Nurses, October 2006

Laurie Scudder, MS, PNP; Marilyn W. Edmunds, PhD, CRNP

Disclosures

October 01, 2006

Journal for Nurse Practitioners

Journal Scan is the clinician's guide to the latest clinical and research findings in The Journal for Nurse Practitioners, The Nurse Practitioner: The American Journal of Primary Care, The Journal of the American Academy of Nurse Practitioners, Journal of Pediatric Primary Care, and selected other scholarly journals having articles of value to advanced practice nurses and other clinicians. Links to article abstracts are provided when they are available. Links to related articles on Medscape are available for readers seeking information that is more detailed.

Ectopic Pregnancy

Selway J
Journal for Nurse Practitioners. 2006:2;509-517

Ectopic pregnancy (EP) is currently the leading cause of maternal death in the first trimester. It is not often clear what causes the implantation of a fertilized ovum in a location other than the endometrium, often in the ampulla of the fallopian tube, but the EP often presents a diagnostic dilemma.

Although there are no precise data on the incidence of EP, it appears that there has been a gradually increasing rate over the last 3 decades. Many women are treated in outpatient venues, but the documented rate probably approaches about 19-20 per 1000 of all reported pregnancies.

A meta-analysis of 36 studies on EP suggested that a variety of conditions that alter tubal integrity or block the migration of a fertilized ovum to the uterus are considered as risk factors. These include previous EP, previous tubal surgery, previous tubal ligation, and in utero exposure to diethylstilbestrol. Previous genital infections, infertility, and a lifetime number of sexual partners more than 1 were weakly associated. Untreated Chlamydia that rapidly progresses to pelvic inflammatory disease is highly linked to the development of EP. Unfortunately, other research has suggested that the link to EP for many of these factors is suspect and that more than half of EPs are discovered in women with no known risk factors.

There is frequent misdiagnosis of EP on the initial emergency department visit. The differential diagnosis includes appendicitis, spontaneous abortion, ovarian torsion, pelvic inflammatory disease, ruptured corpus luteum or follicular cyst, tuboovarian abscess, and urinary calculi. The classic triad of symptoms for EP includes abdominal pain and vaginal bleeding after a period of amenorrhea. Clearly, these nonspecific findings may also be seen in other clinical situations. An EP may be discovered up to the time of delivery; however, the most common gestational age at time of diagnosis is 6-10 weeks. Other common findings include a normal to slightly enlarged uterus, pelvic pain with cervical manipulation, and palpable adnexal mass. No combination of physical examination findings can reliably diagnose or exclude EP.

Glycoprotein hCG is synthesized by the syncytiotrophoblast, the outermost covering of the trophoblast. Its role in pregnancy is to maintain the early corpus luteum to ensure progesterone and relaxin secretion by the ovary until these functions are taken over by the syncytiotrophoblast. The level of this hormone is critical to the diagnosis and management of EP.

In a normal pregnancy, the serum hCG level doubles or increases by at least 66% in 48 hours. The discriminatory zone is the range of hCG at which the intrauterine gestational sac can be visualized on transvaginal ultrasound (TVUS). This sac should be visualized when the hCG level reaches 1000-2000 mIU/mL international reference preparation (IRP), and when it is 2400-3600 mlU/mL IRP, the intrauterine gestational sac should be visualized by transabdominal ultrasound.

A pregnancy of unknown location (PUL) may be suspected when there is a positive serum hCG level but no signs of intrauterine or extrauterine pregnancy on TVUS and no sign of miscarriage. The outcomes of these types of pregnancies include failing PUL (in which the pregnancy fails and resolves spontaneously), intrauterine pregnancy, EP, or a persisting PUL. Tracking of the hCG level helps track what may be happening within the body.

Progesterone has been used to diagnose EP but is somewhat controversial. A baseline serum progesterone of less than 20 nmol/L may correlate with increased chances of pregnancy failure. However, this finding does not help locate the site of the pregnancy. Research has suggested that progesterone alone cannot be used to diagnose EP. TVUS is also employed as a diagnostic strategy for EP in clinically stable women. The diagnosis is made by visualization of an adnexal mass by TVUS rather than by the absence of an intrauterine gestation on scan. If the TVUS is not diagnostic and there are falling hCG levels, a diagnostic dilation and curettage (D&C) may be required. The presence of chorionic villi will differentiate an EP from a spontaneous abortion.

Medical management following early diagnosis of EP may allow conservation of the fallopian tube when it is involved. In specific conditions, methotrexate may be used as a pharmacologic resolution to PUL. Methotrexate is a folic acid antagonist that interferes with DNA and RNA synthesis. It may selectively destroy cytotrophoblasts at the implantation site. The body then reabsorbs the remaining products of conception. Failing this, surgical laparotomy with removal of the involved tube has been both diagnostic and treatment for EP. Today, every effort is made to intervene in such a manner as to surgically preserve the tube.

Women with EP require emotional support. Being told that they are pregnant, that the pregnancy is not proceeding normally, and that they are losing both the baby and perhaps their ability to have children is hard to accept. Clinicians should be empathetic and offer support.

Editor's Note:
This article stresses the need for clinicians to provide emotional support to the mother. Many women believe that they have had a baby die and may have traditions or rituals that help them deal with their grief. They may feel very alone with this problem, and a sensitive clinician may do a great deal to help the mother deal as positively with this situation as possible.

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