Whether they need to do surgery immediately may depend on what is causing the obstruction. If it's a tumor they may have little choice. If it's not they will probably try to manage it with a nasogastric tube for several days in the hope it will resolve on its own, which it often does. Of course they will have to suspend chemo and he would be hospitalized for this.
My husband had a small-bowel obstruction at the beginning of June and spent nearly two weeks in emergency rooms and the hospital as a result. It was not due to cancer, almost certainly it was from surgical adhesions. They waited nearly a week for it to resolve, then he had to be first on clear liquids and then a low-residue diet for 3-4 days to satisfy them that it was resolved before he was discharged.
If they decide they have to do surgery they will probably do it. He was a similar time past Avastin (he is on folfiri+bev) when they were considering surgery. They'd prefer a four-week interval after any chemo, but two weeks or so after Avastin is usually OK.
One problem we encountered is that at least in the US, the hospital protocol is to give a daily injection of a blood thinner, which did seem to possibly interact with the lingering effects of bevacizumab to increase some bleeding. We don't know that for sure, he just seemed to have a lot more bleeding from his ileal conduit than usual, and it may have caused them to suspend the Avastin when he did get back on chemo.
D/H Dx 10/2019 RC age 61
Clinical T4bN2M1a (common iliac and para-aortic lymph nodes)
MSS KRAS G12D
CRT 11/19-1/20 FOLFOX 3/20-7/20
Pelvic exenteration w/LAR 8/20
ypT4bN0Mx G3 0/14 nodes LVI not seen PNI-
CEA 10/19:20, 1/20-11/20:1.6, 4.3, 3.4, 2.7, 2/21:9.0 3/21:18,40 4/21:28,19, 5/21:13.3,8.6
PET 3/21 recurrence in distal nodes, L5 vertebra, pelvis