Massive small bowel resection (SBR) results in villus angiogenesis and intestinal adaptation. The exact mechanism
that causes intestinal villus angiogenesis remains unknown. We hypothesize that hemodynamic changes within the
remnant bowel after SBR will trigger intestinal angiogenesis. To validate this, we used photoacoustic microscopy
(PAM) to image the microvascular system of the intestine in C57B6 mice and to measure blood flow and oxygen
saturation (sO2) of a supplying artery and vein. Baseline measurements were made 6 cm proximal to the ileal-cecal
junction (ICJ) prior to resection. A 50% proximal bowel resection was then performed, and measurements were
again recorded at the same location immediately, 1, 3 and 7 days following resection. The results show that arterial
and venous sO2 were similar prior to SBR. Immediately following SBR, the arterial and venous sO2 decreased by
14.3 ± 2.7% and 32.7 ± 6.6%, respectively, while the arterial and venous flow speed decreased by 62.9 ± 17.3% and
60.0 ± 20.1%, respectively. Such significant decreases in sO2 and blood flow indicate a hypoxic state after SBR.
Within one week after SBR, both sO2 and blood flow speed had gradually recovered. By 7 days after SBR, arterial
and venous sO2 had increased to 101.0 ± 2.9% and 82.7 ± 7.3% of the baseline values, respectively, while arterial
and venous flow speed had increased to 106.0 ± 21.4% and 150.0 ± 29.6% of the baseline values, respectively. Such
increases in sO2 and blood flow may result from angiogenesis following SBR.