Manometry is mandatory as the diagnosis of achlasia requires failure of the LES to relax, so UWorld is not really telling the whole story.
In the real world, all 3 tests are done, without real regard to order.
The following makes sense to me:
Patient with symptoms of dysphagia ----> UGI followed by EGD then manometry (but if I could get the manometry done first, I'd change the order). That's the problem with these tests. Too artificial.
-UGI will delineate dilation/tortuosity of esophagus and help you make sure it isn't Zenkers (for which you do not generally want to do EGD)
-EGD will allow for assessment of mucosa (is there a esophagitis, a mucosal ulcer,mass or submucosal mass) and to remove any retained food; it is not going to give you pressures required for diagnosis
-Manometry allows for assessment of peristalsis and LES pressures (which are again, diagnostic and will assist in surgical planning)
Finally, some add a 24 hr pH probe although generally not necessary.
So which one is right? I'd say neither - manometry is required to make the diagnosis of achlasia but you also want an EGD if you're planning on operating to make sure there isn't a mass causing dysphasia and pseudoachalasia. Only in that case would manometry not be necessary.
The question makes it sound like if the EGD and upper G.I. were normal, then that would be the only reason to have manometry. My sense is that unless one of those examination shows that the diagnosis is not achalasia then manometry is warranted.
That probably wasn't much help was it? 😳