## 3 Results
### Stage 3: Delphi-2 Result  
In Stage 3: Delphi-2, there were two medical doctors who withdrew from the study, resulting in a participation rate of 82%. At this stage, only three experts responded to the form within one month. The remaining responses were delayed by four to seven months. The engineering experts were particularly dilatory, but responses were eventually forthcoming after face-to-face prompting became possible. We found 26 potential failure modes (FMs) in total, based on 419 possible failure causes (FCs): 56% (234 FCs) were related to the tip, 30% (128 FCs) to the flexible segment, and 14% (58 FCs) to the handle. Some examples of data collected using the cascading Delphi FMEA method are shown in Table 7.  
Multi-Criteria Decision Making (MCDM) was applied to address the weaknesses of RPN calculation. Based on the calculations in above equations, the weights for each factor--S, O, and D--are determined as shown in Table 8.  
Risk scores were computed FCs based on MCDM and ranked (Step 13 and 14). On the (Pareto-like) assumption that the failure causes with the highest risk scores posed the greatest risks, the top 20% were examined further. Then, severity scores were applied in selecting FCs. Figure 3: The new identified components of the flexible fetoscope. \begin{table}
\begin{tabular}{c c c} \hline \hline
**ID** & **Potential Failure Modes (26)** & **Number (\%)*** \\ \hline
**1** & **Handle—6 (23\%)** & \\
1.1.1 & Slider breaks & 4 (36\%) \\
1.2.1 & Applying excessive force on wire & 8 (73\%) \\
1.3.1 & Wire suddenly snaps & 4 (36\%) \\
1.4.1 & Excessive air pressure & 3 (27\%) \\
1.4.2 & Air leaks within the handle & 6 (55\%) \\
1.4.3 & Unfiltered or unclean air supply & 1 (9\%) \\ \hline
**2** & **Flexible segment—7 (27\%)** & \\
2.1.1 & Bending or tip positioning issues & 4 (36\%) \\
2.1.2 & Permanent plastic deformation due to excessive forces & 1 (9\%) \\
2.2.1 & Laser fiber snaps—during ablation & 3 (27\%) \\
2.2.2 & Preventing ablation of laser fiber & 2 (18\%) \\
2.3.1 & Wire suddenly snaps & 1 (9\%) \\
2.4.1 & Electrical wire snaps/ disconnects (due to repetitive & 1 (9\%) \\  & large bending) & \\
2.5.1 & Leakage of irrigation fluid and contact with bare & 1 (9\%) \\  & electrical wire & \\ \hline
**3** & **Tip—13 (50\%)** & \\
3.1.1 & The tip breaks during use & 1 (9\%) \\
3.2.1 & Damage of the camera & 6 (55\%) \\
3.2.2 & Camera detachment & 2 (18\%) \\
3.3.1 & Light-source failure & 3 (27\%) \\
3.3.2 & Heating or thermal injury & 1 (9\%) \\
3.4.1 & Wire suddenly snaps & 1 (9\%) \\
3.5.1 & Fluid contact with bare electrical wires & 2 (18\%) \\
3.6.1 & Loosening of the tube end sleeve & 1 (9\%) \\
3.7.1 & Cracking of the glue & 1 (9\%) \\
3.7.2 & Loss of particles (debris) during use inside the patient & 1 (9\%) \\
3.7.3 & Dislodging of the glue & 2 (18\%) \\
3.7.4 & Heating, glue melting & 6 (55\%) \\
3.8.1 & Contamination of the fetoscope & 1 (9\%) \\ \hline \hline \end{tabular}  
* Total 11 FMEA experts.  
\end{table} 
Table 6: Potential failure modes of the new part of the flexible fetoscope. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**ID** & **Potential Failure Modes** & **Main** & **Potential Failure Effects** & **S** & **Potential Failure Causes** & **O** & **Detectability (D)** & **D** \\
**1. Handle** & & & **(S)** & **Score** & **(O)** & **Score** & **Detectability (D)** & **Score** \\ \hline
**1.1 Slider** & & & & & & & \\
**1.1.1** & **Slider breaks** & & & & & & \\
1.1.1A1 & Mother & Device configuration issues & 1 & Slider or handle & 1 & Visual observation & 1 \\
1.1.1B1 & Fetuses & Device configuration issues & 2 & Slider or handle & 2 & Visual observation & 1 \\ \hline
1.1.1A2 & Mother & Device configuration issues & 1 & User errors or misuse & 2 & Visual observation & 1 \\ \hline
1.1.1B2 & Fetuses & Device configuration issues & 2 & User errors or misuse & 2 & Visual observation & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Illustrative examples of data collected using the cascading Delphi FMEA method.