Arthur C. Fleischer
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sonographically, an intrauterine pregnancy is highly likely (Fig. 9–1).
In most cases of ectopic pregnancy, the endometrium is slightly thickened, similar to a secretory-phase endo-metrium. In more advanced ectopic pregnancies (8 weeks and more), there can be intraluminal blood and clotting due to sloughing of the endometrium secondary to poor corpus luteum support.
The adnexal ﬁndings in ectopic pregnancies form the basis for sonographic diagnosis of this entity. In most ec-decidualized endometrium in ectopic pregnancy lacks
the focal thickening in the decidua basalis region seen in normal early pregnancies. In some cases of normal early (less than 6 weeks) intrauterine pregnancy, a double lin-ing of decidua is present, representlin-ing decidua capsularis and opposing decidua vera. When this is documented
Figure 9–1 Composite transvaginal sonog-raphy of normal 6-week intrauterine preg-nancy, showing decidua capsularis and vera.
A yolk sac/embryo complex is also seen in the lower right-hand image.
Figure 9–2 Transvaginal sonography of an unruptured tubal preg-nancy showing a decidual ring containing an embryo.
A Figure 9–3 Enhanced visualization of an unruptured ectopic pregnancy adjacent to a corpus luteum with color Doppler sonography.
(A) Transvaginal sonography showing a normal left ovary with tiny cystic areas. (Continued)
9 First-Trimester Pain or Bleeding
topic pregnancies, an adnexal ring of echogenic tissue with a hypoechoic center can be identiﬁed separate from the ovary (Fig. 9–2). One should be careful not to confuse a corpus luteum in the ovary with the presence of an ectopic pregnancy on TVS.
In some cases, CDS can be used as a “roadmap,” outlin-ing the presence of a corpus luteum as separate from the tubal mass itself (Fig. 9–3). The ﬂow pattern seen in ec-topic pregnancies can vary from absent diastolic ﬂow to low-impedance, high-velocity ﬂow, so this parameter is not accurate in determining whether an adnexal mass is a corpus luteum or an ectopic pregnancy (Fig. 9–4, Figure 9–3 (Continued) (B) Transvaginal color Doppler sonography showing a vascular ring adjacent to the corpus luteum, suggesting the possi-bility of an unruptured ectopic pregnancy. (C) Histologic specimen showing a 3 4 mm unruptured ectopic pregnancy.
Figure 9–4 Transvaginal color Doppler sonography (TV-CDS) of an unruptured ectopic pregnancy. (A) TV-CDS of the uterus, showing mild endometrial thickening with sparse myometrial ﬂow. (B) TV-CDS of the right ovary showing a mostly cystic mass with low-imped-ance ﬂow within the wall. This represented a hemorrhagic corpus luteum. (C) In the left adnexa, a ringlike structure with relatively high-velocity and intermediate-impedance ﬂow was seen. This was an unruptured ectopic pregnancy.
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Intraperitoneal or cul-de-sac ﬂuid that has low-level echoes is highly indicative of a hemoperitoneum asso-ciated with an ectopic pregnancy. The presence of intra-peritoneal ﬂuid, however, does not always indicate that rupture is present because bleeding can occur as the gesta-tional sac is being passed out the ﬁmbriated end of the tube into the peritoneum.
Ultrasound can diagnose uncommon types of ectopic pregnancies, the most important of which include intersti-tial ectopic pregnancy, where the gestational sac is im-planted at the end of the fallopian tube in the corner of the uterus.4One must be careful not to mistake a normal preg-nancy implanted eccentrically within the uterine cavity for an interstitial pregnancy, which is implanted superolateral to and outside the cavity. However, when the gestational sac abuts the uterine serosa and is eccentric to the en-dometrium, this condition should be suspected—particu-larly if there is no myometrium or a very thin layer of myometrium surrounding the gestational sac.
Fig. 9–5, Fig. 9–6). However, using CDS, one can get a gen-eral approximation of the relative vascularity of the ectopic pregnancy (Fig. 9–5). Spontaneous resolution of an ectopic is more likely to occur when there is little or no ad-nexal ring ﬂow than when there is an abundant ﬂow.
“Bizarre” waveforms that exhibit signiﬁcant reversed dias-tolic ﬂow have been described in ectopic pregnancies undergoing necrosis and resorption. If bleeding occurs sur-rounding an ectopic pregnancy within the tube, a fusiform adnexal mass can be seen, especially when associated with hemoperitoneum.
CDS can be used to assess the response of an ectopic pregnancy to methotrexate treatment.3 In most cases, there is an initial increase in blood ﬂow probably due to vasodilatation, as indicated by low-impedance diastolic ﬂow, followed by a gradual increase in resistance to ﬂow within the adnexal mass. Patients may experience addi-tional pain when the decidualized endometrium begins to slough or if hemorrhage occurs.
Figure 9–5 Vascularity of ectopic pregnancies. (A) Composite color Doppler sonography showing a hypervascular ectopic pregnancy, in-cluding ﬂow to the embryo (lower left image). (B) In contrast to the patient shown in (A), this ectopic is hypovascular, probably the result of sloughing.
In abdominal ectopic pregnancies, the uterus can be seen as separate from the developing gestational sac. This condition may not be suspected until the second and third trimester, when the ﬁnding of a “pseudo placenta previa,”
abnormal amniotic ﬂuid collection, or abnormal fetal posi-tion is seen on transabdominal sonography. It should be noted that over one quarter of abdominal ectopic pregnan-cies may be missed sonographically.5
Sonography has become a means for assessing proper management of patients with ectopic pregnancies. In some centers, systemic methotrexate is used for treatment of known ectopic pregnancies, whereas in others, local in-jection is performed utilizing TVS as a means for guid-ance.3In some cases, ectopic pregnancies are observed and followed sonographically for changes in blood ﬂow, as well as abnormal increases in -hCG.