Catherine Glazer, MD, FACEP & Meghan Kelly Herbst, MD, FACEP
Chief Complaint: Vaginal Bleeding
1) Identify the landmarks for the uterus. Do the below clips represent a definitive intrauterine pregnancy?
2) What are your top two differential diagnoses and how do you differentiate between them?
3) What risk factors should increase suspicion for this pathology?
Clip 1 & Clip 2
A 25 year old healthy female G4P1 EAB 2 at approximately 6 weeks, 2 days gestational age by dates presented to the ED with vaginal bleeding for two days. She reports that she used three pads per day initially, but the bleeding had progressed to silver dollar sized clots on the day of presentation. She had a positive home pregnancy test that prompted her decision to come to the ED. She denied any other symptoms including abdominal pain, nausea, vomiting or diarrhea.
Her vital signs were remarkable for a mild tachycardia at 105 bpm and blood pressure of 124/64. She was afebrile and in no distress, sitting comfortably. Exam revealed no tenderness to palpation throughout the abdomen. Pelvic exam revealed mild blood in the vault, a fingertip cervical os, and no appreciable uterine or adnexal tenderness or mass.
Bedside urine HCG was positive and quant HCG was 8500, prompting a transabdominal pelvic point-of-care ultrasound (PoCUS) which revealed a low-lying gestational sac, suggestive of active miscarriage within the cervix or possible cervical ectopic pregnancy. With this concern in mind, OB/GYN was consulted. They repeated the ultrasound with transvaginal approach, visualizing a gestational sac with a yolk sac and fetal pole with fetal heartbeat, and crown-rump-length consistent with a 6 week, 3 day gestation. They were unable to determine the location of the gestational sac with certainty. For this reason, an MRI was performed, demonstrating a complex collection within the cervical canal suspicious for cervical ectopic pregnancy.
The patient was admitted for multiple dose methotrexate and ultimately discharged with a downtrending quant HCG and disappearance of the yolk sac and fetal pole 8 days later. She was never unstable although her stay was complicated by a drop in her hematocrit from 37.6 to 23 with 700 cc of clot revealed on transvaginal ultrasound and minimal vaginal bleeding.
Role of Pelvic PoCUS in the Emergency Department
The primary goal of pelvic PoCUS in patients who present with first trimester vaginal bleeding and/or abdominal pain is to rule in an intrauterine pregnancy (IUP), and thereby exclude the diagnosis of ectopic pregnancy. When no definitive IUP is seen, the possibility of ectopic implantation must be considered.
While collectively only less than 5% of pregnancies are ectopic, some “intrauterine” pregnancies are ectopically placed within the uterus. These include interstitial, intramural and cervical pregnancies. Interstitial and intramural pregnancies are eccentrically located with a surrounding endomyometrial mantle of less than 8mm and an empty endometrium. Cervical pregnancies usually present with vaginal bleeding and vague abdominal pain, are positioned in the endocervical canal and can be confused for abortions in progress.3 Such rare variations of ectopic pregnancies can result in higher maternal morbidity and mortality secondary to delayed diagnosis and association with significant bleeding.
In this case, our patient presented with vaginal bleeding associated with a cervical ectopic pregnancy. This diagnosis could have easily been missed if the transabdominal PoCUS had been misinterpreted as a miscarriage and no further workup ensued. While there are key differentiating features of cervical ectopic pregnancies when compared to miscarriages (described below), it is important to maintain a high index of suspicion for a cervical ectopic among females presenting with vaginal bleeding and/or abdominal pain with risk factors for ectopic implantation (see below). This case highlights the critical nature and potential challenge in diagnosing a cervical ectopic pregnancy using PoCUS.
Answers to questions:
1) The landmarks for the uterus are best visualized in the sagittal plane, and include the bladder (anterior and inferior to the fundus) and the vaginal stripe (posterior to the bladder). The bladder in this clip is decompressed and the echogenic pubic symphysis with posterior acoustic shadowing is located inferiorly to the bladder.
The clips featured in this case depict no definitive intrauterine pregnancy as the endometrium is empty; no endometrial gestational sac containing a yolk sac or fetal pole is appreciated.
2) The differential for this case before and after transabdominal PoCUS included abortion in progress and cervical ectopic pregnancy. Abortions are common, while cervical ectopic pregnancies are rare (fewer than 1% of all ectopic pregnancies).1 However, misdiagnosis of a cervical ectopic pregnancy as an abortion can have catastrophic consequences involving life-threatening maternal hemorrhage in the setting of rupture, or if dilation and curettage is performed to evacuate the fetus. 4
While diagnosing a cervical ectopic pregnancy is beyond the scope of an emergency physician, here are a few tips that may help if you suspect one:
Look for a rounded gestational sac with a yolk sac and/or heartbeat in the endocervical canal. The uterus will have an hourglass or figure-eight configuration secondary to a ballooned cervix. (Image A) In contrast, an abortion in progress will have an irregular gestational sac and the uterus may appear enlarged and globular. (Image B)3,5
Image A Image B
4) Risk factors for ectopic pregnancy: 5,6