deviated or a branching cervical canal. In this instance, time is not a limiting factor because the embryos are loaded into the inner catheter while the outer catheter is already in place. US will then allow ET time to be less than 30 s (Fig. 22.7 ). US guidance is extremely instructive at training facilities as it can provide feedback and reassur­ance to physicians in training. Coaxial live US guided ET allows teaching ET without a decline in the center’s PR.

Some physicians prefer tactile ET to minimize the need to observe the cervix and the US screen simultaneously and avoid the need for additional personnel. They also state that the use of US technique may slow the ET and require addi­tional steps. Pre-ET vaginal ultrasound may be

Because ovarian hyperstimulation syndrome (OHSS) is one of the most severe iatrogenic com­plications of in vitro fertilization (IVF), there have been many attempts to predict which patients are most at risk. Unfortunately, there are no perfectly reliable tests which universally predict the devel­opment of OHSS. Ultrasound determination of antral follicle count, counting the number of fol­licles developing in response to controlled ovar­ian hyperstimulation, sonographic evidence of polycystic ovarian syndrome, assessment of ovar­ian volume, and Doppler fl ow studies of ovarian vasculature have all been evaluated as markers to identify a higher likelihood of developing OHSS.

of the antral follicle pool is considered to refl ect the total number of remaining follicles [ 1 ]. Generally, a low antral follicle count suggests a poor response to ovarian stimulation and a high antral follicle count suggests better ovarian response to gonadotropin stimulation and higher oocyte yield.

ovarian response to IVF varied between ≥15 and ≥20 oocytes. Importantly, the number of oocytes retrieved was used as a surrogate for risk of OHSS; no study specifi cally identifi ed the patients who met diagnostic criteria for OHSS. When these fi ve studies of AFC were evaluated together, the sensitivity of AFC to predict ovarian hyper-response was seen to vary between 20 and 94 % depending on the AFC cutoff used, and the specifi city varied between 33 and 98 %. From these values, the authors calculated a sum esti­mate of the sensitivity to be 82 % and a sum esti­mate of the specifi city to be 80 %. Considering this evidence, there is a clear association between increased AFC and increased risk of OHSS. Given the sensitivity and specifi city estimates of AFC in the studies to date, if the AFC is found to be greater than 14–16, caution should be exe­cuted in the initial gonadotropin dosing and choice of stimulation protocol since there is clearly increased risk of ovarian hyper-response in such patients.

When proposing the use of AFC to predict OHSS, it is important to be aware of the variabil­ity both in defi nition of antral follicle and opera­tor technique in follicle counting [ 5 ]. Interestingly, some authors adhere to the defi nition of antral follicle as those follicles which are measured to be 2–10 mm in the early follicular phase, as above; but other authors limit that defi nition to only those follicles which measure 2–5 mm. The precise menstrual timing of the measurement of AFC is also important. AFC should be performed either between cycle day 2 and 4 or while on oral contraceptive pills for greatest accuracy and reproducibility.

Because patients who have higher baseline AFC and higher functional ovarian response to stimulation have been found to have a greater likelihood of developing OHSS, it is important to identify such patients early in clinical care. It is well known that patients with polycystic ovarian syndrome (PCOS) have by defi nition a high antral follicle count and magnifi ed response to IVF. Ultrasound assessment of ovarian morphology serves as one of the key criteria for the diagnosis of PCOS by the Rotterdam criteria [ 7 ]. The sono- graphic fi ndings which meet Rotterdam diagnostic criteria are either 12 or more follicles in each ovary measuring 2–9 mm in diameter and/or increased ovarian volume >10 mL [ 8 ] (Fig. 23.2 ). In com- bination with either anovulation/oligo- ovulation or clinical/biochemical hyperandrogenism and

The fi nal ultrasound characteristics which have been used to attempt to predict the develop­ment of OHSS are Doppler fl ow studies of ovar­ian vasculature. The concept behind the assessment of ovarian vascular resistance and fl ow is that because OHSS involves third spacing of fl uid secondary to increased vascular permea­bility, one might expect changes in ovarian vas­cular fl ow which may occur prior to clinical signs or symptoms of OHSS and therefore could be used to predict the development of OHSS [ 10 ]. Coupled with increased vascular permeability, there is also abnormal intraovarian angiogenesis in OHSS leading to low vascular impedance. Multiple authors have investigated sonographic characterization of ovarian vascular fl ow, resis­tance, peak systolic velocity, and pulse-wave power Doppler to try to correlate vascular chances with the likelihood of developing OHSS. In 1997, Moohan et al. evaluated 30 patients who were diagnosed with mild or severe OHSS within 2–15 days of oocyte retrieval [ 10 ]. All patients underwent transabdominal ultrasound at the time of diagnosis of OHSS with color Doppler done on low-fl ow setting to characterize the fl ow velocity waveforms within the ovarian vessels. Vascular pulsatility index, resistance index, S-D ratio, and maximal peak systolic velocity were calculated. The authors found that in patients with severe OHSS, there was markedly reduced vascular impedance with a statistically signifi ­cantly higher resistance index in patients with mild OHSS compared to severe (0.49 vs. 0.41, p < 0.005). Surprisingly, there was no difference in maximal peak systolic velocity, but pulsatility index and S-D ratio also differed signifi cantly between patients with mild and severe OHSS. Of importance, this study evaluated only patients diagnosed with OHSS. There was no comparison with patients who did not develop OHSS, so it is impossible to know if these differences in vascu­lar fl ow could have been used to predict the development of OHSS. Other authors including

The clinical fi ndings of OHSS encompass a spectrum ranging from mild disease, unpleasant for the patient but not considered to be danger­ous, to severe OHSS with signifi cant conse­quences and risk of death. Mild OHSS is common and involves symptoms such as lower abdominal or pelvic discomfort, gastrointestinal complaints including nausea, emesis, and diarrhea, and some degree of abdominal distention [ 14 ]. The process of superovulation frequently leads to these mild manifestations of OHSS, and up to a third of IVF cycles may involve these complaints. The only sonographic characteristic of mild OHSS may be enlarged ovaries (5–12 cm) [ 15 ] (Fig. 23.3 ).

laboratory parameters (Fig. 23.4a ). Some authors have described OHSS as an abdominal compart­ment syndrome because the rapid accumulation of ascites can lead to increased intra-abdominal pressure [ 16 ]. Increased intra-abdominal pres- sure can become acute and lead to organ dysfunc­tion. In severe forms, abdominal compartment syndrome affects respiratory function, as in the case of severe OHSS.

Given that abdominal ascites is a key char­acteristic of the diagnosis of moderate OHSS, it is critical that the ultrasound fi ndings be inter­preted correctly in the context of the clinical presentation. Gunabushanam et al. reported the case of a 22-year-old woman who had received