Intrauterine fetal demise

Stage V: Intrauterine fetal demise of one or both twins (Figure 7.13)

Sub-staging 

Classic vs atypical presentation 

In the classic form, the bladder of the donor twin may not be visible in stages III and IV. When the bladder of the donor is visible in any of these two stages, it represents an atypical presentation. The importance of substaging may be useful in terms of explaining the pathophysiological mechanisms responsible for the different presentation as well as potentially useful in terms of prognosis. 

Donor vs recipient Stage III can be further described, depending on which of the two fetuses is affected. For example, if the patient is stage III because the donor twin has UA-AREDV, the patient can be classified as having stage III-donor. Similarly, if the fetus with the Doppler abnormality is the recipient twin, the patient can be classified as having stage III-recipient. Both fetuses may show critically abnormal Doppler findings, in which case the patient is rightfully classified as having stage IIIdonor- recipient. 

Although stage IV is typically associated with hydrops of the recipient twin, isolated hydrops of the donor may also occur. Some evidence is surfacing to explain the different substaging manifestations, but the actual mechanisms responsible for their production are still unclear. Substaging in terms of donor or recipient may facilitate communication between investigators in terms of individual prognosis for each twin. 

Neither tricuspid valve regurgitation nor Doppler studies of the middle cerebral artery (peak systolic velocity or other indices) have been shown to have prognostic value in the assessment of patients with TTTS. Therefore, neither of these two parameters is included in the staging system.