My surgeon said my muscle repair may have failed. What is the likelihood he is wrong? (photo)

Separation of the muscles after tightening is unusual.  Also if it did occur it probably would have caused excruciating pain.  So it’s  pretty unlikely.  Depending on how long it has been since your procedure there could still be some swelling for a few months.

I'm not sure what you are showing in this photo, but if your drains are still in, it would be unlikely to have a seroma. During the first week after surgery, the abdominal wall has not sealed back down and any fluid that may be there should be draining via the drains. The time frame for seroma is typically after the drains are out, unless yours are not functioning or there is some other issue. If you have an area of focal swelling that is getting bigger, one possibility early after surgery is a hematoma (collection of blood rather than serous fluid), and these are harder to drain with a needle, especially if it is clotted. The area can also be painful like a bruise, so if there is pain and bruising over the area he tried to drain, you may have a hematoma. If there is clinical suspicion of hematoma, your surgeon could order imaging, or monitor closely if small and not growing, or take you back to surgery to evacuate the hematoma. Without seeing you in person or having more history, it is difficult to say why the surgeon felt you may have popped or loosened sutures. The technique of muscle repair varies, and personally I do a double layer repair, and one layer has a row of interrupted sutures so even if one were to come loose or break, your repair would not be at risk for unraveling altogether. If you only had a single layer repair, and it was a running stitch, then loosening or a tear would have a bigger impact. Regardless, even if that happened, now would not be the best time to go back when you are swollen. Keep close followup with your surgeon, and alert him to any changes you are experiencing. It is normal to have overall swelling during the recovery, but if there is a focal area of swelling, that should be evaluated to make sure no intervention is needed.

By the look of your picture with the drain still in place, it looks like you are still very early out from surgery.  While there is the possibility of having broken the sutures that have tightened the muscle, another possibility would be a hematoma (blood collection) in the muscle that could have been the result of coughing and would also cause a tender bulge.  Often this cannot be drained early on and simply needs to resolve on its own.  An ultrasound could help confirm the diagnosis although a CT scan would likely be more accurate to detect muscle separation/suture failure, but unless there is a plan for intervention based on the results of the imaging study, it is likely to be a waste of time and money at this point.  Instead, it would probably be best to watch the area as you heal and see if it resolves on its own.  Even if the sutures have broken and need to be repaired, most surgeons would recommend waiting several months for the swelling and scar tissue to resolve before taking you back to surgery.  In all likelihood you will be fine, but it's important that you maintain close follow up with your surgeon.  Best of luck with your continued recovery!