Pregnancy treatment with either surgery or methotrexate. The absence of an intrauterine pregnancy on transvaginal ultrasound evaluation in conjunction with a maternal serum hCG level above a threshold of 1,500 mIU/mL suggests the diagnosis (394,395). Heterotopic pregnancy involves concurrent intrauterine and ectopic pregnancy, usually within the fallopian tube, but ovarian implantations have been reported (395,396). The incidence of heterotopic pregnancy, which is normally rare, is particularly high (1%) after IVF treatment. Multiple gestation, smoking, previous tubal surgery, and prior PID are potential risk factors in addition to ART. As with standard ectopic pregnancies, pain and bleeding are the most common presenting findings with heterotopic pregnancies. Heterotopic pregnancies are most often diagnosed in the first 5 to 8 weeks of gestation using laparoscopy or laparotomy. Only 26% of heterotopic cases can be diagnosed with transvaginal ultrasound, possibly as a result of difficulties in sonographic interpretation in the presence of concomitant ovarian hyperstimulation. After treatment of a heterotopic gestation with laparoscopy, laparotomy, or ultrasound-guided injection of potassium chloride into the extrauterine pregnancy, the overall delivery rate for the intrauterine pregnancy is nearly 70% (395).
OHSS is a medical complication that is both completely iatrogenic and unique to stimulatory infertility treatment (397). Its symptoms are the result of ovarian enlargement and fragility, extravascular ﬂuid accumulation, and intravascular volume depletion. Proposed mechanisms for the characteristic ﬂuid shifts that accompany OHSS include increased protein-rich ﬂuid secretion from the stimulated ovaries, increased renin and prorenin within follicular ﬂuid, and increased capillary permeability mediated by angiotensin. Vascular endothelial growth factor (VEGF), whose expression in granulosa cells and serum is augmented by hCG, and a variety of other inﬂammatory cytokines have been implicated in the pathogenesis of this disease (398). Two distinct patterns of OHSS onset have been described. Early OHSS occurs 3 to 7 days following the hCG trigger and is associated with the administration of exogenous hCG. Late onset disease occurs 12 to 17 days after the hCG trigger; it is the result of endogenous hCG secretion from the pregnancy and tends to be more severe with multiple gestation. Pregnancy outcomes are inconsistently affected by the presence of OHSS, with higher rates of biochemical losses but similar rates of clinical losses when compared to patients without OHSS (399).