago, but it stopped spontaneously after two days. She denies any prior pregnancies, adding that she and her husband of eight years had pretty much given up on the possibility of her becoming pregnant. They tried for years, with no luck, and could not afford fertility treatment. Her last normal menstrual period was approximately 5 or 6 months ago, but she states that she tends to be very irregular. The spotting that she had about a week ago was much less than one of her periods.
She is otherwise healthy, with no other significant past medical history and no prior surgeries. She is allergic only to penicillin and takes no medications. She denies any history of tobacco use or illicit drugs.
“We did a home pregnancy test tonight and it was positive,” says the husband with hope in his eyes, “so we decided to come here . . . Are those tests reliable?”
On physical exam, your patient is alert and looks comfortable. Fortunately she doesn’t seem upset at all about the wait. Her vital signs are reassuring with a pulse of 74 and a blood pressure of 115/73. Her exam is pretty unremarkable overall, with no real flank or abdominal tenderness and a closed cervical os. “We’re going to run a few tests,” you say.
“We’ll double check the pregnancy test and get a urinalysis because flank pain is often due to a kidney condition. You should probably have an ultrasound done, but since the ultrasound tech already went home over four hours ago, we can only call her back for a true emergency. We can probably arrange for a comprehensive ultrasound in the morning, but in the meantime I’ll take a look with the portable machine that we keep here just for circumstance like this. If it looks OK, we’ll have you come back tomorrow, but if something looks wrong, we’ll proceed from there.”
Your patient and her husband seem content with this. “That’s OK,” the husband replies, “You guys look super busy. How do you do it?” It’s so nice to have understanding patients, especially on a night like tonight. You hope they stay that way. You feel a little guilty about your white lie though, knowing that the ultrasound tech only went home an hour ago, while this patient was waiting to be seen. “No reason to give them something else to worry about,” you think to yourself. “They already have enough on their plate.”
An hour later after catching up on some other stuff, you check and your 29-year-old does indeed have a positive pregnancy test, along with a pristine looking UA and an O-negative blood type. You wheel the portable machine to the bedside and take these images trans-abdominally. Of course, even though you have no suspicion for a frank rupture, you always check Morrison’s pouch first to make sure there is not free fluid in the abdomen. You then take the following transabdominal image. What does it show?
Do you need to do anything else before sending her home with an appointment for a comprehensive outpatient ultrasound in radiology tomorrow?
Conclusion on next page
If you answered “Give her Rhogam,” you are partially right. If you added that you either need a comprehensive ultrasound or a stat OB/GYN consult as well, you get full credit. These images show an unruptured cornual ectopic pregnancy, which should scare you for at least two reasons. One, if a cornual ectopic ruptures, it will bleed like stink. Two, a cornual ectopic is to some degree surrounded by myometrium, so it may fake you out into thinking that it’s not an ectopic. Let me explain.
The cornua or “horn” (think cornucopia = horn of plenty) is one of the two lateral parts of the uterus where it joins the fallopian tube. The vascular supply here is quite rich, with large arteries nearby, so if a cornual ectopic ruptures, bleeding is usually much more rapid than if the pregnancy were in the fallopian tube. A cornual ectopic grows surrounded by myometrium, but it is not in the endometrium. To make this distinction sonographically, you need to identify the endometrium and that the pregnancy is lateral to it. This is best done by always being sure to scan the entire organ. If you only focus on the pregnancy and not the entire uterus, you may be fooled. This type of pitfall is a recurrent theme in ED ultrasonography. Though our job is not to do a complete scan, we need to do more than just focus on a small slice that contains the finding of interest. If you don’t at least take a look at the entire organ, you may miss something important.
(If you want to see the transvaginal images of this case, plus other important pelvic ultrasounds, please visit the ultrasound library at ERPocketBooks.com via the link on the left hand side of the page)