## 3 Results
### Patient Population
\begin{table}
\begin{tabular}{l c c} \hline \hline  & **Pre** & **Post** \\  & **(N = 23)** & **(N = 23)** \\ \hline
**Hepatopetal flow of liver veins** & & \\ No & 23 (100\%) & 23 (100\%) \\ Yes & 0 (0\%) & 0 (0\%) \\ Missing & 0 (0\%) & 0 (0\%) \\
**Maximal diameter of portal vein** & & \\ Mean (SD) & 0.963 (0.227) & 1.01 (0.295) \\ Median [Min, Max] & 0.900 [0.600, 1.40] & 0.980 [0.500, 1.80] \\ Missing & 3 (13.0\%) & 1 (4.3\%) \\
**Maximal velocity of portal vein** & & \\ Mean (SD) & 17.8 (14.0) & 18.2 (11.7) \\ Median [Min, Max] & 16.3 [0.700, 69.6] & 15.2 [6.20, 57.0] \\ Missing & 1 (4.3\%) & 3 (13.0\%) \\
**Hepatopetal flow of portal vein** & & \\ No & 0 (0\%) & 0 (0\%) \\ Yes & 23 (100\%) & 22 (95.7\%) \\ Missing & 0 (0\%) & 1 (4.3\%) \\
**Hepatric artery RI** & & \\ Mean (SD) & 0.805 (0.186) & 0.831 (0.125) \\ Median [Min, Max] & 0.795 [0.400, 1.10] & 0.830 [0.470, 1.00] \\ Missing & 3 (13.0\%) & 2 (8.7\%) \\ \hline
**Ultrasound of the spleen** & & \\
**Spleen length** & & \\ Mean (SD) & 12.9 (3.58) & 12.6 (2.66) \\ Median [Min, Max] & 12.0 [8.40, 24.2] & 12.1 [7.50, 18.3] \\ Missing & 0 (0\%) & 2 (8.7\%) \\
**Spleen width** & & \\ Mean (SD) & 4.99 (1.53) & 5.39 (1.33) \\ Median [Min, Max] & 4.40 [3.60, 10.0] & 5.18 [3.40, 8.40] \\ Missing & 1 (4.3\%) & 3 (13.0\%) \\ \hline
**Ultrasound of the abdominal cavity** & & \\
**Pathologic recanalization of umbilical vein** & & \\ No & 23 (100\%) & 22 (95.7\%) \\ Yes & 0 (0\%) & 0 (0\%) \\ Missing & 0 (0\%) & 1 (4.3\%) \\
**Ascites** & & \\ No & 22 (95.7\%) & 19 (82.6\%) \\ Yes & 1 (4.3\%) & 4 (17.4\%) \\ Missing & 0 (0\%) & 0 (0\%) \\ \hline \hline \end{tabular}  
* pre = median 29 days before hematopoietic allogeneic stem cell transplantation. post = median 9 days after hematopoietic allogeneic stem cell transplantation. SD = standard deviation; Min = minimal, Max = maximal.  
\end{table} 
Table 3: _Cont._paralytic ileus at the recto-sigmoid junction, and one patient showed self-limiting signs of gastritis. An increase in body weight greater than two percent between both ultrasound examinations was observed in nine out of 23 trial participants. When comparing ultrasound measurements pre- and post-alloHSCT, a significant increase in the maximum diameter of the liver veins was detected (0.75 cm pre, 0.86 cm post; \(p\) = 0.038). Regarding further ultrasound parameters, we did not find statistically significant changes. Because hyperbilirubinemia and weight gain are required for the diagnosis of SOS, we investigated whether we can identify changes of ultrasound findings in these specific two subgroups by comparing their pre- and post-alloHSCT examination. As thrombocytopenia is reported to be associated with higher probability of SOS [22] as well, we investigated this subgroup (defined by thrombocytes \(\leq\)20 G/L at the day of the second ultrasound examination) additionally. Groups for the other previously described risk factors (e.g., ALT elevation) were too small to be investigated. However, in the investigated subgroups we rarely observed any significant changes in ultrasound parameters. Comparing the difference in measurements between pre- and post-alloHSCT examination within those subgroups, an increase in vertical diameter of the liver showed significant changes. In detail this could be shown for the pre-aortically measured vertical diameter of the liver, when comparing patients with thrombocyte counts of above 20 G/L vs. \(\leq\)20 G/L after transplantation (\(p\) = 0.039; adjusted for multiple testing). Moreover, an increase of the vertical liver diameter in pre-renal measurement was statistically significant comparing patients with respect to their bodyweight gain of above vs. below two percent (\(p\) = 0.0199; adjusted for multiple testing).