Endometrial aspiration
A persistently abnormal hCG trend and an ultrasonography without evidence of an IUP—particularly with an hCG value above the discriminatory zone and/or with reliable pregnancy dating beyond 5 to 6 weeks—is highly concerning for either a failing IUP or an EP. Once a viable desired IUP is excluded beyond reasonable doubt through these measures, endometrial aspiration to determine pregnancy location is a reasonable next step in PUL management.
Endometrial aspiration can identify a failing IUP by detection of trophoblasts or chorionic villi on pathology and/or by a decline of at least 15% in hCG, measured on the day of endometrial aspiration and again the following day. Endometrial aspiration is effective even in clinical care settings that do not have rapid pathologic analysis available, as hCG measurement before and within 24 hours after the procedure still can be performed.
Vacuum aspiration (electric or manual) in an operating room or office setting is an effective tool for diagnosing pregnancy location.33,34 The use of an endometrial Pipelle for endometrial sampling (typically used for an office endometrial biopsy to diagnose hyperplasia or malignancy) is insufficient for determining pregnancy location.35 For all patients managed with this protocol, the hCG value ideally should be followed until it is undetectable, regardless of whether an EP or failing IUP was diagnosed. In rare cases, an EP may be diagnosed by a late plateau in hCG values, following an initial decline consistent with a failing IUP.
Utility for diagnosis. Retrospective studies in patients with PUL following in vitro fertilization have established the utility of outpatient endometrial aspiration with a Karman cannula, followed by a repeat hCG measurement on the day after the procedure.34,36 These data demonstrate that between 42% and 69% of women were ultimately diagnosed with a failed IUP following endometrial aspiration, thereby sparing them unnecessary exposure to methotrexate.
A decline in hCG levels of at least 15% within 24 hours after the procedure indicates that a failed IUP is the most likely diagnosis and further intervention is not indicated (although falling hCG values should be monitored for confirmation); confirmatory pathology with chorionic villi or trophoblasts was present in less than half of these women and is not necessary to diagnose a failed IUP.36 Women diagnosed with a failed IUP after endometrial aspiration also benefitted from a shorter time to resolution of the nonviable pregnancy by approximately 2 weeks.36
Despite the efficacy of endometrial aspiration for the diagnosis of pregnancy location, recent data show that physicians have highly variable approaches to PUL with an hCG plateaued above the discriminatory zone: One-third would first perform endometrial aspiration, while one-third would give methotrexate without further diagnostics.37 Academic physicians were 4 times more likely to recommend endometrial aspiration.37
Presumed EP. Following endometrial aspiration, if pathology does not confirm an intrauterine gestation and the hCG fails to decline by at least 15%, the diagnosis of a presumed EP is made.
For stable patients with neither evidence of intra-abdominal bleeding nor contraindications to methotrexate (such as blood dyscrasias, hepatic or renal insufficiency, active pulmonary or peptic ulcer disease, breastfeeding, or a known intolerance to the medication), methotrexate is recommended for medical management.26 Following screening blood work that includes a complete blood count and liver function and renal function tests, the typical methotrexate dose is 50 mg/m2 of body surface area. The single-dose regimen entails checking hCG on the day of methotrexate administration and again on days 4 and 7 thereafter. A minimum decline in hCG of 15% between days 4 and 7 indicates successful treatment; if the hCG decline is below 15%, the patient should receive an additional dose of methotrexate.
There are several published alternative regimens for methotrexate administration, including 2-dose and multidose regimens; the 2-dose protocol (2 doses within 7 days) may be more effective in women with higher hCG (> 3,000 mIU/mL) or known adnexal mass.26,38
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