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Clinical reports of DVT occurring following IVF treatment indicate that it most frequently presents in early pregnancy [16] between 5 and 10 weeks after hCG administration [17]. This has implications for both the duration for which prophylaxis should be administered in high risk patients, and for the duration for which clinical surveillance should be maintained in order ensure early detection and treatment. It is apparent from literature that thrombophilic tendencies associated with OHSS persist and VTE can present weeks after resolution of the clinical syndrome. Therefore, a prolonged duration of prophylaxis and extended vigilance might be necessary [18]. A 2009 review suggests “thromboprophylaxis should be considered for patients who develop moderate‐to‐severe OHSS for an extended period of 1–2 months beyond the resolution of clinical OHSS” [19]. This approach was not only deemed safe but also shown to be cost effective [20]. In patients who conceive, it may be necessary to continue thromboprophylaxis throughout the antenatal period.

Figure 8.1 A suggested approach to thromboprophylaxis in a patient undergoing IVF.

Additionally, focus should also be placed on the judicious use of methods for preventing ovarian hyperstimulation as it is a major risk factor in developing IVF related VTE, especially in high risk patients. Techniques that can be employed include use of an antagonist cycle [21], milder stimulation protocols and use of gonadotropin releasing hormone (GnRH) agonist trigger instead of hCG. Additionally, cryopreservation of all embryos and natural cycle (if possible) frozen embryo transfer avoids the use of exogenous hCG completely [22].

Many reported cases of DVT following IVF are in sites other than the lower limb, but this may simply reflect publication bias [23]. The jugular vein appears to be a relatively frequent site, with the majority of thromboses occurring here being associated with hormonal ovarian stimulation [16]. It should be emphasized that clinical diagnosis for DVT is highly unreliable [24]. Early recourse to objective diagnosis of DVT is advised, particularly in the at‐risk patient. Compression and duplex Doppler ultrasound techniques have been demonstrated to be reliable noninvasive means of diagnosing or excluding DVT, including those affecting upper extremities and neck veins, and are readily available [25].